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Cadillac & LaSalle Club Forums => General Discussion => Topic started by: Ville on June 30, 2015, 06:12:09 AM

Title: 1974 Coupe deville questions
Post by: Ville on June 30, 2015, 06:12:09 AM
Hi!

I have 1974 coupe deville with 472cid.

Car is rare in my country and i need some help.


First thing which bothers me is chassis. If i drive speed bumbs and other bounces car wont bounce. It goes like newer car. Are these uncomfortabe? I had 79 electra which was more soft and smooth.

My one is not hard but i like very soft and loose.



Parking brake vacuum release wont work because hose are off. I have vacuum diagram but where is that neutral switch and what does it look a like?
Title: Re: 1974 Coupe deville questions
Post by: chrisntam on June 30, 2015, 07:56:56 AM
Go to each corner of the car and push it down with your hands to or three times to get it going up and down.  Does it do that?  My thinking is that the shock absorbers may be bad, though normally, they become too loose and let the car bounce too much.

On the neutral safety switch, it is located on the steering column (on the top side) near the firewall.  It has both vacuum and electrical connections on it.  It is held on the column with a strap with screws.

That's how it is on my '70, yours is likely similar.

Where are you located?
Title: Re: 1974 Coupe deville questions
Post by: Ville on June 30, 2015, 08:21:36 AM
Sorry my bad english. I want that car bounces :) not stiff.

If i press corners, it wont give much stretch.

How about your cadillac? If we compare its softness/smoothness to 80's gm fullsizes.


Thanks about switch.

I live in Finland.


Title: Re: 1974 Coupe deville questions
Post by: chrisntam on June 30, 2015, 08:40:23 AM
Your English is fine, we are communicating! 

I would disconnect the shock absorber and try bouncing it again.  If it bounces with the shock absorber disconnected, they are probably bad and replace them with new ones.

My car bounces.

chris.
Title: Re: 1974 Coupe deville questions
Post by: Ville on June 30, 2015, 08:56:30 AM
Nice to know :)

If my shocks are bad, which one are the most smooth/soft? I only can order rockauto etc so i have to choose: Ac delco, gabriel classic, monroe oe something and monroe matic?

Air shocks were smooth in my cutlass but those are expensive vs normal.

In firewall, under the hood, near to chassis (co driver side) is iron tank. Couple normal hoses goes to it and one nylon hose which goes under the car. Seems like air shock hose. Is that think vacuum tank or auto leveling system?


I tried look options on badge under hood but i only founded color, interior trim, 40/60 bench and vinyl top :D I looked on internet.



Is that eye on automatic high beam to low beam system long lasting? Or can i test it on flashlight?


All dash and cluster lights are also dark. Is there fuse or fusible link?


Title: Re: 1974 Coupe deville questions
Post by: Ville on June 30, 2015, 08:58:36 AM
(http://i11.aijaa.com/t/00080/13886353.t.jpg) (http://aijaa.com/PADdzb) there is tag from my car.
Title: Re: 1974 Coupe deville questions
Post by: TJ Hopland on June 30, 2015, 09:09:46 AM
Iron tank is likely air ride compressor.   It was vacuum powered.   It seems pretty rare to find one that still works and even in the USA finding parts to repair one is not a sure thing.    That could explain why your car feels stiff.   Cars equipped with air ride had softer springs than cars without.   If / when the air shocks quit working this usually means the rear end of the car will sit a little to a lot low especially with a full tank of fuel.    Maybe since American parts are a little hard to find where you are someone improvised a way to get the car to ride at normal height and that is why its so stiff.     Rock Auto should have the air shocks.  If the compressor does not work you can buy a manual fill kit that has a air valve on it like a tire. 

That car has 3 fusible links, all located down near the starter coming off the main battery terminal.  One feeds the headlamp switch for the headlights.   One feeds the fuse box for the stuff that stays on all the time.   The last one feeds the ignition switch and then the rest of the fuse box for the things that come on with the key.    I think a 74 still had a connector on that harness about a foot from the starter that can sometimes cause issues.    I don't think they are your issue because you said just the dash lights don't work.  Those run off the always on fuse box side of things so check the fuse then maybe the part of the headlight switch that operates those and then the lights themselves.  They are not easy to replace unless you have very small hands and fingers so maybe they are all just burnt out.   
Title: Re: 1974 Coupe deville questions
Post by: James Landi on June 30, 2015, 09:20:31 AM
Before you do anything, try inflating the tires to the recommended pressure.  34 psi will give you a harsh ride... not sure what the specs are for a '74, but I'm sure it's not over 30... also, entirely agree with air shock issue... some minor work will get those going again with a tire valve as suggested in the thread but this change will prove valuable.
Title: Re: 1974 Coupe deville questions
Post by: Ville on June 30, 2015, 09:40:55 AM
Thanks!

Tire pressure is ok, ive tried 34-40psi and no change. Tires are 235/70 so those arent hard too.


Rear is like old mercedes and front is up but when i measure and compared to factory measures difference was maybe 1/4 ich but front was higher and rear lower.


So air shocks are my choice. How about front shocks manufactur recommends?

I noticed that bulbs are ruff places. One what I remowed was original so maybe those are just burnt.


Just under 70k miles in gauge.

Is somewhere database where car was in states etc? Arizona dealer sticker in glove box and maybe 2009 shipped in Europe.
Title: Re: 1974 Coupe deville questions
Post by: Ville on June 30, 2015, 09:56:40 AM
And yeah, a/c was problem too. Automatic climate control. Car does pretty good pressure when i press valve after running so i think there is stuff inside.

Vacuum heat switch is replaced with manual switch under the hood. It gives still heat and outside cool air when switch is open (coolant runs trough heater).

No vacuum leaks, only that parking brake hise is off but ive been plugged it.


Voltmeter gived 0.14 and other weird and small numbers when I measured a/c compressor magnetic switch.


What is common problem of these?


Blower runs high on defrost but lower and low with other positions, is that normal?

All positions works.

Title: Re: 1974 Coupe deville questions
Post by: Ville on June 30, 2015, 03:30:41 PM
Okay so fan wont work properly at all positions.

As soon as a/c works im happy.
Title: Re: 1974 Coupe deville questions
Post by: James Landi on June 30, 2015, 07:13:17 PM
Before you do anything, try inflating the tires to the recommended pressure.  34 psi will give you a harsh ride... not sure what the specs are for a '74, but I'm sure it's not over 30... also, entirely agree with air shock issue... some minor work will get those going again with a tire valve as suggested in the thread but this change will prove valuable.
Title: Re: 1974 Coupe deville questions
Post by: Ville on June 30, 2015, 07:30:43 PM
I tried lower pressure, nothing difference. Only tires looked emptier than before :)
Title: Re: 1974 Coupe deville questions
Post by: Ville on July 01, 2015, 09:01:12 AM
Does hood have latch like usual? Mine has not. I can just lift hood up.

Does light system on front fenders (which shows are bulbs ok) need sealed beam/original lights? I have h4 conversion because sealed beam is illegal there.


Is fisher body and shop manyal good or which i buy from ebay?
Title: Re: 1974 Coupe deville questions
Post by: Eric DeVirgilis CLC# 8621 on July 01, 2015, 09:36:07 AM
Quote from: Ville on July 01, 2015, 09:01:12 AM
Does hood have latch like usual? Mine has not. I can just lift hood up.

Does light system on front fenders (which shows are bulbs ok) need sealed beam/original lights? I have h4 conversion because sealed beam is illegal there.


Is fisher body and shop manyal good or which i buy from ebay?

Under the front of the hood there should be a tab to release the secondary (safety) catch that must be lifted to raise the hood after the hood is first released from inside the car.

It's not good if its not there or working.

The lamp monitors on the front fenders work by way of fiber optics.

The normal headlight for these cars have a clear glass "pin" on the rear of the headlamp bulb. When the headlight is on, it projects a small ray of light into a fiber optic cable which conducts light to the the lamp monitors on the front fenders. My guess is that the headlights are lacking the means of projecting light from the rear of the bulb which is why the headlight monitors are not working.

The turn signal/parking monitors (outer lenses of the monitor) should still work however.   
Title: Re: 1974 Coupe deville questions
Post by: TJ Hopland on July 01, 2015, 10:01:23 AM
73 I think was the first year that GM went to the under dash hood release so a 74 should have had one.  With these big heavy hoods what seems to happen is the springs get weak so it does not 'pop' when you pull the lever so it becomes a 2 person job to open the hood, one to sit inside the car and pull the lever and one to lift on the hood.    Instead of fixing the problem many people start doing something like using a long pry bar to trip the release from up front which ends up damaging the cable release part of the mechanism.   I will admit I am one of those 'some people'.   Its been on my to fix list for about 20 years now. 

There is a member here that goes by 'Cadillac Tim' that has written DIY service manuals for the climate control systems.    His manual just requires typical tools and is based on his experience repairing these things at the age they are now vs. when they were basically new.   I bought one to try and get mine working correctly and have read it and it looks like it will help me get the job done but I have not yet had the time to actually do it.   I believe he also has a website.

As far as which shocks to get in the front I have not really noticed a big difference in ride quality with what is currently available for these cars, they all seem to be in the realm of original equipment.   If these were a model that was popular to modify or it shared parts with a more popular cars then there may be more much stiffer options.   
Title: Re: 1974 Coupe deville questions
Post by: Ville on July 01, 2015, 10:37:59 AM
Rockauto says that 65-70 buicks has same shocks and same coil springs are in many same age gm full size.



I need overall shoo manual too, I think that haynes/Chilton books are too global and not specific.

These cars aren't super rare there but advices and tips are hard to get. I think that 80% are museum vehicles and their owners won't know about technic  ;D
Title: Re: 1974 Coupe deville questions
Post by: EAM 17806 on July 01, 2015, 10:53:41 AM
My 76 CDV recommends air pressure to be 23 front and 24 in the rear, but I use 27 air pressure all around 4 tires. 1974-1976 CDV are basically the same cars with minor differences. Check your 74's tire pressure recommendation label which should be on the inside of the glove compartment.
Title: Re: 1974 Coupe deville questions
Post by: Ville on July 01, 2015, 10:57:07 AM
Ive now tried tire pressure between 20-30psi and up. Ride is still stiff and tire pressure wont effect it  :(
Title: Re: 1974 Coupe deville questions
Post by: 35-709 on July 01, 2015, 07:07:35 PM
If we are talking radial tires here, 23 to 24 pounds is way too low and a radial tire of Cadillac size (re: 235-75R15) is under-inflated at that point.  Those numbers are for bias-ply tires and are not proper for a radial tire.  30 pounds would be an absolute minimum, IMO, and 32 pounds would be better.

Do not use the recommended tire pressure label on the glove box door if you are running radial tires.

The best shop manual for your car is the Cadillac Factory Shop Manual, readily available on eBay Motors.  There are several up for sale there now including these ----
http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050890.m570.l1313.TR0.TRC0.H0.X1974+Cadillac+shop+manual.TRS0&_nkw=1974+Cadillac+shop+manual&_sacat=6000

This Fisher Body Manual would also be very nice to have ---
http://www.ebay.com/itm/1974-CADILLAC-ELDORADO-DEVILLE-ORIGINAL-SERVICE-SHOP-BODY-REPAIR-MANUAL-BOOK-74-/131382399576?hash=item1e97005258&vxp=mtr
Title: Re: 1974 Coupe deville questions
Post by: EAM 17806 on July 01, 2015, 10:48:03 PM
1974-1976 Cadillac deville cars all came from the factory with radial tires as standard equipment. The factory shop manual states to set the tire pressure in accordance with the specifications on the placard label which is located on the inside of the glove box cover. It states there 23 psi in the front and 24 in the rear per the 1976 factory shop manual on page 10-2. However, for continuous high speed driving over 75 MPH increase pressure 4psi up to a maximum of 32PSI, but for average driving I suggest 27-28PSI on all fours; remember these three years are basically the same body and weight. Again, this is from the factory shop manual.  EAM
Title: Re: 1974 Coupe deville questions
Post by: Ville on July 02, 2015, 03:52:07 AM
Yes i have radial tires.


Okay i buy that shop manual at least. What fisher body manual includes what shop manual doesnt?
Title: Re: 1974 Coupe deville questions
Post by: Ville on July 02, 2015, 09:15:40 AM
What is basic adjustment of idle mixture screws? I mean turns.

I have vacuum gauge which helps adjustment but its too rich. How accurant is mixture screw? Is 1/4 turn accuracy ok?


Emission tag says co 1% max is that true? If i go to smog test. Its not must in there because car is old but id like to know mixture.
Title: Re: 1974 Coupe deville questions
Post by: 35-709 on July 02, 2015, 10:05:05 AM
"It states there 23 psi in the front and 24 in the rear per the 1976 factory shop manual on page 10-2. However, for continuous high speed driving over 75 MPH increase pressure 4psi up to a maximum of 32PSI, but for average driving I suggest 27-28PSI on all fours; remember these three years are basically the same body and weight. Again, this is from the factory shop manual.  EAM"

That is old and outdated information, unless maybe you are still running radial tires built back in that time period.  Radial tires have continued to evolve since then in construction and technology, and I stand firmly behind what I have said.  Your car, your tires, do what you will.
Title: Re: 1974 Coupe deville questions
Post by: TJ Hopland on July 02, 2015, 10:45:16 AM
I did try running mine that low and it didn't really seem to soften the ride but made the handling seem extra soft.  Also noticed they seemed to run a lot hotter even at moderate speeds.    Take em up to the tire max of 45 and the ride does get really bad but in the 30-35 range I didn't think the overall crusing comfort was much different than in the 25 range.
Title: Re: 1974 Coupe deville questions
Post by: bill06447 on July 03, 2015, 08:28:20 AM
it sounds like the rubber body mount bushings may have deteriorated, and the body is riding directly on the frame, might want to confirm the body mount integrity.

Bill
Title: Re: 1974 Coupe deville questions
Post by: Ville on July 03, 2015, 08:40:43 AM
Ill check rest of these. I've already checked from because it rattles. It was caused by windshield which is off on bottom at least, maybe sides too.



By the way, I hear that same aged Lincoln were the most smooth cars on road. Is Cadillac smoother than Buick,Chevy,olds or mopars? Just thinking...



Does shop manual include nothing about a/c troubles,or do I have to order Cadillac Tim troubleshooting guide too?


Title: Re: 1974 Coupe deville questions
Post by: TJ Hopland on July 03, 2015, 09:08:21 AM
The shop manual does have info on the climate control system.   The difference between that and Tim's book is that Tim wrote his like 10 years ago based on his current experience repairing the systems so his book focuses on what usually fails or needs attention at this age.  His book also does not require the special dealer type tools. 
Title: Re: 1974 Coupe deville questions
Post by: Ville on July 03, 2015, 08:09:05 PM
Happy independence day folks!
Title: Re: 1974 Coupe deville questions
Post by: Ville on July 07, 2015, 02:23:43 PM
Can someone help and tell which colored wire is for headlights? That what is visible link to start ->

I've replaced all fusible links from start but headlights are tricky. Yesterday they started to work when I re check links under car. Today they suddenly went off.

Maybe fusible link wire is bad or switch?

If link is little bit too small, can it cause that kind of problems? All links are fine, no burn or voices when I touch those.


Title: Re: 1974 Coupe deville questions
Post by: The Tassie Devil(le) on July 07, 2015, 08:45:23 PM
G'day Ville,

You have an email that requires your immediate attention.

Bruce Reynolds
CLC # 18992
Message Board Administrator
Title: Re: 1974 Coupe deville questions
Post by: Ville on July 07, 2015, 09:12:49 PM
Sorry Bruce! Im lazy what comes reading emails.

Hope all is now okay?

Good day too even in there Finland clock is 4.12 a.m  ;D
Title: Re: 1974 Coupe deville questions
Post by: The Tassie Devil(le) on July 07, 2015, 09:15:53 PM
Good job Ville,

So you also missed my email about the $9 Million that you won the other day? ;)

Down here in Tasmania, it is 11.14am, Wednesday.

Bruce. >:D

Title: Re: 1974 Coupe deville questions
Post by: Ville on July 21, 2015, 08:13:08 PM
Heh.

Been some pause for cadillac.


Automatic level control hoses are now stucked. Now vacuum gauge won't wobble anymore.

But! I can't get more than steady 15-16hg. Timing is ok and new dist cap etc. What can cause it? Works still good.


Also measured acceleration with GPS today. 0-100kmh (about 62miles?) was 9.1 seconds, woah! 0-80kmh 6,1. I'm surprised.

But over 100kmh/60miles it will slow down and I see the limitations of big car.



I inspected car too, first time in my country. Was good and passed. Shocks are bad because test gives only 50%.

Rear are still air shocks but hoses are cutted off. Is it possible to fit new hoses and try them?



Title: Re: 1974 Coupe deville questions
Post by: Ville on July 22, 2015, 06:18:55 PM
I removed dash covers and panels. Now I can switch bulbs etc. But main fault is somewhere else. Won't  give 12v in sockets. Can faulty light switch / dimmer cause that? Fuses under dash ok.


Removed a/c temp sensor too. Now it gives only heat. So that means my sensor is working because,I can adjust temp when its on. Only a/c cool is missing.


All warning lights should go on when power is on before starting?
Title: Re: 1974 Coupe deville questions
Post by: Ville on July 22, 2015, 07:50:14 PM
Is there some place in engine where i can but coolant temp sensor for gauge?
Title: Re: 1974 Coupe deville questions
Post by: Ville on July 26, 2015, 12:11:17 PM
Nobody?
Title: Re: 1974 Coupe deville questions
Post by: 64\/54Cadillacking on July 26, 2015, 03:37:51 PM
Quote from: Ville on July 03, 2015, 08:40:43 AM
Ill check rest of these. I've already checked from because it rattles. It was caused by windshield which is off on bottom at least, maybe sides too.



By the way, I hear that same aged Lincoln were the most smooth cars on road. Is Cadillac smoother than Buick,Chevy,olds or mopars? Just thinking...



Does shop manual include nothing about a/c troubles,or do I have to order Cadillac Tim troubleshooting guide too?


Maybe not in the 60's, but In the 70's, this is generally true. The Lincolns were smoother riding cars that felt like you are on cloud with Zero rattles, as their suspension was tuned more for comfort and softness rather than for handling more so than a Cadillac. The bodies are better constructed not just the way the frame and body mounts are designed, but the actual quality of construction of the BODY itself. The doors, the hood, the cabin, rear sail panel. Panel welding, the strength and torsional rigidity of the metal, all that contributes to a more solid more comfortable ride. It's not just the suspension setup, but the actual construction of the entire car is what makes for a great ride.

I used to own a 72 Cadillac Sedan Deville that is exactly the same car of your 74, and that car rattled, shook, and shivered over rough pavement. I was very surprised by this for it being a Cadillac. Even with shocks and control arm bushing replacement, new tires with an alignment, new steering components, the car still rode rough. The quality of this year was terrible IMO compared to the older models.

I heard that from 71-73, these particular model Cadillacs had body integrity issues. Because I remember riding in a 70 Cadillac years ago, and that car was amazingly smooth, quiet, and comfortable.
Title: Re: 1974 Coupe deville questions
Post by: Ville on July 26, 2015, 05:45:53 PM
Okay, lincoln is winner in smoothnes. So many has told that  :(


How about in other marks? Or i just wanna know which place cadillac gets in smoothnes? I had 74 impala stw which feeled same but rear leaf springs stiffered bouncing a lot i think.


Title: Re: 1974 Coupe deville questions
Post by: Ville on July 28, 2015, 09:08:59 AM
Clock is not working because one little red pinion is broken, just besides the clock "motor".

Does someone sell those anymore or do i have to get whole "new" clock?
Title: Re: 1974 Coupe deville questions
Post by: TJ Hopland on July 28, 2015, 09:29:45 AM
There are still several places around the USA that repair automotive clocks.   I just sent one in.   Repair and restoration seems to run in the $100-250 range.   Quartz conversion when possible $150-250 range.    One thing I did learn is Borg was the most common manufacturer, tended to be the most reliable, and the one with the most parts still available.   Also the one with almost drop in quarts movements available.   Look at the back if it says Borg you should be good.  Any other manufacturer you will have to contact one of the repair places and see what they say.  I guess the Borg movements often interchange between years and models so chances are really good about fixing one.   Other manufactures apparently not so much the same.   

Other than being generally gummed up and un able to move the next most common issue is the coils being burnt up.  Coils burn up from a combination of having to work hard from being gummed up and low voltage (battery going dead from sitting).   The shops can re wind most of the coils for extra cost of course but at least its usually possible. 
Title: Re: 1974 Coupe deville questions
Post by: Ville on July 28, 2015, 08:01:59 PM
Thanks for info! Maybe i just buy one gor spare parts and try do one working one :)


How much headers and/or double exhaust will ad hp/lb ft to stock 472cid?
Title: Re: 1974 Coupe deville questions
Post by: 35-709 on July 28, 2015, 09:51:54 PM
"How much headers and/or double exhaust will ad hp/lb ft to stock 472cid?"

That alone?  Not enough to make any apparent difference except to your pocketbook.
Title: Re: 1974 Coupe deville questions
Post by: Ville on July 29, 2015, 04:54:35 AM
Yeah alone that was the word.


Ive heard that many oldsmobile engine has poor exhaust manifolds and headers can give 20hp more but cadillac design is okay in stock?
Title: Re: 1974 Coupe deville questions
Post by: TJ Hopland on July 29, 2015, 07:58:46 AM
I too would stay in a 74 you are not going to see a big change.   75 you would / could due to the way they did the crossover and early cat but in the pre cat days the stock systems were not that bad.   If you start talking about a different cam and other internal changes then you would want to do some exhaust work but if all else is stock its not likely worth the trouble. 
Title: Re: 1974 Coupe deville questions
Post by: 35-709 on July 29, 2015, 06:18:48 PM
Quote from: Ville on July 29, 2015, 04:54:35 AM
Yeah alone that was the word.


Ive heard that many oldsmobile engine has poor exhaust manifolds and headers can give 20hp more but cadillac design is okay in stock?
You would be hard-pressed to notice 20 extra horsepower except at the drag strip --- maybe.  Also, horsepower and fuel consumption tend to go hand in hand.
Title: Re: 1974 Coupe deville questions
Post by: Ville on July 29, 2015, 07:21:17 PM
Okay so let it be. I got shop manual tomorrow if all wents fine so i can see wirings then.
Title: Re: 1974 Coupe deville questions
Post by: Ville on August 11, 2015, 02:20:20 PM
Help.

I cut muffler off because I started exhaust job.

Now exhaust backfiring is better to heard.

Carb is adjusted like shop manual says and ignition timing too.

Every time when I lift foot off the pedal it bangs.


I tried to use more timing, 14deg too but it helped only for engine hesitating on idle. Hesitate wasn't big at all so its not problem.


Loose timing chain was on my mind but more advance would help if its retarded couple degs?


And.. Biggest problem. When engine is hot and I stop the car. About. 20-30seconds and upper radiator hose (intake side) makes noise, like water boils. What is that? More advance didn't help or long idle before shutoff either.
Title: Re: 1974 Coupe deville questions
Post by: Ville on August 12, 2015, 12:04:45 PM
Radiator and hoses are pretty new, flushed today and no rust or anything so water flows well i think.
Title: Re: 1974 Coupe deville questions
Post by: TJ Hopland on August 12, 2015, 12:16:29 PM
Is the cooling system building pressure like it should?

If you have half the exhaust system missing it will be normal to get a little popping in the exhaust on deceleration but it should not so loud that people are running for cover. 

Does this car have a AIR (called a smog pump in the USA)?  Its a belt driven pump below the alternator that has a hose that wraps around the alternator that connects to a crossover tube between the heads.   If that system is not working properly it will make significant pops in the exhaust.
Title: Re: 1974 Coupe deville questions
Post by: Ville on August 12, 2015, 06:31:56 PM
Air pump is and it has belt on so it works but i dont know will it work perfectly? How i can see that?


Radiator cap is 16, not so old. I dont know about pressure but coolant reservoir works so it brings there coolant when engine gets warm. Just normal cold to hot you know.


Hot start is also little bit bad and it puffs black smoke when starts and i dont even press pedal to the floor.


But that boiling thing is bad and nasty.

I put coolant temp gauge on tomorrow but it wont fix the problem.
Title: Re: 1974 Coupe deville questions
Post by: TJ Hopland on August 12, 2015, 07:04:34 PM
The failure in the AIR system that causes the popping is the diverter valve not working.   I don't remember the details but what is supposed to happen is when you take your foot off the gas the valve operates and for a period of time it diverts the air flow from the pump out a muffler on the valve instead of into the heads.   Most of the time it is pumping air into the heads.  This is done to allow the burning to complete in the exhaust system and lower emissions.   Problem is when you take your foot off the gas the mixture goes very rich and with the extra air added from the pump it really burns.  The fix for that was the valve to temporally divert the air during that deceleration condition. 

When my 73 started doing that real bad I just pulled the hose off that went between the pump / valve and the crossover on the heads.  Removing the system really does not seem to hurt anything on the pre cat converter cars.   With the hose removed there should be no exhaust leak from the crossover.  If there is the check valve is bad and likely what killed the valve and is hard on the pump too. 

Can you get one of those non contact thermometers?    Those are really handy to troubleshoot cooling system issues.   My test procedure is to start with the engine dead cold.   Take the cap off and check the level then re install it.    Squeeze the upper hose to get a feel for what its like with no pressure.  If you are not used to grabbing hot things maybe do this with a glove so later when its hot you will still be used to the feel.  Start the engine and keep feeling the upper hose for pressure.  You should not feel any pressure till things start to really heat up.   If you feel pressure right away you have to suspect a problem like a head gasket which has a different set of tests.   The pressure should start to build as the temp comes up.   With the gun take readings at several locations like the upper hose and the front of the engine around the thermostat.    You should see the temp around the stat start to come up but the upper hose should remain fairly close to ambient till the stat begins to open.   Assuming a stock stat this should be around 190 F.  If the upper hose starts heating at about the same rate as the front of the engine the stat is stuck open or missing.    The stat should be fully open around 200 F and at that point the upper hose should be in that same 200 F range.   It should also be fairly firm at this point but remember its will also be 200 F so this is where the glove may be required.    At idle it should sit around 200 F pretty much all day long.   If it keeps climbing let us know and we can give you more things to check.   If the upper hose is still soft at that point you have a leak somewhere that is not letting the pressure come up which may not be a problem under some conditions but when you shut it down the normal heat soak could push the temps up over the boiling point.  The pressure is the primary thing that raises the boiling point from the 212 F range to more in the 250 range.  With the engine's normal temp around 200 that does not leave you much margin without the pressure.       
Title: Re: 1974 Coupe deville questions
Post by: Ville on August 13, 2015, 01:00:36 PM
Thank you! I dont have gun :( Tomorrow when sealant is dry i start engine.
Title: Re: 1974 Coupe deville questions
Post by: Ville on August 13, 2015, 03:56:56 PM
Thermostat was ok, i found similar gates in my garage, hah lucky. Its cadillac oe style i checked that.


That brass pipe in radiator where is attached coolant reservoir hose is loose. It drops and now i cant get it tight enought. Any ideas? If i wider it it wont go in the hole.
Title: Re: 1974 Coupe deville questions
Post by: Ville on August 14, 2015, 09:02:41 AM
Well, i got the infragun. It gives 140deg on mechanical gauge and upper radiator hose, intake side. Radiatior side couple degs less. Heater hoses give 160. That one which goes to block is couple degs hotter but no big difference.


So the burbing can't be boiling water. It buts air and water in coolant reservoir after shutdown.


But why its not heating? I tested thermostat before installation and it was ok.
Title: Re: 1974 Coupe deville questions
Post by: Ville on August 14, 2015, 09:06:45 AM
Sorryn it seems to suck at the reservoir after shutdown.
Title: Re: 1974 Coupe deville questions
Post by: TJ Hopland on August 14, 2015, 09:47:16 AM
160 F is too cool but at least should not be boiling even on a hot shut down.   Its not a common issue with these engines but you have to wonder about a possible head gasket issue.  Does it seem to be building and holding pressure?  How quickly does it build?   

What happens when the engine is running with a crack or gasket issue is the compression pressures push air in to the cooling system.   The air causes hot spots which could cause boiling in places even though the overall temp may not be that high.  If and when the bubbles get to the water pump they can cause the flow to stall which then also causes localized hot spots and boiling. 
Title: Re: 1974 Coupe deville questions
Post by: Ville on August 14, 2015, 10:00:44 AM
Upper hose is not stiff,  maybe little loose i think. Ive checked cylinder pressure whit test and coolant wont smell bad etc oil is good. Cap seems working because if i press upper hose, it gives coolant to reservoir.

It just burbs about 20-40s after shutdown but no hot point even then. Inside air is about 135deg on foot when its full hot and def.
Title: Re: 1974 Coupe deville questions
Post by: Ville on August 14, 2015, 10:02:30 AM
And gauges needle is stable when it gets 140deg.

Vacuum gauge readings also straight, no wobbling etc so nothing seems not head gasket hopefully?


Heater hose vacuum port is converted to hand switch.

When switch was open and radiator cap open, it gives lots of coolant in radiator. Switch off and it stops. Normal? Engine was just started. I didn't try that in hot engine.
Title: Re: 1974 Coupe deville questions
Post by: Ville on August 14, 2015, 02:28:21 PM
Now check radiator level after fully cooled engine. About two inches from cap. So its not so empty that can cause poor heat? I but water on garden hose so i dont know how much it went. I dried system before this job.


Title: Re: 1974 Coupe deville questions
Post by: Ville on August 15, 2015, 04:12:26 AM
Heater hose switch closed or minimum, engine temp was little bit lower but no big effect no matter what.
Title: Re: 1974 Coupe deville questions
Post by: Ville on August 15, 2015, 07:45:24 AM
I checked air pump. I removed hose between check valve and pump. In idle pump gived continuous air but check valve gived liiitle back pressure on finger when i tested. Little noise flaflaflafla too. Normal? I forgot try on higher rpm.
Title: Re: 1974 Coupe deville questions
Post by: TJ Hopland on August 15, 2015, 08:44:19 AM
Its normal to have air out of the pump at idle, the only time it does not pump air is deceleration.  I think will do its thing not driving.  I think you can raise the RPM and then let it come down fairly quickly the dirverter valve should operate and not pump air to the heads for the few seconds the engine is decelerating.   Its been a long time since I have worked on a non computer car that had this system working so I could be wrong about being able to test it not under load. 

There should be no flow from the crossover pipe.   If there is flow the check valve is bad.   The valve is there to keep exhaust from backflowing into the AIR system.  The exhaust tends to damage the system.  I'm not sure about where you are or even in the USA anymore but those valves used to be somewhat universal and easy to find.   The same basic valve fit most American cars in the 70's and 80's when the AIR (smog) pumps were commonly used.     
Title: Re: 1974 Coupe deville questions
Post by: Ville on August 16, 2015, 04:00:52 AM
Thanks i will check that.

I dont get anything else than take coolant and thermostat off again today and just wonder why it wont goes normal temp.
Title: Re: 1974 Coupe deville questions
Post by: Ville on August 16, 2015, 01:22:45 PM
Air pump hose off and backfire was gone  8)

I dont get pretty easy new part. Does it matter if i but plugn valve and turn air hose to blow free?
Title: Re: 1974 Coupe deville questions
Post by: Ville on August 17, 2015, 09:18:51 AM
I didnt  found nothing bad to thermostat. It was closed position when I pulled it off. Now there is old thermostat and lets try with that.
Title: Re: 1974 Coupe deville questions
Post by: Ville on August 17, 2015, 11:17:24 AM
Nothing changed.

Does someone had temp gauge on this type engine? Will it show real temp in that spot?
Title: Re: 1974 Coupe deville questions
Post by: Ville on August 17, 2015, 05:10:14 PM
Couple problems more:

Headlight switch will not always work. Park lamps position works always but headlight no. It does it couple times per day, works ir no. I overhauled that switch month ago and it worked well a while but not anymore. There was only old stuff inside but when I cleaned it it's like new.


Car was with on/off switch and push button start. Now I did wiring to the original ignition switch with shop manual. All works fine but warning lights were all gone. All wires are like should be. Before wired was in big sump to on/off switch and couple for start button.
Title: Re: 1974 Coupe deville questions
Post by: Ville on August 18, 2015, 06:57:18 AM
Thermostat is ok. Gauge was faulty.
Title: Re: 1974 Coupe deville questions
Post by: Ville on August 19, 2015, 06:21:59 PM
What is most common part to fail in guidematic? Will it be able to test with flaslight etc? I mean that eye on front grille.


Double checked wires, ground and ignition switch. No warning lights. Fuel gauge works but not trunk open.

Brake light has been dark all the tine. Bulb is ok.
Title: Re: 1974 Coupe deville questions
Post by: Ville on August 23, 2015, 05:01:32 PM
With 16lb raditor cap and 180f thermostat, what is normal temp in idle/highway?
Title: Re: 1974 Coupe deville questions
Post by: Ville on September 02, 2015, 05:44:17 PM
Blower works only at vent (low) and defrost (hi). What causes that?

Also heat will not come allways. Hoses are hot so problem is inside. All vacuum lines checked and control head works.

Title: Re: 1974 Coupe deville questions
Post by: TJ Hopland on September 02, 2015, 05:48:50 PM
There is a 1 wire sensor in the corner of the head just behind the alternator.   At 120*F it grounds which then lets the blower run on speeds other than low for heating modes.   Its possible that the wire got knocked off and sometimes grounds which then lets the blower run.   
Title: Re: 1974 Coupe deville questions
Post by: Ville on September 02, 2015, 06:03:19 PM
Thanks i check that. Relay blinks when i switch off the vent or defrost.

Does that air door under glovebox allways get always opened when temperature is max cold?
Title: Re: 1974 Coupe deville questions
Post by: Ville on September 04, 2015, 03:53:46 PM
It was connected but not grounded. I grounded it to body and now blower works hi on auto, hi, bi level and defrost. Vent is low. Thats good. But is it now that kind speeds no matter what?