Need some underhood pictures of an original(ish) 73-78? Eldo

[TJ Hopland]

Could someone shoot some pictures under the hood of their Eldo?  Mine is a 73.  I think it has to be 73-78 because they changed the layout up front for 73 but I think it more or less stayed the same till the downsize in 79.   What I am after is the location and sizes of all those seemingly useless rubber like flaps and air dams up front by the radiator, under the radiator, and around the inner fenders.   I am trying to get the temps to run below 230 on my car and that is about the only thing I have not messed with over the years of having the problem.   I am suspecting its a airflow issue and my car does not have any of those pieces in place.  I was hoping with some photos I would be able to fab up something that would function at least long enough to see if that will solve my problems.   Post em here or email them direct to me.   

[76eldo]

TJ,

Have you installed a NEW or recored radiator?

Those air dam flaps are not going to be the cure.

You either have a plugged up radiator, lots of sediment in the block, a bad impeller on your water pump, a slipping shaft on your water pump, or a seriously out of time engine that somehow runs well.

That car should not run that hot.  A stuck thermostat?  Don't run it with no thermostat, but maybe run it with one that has the guts removed just as a test.

Have you taken temp measurements with an infra red thermometer?  It's a little hand held scope that you can get at a lot of places for $30 to $40 and you can see what your radiator is actually doing, measuring the temp difference from the top to tge bottom and checking the temp differences on the hoses.

Good luck,

Brian

[TJ Hopland]

This has been one of many issues this car has had since I have owned it the last 15 or so years.  Yep got a infared meter.   Been through several stats over the years.  Did run not stat for many years.  Current stat is possibly a premo John Deere one that happens to be identical to the Cad one and even had the bypass plug on it that many of the replacements dont have.  This is the 3rd engine, first one that was fully rebuilt (twice now) so the internals are clean.  Its got EFI with a wideband and its happy as far as fuel and timing goes.  Its had 2 radiators over the years.  One was an original one and the other is a Modine 4 row.   Current water pump is one of the 'hi po' flow kooler models.   Current motor has got maybe 3-4000 miles on it.    Its never boiled over but like today when its low 80's ambient it started climbing from 200 when I got on the highway and after about 5 miles was up to 230 and still climbing.   I was towing my boat which I have not done with it for a few years but used to do all the time.   I dumped the boat and its still running 220.     

[CEC #20099]

TJ, You need to check for combustion gasses in the coolant. Cracked casting , blown gasket, etc. Using a radiator pressure tester with a relief valve, Pump it to 10 psi & let it run at fast idle, monitoring temp & pressure. Do NOT let it go over 18 psi. If you have a combustion gas analyzer, sniff the radiator neck for hydrocarbon gas. Let us know the results.
#20099

[TJ Hopland]

Wouldn't there usually be some coolant loss or at least blowing it into the overflow if there was combustion getting in?   I drove 150 miles today with no loss.  I dont remember ever having to add coolant to this car.

Anyone with a 472 or 500 and an IR gun care to take some readings at various places around the engine on a hot day?   It sort of appears that the temp sender location is a hot spot.   I will jot down the readings next time I have it out but when I was getting 235 at the stock sender location I was reading 210 at the stat housing. 

[Glen]

If this is your third engine I would say the problem is not in the engine.  If you do not have the rubber shields around the radiator there is the possibility the air is bypassing the radiator. 

Check Rubber The Right Way and see if they have a set of shields for your car.   

[TJ Hopland]

Ya over the years I have changed just about everything else so that is why I am thinking its just a air flow issue.  All that plastic stuff had to be there for a reason.

Later today I was going to mess with the hood adjustments and see if I can get the hood to pull down better by the windshield. 
Maybe it will be something simple like that.   I had the hinges rebuilt several years ago and its a lot better now but its still not perfect.

I am going to see if I can find an old time radiator shop and even though the rad looks clean inside and out I will take it in to make darn sure.  Maybe the side of the tank without the cap on it has all the crud in it?  One of my previous engines did have an amazing amount of crud in the cooling system. 

I have had this car for 15 years and finally am trying to address the most annoying features its had the whole time, one of them being that it runs hot (after this is solved I may even re install the AC).  2nd is vibration.  3rd the top was poor quality and poorly installed 30 years ago. 

[pulteney]

   After buying my 76 Eldorado, I checked it carefully for overheating with an IR remote thermometer. I drove it at 50 mph, pulled over to the side of the road and measured the temp at the thermostat and various locations around the engine and radiator. I then let it idle for 30 minutes inside my garage so no additional airflow went through the radiator. I never saw more than 205-210F. This is a common range for some other vintage cars I have owned.
   Considering that a 50-50 mix of antifreeze and water boils at about 260F with a 15 psi radiator cap, I was happy.
   In general, I have always started troubleshooting overheat problems based on when the problem occurs. If it overheatrs only at idle, it is probably an airflow issue. If it overheats only at cruise, it is probably a coolant flow problem.
   The baffles that you wish to replace prevent the air that has gone through the radiator from flowing back around the edges of the radiator and passing through the fins again. Once the car starts moving, this problem goes away.
   Specific to your situation, how are you measuring the temperature while driving? Probably it is with an aftermarket gauge as, at least in 76s, they only have an idiot light (actually 2). Considering all the ways you have already tried, I would start by calibrating the sender/gauge with boiling water. Don't forget to allow for your elevation where you live.
Hope this helps.   JB

[TJ Hopland]

Im in Minnesota so no unusual elevation.   Compared to the IR gun the aftermarket mechanical gauge seems fairly accurate.   It does alright at idle unless its already hot then it wont cool, if im lucky it will just maintain a temp.   Since I went EFI at least the engine stays running.  Before the EFI it would vapor lock and boil the fuel out of the carb.   Its always been that way at low speeds and idle.   What is bugging me is that its seems to be building temp at cruise.   I have some laptop issues to deal with but once I get that solved I was planning on doing some data logging towing the boat to see if perhaps the extra load is pushing things too lean.  I did not notice any detonation but its running non oxy premium right now so perhaps that is buying me the headroom. 

Last fall I put some cardboard between the bumper and radiator and from the grille to the top of the radiator so I presume that should help ensure air can get into the radiator.  What I dont know is what is going on past that.  I know enough about airflow to know it does not work the way one assumes it works with low and high pressure zones.    One of the things I wonder about is if its just general airflow around the engine that is forcing the coolant to do more work.  I assume that is one of the things those little flaps and the hood seal addressed.     

[TJ Hopland]

Anyone know for sure what temp the engine (metal) temp switch comes on at?   How about the coolant temp light?  My metal temp sensor is missing so I cant go test it.  The coolant one is replaced with the mechanical gauge, the other port is used for the EFI.  Just thinking maybe I get the metal light working and assume no light, no boil over so its all good?   I have a shop manual but cant remember where or if it stated those values.  I looked quickly and did not see it but the schematic must be in a different pile so maybe that is where the values were stated.   

["Cadillac Kid" Greg Surfas 15364]

TJ,
To answer a couple of your questions, the left head metal temperature sensor closes at 265 degrees, and the water temperature sensor (the on you replaced with a mechanical guage) closes at 230 degrees). All are +/- some tolerance,.
The later large chamber motors seem to run cooler, probably due to their de-tuned state. I had a temperature guage on my '72, but got tired of seeing the temperature on the highway running at about 220 with the AC on in the summer at 75+ MPH. That was in 72, so I guess since the car has never blown out coolant 220 is OK.  Incidentally, that is the reason for the vacuum valve on the drivers side cylinder head. When the temperature gets  to (I believe the temperature is) 230 degrees, the distributor gets intake manifold vacuum which would typically occur in heavy summertime traffic.
I  am going to make a big assumption that the distributor timing is correct with the correct mechanical and vacuum advance, and that the FI is not leaning out at highway speeds for what ever reason.
These cars run what I would consider hot, and the '73 if stock tended to run a little bit hotter, due to the attempt of the factory to pick up some additional power with the increase of emissions controls (first year for the EGR).

Greg Surfas

[TJ Hopland]

I have 73, 77, & 80 manuals.   The only temps I found in the 73 is the vacuum switch at 220 and it says the coolant temp is 320 which I assume is a miss print and they meant the metal temp switch.     The 77 I believe says the coolant temp is 260.  80 says the metal temp is 320.    Its annoying that no one manual has all the information.    I was looking at some of the parts places and so far there appears to be 4 versions of that switch so they must have messed with the temps over the years.  Of course none of the part descriptions say what the temps are.  Most dont even give the location.

[76eldo]

TJ,

I have a 76 and I would be happy to take some specific photos for you, but the 73 might be different.

I guess the 73's having a higher compression engine run a bit hotter.  Maybe figure out a way to pipe in a mechanical temp gauge while you are working this problem out.

There's a flap on the bottom of the radiator support and  a couple of other pieces.  Maybe one of the repro parts vendors has an exploded view available of their parts?

Good luck,

Brian

[TJ Hopland]

I think the changes were pre 73, seems like the core support and other things moved around the front.    A shot of that under radiator dam thing would be good and also was there something on or around the inner fenders?

71+ was the same compression, what changed was originally they dished the pistons to lower the compression. 74 they changed the heads and went back to a more normal piston.   My current engine has the later heads.  I got my laptop setup to connect to my EFI, the last time I connected was with a now dead computer.  I should be able to go out and run some logs to see whats happening AFR wise.   I also see there is newer firmware for the system so I may upgrade that also.   So far its running of a regular HEI but I have the parts to convert it to computer control.   Just trying not to change too many things all at once. 

The temps ran high with the original 73 motor and original fuel system.    Im beginning to think the whole problem may be that I have a gauge and know the temp.   If I did not have the fuel boiling problem I would not have put the gauge in, guess I can thank ethanol for that.   

Anyone have the GM part numbers for the 3 temp sensors that were used on a 73?   If you also have the books what years used the same sensors?

[Paul Tesone]

TJ - Here are some photos of my 76 Eldo engine bay . I have no reason to believe anything has been changed from the factory as I am the second owner of this 21,000 mile car . I'm not sure the photos will be much help  as the engine bay , as you know , is quite cramped and it was difficult to get good photos . I did not see anything around the radiator other than what you would call the radiator support frame. I couldn't get any photo of the area below the radiator . Hope they are of some use to you . Paul Tesone CLC #6876 

[Paul Tesone]

Three more photos. Paul Tesone CLC #6876

[Paul Tesone]

Last photo . Good luck. Let me know if you need anything else . Paul Tesone CLC #6876

[TJ Hopland]

Thanks for the photos.   I was really expecting something to be up front on the top of the radiator.    If you look down from there is there anything at the bottom between the bumper and radiator? 

I have been out of town working so no time to go tinker with my project, maybe will have time this week.

["Cadillac Kid" Greg Surfas 15364]

TJ,
This thread jogged my memory on this subject.  Regarding underhood "baffles", the pictures of the '76 above reminded me that in my '72 eldo there were no possible spaces left uncovered by said baffles.  Over the years they tend to harden and frequently fall off, but originally I believe you will find that EVERY possible space where air could bypasss the radiator was covered.
Greg Surfas

[TJ Hopland]

That is what I was thinking that they were there but they either fell off or were never re installed when something like a radiator was replaced.   I sort of have a slight recollection of finding those parts in the trunk of my 73 when I bought it (along with the quarter pannels and the rest of the front clip).   That was many years ago and of course I did not think they were of any use so I dont even know if I saved them.  Since I have moved 4 times since them I doubt I still have them.    I was hoping enough people would reply so we could maybe figure out which ones were important and maybe we could all run a little cooler.   I would think it would especially be of interest for those who are running converted AC systems.