Squeaky noise coming out of ‘78 Eldorado engine bay. Belt?

[Tornike]

My 1978 Eldorado has been having squeaky noise coming from the engine since I got it several days ago. It goes away after 5mins or less. Sometimes comes back briefly. Rarely it won’t squeak at all.
The car has been sitting since 2012 and I’m pretty sure it’s coming from those rubber belts. They don’t have much play when I push the finger, and seem to be well aligned. Don’t see any serious cracks either.
I guess could be surface rust that interacts with rubber or could be a bad something else. ?
To Somehow diagnose the rest of the parts, I’m thinking of changing the belts (both of them) as they aren’t that expensive at Autozone, as long as changing them isn’t huge of a deal.

My question is, how straightforward is it to change the belts on 1978 Eldorado? Is there anything to keep in mind? Any tips or good sources you can refer me to?

Right now everything seems to be working fine except of that annoying noise that comes on and then goes away after few minutes.

[TJ Hopland]

Alternator belt would be the most likely one.   At first its working hard to try and recharge the battery from the start.    Being such a small pulley it doesn't get a lot of grip on the belt and it doesn't help that modern belts don't seem to be quite the same shape as the originals.   If the tension feels good what I would do is clean then lightly scuff up the inside of the alternator pulley.   One time out of frustration I really went crazy on a pulley thinking having to replace the belt in a year would be better than having it squeal all the time.   Ran 40k over 3 years with no more wear than the other belts on the car. 

The alternator belt isn't hard to change and tension because the alternator is the tensioner.  It and its bolts are easy to access and there are places to pry.   The big pain one on these cars is the PS/AC.   Its tensioned by the power steering pump.  Its like GM went out of their way to put the bolts in hard to reach places and had a special design team to make sure there wasn't an easy place to pry.   Could have been the same team that designed the smog pump belt on cars so equipped but most 78's didn't have em so not a problem here.   

["Cadillac Kid" Greg Surfas 15364]

Tornik,
A squealing can come from several sources.  Number one aside from the belts would be the Air pump. Then you have the water pump and the alternator.  If the noise is there when the car is cold and then goes away I might suggest determining what the source is by waiting until the car is cold and removing the three belts AC/PS, Alternator/water pump, and the air pump if so equipped.  With the belts off, check each of the rotating components by turning them by hand to find the noisy culprit.
Changing all the belts would probably be good since they are old and the car has been sitting letting the belts take a "set".  BE SURE that the belts you get are the correct width and pitch, as well of course as the correct length. There are several replacement belts listed "as correct" with different widths, but unless you have the correct width the belt will not ride in the pulley groove correctly and life expectancy is greatly reduced. The  AC/Power steering belt should be 0.500 inches as is the Air pump. The Alternator/water pump belt is 0.410 inches.
Greg Surfas

[Jakes]

I just wanted to add my two-cents to Greg Surfas' good advice.  I also have a 78 Eldo.  When I replaced the AC compressor I not wisely used the same belt and the unit would squeal for a few seconds after turning on.  I did my research and discovered subtle (?) differences in belt applications for the car, particularly belt length.  See the attached table from the shop manual and note the dimensions.  The belts I used were: PS/AC -- Dayco 17600 or Gates 9600; Alternator (assuming its 63 amp) -- Dayco 15380 or Gates 7380; Air Pump -- Dayco 15445 or Gates 7445

Because the AC/PS belt rides on a small segment of the AC compressor pully, the belt has to be tensioned to the high side of the indicated range, otherwise it'll slip and squeal.  As TJ pointed out, the tensioning is a pain because you have to pull hard on the PS pump pivot.  I fashioned a "pry bar" from a long piece of hardwood which worked pretty well.  Once the belt is tensioned properly there's not much "give" when pressing on the open segment. 


Regards..
Paul Jacobs

[35-709]

There is a "special tool" to tighten the power steering pump/AC belt, it is easy to make and the "How to make it instructions" are on page 9-30 in the 1973 Cadillac Shop Manual and I ASSume in other year manuals also.  Makes it easy to tension the belt.  Pulling on the PS reservoir or using a pry bar against it is a definite NO-NO!  To quote the shop manual, "Do not pull or pry on pump reservoir."  This tool should also work on just about any PS pump GM made back in that era to properly tighten the belt.

[Jakes]

In reply to G. Newcombe.. where was my head?? -- you're absolutely right: DO NOT pry on the PS reservoir -- it says so in the shop manual!  Sorry for the misleading advice.  Thx for setting me straight.  It's been so long, I don't remember exactly how I was able to tension the belt.  I must have used my hardwood pry bar to wedge against the PS bracket, but definitely NOT the pump. The 77 shop manual (applies to 78 in this case) also has a schematic for making a tensioning tool.  I've attached a photo of the pertinent pages.  The 78 Eldo has the Hydroboost PS system, so note the position of the tool in the pump casting in the photo below

[35-709]

   A little different from the adjuster in my '73 manual but the same in principle.

[bcroe]

Part of the problem comes from a small pulley and not enough
degrees of belt wrap around the pulley.  Alternator pulleys come
in a lot of different dia, not too hard to change.  The right tool
really helps. 

I see the K car also on the drawings, the Olds engine belts bugged
me for a decade.  My 81 had a far superior belt setup, which I
converted 4 other Olds engines to with yard parts and little difficulty. 
Bruce Roe

[76eldo]

Old mechanics trick to figure out which belt is squealing:

Take something that you can dribble a few drops of water out of and wet each belt just a little bit. The water will stop the squealing for a few seconds when you get the right belt just a little wet.

Never use any kind of "belt dressing" spray on belts. It ruins them.

Brian

[Tornike]

As per Brian’s advice I sprayed just a little water to the pulleys one by one. And I’m almost certain I found one. It looks to be an Air pump + fan belt squeaking from the lower pulley.
Is that bottom pulley anything else other than just a pulley?
Is it easy to replace that belt? Attaching photos

[The Tassie Devil(le)]

With the size of the belt, in relation to the size of the pulley, I am tipping that there is minimal side-wall contact, as it looks like it is running too deep in the groove.

Bruce

[35-709]

"Is that bottom pulley anything else other than just a pulley?"
That is your A.I.R. (Air Injection Reactor) pump pulley and Bruce is right, that belt looks too narrow for the application.  Be mindful of that belt and its condition, if it fails you lose your water pump and Alternator, but the water pump will be of the most immediate concern.

[35-709]

If you don't know the age of that AIR pump you might consider replacing it just for peace of mind.  A common failure mode for those things is the bearing seizes and then (once again) you lose your water pump and alternator.  I am not all that familiar with AIR pumps, with the few I have had I got rid of them right away with an AIR pump eliminator kit.  Might be the bearing that is squeaking now but not being there that is just conjecture on my part.

[Tornike]

Thanks for the feedback.
The AIR belt seems to have the most play when I push a finger. Which part do I loosen to replace the belt?

["Cadillac Kid" Greg Surfas 15364]

Tornike,
From what I can see of the pictures it really looks like time to change ALL your belts. An explanation of what and where to loosen the bolts of both the PS/AC belt and the air pump are in my opinion best left to the FSM, since a few of these "Monkey motions" are counter intuitive.
The bolts at the front and rear brackets of the AIR pump should be loosened and the pump swings on its brackets.
You cannot remove this belt until you remove a couple of the others and they all look like they need replacement.
Tbhe actual size and the belt WIDTH are listed in the FSM.  Be sure the belts ou get meet these specs as a lot of belts being sold as replacements are too narrow.
Greg Surfas

[35-709]

Agreed!

https://www.ebay.com/itm/1978-CADILLAC-SHOP-MANUAL-SERVICE-BOOK-GOOD-ORIGINAL/163174696546?hash=item25fdf84662:g:ll8AAOSwf7Ja5JWb

In your case you will also need the '77 manual ---

https://www.ebay.com/itm/1977-ORG-Cadillac-Shop-Manual/162027548380?hash=item25b9982edc:g:a2YAAOSwJblXAYZ5

Several available on eBay.

[gkhashem]

I should not bother reading these threads since it seems to always come down to someone wanting to change only one belt, one hose, one wheel cylinder, or one brake hose.

Can we get some common sense here. You buy a car that's been sitting for years and has most likely been neglected. Or the guy selling is so cheap he does not want to spend a dime more on the car.

Why not change all the fluids, all the belts, all the hoses, all the wheel cylinders if you have drum brakes, and brake hoses. Also throw in the thermostat too. I often do the valve cover gaskets if I see them leaking. Then the spark plugs, clean the carb if she runs like she needs it and maybe spark plug wires if they look 50 years old and a tune up. (with all the parts that may be needed.) Most of this you can do yourself too if you need to save some money. Which I am all for doing too.

The biggest parts cost may be the tires.  Leaving out the tires what does all that I have mentioned above cost for parts and fluids? Maybe $200.00 to $250.00 tops excluding the tires?

But here we are changing one belt  or one hose? On a car that you know little about, that let's face it has been neglected for a time!. This is especially foolish on brakes as I am reading in another thread.

I guess I am not sensitive to the fact you do not have the money to do this. But you had the funds to buy the car?

Wow I am never amazed anymore.  With that said if anyone buys one of my cars, most likely all you need to do is turn the key.

I must be a fool I guess, since I always do the routine maintenance on cars I have just bought.

[bcroe]

Why not change all the fluids, all the belts, all the hoses, all the wheel cylinders if you have drum brakes, and brake hoses. Also throw in the thermostat too. I often do the valve cover gaskets if I see them leaking. Then the spark plugs, clean the carb if she runs like she needs it and maybe spark plug wires if they look 50 years old and a tune up. (with all the parts that may be needed.) Most of this you can do yourself too if you need to save some money. Which I am all for doing too.

The biggest parts cost may be the tires.  Leaving out the tires what does all that I have mentioned above cost for parts and fluids? Maybe $200.00 to $250.00 tops excluding the tires?   

All those things are actually quite cheap if you can do it yourself.  I
think a lot cheaper than on some late models.  It even includes a
timing chain replacement and trans remove/refresh here.  Things
like minor leaks might get postponed  after all critical functions are
taken care of.  Bruce Roe

[Tornike]

In reply to G. Newcombe.. where was my head?? -- you're absolutely right: DO NOT pry on the PS reservoir -- it says so in the shop manual!  Sorry for the misleading advice.  Thx for setting me straight.  It's been so long, I don't remember exactly how I was able to tension the belt.  I must have used my hardwood pry bar to wedge against the PS bracket, but definitely NOT the pump. The 77 shop manual (applies to 78 in this case) also has a schematic for making a tensioning tool.  I've attached a photo of the pertinent pages.  The 78 Eldo has the Hydroboost PS system, so note the position of the tool in the pump casting in the photo below

Surprisingly, according to the page 6B-12 from the same manual, Tensioning the steering pump belt is much easier and requires loosening 1 top adjusting nut and two lower bolts, and tightening them again. They don’t mention using custom tool from page 3B-24. Am I missing something?