Re: A dumb question about coolant

Think of the entire cooling system - engine, hoses, heater core, radiator - as a large somewhat flexible balloon. Under even moderate pressure some parts expand and increase in volume capacity. You release the pressure and coolant rises in the surge (not overflow) tank as the system "shrinks" to normal volume. Also, coolant expands a LOT as it heats, thus increasing system pressure to the design value in order to raise the coolant oil point, prevent water pump cavitation, and increase heat transfer from the engine metal to the coolant to the radiator.

 

Re: A dumb question about coolant

Think of the entire cooling system - engine, hoses, heater core, radiator - as a large somewhat flexible balloon. Under even moderate pressure some parts expand and increase in volume capacity. You release the pressure and coolant rises in the surge (not overflow) tank as the system "shrinks" to normal volume. Also, coolant expands a LOT as it heats, thus increasing system pressure to the design value in order to raise the coolant oil point, prevent water pump cavitation, and increase heat transfer from the engine metal to the coolant to the radiator.

Thanks, this actually makes what's going on make a lot more sense now. I was wondering where that coolant could be coming from!

 

Re: A dumb question about coolant

Our systems should operate at somewhere near 16 - 18 psi at 190 - 210 degrees F.

Here's what the boil points are for different coolant concentrations - our 50/50 recommended is the bottom line. Cadillac allow us to run a max of 70/30 coolant/water. ??? 60/40 or 70/30 ??? Think: N Canada/Alaska for cold (freeze), Saudi Arabia for hot (boil) climates.

 

Re: A dumb question about coolant

Have you thought about the night gremlins coming around and adding extra coolant?

 

Re: A dumb question about coolant

Have we covered "new pressure cap" ?

The OP should use an 18 psi cap.

 

Re: A dumb question about coolant

No, that won't affect anything at all. A 16 psi cap will work as well as an 18. The only difference is the pressure at which the cap will begin to vent and a few more degrees in the boiling point, neither of which you should ever be near with a properly operating cooling system.

 

Re: A dumb question about coolant

Alright so, I guess I will just ask this question here, since it's related to the cooling system, and I don't want to plug up the forum with a bunch of threads from me.

I finally managed to figure out that this sound I've been hearing for the past few months (at least) was not in fact some sort of vacuum leak, but was actually a bearing wearing out in either my water pump, the pulley or the tensioner. Now that it's gotten louder I can more clearly hear that it's more of a whirring, metal on metal, "ungreased bearing" noise, whereas before it was hard to pinpoint and really sounded like a sort of vacuum leak whoosh noise. It didn't help that the sound increased in intensity whenever I accelerate, and I was unsure whether or not engine RPM affects how fast the water pump/pulley spins (I now know that it does!)

Anyways, I took off the the belt and found that the wheel on the tensioner is very gummed up and barely spins, so that clearly needs changed. The thing is, the pulley itself doesn't spin at all - is it supposed to spin when the car is off? Obviously it spins when the car is running or I'd have big problems, but it didn't spin at all when I tried to spin it myself.

Edit: After looking at it some more, I'm guessing it's probably not supposed to spin, since it's just a piece of plastic that sits on that, err, metal rod thing which goes into the engine. I was just confused because I thought people were telling me to spin it and see if it makes any noise.

 

Re: A dumb question about coolant

The water pump drive system consists of a drive pulley, tensioner/pulley, the water pump and a 3-rib belt.

The large plastic pulley is TIGHTLY pressed onto the left bank intake cam extension. DO NOT twist, hammer, rap, force that pulley. It comes off with a special puller in the groove of the metal hub. Your engine may still have a black plastic thread protector screwed into the can extension snout the threads are used with the install tool, to pull the new pulley onto the extension. DO NOT hammer it !!!.

The belt tensioner consists of a spring arm and removable ball bearing pulley. $25 at a NAPA. If that pulley freezes it causes hundreds of dollars in damage. Replace it yesterday, and every 75,000 miles.

The belt and water pump are very reliable BUT if that tensioner pulley freezes the belt overheats and WILL destroy the drive pulley and maybe the water pump.

I believe that I have advised that you subscribe the car to www.alldatadiy.com. It's the online GM/Cadillac service manuals for your car and you sure need it. Sounds like you're flying blind. If you don't understand this engine and car you WILL make some very, very expensive "maintenance" mistakes. Guaranteed. I added "2000 Deville" to your thread title because it makes a BIG difference due to the extensive Northstar engine changes for 2000 and later.

Click a thumbnail to enlarge, follow the prompts on the lower border.

 

Re: A dumb question about coolant

Thanks Sub, don't worry though I'm not really flying completely blind - YouTube and you guys here have been very helpful. Luckily for me there are several great videos about replacing the pulley, tensioner and water pump on these cars, which I've been watching basically on repeat for the past several days. I've done the job about a hundred times in my head already while I'm waiting for the parts to arrive. Originally I was planning to replace everything (pulley, tensioner, belt and water pump) but now that I understand how the pulley works better I think I'll leave it alone because it appears to work and looks fine, and it'll save me the trouble of having to rent that tool as well. I'm still debating about the water pump, since it's so difficult to get to - when I change the tensioner tomorrow I'll check it while I have the old tensioner off to see if it spins good and doesn't make noise, and I guess if it's fine I'll leave it alone too.

Here's a video of the sound it's making: https://www.youtube.com/watch?v=rC_IitynM6c

I sprayed WD40 on it when I had the belt off earlier and started it up and that squeaking was gone, but when I drove it still had the whooshing/bearing noise, so I figure either there is a problem with the water pump or the WD40 was enough to get rid of the squeaking but not enough to "fix" it completely. It wasn't exactly spinning nice and freely when I put the WD40 on it.

 

Re: A dumb question about coolant

I sprayed WD40 on it when I had the belt off earlier and started it up and that squeaking was gone, but when I drove it still had the whooshing/bearing noise, so I figure either there is a problem with the water pump or the WD40 was enough to get rid of the squeaking but not enough to "fix" it completely. It wasn't exactly spinning nice and freely when I put the WD40 on it.
DO NOT DRIVE THE CAR - until you replace the tensioner pulley -

the tensioner pulley has a permanently lubricated - sealed bearing -
over time the bearing has worn out - and most of the grease has either dried up or been expelled -

the WD40 is NOT a good lubricant - but it IS an excellent cleaning solvent -
spraying WD40 on that worn out bearing added a tiny bit of lube -
but it also dissolved the old grease that was still there -

if you drive the car now - I GUARANTEE that bearing will seize -

and when that happens the belt stops moving -
but the plastic drive pulley continues to turn - thus destroying/melting it -
causing a LOT more problems and expense -

 

The SMALL one spins; the BIG one doesn't.

 

Re: A dumb question about coolant

Hmm... I read somewhere that you can try to weed out pulley noises by spraying the bearings with WD40 to see if it stops the squeaking. And I guess it's technically true, because it did get rid of the squeaking, but they left off the part that it's actually bad for the bearing and you shouldn't drive it like that. I drove a couple miles after I did that but nothing happened, and my new tensioner comes tomorrow so everything will be okay.

Edit: I figured I'd go out and just take the tensioner off right now since you said not to drive it, and it actually spins free as a bird now. Way better than earlier when I could barely turn it at all. Although I'm guessing it's only temporary and once the WD40 dries completely it'll lock up like you said.

That being said, I'm pretty sure I found my "vacuum leak": https://www.youtube.com/watch?v=AJKL895E1E4

FINALLY! Also more good news, my water pump seems to be perfectly fine, so I don't have to deal with that headache.

 

Re: A dumb question about coolant

Hmm... I read somewhere that you can try to weed out pulley noises by spraying the bearings with WD40 to see if it stops the squeaking. And I guess it's technically true, because it did get rid of the squeaking, but they left off the part that it's actually bad for the bearing and you shouldn't drive it like that. I drove a couple miles after I did that but nothing happened, and my new tensioner comes tomorrow so everything will be okay.

Edit: I figured I'd go out and just take the tensioner off right now since you said not to drive it, and it actually spins free as a bird now. Way better than earlier when I could barely turn it at all. Although I'm guessing it's only temporary and once the WD40 dries completely it'll lock up like you said.

That being said, I'm pretty sure I found my "vacuum leak": https://www.youtube.com/watch?v=AJKL895E1E4

FINALLY! Also more good news, my water pump seems to be perfectly fine, so I don't have to deal with that headache.

=============================
https://www.youtube.com/watch?v=AJKL895E1E4
THAT is an absolutely DRY bearing that is worn out -
you will notice a BIG difference with the new one -

FIRST it will be absolutely quiet -

SECOND - it will NOT spin freely -

 

I'm installing my new water pump and I have another dumb question but I just want to be sure. Are the black tabs of the water pump supposed to be completely behind the silver tabs of the housing? My guess would be yes, but when I was putting it in just now it kind of "clicked" into place, and when I pull on it to get it to go further it doesn't move. Although I'm not pulling as hard as I can because I don't want to break it and I'm unsure if it's supposed to go any further.

Also, Sub, one of your pictures says the locator tang should be at 1 o'clock, but the instructions that came with the pump say it should be at 7 o'clock. I'm not sure which to believe.