Diagnosis help/opinions needed...

[78SilvAnniv]

Well, today was the third water pump we installed in 5 days, doing the work ourselves. (...when Kenny picks out the tools for me, I can help with the wrenching and I'm also good at retrieving small, dropped items from under the car...I am also the designated part-painter...)

Original pump was making a loud, squealing noise.
1st replacement was installed, brought up to temperature and HAD A LEAK! There was a crack in it so we returned it.
2nd replacement, same numbers on the box/receipts, had too much material around it and the belt pulley would not spin. At all. Kenny tried removing some of the material, but was afraid to remove more and damage its' structural integrity. (I did take 78 for a test drive up the street and her temp was fine, did come up a bit (205) as I slowed to enter the driveway but returned to normal (195) as I parked it. Pulley was stilll rubbing on pump so we removed it.)
3rd pump (correct fit) installed today.
*also installed new 190 t-stat with 2nd pump installation. Coolant/water mix is appropriate.

Here is where we are encountering our problem.
Third installation was completed in record time, since we are so experienced now, and the engine was brought up to temperature. Normal operating temp is 195. Temp climbed to 220? or thereabouts. Revved it a few times (thinking there was an air pocket) and that didn't work. Kenny removed the radiator cap and added more water. Temp came down, but then climbed again. Everytime he removed the cap and replaced it the temp would come down. Kenny thought the water in the radiator was pressurized as it seemed to come out more forcefully than it usually would when not overheated. (he was protected when opening rad cap) This third water pump was also making a squealing noise after it had reached operating temperatures.

We are afraid we have a head gasket problem at a water jacket. No water/oil mix in the radiator or oil pan. No external leaks. Neither of us noticed any steam from the tailpipe, and plan to check that tomorrow.
Someone we called mentioned detonation, but I would think that would have surfaced before the water pump changes. With installation of 1st pump, Kenny removed the t-stat. Installation of 2nd pump we installed the new 190 t-stat.

I have had no temperature deviations from normal until the second pump was installed (could have been because the pulley was hanging up on the pump) and then again today with the 3rd water pump.

Does anyone have any ideas as to what we are missing?
Heidi

 

[Scott Winebarger]

Find another place to buy your water pump? It was fine before wasn't it? Stay far away from Autozone and Advance when buying a pump... Low prices means lowest bidder got the job rebuilding them. just .02

 

[wishuwerehere82]

Get a GM or NAPA pump. Something is not right with their computer if they are giving you a part that works different, or doesn't fit the same as the original. There's no reason to suspect that anything other than the pump is wrong.

Put the original thermostat back in. If it wasn't broken, no need to fix it.

Good luck!

 

[bill81vette]

do you still have the old t-stat? try putting that back in,or get another t-stat from a more reliable source.


good luck,bill

 

[Dave Z]

Here's a silly little idea. Since removing the radiator cap each time seems to bring the temp down, how old is the radiator cap? Replaced mine with new and it brought down my temp from 220 to 200. Then I replaced the thermostadt and that brought it to 195. Another 0.2 cent opinion.

 

[Vettehead Mikey]

You need get yourself a decent quality water pump. If the problems still continue it's most likely air in the system. Do not open the cap once the car is warmed up- it serves no beneficial purpose and is very dangerous.

With the car cold, fill the system as full as you can via the radiator. With the cap still off, squeeze the upper radiator hose a few times, this will usually burp out a big pocket of air. As the level drops, replace with more coolant and repeat till no more air come out. Put the cap on. Make sure your overflow bottle is full, even overfilling will not hurt other than possible spillage.

Take the car for a short ride till it comes up to temperature. Let it cool to ambient temp and see if the level dropped in the overflow bottle. If so, then the system has expelled additional air. Remove the radiator cap to confirm that it is still full. It make take four or five heat/cool cycles till the system finally gets the last bit of air out.

 

[curtis]

Sometimes the lower priced thermostats don't always open at the correct temperatures. I got a pressure balanced one(performance) for $14 that solved my problems with fluctuating temps. If the stat is intalled upside down it won't work correctly either.

 

[78SilvAnniv]

First two water pumps were from AutoZone and the last one was from Napa.
T-stat was from AZ. We are pretty sure the t-stat is installed correctly. The curved part is on top while the spring is on the bottom down-side, right? (just like the picture on the box)
I don't know how old the radiator cap is, but that may make a good purchase...won't hurt to try!

Original water pump was working correctly, cooling-wise, but was squealing and making noises to warn us of its impending demise and this is why we replaced it. Thank you for the suggestions and I'll keep you informed of what we find.
Heidi

 

[Scott Winebarger]

Bring it up here and I'll fix it for you... Pretty sure i can get Andre in on it too...lol

 

[Barryki]

Sounds like radiator cap to me?

Make sure proper pressure and as cheap as they are take the gamble.
Since you have two different brands of water pumps on the car, I think you can eliminate that as the problem.
Barry

 

[curtis]

Heidi, My Haynes says "the spring is normally directed into the housing."

 

[78SilvAnniv]

Bought a new radiator cap this afternoon. Raining today and I don't know if we will work on it tonight or wait until later this week.
Heidi

Thanks for the offer of help if I brought the 78 up, but Kenny actually likes being The Mechanic for this vette.

 

[78SilvAnniv]

Problem solved!

KISS Always remember to Keep It Simple, Stupid.
We did put in the new radiator cap, and then Kenny went back to the basics and when he checked timing, he found that it was waaaay out. Now we're running good at idle and all rpm ranges with no overheating issues. Temp stays below 200, like usual.

Thank you for all of your suggestions!
Heidi

 

[wishuwerehere82]

YAAAAAY!!!!

 

[grapeknutz]

How did the timing move so far out? was the distributor loose?

 

[Scott Winebarger]

Congrats , ready for Cruisefest now?

 

[78SilvAnniv]

We had recently replaced the distributor and we probably didn't get it timed correctly at that time, though it ran fine. Either that or it did work loose. I didn't ask Kenny how it happened.
I'm just happy I'm on the road again! I don't get to enjoy very many activities outside the house and one of my greatest joys is driving the 78 when I am able.

Sorry, no cruisefest for me. :cry Health problems prevent traveling more than an hour or two by car so I stick to local BBQs and get-togethers with the SouthEast Gang.
Thanks again to everyone who had suggestions. I am SO happy it isn't a blown head gasket. (whew!)
Heidi

 

[Scott Winebarger]

Maybe we can have a get together in the southeast sometime. I am from NC , stuck in Ohio. Long story but I don't know how much more long distance is left in me either ...But till I can't go anymore I plan to see all i can. I am so glad you got you car fixed !

 

[78SilvAnniv]

...I don't know how much more long distance is left in me either ...But till I can't go anymore I plan to see all i can...

It's terrible, getting older.
I usually feel like I'm 27, but there are days when I feel like I'm 72! :eek I've got 40 in my sights...the hill is still a decade or two away.
Heidi

 

[76 Sting]

Here's a silly little idea. Since removing the radiator cap each time seems to bring the temp down, how old is the radiator cap? Replaced mine with new and it brought down my temp from 220 to 200. Then I replaced the thermostadt and that brought it to 195. Another 0.2 cent opinion.

Hey all
I know this post was answered on the following page but I just read the above statement and wondering how this works. Meaning replacing the cap brought down the temp.

if I can not ge the answer i will create a new post, butr would rather not.

Thanks