Mikey65

So most of you have read my ongoing saga with the water pump and blowing gaskets again and again. I just finished putting everything back together, and ran the car mildly for the past couple days putting about 50 miles on, running through some heat cycles, and making sure the bolts remained tight. Everything seemed ok for the most part. So today I warmed the car up again, got on it a little more... and drove home. In the driveway I pulled the motor to about 6000RPM to see how it would do. Everything seemed fine.. no fluid, checked the bolts, and everything seemed fine. THen I noticed this:









While it hasn't leaked yet, or blown the entire gasket, it looks as if it's on it's way. The two previous times have been on the top passenger side, and this one is on the top driver side. What gives??

I have been through 2 water pumps, the pulleys all match a L79 and are correct, fixed the alternator bracket, made sure the fan clutch was centered, replaced the coolant cap.

I assume my two problems could be either the pump or block mating surface are not square (allthough I checked this) or excessive pressure is pushing the gasket out. I can't see it being the mating surface of the pump or block as I have been through a few pumps, and this time the gasket is pushing out on the driver side. What are the odds that both mounting surfaces are not level? As for excessive water pressure... I have no idea if it's the case, or what would cause it. Help.

MikeM

Those gaskets don't look compressed. Are you using paper gaskets or cork?

nassau66427

Just a WAG. Do the waterpump bolts go into blind holes? Those look like aftermarket bolts. Could they be a little bit long? If that is the case, they could be bottoming out and giving you a good torque reading but not providing sufficient clamping. Another thought. Do the bolts have sufficient threads or are you running out of threads before the bolt is in far enough?

midyearvette

i have been following this with some caution as i have never seen this problem before.......it appears that the bolts are over tightened.....that is why the gasket is split??...i am not saying i am correct but this is getting silly and i am sure very frustrating for you.....several years ago at a sema show, a dana felpro rep gave me some proto type new gaskets for a small block chevy that looked to be indestructible......he said they were re usable...they are at a friends house and i will be there tomorrow..pm me an address and i will fed x them to you....i dont know if you have a warp problem but after replacing the pump if there is a fitting problem it could be the block although i have never encountered this but maybe others have...if it is a fit problem, i think these gaskets might do the trick....i dont know if they ever produced them , they look bulletproof.......if you are using a torque wrench, i think you should simply tighten by box end firmly .........

Mikey65

They are the bolts that came with the pump. The previous bolts that I used on other pumps were a tad shorter as I was using grade 8 and it was all I could get locally. These bolts came with the edelbrock pump though. I would assume that the bolts they supply you are designed to work with their pump, and a SBC has standard depth on the water pump holes?? Either way, the other bolts I used, as I said were a tad shorter.

The gaskets are paper Fel Pro gaskets.

GCD1962

With the pump off and everything cleaned from old gaskets, you can hand press the pump against the motor mount to see if it rocks at all. If it seems to be flat you could double check by trying to slide a very thin feeler gauge at various points (just to check that there are no gaps even though it appears to be flat). On the gaskets, put a thin layer of #2 Permatex on each side. The #2 is sticky and stays that way. As others mentioned make sure the bolts don't bottom out. Criss cross on tightening and then final torque once up snug.

vetrod62

I have seen this happen before. All good comments above. But is there a bypass for when the t-stat is closed? If not the pressure from the water pump will push the pump gaskets out. Also if your camera has Macro, looks like a flower, it will make close shots look clear.

65 vette dude

Wow! I can't believe your still dealing with this. Were both water pumps you tried Edelbrock? If so, I think I would get a GM rebuilt cast iron pump and give it a try. Why don't you give Arthur Gould a call. Nice guy, and he's been rebuilding water pumps for 25 years. He might have the answer for you. I bought the correct pump for my L79 from him, installed it with dry, paper gaskets, and didn't use a torque wrench. No leaks. That was 6 months ago.

Mikey65

Bypass? No I don't have a bypass. Do you have pics of a bypass for the stat? No idea if the stat it sticking or not.

I have already checked all the above...many times over. Yes both pumps were edelbrock. I will try something else this next time, but don't understand why that would be it... many people use this pump.

mechron

OK, mikey. lets see if i can solve your problem since i've been following your problem from the beginning. there are short and long water pumps, are you shure you have the correct length bolts with all the brackets installed???
i have replaced thousands of water punps and never had this problem.
the water pump bolts to the block with 3/8s bolts, so 3/8s into the block will give you max. strength. if the bolts are a little too long they will cantact the bores in the water jacket. if the non-threaded portion of the bolt (incorrect bolt), IT WILL NEVER SEAL. the water pump will leak.
measure the bolts beyond the WP surface and find the correct bolts...

AZDoug

Or, just add a simple lockwasher (preferred) or flat washer (in a pinch) under the bolt head.

Doug

TopLess62

And make sure there isn't part of an old bolt broken off in the hole...it could be very short so take good measurements of the hole depth at all 4 spots.

aworks

Thats my take on this also.
Never depend on any aftermarket vendor to give you the correct hardware. Water pump bolts can be a PIA. Most pumps will be diff. from each other. When you try using hardware store bolts they tend to be to long or to short. Or as mechron stated the shank of the bolt may be against the block before it has pulled the pump up tight. I always check length before installing any pump. If they are to long you could be hitting the back side of the bore. Many times I have had to thread my own bolts. I would also lose those crapy paper gaskets. They do work ok but a good set of Perma seal gaskets from Felpro are a much better choice.


As mechron said I have installed many SBC and BBC pumps and never had one leak. Your are missing something. Go back and check everything again.

crw41

On your next install use the blue permatex gasket former on both sides (light coat)

NEVERL8

I had a water pump sealing problem on my L79 after a rebuild, similar to what you are experiencing. My water pump would start leaking after a couple of high RPM excursions. After a lot of investigation I found the root cause of my problem was a vibration in the fan/clutch assembly that showed up at high RPMs. It was hard to detect because there is so much happening at high RPMs in these old cars. I originally blew off the vibration as exhaust pipes hitting the frame, driveshaft issues, transmission vibration, etc., etc. In my case the fan clutch was not correctly mounted onto the water pump shaft. This caused a slight imbalance in the fan/clutch rotating mass that you would only manifest itself at high RPMs. It was enough to torque the water pump mounting sufaces and cause a small leak. I chased this for several frustrating weeks before I figured it out.

I agree with much of the advice given previously. Though it did not end up being the root cause of my problem, it is something you still need to check.

Check to make sure the mating surfaces of the pump and engine block are perfectly flush. With all the mating surfaces clean hold the water pump up against the block and make sure it does not rock at all. It needs to sit perfectly flush up against the engine block.

Clean the threads going into the engine block. I used a bottoming tap and then blasted in some Brake-Kleen. With no water pump on the engine, take the pump bolts and screw them in until they bottom out. Measure the distance between the underside of the bolt head and the surface of the block (I used calipers but there are other ways to do it). Then measure the thickness of the water pump flange for that particular bolt location. Do the math and make sure the bolt is not bottoming out when you mount the pump.

If all this looks good, and your fan/clutch assemlby is balanced, then mount the water pump with quality gaskets and apply a thin coating of sealer (I used Permatex) and torque down according to specs.

Frankie the Fink

Sounds like you need to:

1) Check the flatness, integrity of all the mating surfaces
2) Make sure you have the right bolts of proper hardness and length
3) Ensure there is not a broken bolt in any of the holes
4) Make sure you have a quality gasket set
5) Use a quality gasket sealant compound
6) Properly torque bolts on installation and re-torque bolts after running for a while.

And finally I'd be tempted to run without a thermostat for a while to make sure there is no restriction creating undue pressure in the system.

Have to say - this is a new one on me. I've replaced more than a few water pumps on GM products and the worst problem was snapping off some bolt heads during removal.

GCD1962

If it took that much pressure to push the gaskets out I would think the hoses would be bulging before that would happen.

jim lockwood

A simple way to answer the question about whether the bolts are bottoming out is to unscrew them, remove the washer, and put them back in. If they will readily seat against the body of the pump, there is no thread length or shank length issue.

And I agree with another poster..... it'd be a lot easier to figure out what is going on if your pictures were in focus.

Jim

Mossy66

Are the bolts still at proper torque? On my car, when the fan clutch was not centered, it was the bearing that failed, never the gaskets. I don't know if that would rule out vibration or not. Maybe it has something to do with it being a high flow water pump? Too much pressure at high rpm? I would be tempted to get a stock water pump from your FLAPS or maybe someone on the forum that lives close by can lend you a spare and try that. At least that would rule out the pump if it still happens.

I'm sure you checked the bolt length enough times by now to be certain that they are not too long.

What about a leaking head gasket or something that would cause the cooling system to get pressurized from cylinder pressure.


Is there some easy way to pressurize the cooling system to test this?

I'm out of ideas.

Hang in there, it's frustrating now, but you will conquer this problem.


Gerry

Shurshot

I mentioned that way back when in this ongoing saga and there were others here that voiced the same concern.

Doug