C1 Water Pump leakage fix?

[Dave Christensen]

It has been six months since the last time I replaced the gaskets between the water pump, motor mount, and engine block. They are leaking again. I have torqed them up about once a month since I replaced them last summer. I have tried no sealant, Permatex, and silicone rubber on the gaskets. They still leak after about six months/3000 miles irregardless of what I do.

Does anybody have any suggestions on how to avoid this bi-annual repair? It is a PITA! I am thinking about cutting O-ring grooves in the motor mount and using O-rings instead of gaskets. Has anyone tried that? Any reason not to?

thanks
Dave Christensen

[Joe L.]

Re: C1 Water Pump leakage fix?

Dave-----

I think that the o-ring would be a perfect and permanent solution to the problem. I can see no "downside", whatsoever, to installing one as long as you have the capability to do it or have access to someone who can do it.

I expect that part of your problem likley relates to the design of the early small block water pumps. The type with the "flat plate" rear are very difficult to seal. GM went through several iterations of design before settling on a type with stamped-in ridges on the sealing surfaces. This is the ONLY type that will seal well. Several years ago, I did a little experiment utilizing several of the different rear plate designs on a small block waterpump. I had made up a testing set-up so that I could pressure-check the pump after installing each of the waterpump gaskets.

I found that NONE of the plates, EXCEPT the last type with the stamped-in ridges on the sealing surfaces, would seal when the pressure exceeded 7-10 PSI. So, that's the plate that I recommend that you install as an alternative to o-ringing if you don't already have one.

This type plate should be directly retrofittable to your waterpump and they're easy to find on later small block waterpumps. If you want to maintain the flat plate type version for "originality" purposes, then I think that the o-ring is the best solution.

[Dave Suesz]

I gotta think...

something is warped. My 265 had no pump leaks from 1972 until 1990, when I worked on the timing chain. Hasn't leaked since then, either. Check for true mating surfaces.

[Mike E.]

Re: C1 Water Pump leakage fix?

Back in my early years, I had a similar problem with my 62 fuelie. Problem was mostly me, because I wasn't observant. The front mount had corrosion the precluded the surface from sealing well for any length of time.

[Dave Christensen]

Re: C1 Water Pump leakage fix?

Joe,
O-rings it will be. I don't have any corrosion on any of the surfaces. The motor was fresh 18 months ago. I bead blasted and painted the mount, and the water pump is new. It is possible that the mount is warped. I need to put it in a mill to machine it flat. I might as will put it on the rotary table and cut grooves for O-rings at the same and be done with it.

What plate are you talking about with the stamped in ridges? Is this the motor mount plate? From your description, it sounds like you are talking about a plate on the water pump. I have the correct 3704911 1956 pump and there are just flanges in the casting, no plate.

thanks
Dave Christensen

[Mike M.]

Re: C1 Water Pump leakage fix?

Dave: i have a 364 ci 548 cast "283" making about 400hp in my 57 vette. prior to installing the cheater engine, the 283/283 never leaked between engine, engine mount and water pump. once i installed the 364 ci bored and stroked mouse, it leaked after a couple of 1/4mile runs. came home , cut new gaskets out of old, thick paper gaskets(about 3x as thick as that which comes in an overhaul gasket set) Smeared a little "Right Stuff" by permatex on the 4 home-made gaskets, re-installed the pump and engine mount and must have about 20 1/4 mile passes and a half dozen auto-X's on the setup. no more antifreeze on garage floor. I suspect the cheater engine , with more torque than the baby 283, stressed the cheap, thin gasket material. Joe is referring to the plate on the backside of the water pump. he's, as usual, 100% correct in noting the gusseted pump plates least likely to leak at pump/plate interface. good luck, mike

[Jon #40768]

Re: C1 Water Pump leakage fix?

O-rings are a good way to go. O-rings also come in differing types. Go to a good hydraulic shop and you will find that high temperature o-rings exist. The high temp ones are usually color coded.
Jon

[Peter Cipriani]

Re: C1 Water Pump leakage fix?

Dave,
I had this problem. I replaced gaskets, it continued to leak. I found that one of the water pump mounting holes on the block (drivers side) had a small corroded hole at the bottom into the water jacket. I dried it up and filled it with permatex gasket sealer.
Poke the mounting holes with a scriber or scratch awl to see if they are corroded.

[Tom Spurgeon]

If you have the resources. . .

O-rings will work. However, the method that Mike M. describes is the method we used in fixing all water pumps to engine mounting leaks. Never had a problem after... Hope it helps.
Tom Spurgeon

[Joe L.]

Re: C1 Water Pump leakage fix?

Dave-----

The plate that I was talking about is the water pump backing plate. I thought that I understood that was where your leak was coming from. Looking at your post again, I see that you may be talking about the seal at the "legs". I think that it will be more difficult to seal these with o-rings, but I'm sure that it can be done.

[Bernard M.]

Re: C1 Water Pump leakage fix?

When you put it back together, here are a couple things to check. All but the top left bolt passes into the water jacket so be sure to seal the threads on the attaching hardware. If it's leaking there, o-rings won't help. The top left bolt can bottom out and leave that leg loose enough to leak, be sure to use correct length hardware (the three short bolts should be 1-7/8" long). Good luck.

[Dave Christensen]

Re: C1 Water Pump leakage fix?

I don't think that I put any sealant on the threads for these fasteners. It appears that the coolant is leaking from around the head of the one of the bolts - top drivers side. What sealant do you recommend? Permatex? Silicone?

This may be my problem.

thanks for your help.
Dave Christensen

[Bernard M.]

Re: C1 Water Pump leakage fix?

I bought a Permatex brand high temperature thread sealant. Any parts store should have it. I hope it helps.