Raw water pump paper gasket or silicone?

[dawg6]

On my 1987 12v71 raw water pump I took the cover off to check the impeller and cleaned everything up good.

Previously there was no gasket (a previous owner had sealed the cover using silicone). I bought new gaskets from dieselpro.com and reassembled everything and was getting a slow drip next to one of the bolts.

I slowly tightened the bolt down and the bolt snapped. No biggie, took everything apart, extracted the broken bolt and put another new gasket on.

Again it leaks and when I try to tighten a (different) bolt snapped.

I replaced with a new cover thinking maybe the old one was just worn out (previous owner already had a couple new ones on the boat) and this time I try RTV sealant instead of the paper gasket. This time it still drips but instead of a bolt breaking a (different) bolt ends up with stripped threads, so I have to tap it out to 5/16.

But now I'm at the point where I have to wonder if I'm doing something fundamentally wrong? Am I overtightening the bolts or is there some other issue I should be correcting? Should I be using silicone instead of the paper gasket? Maybe I just need to put a lot more gasket material on so that the bolts don't need to be quite so tight?

 

[JD5652]

If you are snapping bolts and stripping out holes, then I would say you are definitely putting too much torque on the bolts.

Are you using a torque wrench?... or just doing it by feel?

If I was getting a leak, I would use the paper gasket in combination with high tack gasket adhesive

Amazon.com: Permatex 80062 High Tack Gasket Sealant, 4 oz. , Black : Automotive

Or use the Red RTV in combo with paper gasket...

Amazon.com: Permatex 81160 High-Temp Red RTV Silicone Gasket, 3 oz : Automotive

You could also try to double up the paper gasket....

 

[dawg6]

Thanks. Not using a torque wrench.

I'll try the paper gasket plus RTV and see how that goes.

 

[Captain Ralph]

If you have a large flat file and know how to use it, smooth over the back plate and the housing. It takes just one scratch to raise up a lip and cause a leak.

Paper gasket and grease usually works for us.

We use RTV when we have to on damaged surfaces.

 

[cww]

Personally I like dieselpro, but their gaskets and seals are crap. Order it from your local Detroit diesel dealer and I’d bet you $1.00 it doesn’t leak.

 

[SKYCHENEY]

Is the impeller fully seated/ all the way in there? The original "bolts" on these pumps were actually slotted screws so you couldn't over-tighten them, but most have replaced with bolts. I would make sure that impeller is pushed all the way in or put a straight edge across it to be sure.

 

[whoover]

If you try to double the gasket you will not get it to prime. Loctite gasket maker and go around each bolt hole. It's more clean up at the next impeller change buy it will seal.

Walt Hoover