Water pump leaks after changing impeller? (PCM 351)

[SierraDump]

I changed the impeller on my water pump. I have the PCM 351 Ford motor. When I fired it up, it would leak when I turned the hose water up... The water pump has 2 bolts that hold it to the motor, and 3 little 7/16 or 1/2 bolts that hold the cover on... There is a rubber O-ring on the pump/water side, and just a flat metal gasket on the other side... doesn't seem like a good design but what do I know...

How tight do I tighten the 3 bolts that hold the case together? I torqued them down to like 10-12 ft/lbs but felt like they were going to snap if I went tighter.

[Chicago190]

Could the pressure from the hose be causing it to leak? You could disconnect the hose from the raw water intake and stick it in a 5 gallon bucket to see if it only leaks when pressurized.

[coz]

I changed the impeller on my water pump. I have the PCM 351 Ford motor. When I fired it up, it would leak when I turned the hose water up... The water pump has 2 bolts that hold it to the motor, and 3 little 7/16 or 1/2 bolts that hold the cover on... There is a rubber O-ring on the pump/water side, and just a flat metal gasket on the other side... doesn't seem like a good design but what do I know...

How tight do I tighten the 3 bolts that hold the case together? I torqued them down to like 10-12 ft/lbs but felt like they were going to snap if I went tighter.

Don't crank those little bolts too tight or they will snap, they're brass. You could replace them with stainless bolts from home depot or boat place that are tougher and won't snap as easy. Good luck :D

[SierraDump]

Don't crank those little bolts too tight or they will snap, they're brass. You could replace them with stainless bolts from home depot or boat place that are tougher and won't snap as easy. Good luck :D

I think I read that replacing with stainless bolts will actually strip the housing???

I seem to think too that it may be the pressure from the hose?

Is there supposed to be just 1 O-Ring in the pump? The back side is just a metal to metal mating surface, that doesn't seem like it would seal very well?

Wondering if I should buy a new metal plate and what looks like a cork gasket that SkiDim sells???

http://skidim.com/prodinfo.asp?number=R109029

http://skidim.com/prodinfo.asp?number=RM0125

[bigmac]

Don't crank those little bolts too tight or they will snap, they're brass. You could replace them with stainless bolts from home depot or boat place that are tougher and won't snap as easy. Good luck :D

Although the pump body is brass, so with stainless steel bolts, overtightening would instead lead to a stripped pump body.

[WilliM1940]

It is easy to catch the o-ring out of its track which will cause leaking. There is also a paper gasket in the assembly which you seem to be missing, go to ski dim to locate it.

[WilliM1940]

Sorry, looks like you found it. Last year I forgot this also and substituted a light layer of silicone in its place.

[ski_king]

Mine dosn't have the gasket, just the o-ring. If your is leaking, I bet the o-ring came out of the groove as you put it back together.

The bolts on mine are steel and the body is brass.

I changed my impeller last week and manage to break one of the bolts. It appears to have been fatigued from assembly and disassembly every year for 26 years and the lock washers were compressed flat, so I replaced all 3 bolts and lock washers.