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New Water Pump Still Leaks

The car is a 1988 Mazda with a 4-cylinder 1.6L B6 engine. I noticed earlier in the year a puddle of coolant under the engine near the crankshaft pulley. Since it was time to replace the timing belt I bought a replacement water pump. I did note that the bottom right bolt holding on the original water pump came loose with not much effort. Pulled the old water pump off and saw what appears to signs of leaking at the gasket with rusting of the mating surface. Here's a picture of the mating surface:

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Scraped off the old gasket, put the supplied new gasket in place, bolted the new water pump in and torqued the bolts to spec (17 foot-pounds), put everything back together, poured new pre-mix coolant into the radiator, and immediately start to hear dripping at the water pump!

I checked all the bolts and even made the bottom bolts tighter, still I see a drop of coolant appear at the bottom right of the pump. I figure if it can't hold coolant with the engine not on, it's not going to hold under pressure and heat. So I go out and get some Permatex gasket sealer made just for water pumps. Use it all around the engine mating surface and the attaching bolts, reusing the gasket that leaked also. Put it all back together again and the coolant seems to be holding - sort of. I'm still seeing about a tablespoon of coolant collecting at the bottom of the engine after the car has been driven and sitting for the night.

The Permatex directions cautioned to not overtighten the bolts or the sealant will squeeze out and won't do any good. I just don't know what to do. Does the engine surface that contacts the water pump need to be sanded down to bare metal? I was afraid to get too aggressive with a chisel and scratch the surface, causing more problems. Is there a tightening sequence for the bolts? More gasket? Permatex form-a-gasket? I'm very sure the water pump itself isn't leaking, it's coming from the joint of the pump and engine, I just don't know how to make a tight seal that won't leak. It almost appears by design that the bottom right bolt is too far away to pull the water pump close to the engine.....

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Reply to
George Orwell
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It does look like there is still some crap or rust on the mating surface that needs to be scraped off; can you use a straight edge to verify that the surface is flat? Also, could there be some material in bottom of the bolt hole that is keeping the bolt from pulling the water pump body in; you might try a tap to chase the threads and blow out any loose junk.

Ron

Reply to
no_one

You expect -that- to seal?

Reply to
aarcuda69062

Sure that's one of those Japanese high quality cars. It can't possibly have a defect.

Looking at that hole on the bottom, it almost looks like it has been partly stripped. Looks like a job for a Time-Sert. I would REALLY clean that surface off first and see if there is any real damage to the block. It also looks like you need to change the coolant more often.

Reply to
Steve W.

The car is 20 years old, Steve.. Has nothing to do with Japanese quality.

That gasket surface is not clean, OP. Dont gouge it, but clean it down to bright flat metal.

It is a good idea to chase the threads with a tap as was mentioned earlier. If you have bolts with bad threads, replace them. If you have stripped the threads in the bores, you will have to decide if a new bolt or stud can be made to work, or whether you will have to use a thread renewal or replacement technique.

When you use a gasket sealer, some of them can tolerate coolant contact immediately after installation. Others, in my experience, need to be applied to the clean and dry surfaces, torqued into place and allowed to cure for several hours before they will do their job.

Reply to
HLS

Agreed... that.... needs a little cleaning and some sandpaper.... well, actually a whole lot.

--scott

Reply to
Scott Dorsey

All I hear form the rice supporters is that the Japanese vehicles are perfect and that they never have the problems that the domestics have. The AGE of the vehicle never comes up.

Looking at that bottom edge it looks like the gasket was glued in place.

That lower hole looks like a thread chasing isn't going to help. Not sure if Loc-tite form a thread would work there or not. It looks like all of those are open holes.

About the only ones that are rated for instant use are the older styles of varnish, or Perm-A-Tex brushable. ALL of the silicone types are meant to be installed, snugged, let cure, then torqued.

Reply to
Steve W.

Not the Modern RTV's.

Permatex says to install it's RTV silicone wet, torque it down immediately and wait 24 hours for a cure before using.

If you torque them 'after' they have cured, you just brake the seal and have to start all over again or live with a leak.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 'New' frame in the works for '08. Some Canadian Bush Trip and Build Photos:
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Reply to
Mike Romain

On a water pump, the factory put it in clean and dry. If you prep the surfaces nicely you dont need *any* sealant whatsoever. Goops have their place, but should be avoided if at all possible. Ben

Reply to
ben91932

Depends upon the application. Maybe generally true but not universally true.

Reply to
HLS

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