Chevy & GMC Vans

For the third time in about a year Green has blown a water pump gasket.

I don't remember the other times, but this time it's the passenger side gasket. Any guesses what's causing these repeated failures?

Aaron-check both mating surfaces with a straight edge.Might want to consider form-a-gasket along with the gasket it's self.

I use a 3m cleaning disc on my 2" air grinder.

If it's the same pump that keeps blowing gaskets, check to see if the mating surfaces of the pump are true and there is no scoring on the block.
I have "always" used water pump gasket sealer on both sides of the gasket.
Let the sealer set up while the bolts are about 3/4 torqued. Once the sealer has had a chance to set up then do your final torque.
By doing this you will be compressing the half hardened sealer for a better fit rather than sqeezing it out from between the two parts while it is still wet and not creating a pressure fit.

Peter

Overtightening could cause this. I have no doubt you are getting the surface clean.

Did this problem begin with a pump replacement? I'd blame the pump in that case.

What gaskets are you using? I use the blue Fel-Pros. I very, very lightly (like a film) coat the gaskets with black gasket maker, and don't refill the antifreeze until the next day. I also coat the bolts with Rector Seal pipe dope, the bolts will leak if not sealed in some manner.

The other posts all make sense also, especially Kabey's one about torque.

Stop using gaskets. Put a bead of RTV on the water pump and be done with it. The RTV will fill any irregularities and will not rot away. As a side note, both surfaces have to be perfectly clean for a good seal.

Aaron,

I am having a problem locating a coolant leak on the 94LT.I took the top haft off of the shroud to see what looked like a W/P leak because it was wet on the drivers side of the lower front of the engine.So I sprayed it with brake cleaner and I bought from H/F a blow gun that you can extend to get into tight areas.Once I cleaned off the block,the W/P didn't seem to be leaking.The W/P was very rusty only on the driver's side.Seems it has been leaking for quite awhile and I never noticed it before.But none the less,no leaks from the W/P gasket or the W/P.So I cleaned from the intake manifold and the thermo housing down to to the W/P and it too was dry as a bone.I am looking on top and from the bottom and still I have a very small amount of water running down the front and along the oil pan rail to the bellhousing and dripping on the ground,but I can't see where the hell it's coming from.Then while I am laying under the van kind of cursing about all the things in my way to see,it stuck me.Mind you I am running it laying under it and looking on top and shutting it down to see what I can.I got to wondering if the W 4.3's had the same soft plugs/expansion plugs location as the V8's and the V8's have one just below the parting line of the front driver's side head.Somewhat close to the W/P and W/P gasket.There is a bracket that the power steering pump attaches to and I think on top the A/C pump is on it too.Makes it really hard to see it clearly.So I did what I could to spray it and blow it off and I now think that is the source of the leak.If that is true,it would make it seem like the W/P gasket had failed because the coolant is being blown all over by the fan and the wind at highway speeds.I am like my thread states going to Autozone to buy a dye coolant trace kit today to confirm the source of the leak mainly because to replace the soft plug would be a whole lot of work given I have to take off that bracket.

So now that I have posted all the above,my suggestion would be to clean the heck out of it and be sure it isn't a soft plug that is leaking making it seem like the W/P gasket.Check real closely behind the drive system brackets where those soft plugs are and are very hard to see the leak.

I replaced the water pump gaskets the next morning. Did it in the parking lot of the restaurant that I managed to limp it into the night before, had a bunch of people ask if everything was alright. Luckily I had grabbed my tool bag and had most of the tools needed to do the job, only had to buy a big adjustable to remove the fan. Leaking gasket looked torn up. Hopefully I don't have to do this job again any time soon.

Stop using gaskets. Put a bead of RTV on the water pump and be done with it. The RTV will fill any irregularities and will not rot away. As a side note, both surfaces have to be perfectly clean for a good seal.

Skips right once again. First time I ran across seeing this done was when I lived in north Alabama. My next door neighbor was building a motor for his El Camino and was putting the exhaust manifolds on with no gaskets. I asked him about that and he said,,why should I use a gasket,,both surfaces are machined and will mate up with no leaks. Will also work on expensive headers that have a thick flange. It really will.

Aaron,

There is tons more going on here than gasket failures.A gasket should seal and the only way it isn't is surfaces that are not flat.I use a 3m 2" pad on my die air grinder to cure that.But I would take the W/P you bought and have a serious talk with them.Tell them it's junk and you want another one.I think you get a free pass not to be nice about it either.Not your problem because you didn't have it before the pump you bought.Threaten them with if the next one fails,they will be paying for a replacement and the labor to have a dealership fix it.

You do need to close this chapter on the van.It's not you bud,it's the part.Because of that,you shouldn't have to fix their junk pump.

Gary, it's the stock pump. Appears to be in good condition, bearing feel good.

Drove the van around all week and another trip to my parents. On the way back about 15 miles from home Sunday night the van jumped from 177° to 207°. Van held that temp the rest of the way. Yesterday morning I checked the radiator to find it low, added water to it, and looked under with a flashlight. Leaking again. Argh!!!

Pulled the pump and T-stat after work, then flushed the system. Installed the pump, no gaskets this time, just the water pump specific RTV gasket maker stuff. Going to let it sit the full 24 hours before I fill the system with water. If it holds till the end of Sept I'll drain the system and fill with 50/50.

Wow Aaron, you have the patients of a saint.

Peter

wow i've never heard of one person going through so many gaskets

Me neither.

1Gary wrote:
...Tell them it's junk and you want another one.I think you get a free pass not to be nice about it either.Not your problem because you didn't have it before the pump you bought.Threaten them with if the next one fails,they will be paying for a replacement and the labor to have a dealership fix it...

And tell 'em "Get off my lawn".


Lump

Aaron,

Thought you recently replaced the W/P.Never the less.It has to be a substantial uneven surface on the water pump or w/p bolts that have threads not completely up to the head of the bolt and not tightening down the W/P(like the bolts have to go in the holes they where in from the factory) or bolts that are stretched that far as to not tighten the pump down.

The w/p not being flat is the plan "B" use of the 3m pads on a air grinder.