Oil leak at waterpump on ecotec engine - Maintenance and Repair Forum

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Oil leak at waterpump on ecotec engine
Saturday, June 08, 2013 11:48 AM
Hello Everyone,

The oil is leaking from the mating surface of the waterpump and the front face of the engine on my 06 Cavalier. The car has about 60KMiles on it.
Has anyone had that before?
Is that the gasket or the oil seal around the shaft?
Looks like an ugly job to fix it!
I have not checked if I have oil in the coolant.

Thanks, Peter

Update, Re: Oil leak at waterpump on ecotec engine
Thursday, July 04, 2013 5:12 AM
Just an update.
Went to the dealer to look at the parts diagram of the waterpump ant its seal. It is a molded special O-ring between the waterpump and engine block sealing the oil from coming out.
It is about 3 hours work for the dealership to replace it.
They mentioned they had seen it seeping.
I tightened up the bolts attaching the waterpump, they were not loose, but I did not check with a torque wrench.
I will keep an eye on things how they develop.

And the car is an '05, that is a typo in the original post.

Peter
Re: Update, Re: Oil leak at waterpump on ecotec engine
Friday, July 05, 2013 9:31 AM
Sounds like you have an issue... Just tightening the bolts will not fix...



Re: Update, Re: Oil leak at waterpump on ecotec engine
Sunday, July 07, 2013 7:34 AM
BuiltNBoosted wrote:Sounds like you have an issue... Just tightening the bolts will not fix...


I agree with that!

Theoretically, an o-ring type seal is more reliable than a paper or some other fiber gasket seal. It is a solid design, but it looks like the quality assurance was slipping.
Such a seal relies on the proper compression on the o-ring. The water pump body is a die cast piece, and the groove for the o-ring is cast in and not machined. The depth of the groove depends on how much is machined off from the face of the rough casting.
The other factor is the thickness of the o-ring.
Looks like some of these parameters were creeping out of tolerance resulting in the failed seal.
As mentioned replacing that seal does not look like fun. First the water tube from the water pump to the thermostat need to re removed, then the water pump can be removed. The water pump is driven by the chain drive of the balancing shafts, and the sprocket need to be removed from the shaft of the ware pump. There is a special tool, a plate, that holds the sprocket and the chain while the water pump is removed.
I am lucky, my car has manual transmission. Cars with automatic transmission even the exhaust manifold need to removed to be able to remove the water pipe from the water pump.
As mentioned, the screws holding the water pump to the engine were not loose, but the bolt where the leak is was certainly not as tight as all the others.

Peter
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