99 Chevy Suburban. I had a coolant leak from what I thought was a bad water pump, so I replaced it. I still have a leak and appears to be coming from the cover behind the water pump but its hard to tell. I don’t see any leakage looking down from the top of the engine. However, looking underneath, coolant appears to be coming from one side of the cover plate. Is this possible?
No, not possible…The cover behind the water pump is the timing cover…The timing chain and gears are behind it, lubricated with engine oil…There is a cover on the back of the water pump. Maybe it’s leaking. “Rebuilt” doesn’t mean much anymore…Use a hand mirror and bright light to see under the pump…
I wouldn’t have thought so either. Looking at other blogs, there was mention of water gallerys behind the cover which is why I asked. Anyway, the pump is NEW not rebuilt. I’ve tried using mirrors and lights but with all the ‘stuff’ around the front of the engine, its difficult to look in the nooks and crannys. Mystery continues, so if you have any tricks of the trade, I’d really appreciate it. Thanks.
Not by chance a diesel engine model is it?
A quick look at some pics of the gaskets involved shows coolant circulating through the timing cover on the diesel engines so it could be entirely possible the cover gasket is leaking between the cover and engine block.
No, its a gas engine (5.7L) but thanks for the reply.
Did this gasket get changed along with the 2 small ones?
The gasket shown in the picture is for the back plate of the water pump, so no, I did not replace it since the pump itself is new, not rebuilt.
I’m running out of ideas unless there is some fluky problem with that gasket between the plate and pump.
My memory is very very hazy on this but I vaguely remember running across something like this on one of my project cars a few years ago. (Ford 5.0)
The gasket between the pump and plate was leaking and returning it was not a problem, although ripping it all back apart was an aggravation.
This would be so unusual though that I’d hate to recommend tearing this thing back apart unless it was known for a fact to be the cause. In the case of my Ford it was about a 90% certainty so that’s why I bit the bullet and disassembled it again.
Any chance of obtaining a cooling system pressure tester from AutoZone, O’Reillys, etc. (their tool rental program) and having someone pressure the system up while you eyeball things as closely as possible with a flashlight and/or a mechanic’s mirror?
On these engines there is that large hose that snap fits into a cast fitting on the manifold, I have seen this line (o’ring sealed) leak, give it a look.
Replacing the water pump with a new one doesn’t mean that the work was properly done. Was the mounting surface on the engine cleaned thoroughly? Was the mating surface on the new pump cleaned and coated with a tack film, NOT RTV. Were the mounting bolts run in and tightened diagonally in stages?
Also, NEW water pumps fail. Parts houses are selling really cheaply made new pumps from China that are failing out of the box.
Oh my! this is embarassing but thought I’d confess anyway. One of the gaskets tore during the initial installation. All is well…Thanks to all!
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