3sge phantom coolant leak

[Dale]

My 3sge (gen1 in an st162) has been leaking coolant, but only leaks it when the car has cooled right down after a long drive on the highway. I was guessing it was the water pump leaking as it seemed to be coming from behind the timing belt cover, and only leaking after a long drive having something to do with expansion/contraction of a seal that was nearly stuffed.

Anyway I pulled the timing covers off today to find out for sure expecting to see water coming from the weep hole on the water pump but it was dry!

I first thought thermostat housing but there's no water dribbling from there and it's dry underneath it on the mating surfaces, the bottom radiator hose isn't leaking either, nor the thermofan switch.

I took a couple of pictures of where it's first appearing before dripping down - circled in green is the area where it pools up first. - If you've read this far check the links!

http://dalec.clan-umr.com/celica1/tech/DSC00527.JPG
http://dalec.clan-umr.com/celica1/tech/DSC00528.jpg

Sorry about the long winded post, I'm guessing its probably the water pump leaking where it seals onto the block but don't want to go pulling it off unneedingly..

[urantia]

hmmm i was going to suggest make sure you have a good watertight connection between your radiator blow off and coolant resivour as that will do as you described. But if your finding coolant near the water pump there, then i'd say it's the water pump, either mating surface to the block or thru the water pump pulley. The weeping hole in the water pump bieng dry would suggest waters getting thru the mating surface gasket instead.

And your sure its coolant and not power steering fluid there in the picture? (assuming you have red toyota coolant and red PS fluid)

Not many other places in that region to leak coolant except for that radiator pipe and you are positive it's not dribbling from there?

[Dale]

It does seem like it's most likely the mating surface, just so hard to tell in that spot!

Come to think of it though, the coolant res might have been close to empty.. even empty, which would screw around with the seal it would get.. and a couple of times after driving I've heard it bubbling away while the temp gauge is fine - so obviously it's run dry at those times, but once it fully cools there's water in there again would it running dry

The radiator was reco'd in 04 so it should be fine and I know it's not blocked or anything, the thermofan is running all the time but that's just due to the switch being stuffed.

Yeah it's definitely coolant, the first picture didn't show it too well I think the red stuff there was old oil or ink, the second one the coolant is a greeny colour (it's pretty watered down now from my topping it up with water ).

Pretty much positive it's not coming from the radiator pipe.. it feels dry as a bone!

I guess the coolant res running empty is either related to this leak, or related to the radiator cap being stuffed or something?

[urantia]

Hmm well i have had many instances where the seal between the radiator and resivour were not water tight, and it would expel coolant when hot and suck back in air when cooling down. (instead of sucking back coolant)

But still the fact that your finding coolant in that location indicates why your overflow is disapearing. (altho it's normal for it to suck in coolant from the resivour when hot and expel it back out when cool).

Spose its not easy to get the motor running upto temp and reving the engine to put the cooling system under pressure more and watch for where it could be leaking from?
(the general location of the leak, and stuff that has to come out such as the timing cover etc to get a good view sounds like it could be abit of a pain in the ass)

[Dale]

Wouldn't be too hard to get enough stuff on to get it running and up to temp.. but the problem is it only leaks when stone cold, when warm and under pressure it doesn't. Most of the time it won't leak at all, just the instances after it's had a long run out on the highway (say an hour or so at 100km/h).. just driving it around the city day to day it doesn't leak afterwards.. very odd how it does that.

Thanks for your ideas so far though!

[urantia]

yes that is very odd! as if the heat is closing up a gap somewhere maybe?

Let me think about that one and get back to u.

[Dale]

That's the theory I came to.. the heat must have been expanding something and closing the gap up.. and the long drives must mess with it more so it leaks once it cools down and contracts again. Hard to say really but that's all that makes sense!

[airfireman1]

The solution is to pressure test the cooling system, take it down the servo and get it pressure tested when everything has cooled down. test it to a couple of pounds above the rating on the radiator cap.if you can use one of those little dentist style mirrors as well to inspect around all the hoses and water pump areas it will be worth while.

[jonra23]

Looks like it is dripping from water pump shaft down to where you see it, there apears to be a spray pattern where something has been thrown outwards from water pump shaft.

regards
jon

[Dale]

I don't think it's from the shaft, because while it's dripping away I can't see any water coming out from under the shaft, nor feel any there.. the path of water dripping down starts at the spot circled, no higher weirdly. The pictures don't show a great deal unfortunately. Also it doesn't leak while it's running/warm, oddly so I doubt it would be that.. I think the spray pattern is old oil and stuff from when one of the cam seals was leaking a while ago.

Cheers though

[jonra23]

Sorry i misunderstood, didnt realise that you actualy saw it leaking.
Almost defintely comig from gassket then, are the water pump bolts tight?
If a little loose may contract enough when cold to allow a leak, when warm hot the aluminium housing expanding wnough to tighten up mating surfaces.

regards
jon

[Dale]

I'll double check they're all tight and torque them up a bit if needed. Failing that is it acceptable just to pull the water pump off, put a new gasket on it and refit?

Sorry airfireman1 I missed your post, once I fix up the leak I'm thinking I'll probably go and get it pressure tested if I have any more dramas with it. The thing is the car doesn't overheat or fluctuate temperature at all. Good idea on the little dentists mirror, would save my hair from grease!

[jonra23]

No worries with just replacing gasket with existing water pump.

regards
jon

[Dale]

Looks like that might be the go for tomorrow then if tightening the bolts up doesn't do anything, hopefully the gasket isn't a hard one to get hold of!