Water pump replaced, still leaking coolant

Mozambique

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The coolant leak saga continues!
To recap, water pump, crossover pipe and heater manifold pipe replaced in August in response to long term slow leak that was progressing. That seemed to fix it.

Now noticing another even slower leak. Level drops bya few mm after 100 miles.

This is where I admit that previously during bleeding I did not use the correct technique initially, resulting in the temperature gauge reaching max temp momentarily. Stomach churning pondering if I cooked the head gasket? No mayonnaise on oil cap, but figure minor leak may not show. No white or black exhaust on start up, no bubbles in coolant tank, no misfire. Is there a definitive method of diagnosing a failing head gasket?

The optimist in me says could be weeping radiator, hoses etc. A pressure test done by garage in August failed to detect leakage from crossover pipe, so have little faith it will diagnose smaller leak. What about UV dyes - has anyone experience with them. Are they coolant-type specific?

Thanks in advance as ever!
 

jlglr4

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With no other symptoms, I doubt it would be a head gasket. If you overheated badly enough to warp the heads, I think you’d have other problems. And, even if it is a tiny gasket leak, I don’t think there is really nothing to do about it unless it gets much worse (which might never happen). So, I’d put the head gasket thing out of my head unless I had other reasons to think about it - just keep an eye out for the other symptoms you mentioned. (Anyone who thinks this is bad advice - please chime in. I just think if you’re not seeing coolant in the oil and no other performance issues, the leak would be so small as not to be worth fixing - but I’m no mechanic.)

There are still other things it could be. For one thing, it could still be working a little air out of the system. There’s a lot of coolant passages in this car, and I imagine small air pockets could stick around for a long time. Could also be the reservoir cap. They are supposed to vent only at a certain pressure, but yours might be leaking a little vapor.

It could also be a leak anywhere in the lines going to the rear aux heater. There was recently a report on a leak back there - can’t remember what forum I saw that on. Finally, it could be a small leak in one of the heater cores (front heating system or rear aux heating system).

Finally - I see you are in Toronto and it’s probably starting to get pretty cold up there. Maybe very small decreases could be the result of falling temps?
 

gsxr

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A pressure test may help... cost to buy the tools may be cheaper than taking it to a shop. Worth a try if you keep losing coolant and can't find the source.
 

Mozambique

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I like your reassuring thinking!
I have zero experience with head gasket issues i.e. if they develop a small leak will it inevitably progress to a catastrophic one?
If heater core leaking would I be smelling coolant?
Will replace the coolant tank cap as a precaution. Actually we have had a balmy fall. Only just getting down to 5 deg C or so. Currently half way through a 1,600km road trip. Should give me a better idea of leak status. Thanks for your help!
 

Mozambique

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A pressure test may help... cost to buy the tools may be cheaper than taking it to a shop. Worth a try if you keep losing coolant and can't find the source.
Well, the garage did do a pressure test previously and could not detect the leaking crossover pipe seal, even though I had coolant dripping onto the driveway? And I have faith in them as have been using them for years
 

greiswig

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Watch for white exhaust smoke (not steam) when you first fire it up. That’s another tell that you might have a leaky gasket or crack in the head.

But as others have said, if I were in your shoes I’d be in “monitor it” mode rather than panicking. Do another leak down test or two to see how the system acts when warm and when cold.
 

Davidinseattle

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The coolant leak saga continues!
To recap, water pump, crossover pipe and heater manifold pipe replaced in August in response to long term slow leak that was progressing. That seemed to fix it.

Now noticing another even slower leak. Level drops bya few mm after 100 miles.

This is where I admit that previously during bleeding I did not use the correct technique initially, resulting in the temperature gauge reaching max temp momentarily. Stomach churning pondering if I cooked the head gasket? No mayonnaise on oil cap, but figure minor leak may not show. No white or black exhaust on start up, no bubbles in coolant tank, no misfire. Is there a definitive method of diagnosing a failing head gasket?

The optimist in me says could be weeping radiator, hoses etc. A pressure test done by garage in August failed to detect leakage from crossover pipe, so have little faith it will diagnose smaller leak. What about UV dyes - has anyone experience with them. Are they coolant-type specific?

Thanks in advance as ever!
If you didn't bleed the system properly, that means there may be air still trapped in the system. After about 1 year of driving with our 2015, it suddenly just lost coolant enough to trigger the light. Dealer added coolant and told is it was pretty common with these having air trapped in the system and suddenly working its way out. Not sure if that was BS or not, but we never had to add again and that was 5 years ago.
 

Mozambique

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I did ultimately bleed the system correctly, just not at first attempt.
Thanks guys for your reassuring thoughts!
 

MJ HARRY

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I had the same problem and got the crossover pipe from amazon $25. Replaced it in 2 hours with my neighbor one night. Saved like $700. Same coolant in the manifold toward the front.
 

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