Disappearing coolant?

Throws · Feb 4, 2016

So, I do a weekly-ish check on fluids. I've got almost 250k miles, so I try and stay on top of it.

However, every so often I top up the coolant. It's not a heater leak as far as I can tell, since there no fogging and no smell. Oil looks normal, nothing obvious.

I'm planning on building up a new engine (eventually), but I'd like to see what I can address on this in the meantime.

Ideas?

-P
'99 XJ Auto 4.0L 4WD

notamos · Feb 4, 2016

I'd do an oil analysis (Blackstone) to see if coolant is present.

But, it could be a seeping water pump, leaking hose, etc. -something slow that isn't dripping on the ground.

Throws · Feb 4, 2016

New water pump, them, housing, rad, and all new hoses about 2000 miles ago (rad was leaking and PO ran copper Stop-Leak through it).

notamos · Feb 4, 2016

Well, if all was replaced 2k miles ago - I'd lean even more toward a seeping leak somewhere. Stop-Leak, ugh. I'd do an oil analysis.

Digger87xj · Feb 4, 2016

A failing radiator cap will cause coolant loss without any signs of leakage. It will escape as steam and then draw water from the overflow as it cools.

garr · Feb 4, 2016

Look for obvious leaks.
Look under the oil filler cap for green goo, it's a 99, that means 0331 head, look in the filler hole with a flashlight you will see the head crack if it's there.
Check your transmission fluid for a foamy look.
You'll find it, good luck.

shanesaw · Feb 4, 2016

I had this recently with my 1987. It turned out to be the junction where the factory hose was crimped to factory piping right before the heater core. Slow drip that burned off on the engine.

thanasi85 · Feb 4, 2016

Do you see bubbles in the coolant reservoir if its up to temp and you rev the engine while looking at the bottle?

Throws · Feb 5, 2016

Digger87xj said:
A failing radiator cap will cause coolant loss without any signs of leakage. It will escape as steam and then draw water from the overflow as it cools.

Ok... New cap on order.

garr said:
Look for obvious leaks.
Look under the oil filler cap for green goo, it's a 99, that means 0331 head, look in the filler hole with a flashlight you will see the head crack if it's there.
Check your transmission fluid for a foamy look.
You'll find it, good luck.

It's a 0630 head. Nothing weird about trans fluid.... nice and red.

shanesaw said:
I had this recently with my 1987. It turned out to be the junction where the factory hose was crimped to factory piping right before the heater core. Slow drip that burned off on the engine.

Replaced all the hoses and used new worms clamps.

thanasi85 said:
Do you see bubbles in the coolant reservoir if its up to temp and you rev the engine while looking at the bottle?

I'll check that tomorrow.

Thanks!

md21722 · Feb 5, 2016

Most 99's did not yet have the 0331 head. Any cream under the oil filler cap? After the basics like leaks and the cap, I'd do the oil analysis. I've used it over time to identify these problems and there's no fooling the lab. Potassium in oil = coolant = head gasket blown, head cracked, or worse. Some vehicles have coolant to oil heat exchangers that can cause the problem but Cherokee's don't have anything like that.

obxxj · Feb 8, 2016

Check to see if any of your hoses is rubbing against something. I just found a pinhole leak worn in one of my hoses.

Disappearing coolant?

Throws

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notamos

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Throws

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notamos

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Digger87xj

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garr

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shanesaw

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Throws

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