Can not find coolant leak...any ideas?
 

My wife has a 2003 Jeep Liberty with a 3.7 V6. I have needed to add a quart or more of coolant every week for the past month. I can't find the leak.

- I have had the system pressured checked by a shop. It held pressure okay.
- No drips on the ground.
- I have looked all over the engine while it was running at operating temp and no signs of a leak.
- Hoses are in good shape.
- No water in the oil.
- Check the heater core, no leaks.
- Tried a can of Bar Stop leak stop gunk - no luck.

Hoping it's not a head gasket. (I thought the pressure check would show something like this) Is there a way to check for that?

Does anyone have any suggestions what else to check?

have you looked at the overflow tank or pressure tested the radiator cap. had a 850 wagon that had the same thing as you. turned out to be the overflow tank and radiator cap. the fluid was leaking while driving.

Remove the radiator cap ( do they have one - or just a over-flow bottle?)

Anyway - check it cold and hot, You are looking for excessive bubbling in the coolant. Culprit = Head gasket

But it could also be an intake-runner leak also. Any tell tale signs at exhaust pipe?

Remember - If it isn't leaking it - it's digesting it.

Edit: You could pull the spark plugs and look for 'washout' on a particular cylinder.

Sounds like classic head gasket unfortunately.

My Mom had an Oldsmobile with that Quad 4 thingie and you'd drive along just ho-hum, all of the sudden coolant steam rolling out from under the hood everywhere, pull over pop the hood and then nothing. Coolant was leaking from the head gasket to the outside of the head, just dropping back a couple degrees in temp would seal it right up again...no coolant anywhere to be found. Weirdest failure mode ever and confirmed by the GM dealer.

Sounds like a head gasket. Do as Mo Gearhead says, pull the plugs and you may confirm the answer right away. If coolant is getting into a combustion chamber, that spark plug will be much cleaner than the others.

Could be a bad EGR valve. Check for white smoke out of the tail pipe.

I am assuming that this a 3.7 Litre?? I have been doing quite a few head gaskets on these lately. A dye test will show if it is in fact leaking.
For the life of me, I cant figure out why they did away with the tried and true 4.0.

How's your oil? Any milkshake looking substance in it?

If it isn't a head gasket, it could be a crack in the head - that only shows up if the engine is hot, so normal leakdown tests won't show it.

-Z-man.

Oil is dark, no sign of water. I will pull the plugs and see if I can see any signs that water may be getting into the combustion chamber. Then see if I can get a pressure test while it hot.

Pressure tests can sometimes do more harm because often the tester puts more than the system is rated for to "find" the leak. This ends up popping the end tanks off the heater core and radiator in short time down the road. If its not a head gasket then you should get some dye and a blacklight on there.

Can someone please tell me more about the dye test? Is this something I can do at home?

There is a test that checks for the residue of hydrocarbons in the coolant. not really a dye test.

Does the exhaust have a sweet smell to it?

Turn on the heat and see if you smell coolant through the vents.

When you pressure test the system do it when the engine is dead cold.

Hope it's not your head gasket.

Good luck

-Adam

it is a dye that fluoresces under UV light - dye = cheap; light = $

I fergit what they call it in the auto world... ask at a FLAPS or a good repair shop -- FLAPS might loan you the light/tool to check for the dye with...