Coolant leak question

[bttlshp]

My wife's 170K mile 3.7l is leaking coolant, and I'm trying to track down the source. There's steam from the exhaust, but the oil is clean. I ran a compression test last night to see if one of the cylinders wouldn't hold pressure, but the results weren't as conclusive as I'd like. There was one steam-cleaned spark plug,and I thought that plugs cylinder would be the culprit. But I was able to hold 160 psi on all cylinders. I know this is low, but it could be the engine's age or that I wasn't able to tighten the pressure gauge adapter tight enough (I was only able to twist it in with the tube coming off of the gauge).

My question is, could the coolant be leaking from the intake manifold instead of head/head gasket? I don't know if there is coolant running thru it or not. It seems like if it were the head/gasket, that one cylinder's pressure would be noticeably lower than the others.

Thanks!

 

[ltd02]

No coolant passages in the intake. Have you carefully checked the radiator (upper front corner driver side), hose connections, water pump weep hole, coolant reservoir, heater hoses. Could have coolant tested for exhaust gases. Does coolant system hold pressure? Any bubbling in the reservoir when running? Is there steam from the exhaust when fully up to temp?

 

[bttlshp]

There is steady, although faint steam from the exhaust when everything is up to temp, so it's getting into the combustion chamber.

 

[dude1116]

There is steady, although faint steam from the exhaust when everything is up to temp, so it's getting into the combustion chamber.

It's pretty normal for some condensation to come out of the tail pipe even when fully warmed up. I suggest checking out your radiator. If you haven't changed it in 170k miles, I would bet you have a leak somewhere there. The common spot is the driver's side upper corner. It leaks out and down the radiator and will leave a white residue (dried coolant):

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

Most of the time it won't leave much of a puddle because it will evaporate before it hits the ground. At times I had a coolant smell coming through my heat as well as steam coming off my grille.

 

[bttlshp]

The radiator has been changed and I have checked for visible leaks.

 

[bttlshp]

This diagram shows a coolant temp sensor (item 3), which leads me to believe that there is coolant somewhere in there.

Manifolds, Intake and Exhaust, 3.7L [EKG]. Fits: 2002 JEEP LIBERTY | FACTORY CHRYSLER PARTS

 

[uss2defiant]

could do an engine block test.

 

[dude1116]

Interesting that the part shows for "2.5L and 4.0L" even though it is pictured in the diagram of a 3.7L :shrug: