That's another good point. If that much coolant were going into the oil, over time it would probably fill the engine up and start spilling out of the dipstick tube and oil filler.

Don't forget to check that all hose clamps are nice and tight. I had another vehicle that had a slow coolant loss, when I pressure-tested the system it started seeping out of several hose ends.

 

Not likely. The internal temps of the motor are high enough to vaporize water and coolant.

It's normal to have some moisture in the motor from condensation when the engine cools down. One of the major functions of the detergent package in the oil is to bond that moisture to reduce damage to the engine while the motor reaches operating temperature, when the moisture will boil out. If you get more moisture in there than the detergent package can handle, the water forms an emulsion that appears as milky crap. The detergent packages in some of the newer oils are so good you never see that emulsion, even though the coolant is still in there doing damage.

If you're leaking coolant into your oil, it's also going to boil out at operating temp. When you see the oil level rising, you have a pretty serious leak at that point. However, I suspect that before you get to the point that it's blowing out anywhere, you would have already wiped your bearings and parked it. At a minimum your oil pressure would have dropped, and your oil light would have come on.

 

I mean, a gallon a week is a LOT - if it were leaking it would be pretty apparent.

It could be a head gasket or a crack on the underside of the head (if the mechanic pulled the valve cover off and there were NO visible cracks).

Are there any bubbles in the radiator (indicating exhaust leaking into the cooling system through the head)? Pull the rad cap and let it idle for a bit, you will see bubbles if so.

Get a sample sent to blackstone labs, they can tell you for sure if there is coolant in the oil. Beyond that, pulling the head off and getting it checked at a machine shop is your next step (magnafluxed);

Although, if you suspect the head is bad I would get a new one from Clearwater Cylinder Heads ($500) rather than a junkyard or having the head rebuilt. It is an easy swap on the 4.0L but if you are having a mechanic doing the work, labor is going to be a killer and really it may be only marginally more expensive to replace the head and gasket.

How is the oil pressure on the motor (at really hot idle, after at least 30 mins on the road)?

 

I am going to say your head is cracked from reading this.

 

 

X2

 

I havea 2001 jeep Cherokee burning antifreeze too, it overheated once,and I've been on top of it since,but my mechanic can't find any leaks either. Did you ever figure out the problem with yours?

 

Welcome to CF.
You really should start your own thread. If your not familiar with the 0331 head failure issues on the 00-01 4.0 XJ's you need to familiarize yourself with it.
https://www.cherokeeforum.com/how-to...rmation-398176