chrisl757

Hi,
2001 XJ, 220k miles. I have been slowly losing coolant for about 3 months. At first I thought it was a leaky heater core because my cabin smells like antifreeze when the heat is on (smell comes through vents).

Then my son saw steam coming out from hood of jeep--I had a check engine light on at the time, but I thought it was for 02 sensors. I looked under the hood and there was a seam leak in the radiator. The radiator was under warranty from Autozone, so I put in a new one a few weeks ago.

I also replaced all 02 sensors and that cleared the check engine light.

The overflow bottle is still losing coolant though. Hoses seem good. I don't see any drainage under the hood except for by the overflow bottle (but that is probably just from when I spilled it putting coolant in).

I just pulled the filler cap on top of the valve cover and for the first time I'm seeing chocolate milk gunk/gel under the cap.

The oil dipstick seems totally normal--no milky substance.

What baffles me is this: the jeep drives fine, no noises, temps are normal, no overheating.

I know about the 0331 head issue and here are my questions:

1. Is there any easy way to confirm the cracked head myself?
2. How long can I "get by" with this assuming there is no overheating?

If I order from odessa to get a new head, the shipping date shows arrival in 8 days (not sure I want or can wait that long).

Any thoughts please? Thanks.

tjwalker

You likely have 2 things going on.

1. A leaking heater core, that is why you smell coolant in the cab.

2. A cracked head. If you're adding coolant, you're either leaking it or burning it. Be sure you don't have a leak with a comprehensive search first.

3. First quick and dirty test for a cracked 0331 head is to get the engine hot, then remove the oil filler cap and with a good flashlight, peer into the hole in the valve cover. Sometimes (not always) if the head is cracked, you can see the green coolant seeping up through the crack, as the 0331 head cracks between cylinders 3-4 and that area is visible through the oil filler cap.

4. Other test for a cracked head include a block test (tests coolant for the presence of hydrocarbons) and the cylinder leakdown test. A compression test is NOT a good test for a cracked 0331 head.

5. Your homework is to read the 1.5 million threads on this and other XJ forums on the 0331 head. Too much information to recreate here about more complex diagnosis and troubleshooting.

6. If this head has been cracked long enough, (and you mentioned 3 months) you will likely have bearing damage. How is your oil pressure? If your engine bearings are damaged, slapping a new head on will not be the total solution. If bearings are damaged, you will likely need a rebuild or a different engine.

Good luck!

chrisl757

Thanks TJWalker. I have read many of your information on this in other threads. Hugely helpful.

My oil pressure is steady at 40 which is normal. Sometimes if it's running hot at idle, it may dip down to 30, but never lower than that. It runs, sounds, and drives well. It's hard to tell about white exhaust because it's cold and every tailpipe has white exhaust in this weather.

So I am wondering about how much I need to worry about the bearings. I can buy the head now and put it in. I don't know enough to check the bearings on my own.

So let me ask this question: If my bearings were bad, would I be able to keep 40psi on oil pressure?

Thank you very much!

tjwalker

Chris,

As the oil pressure gauge in your XJ is subject to accuracy issues, it's very hard to tell you what to do here. You could put a mechanical oil pressure gauge on it to see where you are at. The oil pressure spec for the 4.0 is not less than 13 psi at HOT idle and between 37-75 psi over 1600 rpms.

3 months with a cracked head and my gut tells me that you have some bearing damage. But with that being said, I have seen guys with a similar situation to you slap on a new head and get many miles out of their engine. I don't have a crystal ball. The only way to know is to measure some bearing clearances and a shop could do that for you and give you a better idea as to where you are at.

Otherwise, slap that new head on there, change your oil a couple three times in quick intervals to rid the oil of any traces of coolant and cross your fingers. If the engine craps out down the line, find a salvage yard engine (usually not that big of a problem) and install that WITH your newer head.

Remember that the engine is a component and can be changed out relatively easily. Sure the engine is a big component, but it is a component and as such, can be replaced. Most everything on the XJ can be replaced; it's when rust takes a hold and structural integrity is compromised that is when it's time to say bye-bye. A failing engine is not a death knell to the vehicle as some seem to think.

Sorry, but this is very gray area here without hard diagnostic testing data.

chrisl757

Thanks.

How much would you figure for a shop to check bearing clearances? I'm assuming they need to drop the oil pan to check?

Thanks again. I can see that there is no clear answer here and the gauge may be feeding me lousy numbers.

extrashaky

If you're seeing milky stuff under the oil filler cap, that's probably coolant in the oil. In addition to all the tests already mentioned, you can pull an oil sample and send it off to Blackstone for analysis, which will tell you if there's coolant in it. (You will want to send it via UPS or FedEx, because the Postal Service will hold your sample in limbo for a month while they figure out whether oil is hazardous material.)

Another easy test is a combustion leak test, to see if there are exhaust gases in your cooling system. You can sometimes rent or borrow the test kits, or you can get a mechanic to do the test for you.

If either of those tests are positive, you either have a blown head gasket or a head crack. Even if it's just a head gasket, you still have to pull the head to fix it. Since you have an 0331 head, if you're going to have to pull it anyway, I would just replace the damned thing and be done with it.

There's no single answer for this. Every mile you drive it with coolant in the oil is potentially damaging the bearings. If you can't park it pending the repair, you can at least mitigate the damage somewhat by changing the oil to get the contaminated oil out of there.

chrisl757

Hi. I had a shop check it today, and they could not find any leak at all. The looked at the oil in the pan and in the valve covers and they said it looked great. They did a coolant compression test at 20 psi and there was no leak.

They did find some other leaks (rotting oil pan).

So I am supposed to just monitor the coolant level.

I'm relieved. But in the future, I will be looking for any trouble with the 0331 head.

Thanks to all!

extrashaky

That's sort of good news, but a pressure test of the cooling system will not necessarily detect a cracked head. Mine was cracked and still passed a pressure test by a mechanic. All we could figure was that the crack was opening under certain temperature/load situations. The 0331 head crack can be very frustrating to diagnose.

You may not have one, but I don't think you have completely ruled it out.

I would still suggest you send off an oil sample at your next oil change. Blackstone will send you a free test kit, and the test itself is only $25. The oil analysis can tell you a lot about what has happened in the engine over the period the oil has been in it, rather than just telling you what's happening right at the moment a mechanic is pressure testing your cooling system.

I get so much peace of mind out of the oil analysis that I have them done on both my vehicles now at every oil change, just to monitor what's going on inside. It's cheap early-warning insurance.

wingit

I had this same problem a year ago. I sent an oil sample to Blackstone and they confirmed coolant was in the oil. I put a Clearwater head on and that fixed the problem with the disappearing coolant. I have put 15,000 miles on it since then

Kalali

There are three conditions that can cause "milky" substance on the oil filler cap; short drives in cold weather, compromised cylinder head gasket, or a cracked cylinder head. First is easy to rule out and blown cylinder head gaskets are very rare in 00-01 XJs. You do the math.