elraksaz

Just bought an 00 Cherokee sport with 118,000 miles. It's losing coolant somewhere(It was low when I bought it and I've been monitoring the reservoir). It doesn't smoke when I start it or when running. I did a coolant system flush and topped it off with 50/50 mix. It runs under 210 all the time, I can find no visible leaks and the heat seems to be fairly hot once its at operating temps. I do however have some signs of condensation build up under the oil fill cap. I recently changed the oil and it was a fairly nasty brown but no signs of coolant. Any ideas? Thanks for any input. Mike

tjwalker

The #1 symptom of a cracked 0331 cylinder head is "unexplained coolant loss". Sound familiar?

I'm not saying that is your problem, but it certainly could be.

SEARCH for tons of threads and information about the infamous 0331 cylinder head, which came from the factory on each and every 2000 and 2001 XJ.

Good luck!

AbsoluteAggressor

But of course, also everywhere for a leak. Around the T-stat, all hoses, around the water pump, all around your rad, and your carpet in your passenger side of the cabin.

Simple stuff first, then worry your *** off. Hoping it's easy and cheap fix!

djb383

All of those r obvious and "explained" and r cheap easy to fix except for the wet carpet leak. I would think changing a head would be easier than changing a heater core. The OP and tj r referring to "unexplained" coolant loss.

elraksaz

Thanks for the info! I did the advanced search and found plenty of info on the cracked cylinder head. Sounds like that might be it. How long can you drive on one? I'm assuming like with any other engine as long as I keep coolant and good oil in it shouldn't get worse if I'm not abusing the motor. I know these 4.0's are pretty darn bulletproof.

tjwalker

Incorrect assumption. If it is a cracked head, it WILL get worse.

Even trace amounts of coolant in the oil (inevitable with a cracked 0331 cylinder head) will create excessive wear on the bearings in the engine and eventually it's either rebuild or replace the engine.

bigbadon

That all depends:
1. How often are you adding coolant and how much?
2.What is your oil pressure at idle and cruise speed
3. Any knocks or ticks?
4. What type of antifreeze are you using? HOAT,OAT or IAT
5. How often do you change oil?

You can buy some time until you decide to fix it or drive it until the catastrophic happens. Some tips for adding life if you do not want to repair it now are:

1. Flush coolant system again and use OAT anti-freeze. IAT & HOAT have silicates which will destroy your bearings. Add one jar of Bars stop leak, the brown type that looks like molasses with pellets in it.
2. Change your oil and filter every 3k or sooner if you detect water in it. Test for water by letting dipstick drip onto your exhaust and listen for crackling sound.
3. Reference your oil pressure and engine noise and monitor for change.
4. Do not drive it unnecessarily hard.

I have the same issue. I bought an "04 and found out later it has a '00 engine in it with only 4 psi oil pressure. That was a year ago and I took the above steps and I am still driving with a very busy daily schedule, short trips, long trips and pulling a pontoon boat on mountain roads occasionally. Since this is a DD and I don't have time to rebuild, I am keeping an eye out for a good salvage engine to buy ahead of time for the inevitable.

Reece

Does anyone have experience with pulling the rocker cover and pressurizing the cooling system to identify A small crack? I have small amount of coolant loss and verified coolant contaminant in my oil by Blackstone labs. (2001, 66,000 miles)

I'm ready to accept a cracked head if I can verify it. I'll replace it myself.

If it's not a cracked head, could it be something else like a botched head replacement job? The PO replaced my head with an aftermarket (casting "DD"). What about the one head bolt that calls for sealant? Nobody wants to talk about that. Could that put coolant into the oil?

bigbadon

Could also be a head gasket leak. IMO I would try a bottle of Bars then monitor my coolant.

elraksaz

I'm just gonna order a head from Clearwater cylinder heads. I'd rather not take the chance since i bought it used and have no idea how long it was driven with the current problem. It's got 40-45 psi of oil pressure at start up then drops to around 25-30 after its been driven awhile. I haven't driven it hard at all since I bought it..just hwy driving. I just changed the oil and coolant a couple days ago. I've only had the jeep 2 weeks. I typically do a fluid flush anytime I buy used. All the other fluids looked good. Hopefully the bearings aren't trashed. The motor seems to have plenty of power and it does have a little tick at idle but goes away with any movement of the throttle.
Thanks for all the info thus far!

Firestorm500

You people using Bars or anything similar are going to clog your heater core sooner or later.

Then you will still end up replacing the head, as well as tearing out the dash and replacing the heater core. Maybe the bearings, too.

I also like it when people say, "My oil is the color of chocolate milk, but I didn't see any coolant."

elraksaz

From my experience if there is a significant amount of coolant in the oil it will form a sheen on top of the oil after it's been drained. Mine did not, but it was pretty broken down so I'm assuming it's got at least some in it.

Either way I'm not gonna take a chance. A head is much cheaper to replace then the entire long block.

bigbadon

I little added ONCE will not clog....the factory has done this to every vehicle that came off the line until recently. Now they add an organic sealer that is more compatible with HOAT coolant. I have used the stuff for years and I am in my sixties and have had plenty of success with it. It will not fix a 0331 cracked head but it will fix leaky head gaskets.

Firestorm500

I'm glad that you feel like it works for you, but I don't think it is good advice.