I bought my 2001 last winter with 58,000 miles on it. The head has beed replaced, casting mark "DD". I assume the 0331 head cracked on the P.O.
The Cherokee Forum has been a great help while I've been going through my new hobby/D.D. for the last 8 months. I've spent considerable time and money bringing my baby up to near perfect condition. I did a complete cooling system flush and replaced the thermostat 2 months ago. Naturally I began watching the coolant level to catch any leaks. I had one loose hose but still noticed a coolant loss of about 8 oz. per week on my 225 mi. weekly commute. The oil has never been milky but I decided to send off a sample to Blackstone for analysis anyway. I ran this oil for about 5,000 miles to accentuate any coolant contamination. See the attached file.

Now my brothers, I need help deciding what to do but first I think I'll go throw back a shot of whiskey.

 

I'd say toss back a few shots as you already know that "the #1 symptom of unexplained coolant loss" is a cracked head.

I'm not sure what the casting mark "DD" means. Some type of aftermarket head I would imagine.

I'd take a close look through the oil filler cap with a good light, or better yet remove the valve cover and inspect the area between cylinders 3-4 to see if you can see a crack on this head where coolant is seeping through.

How is your oil pressure holding up? With coolant in the oil, it usually toasts engine bearings in pretty short order. And that results in reduced oil pressure.

If the rest of your baby is in great shape, I'd probably look for a new engine or get a rebuild if you have confirmed another cracked head.....

 

Oil pressure is consistent, 15 at hot idle, 45 at 2,000 rpm highway driving.
Working on a tequila shot now!

 

Get a older Engine And rebuild that. I would stay away from them newer heads

 

Look for a 97-98 engine

 

For the time being, throw a bottle of Bars head gasket/head crack leak in it. When my wife and I first started off together we bought a mercury sable from a shady car lot, about 6weeks after owning it we discovered it has a coolant leak of some sorts. Well we couldnt afford a new car, or the repair. I was brand new in the military so I was screwed. I put a bottle of that in as a last resort. Almost 2years and 35k miles later still no further issues or coolant loss. In those 2yrs I saved up a nice down payment for something better.

 

Does anyone have a fix on my contaminant levels (Blackstone averages are based on 4,200 miles) or Blackstone's comments - change the oil at 2,000 mile increments? Molybdenum is low Iron is high? Does high Iron mean crankshaft journals are wearing? They said Potassium indicates coolant contaminant. I guess I need to call them.

Maybe I'm grasping at straws but it seems like I might be able to carry on for a good while by changing my oil every 2,000 miles. Also, Blackstone noted my low viscosity. Could that be due to contamination? I had 10W30 in it now.

I'm going to change it this weekend to Rotella 15W40 with a Wix 51515. I want to see how my oil pressure holds with proper viscosity - an indicator of how much bearing life I have left? I'm trying to weigh a complete rebuild against head replacement. Rebuild is our of above my pay grade. Head replacement I could manage.

I'm thinking about running it for 2,000 miles and sending in another sample. Hoping against hope.

Problem is, I love my Cherokee but I don't want to be stupid, throwing good money after bad. I just can't think of any vehicle I'd rather have right now. BTW, that's not my Cherokee in the avatar. That one hangs out at the water company near my house. Mine is much nicer.

 

It's really difficult to tell how much bearing wear you have without sampling some with measurements.

As for the engine's future? It sound like it already had a previous head replacement and if this is the second time around, I wouldn't recommend another head replacement; I'd recommend another engine WITH a solid head!

You have bearing wear; you just don't know how much. Your oil pressure is within spec, but not by a whole lot......

 

I would suggest buying a 97-99 engine from a junk yard, and rebuilding it yourself. Then replace the current engine, and rebuild that with a new head.

 

High iron readings seems to be common with the 4.0's, I've seen that over and over at BITOG. The consensus seems to be that it doesn't affect longevity.
You aren't showing terribly high levels of bearing material (copper, lead etc) in the report, which is good.

The 2K oil changes are a stopgap thing to deal with coolant contamination. The more of it in your oil, the faster you lose the bearings. It keeps the damage down until you address the underlying problem- which you should do ASAP.
I'd pull that head, check for cracks and replace as needed. Doing so now might save the rest of your engine.

 

Most definitely pull the head and at minimum, replace the gasket. The previous owner/mechanic may have botched the gasket during the head replacement and all you need is a new one.

 

I agree with Radi. You still have a good solid engine so I would replace the head ASAP. What type of coolant have been using? the newer OAT and HOAT coolants are silicate free. It is the silicates in the anti-freeze that eats the bearings. The 4.0 is a very hardy engine and your oil pressure is GOOD!!!

 

So this is what i'm hearing:
1. If I feel the need to check for wear, I drop the pan and Plastic-gauge a main bearing?
2. After my oil change today, if I have killer oil pressure and I'm feeling lucky, I pull the head for at minimum a head gasket replacement but be prepared to replace it?
3. To help me decide, I should first pull the valve cover and have a closer look. My understanding is that cracks aren't always evident, right?
Logistics may be problematic. This is my D.D. Where can I get a head on will-call if I need it? Where do I get a good head anyhow? Maybe my mechanic can get a head and then return it if it's not needed. I know, I know, I'm building an elaborate dream that could easily turn into a nightmare but I stepped out with the dog this morning and there was my Cherokee, pretty as ever. She's just a little sick. My wife wants me to trade it off and cut my losses but I don't feel good about passing it off with known defects. That's what the P.O. did to me.

 

It does not sound like gloom & doom....fix it! If it makes you feel better, i inherited the same problem but far worse I only have 4 psi and 25 at 2000rpm. This thing refuses to blow up and I drive it every day. I had planned on replacing the bearings a year ago but haven't had time to get to it yet. If I hear it knock I will do it ASAP.

 

I'm using Prestone Extended Life which is silicate, phosphate, and borate free. I changed my oil today to Rotella T 15w40 with a Wix 51515 filter. I'll be watching the oil pressure on my commute tomorrow.