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0331 Strikes Again...?

Ol Blue

NAXJA Forum User
Arvada, CO
I finally got around to doing a Blackstone oil analysis on my 2001. I use Mobil 1 10W-30 Full Synthetic High Mileage and run the recommended amount of Seafoam in the oil a few days before the oil change. It has 147k miles and runs great. Thought the test would be for peace of mind and was curious about wear metals. Turns out they found coolant in the oil with the high potassium (496 ppm) and sodium (294 ppm). Also wear metals are pretty high. This really surprised me because it doesn't overheat, doesn't smoke, no milkshake in the oil, no oil in the coolant, and here's the kicker...it doesn't (noticeably) use coolant. I've owned this for 3 years/13k miles and never had to top off coolant. As long as I've had it oil pressure has always been on the lower end but seems fine (12-13 psi hot idle but up to 30-40 psi driving).

Current coolant level is halfway between Full and Add. Roughly 2 years ago I did a coolant flush and fill. Can't remember where I filled to but I'm assuming I filled to the Full line. So that would be a consumption of Full to halfway above Add in a span of two years, assuming that none evaporated. This XJ is not a DD, its mainly a winter beater when it snows and trail rig.

So how concerned should I be about this? Any thoughts on how long it will run like this? I'd hate to dump money on a new head with the high mileage and damage likely already done to bearings (lower oil pressure and high wear metals). Kinda tempted just to do short OCIs and save for a stroker at this point. I have to pass Colorado emissions so a stroker is really my only possible engine upgrade.

When did you collect the sample? Where you live and your driving habits can collect a lot of water. I wouldn't be to concerned but I would keep a closer eye on things.
The sample was taken 2/2/24, during the oil change. I let a little oil flow first then filled the provided sample bottle like they recommend.

I did go on a deep snow bashing trail run in January. Could it pick up water from that?

Definitely will keep an eye on it. I think I'll run another analysis in a few hundred miles and see if anything changes.
The moisture that gets in the system would mostly be from your CCV system. I would wait for summer before taking another sample.
Yea I didn't see anything but it's not easy to see in there. Was considering pulling the valve cover for a better look when it warms up
Something to think about is the harmonic balancer might be bad. It would not explain the coolant in the oil though.
Something to think about is the harmonic balancer might be bad. It would not explain the coolant in the oil though.
I'm not following, could you explain your thoughts on the harmonic balancer?

Regardless, I replaced the harmonic balancer a year and a half ago
IMO cracked head, the crack opens up when engine is warmed up and seals back up when cold so it's not (yet) going full milkshake. Start looking for a '03-'04 WJ 0331 TUPY head.

The metal number that caught my eye is the elevated IRON number, the bearing numbers (Aluminum/copper) are high but should be way higher coupled with the IRON number if the Mains or Rods have gone south, I would think iron is coming from somewhere other than crank area, Oil Pump likely suspect.

You caught it early, I bet you could get away with fresh head, oil pump and bearings.
Another thing you could do in mean time would be to check the plugs and the chambers.
Glasply's post reminded me of one of the early 0331 heads that my neighbor worked on. So, around 2003-04. One of the cam lobes wore down. I sold him or the dealership a 2003 Tupy head. 3K on it, looked new. They replaced the motor with a new one. I ended up with the block etc.
Pulled the valve cover Saturday and saw nothing notable. No evidence of coolant or any visible cracks. Ran the engine maybe 10 minutes and still no signs of coolant. Doesn't mean that a crack doesn't exist (evidence says it probably does exist), but nothing is visible. If a crack was visible it would be much easier to justify buying a new head. Makes me wonder if the analysis had an error or contamination.