Milky residue on underside of valve cover

Hi all,

I recently bought an 01 4x4 XJ with 180K miles on it. I changed all fluids, flushed cooling system and replaced rear main seal, oil pan gasket and valve cover gasket about 1 month ago. I only have a few hundred miles on Jeep.

Yesterday, one of the PCV valve elbows disintegrated when I was changing vacuum lines (running down a vacuum leak). So I pulled the valve cover because I am basically having to chip the grommets out because they are so brittle and cracked. That is when I noticed pic related on the underside of the valve cover over cylinders 5 and 6. I DID NOT notice any milky residue like this when I changed the valve cover ~1 month ago and the oil and coolant looked normal when I drained them. Also I tried to take a pic of the valves as best I could. Thoughts? Should I be concerned, what to do, etc?

Was the coolant flush due to overheating issues or a case of "just bought it, might as well start all fluids fresh from now"?

I'd think that at the very least a quick look at the oil (via dipstick) and the coolant (via radiator/overflow bottle) is probably in order to see how it looks now that you've found that residue.

Rob Mayercik said:

Was the coolant flush due to overheating issues or a case of "just bought it, might as well start all fluids fresh from now"?

I'd think that at the very least a quick look at the oil (via dipstick) and the coolant (via radiator/overflow bottle) is probably in order to see how it looks now that you've found that residue.

Click to expand...

It was a case of just bought it and start fresh with everything. The oil and coolant look fine so far, but again, not very many miles yet. Could the pvc elbow being cracked account for condensation getting in the valve cover?

That and with your cold temps lately you may not be driving it around enough to get to full temp and burn that out!

RCP Phx said:

That and with your cold temps lately you may not be driving it around enough to get to full temp and burn that out!

Click to expand...

Hopefully this is the case.

At this point I would be inclined to think condensation, but I would also monitor the oil condition more frequently (remove the fill cap and look for condensation, pull the dipstick and look for chocolate milk).

If you have access to a block test kit (involves a chemical which changes color if combustion gases are present in coolant) you can get a quicker answer.

Anak said:

At this point I would be inclined to think condensation, but I would also monitor the oil condition more frequently (remove the fill cap and look for condensation, pull the dipstick and look for chocolate milk).

If you have access to a block test kit (involves a chemical which changes color if combustion gases are present in coolant) you can get a quicker answer.

Click to expand...

Not necessarily, the way the 01 heads crack you get coolant in the oil but not combustion gasses. Any other year I would chalk it up to condensation. Being an 01; 50/50 shot at a cracked head.

Anak said:

If you have access to a block test kit (involves a chemical which changes color if combustion gases are present in coolant) you can get a quicker answer.

Click to expand...

Thanks for this. I did not know that product existed.

Unclewolverine said:

Not necessarily, the way the 01 heads crack you get coolant in the oil but not combustion gasses. Any other year I would chalk it up to condensation. Being an 01; 50/50 shot at a cracked head.

Click to expand...

So far, I have seen no signs of coolant in the oil. The oil looked normal when I initially changed it, and dipstick currently looks normal. If it is a cracked head, will it get progressively worse until it is obvious?

So far, I have seen no signs of coolant in the oil. The oil looked normal when I initially changed it, and dipstick currently looks normal. If it is a cracked head, will it get progressively worse until it is obvious?[/QUOTE]

This is how it starts. It gets worse. No there is nothing you can do besides get a new head.

boncrshr said:

Thanks for this. I did not know that product existed.



So far, I have seen no signs of coolant in the oil. The oil looked normal when I initially changed it, and dipstick currently looks normal. If it is a cracked head, will it get progressively worse until it is obvious?

Click to expand...

Sometimes look won’t show it.

Next time you change your oil send a sample in to Blackstone for analysis. They’ll tell you if chemical components of coolant are present in your oil- potassium and sodium.

I had mystery coolant loss in my 01 with no other symptoms

IslanderOffRoad said:

Sometimes look won’t show it.

Next time you change your oil send a sample in to Blackstone for analysis. They’ll tell you if chemical components of coolant are present in your oil- potassium and sodium.

I had mystery coolant loss in my 01 with no other symptoms

Click to expand...

That sounds like the best plan. Will do.