New Clearwater head, still coolant in oil

So a little over a year ago I bought my TJ (4.0) with a cracked head, the engine had been rebuilt 11,000 miles earlier but they used the original head which must have been cracked, or cracked later. So the shop that did the rebuild installed a new Clearwater head supplied by me.

Potassium levels went from 1800 to 139 to 42 to 26 with successive oil changes. At first I changed it at 175 miles then every 700 miles till we were down to 26ppm in September with 1,000 miles on that oil . Figuring it was residual I drove on that oil for another 2,000 miles then changed it and sent in another sample. Much to my surprise the sample came back with 58PPM, so apparently there is still a small amount of coolant getting in.

What's next? Is it possible the shop damaged the head gasket? I know they used Felpro including new bolts (well, they said they were going to use new bolts). I don't have a problem pulling the head myself and replacing the gasket and bolts, I can do it in my garage and take my time to get everything right.

What would you do? I mean, unless I am missing something, how hard can it be to properly install a head on this simple engine? I'm having a hard time imagining how they could have screwed it up, and the deck should have been checked at the machine shop when the engine was rebuilt right?

Barring a cracked block is there any other place coolant can get into the oil on the 4.0?

hear said:

I would like to know what the error bars are on those measurements. Like if you took 5 samples at the same time and had them analyzed would they all come back with identical results? I would expect not, since PPM is usually the result of a statistical analysis. I bring this up because while 58ppm is more than double the lowest value you've seen, that delta is also only 1.7% of the max value you saw, which is much less dramatic.

I don't know any other answers, I'm just here for the mafs.

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I was thinking that as well. To add another factor to the test method, I usually take all my samples thru the dipstick tube with the pickup tubing about in the middle of the oil, after getting the oil hot. The last one I forgot and pulled the sample from the drain stream after I first had let out about a quart or so.

My first action before doing anything drastic will be to put about 700 miles on this new oil and send in a sample.

WVJeep304 said:

This is my thought. I have never seen the results of leaving that sealant off, but in my mind, I'm not picturing it being very dramatic. So a small amount of coolant making it into the oil because of this seems plausible to me.

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Well I was thinking that at first and it would be an easy fix, but upon investigation I'm told that the #11 ends in the water jacket so if any coolant were to get past the threads it would force it's way up the bolt shank to the bolt head where it would leak out externally as that bolt head is outside of the valve cover. Where it passes thru the head, the head gasket would seal it out so unless I am missing something I don't see a path between the coolant and the oil thru bolt #11.

Rickyd said:

I wouldn't be surprised if traces of cooland hung around in the oil for quite a while. There are lots of places for oil to pool without much circulation.

The lifter gallery comes to mind. There are pockets there that were absolutely filthy on the block i built a stroker from

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That's a thought, and they could have got displaced when I went to Redington with @MikeE024 on those trails where Mike kept saying "it gets better up ahead"