was using coolant, took head off, now question

I took the head off my 97 XJ because it was using a small amount of coolant. The piston tops for cylinders 1-5 had black stops with no major carbon build up. The top of #6 was whiteish. I could not see any major defect to the head gasket, but it was a small leak. It looks like coolant may have been entering where the water jacket is very close to the cylinder. Is this at all common where head gasket problems are involved in the 4.0? Also, I found that the manifold side head bolts were tight. I put a pipe on a 3/4" breaker bar to get them loose. The head bolts on the passenger side were much easier. I'm not sure that matters because one is outside the valve cover and one is inside. I also found that the passenger side of the head gasket was pretty well stuck to the block. I used a putty knife down the entire side to get it to come up. I am just wondering if any of this is common on the 4.0. I have only pulled the head on one other 4.0, and that had already been done once using a Fel Pro gasket that basically came off stuck to the head. This 97 appears to be "all original".

With good all around compression, 163, 162, 166, 169, 173, 153, I am wondering if its even worth a valve job. I was originally thinking valve job and replace the valve seals. I planned on having both done at the machine shop while they check for any problems, clean it up, and make it ready to reinstall.

My 1997 hunk of driveway art has a problem at #6. I have yet to tear it down.



It is tough to second guess the valve job question without a wet/dry comparison.

Mine dumped enough coolant into number six to either have a small steam explosion or even maybe hydrolock and I bent a valve. The shank of the valve was still straight, the valve circle itself was bent like an upside down mushroom or looked kind of like a *Y*.

Mine was kind of a head scratchier because my head gasket leak was periodic and not constant.

I did have my head hot tanked, they are so much nicer to work on when they clean.

I colored my valve seats with a permanent red magic marker and checked them with a little lapping compound. Checked my head flatness with a straight edge at numerous angles, back lighting and a mirror helps . Put in new seals, measured my spring height and put it all back together.

Good data. I stopped with a dry compression check because the compression was 153-173. #6 was 153, 9 lower than the next lowest. In the future I'll do it both ways.

8Mud that is called a tuliped valve. Usually that results from very very high heat inside the combustion chamber.

joejeep92 said:

8Mud that is called a tuliped valve. Usually that results from very very high heat inside the combustion chamber.

Click to expand...

Thanx I never knew what to call it, the first time I'd ever seen it exactly like that. The really odd thing was that cylinder still had good compression, the valve still sealed. I have seen exhaust valves that looked like a clump and valve seats that had a groove burnt into them, but never anything like this.

I noticed around the same time, that my intake/exhaust manifold bolts had come loose. Maybe that cylinder (intake) was sucking extra air, running way lean and the deformed valve had little or nothing to do with the tiny coolant leak I had.

I did find where the head gasket had been leaking. With a good flashlight and close inspection. I could see a slight discoloration leading from a water passage to the number six cylinder bore edge. I figured that had to be the cause.

Yep the intake/exhaust bolts could be your culprit. Sometimes they are only tuliped to where comparing them to a good one is really the only way to tell and sometimes they are as you describe, you KNOW haha

I'm glad my old spark plugs looked nothing like that! The cylinder head shop looked at the head gasket and found nothing obviously wrong with it. They are going to magna flux it and go from there. They recommended a valve job based on the miles and also said they often find the exhaust valve seats are pitted. Thanks for the feedback.

thats good compression there. I am at 120-150 across all 6. mine is tired...

Looking down at the lifters, at the very front of the engine, there is a jagged edge between the front of the block and the first lifter bore. It almost looks like a piece of the block may have broken off. Is this just the way they were machined?

pix?

It was hard to get a photo because of the angle, see if this works?

I don't see a problem.

Install tip. Clean everything up, paint head gasket with copperkote before installation