So after some time thinking about it i finally went out and bought a compression tester and it has highlighted the fact that i need to take the head off the car (#2 cylinder is 80psi)

The car (87 XJ6) has just under 90000 miles so it's almost new!!!!

I'm wondering if any of you could please let me know if here are some things i should consider doing whilst the head is off the car...., depending on what is wrong i might be in for at least some new valve seats and if that's the case should i install a stakedown kit OR would new guides solve the problem?

Any other things that could and should be done whilst i'm knee deep in it?

thanks

 

Always install the stake down!!

 

Thanks Darren...

I have seen a couple of trains of thought on this, i know the exhaust side is "required" but others also install on the intake, is this really needed?

 

The train of thought there is that the exhaust side gets hotter and therefore allows the bucket to lift so exhaust side is mandatory. Intake side is cooled by fuel.charge so its less likely to happen, i can see no downside to doing intake side as well. It wont hurt anything plus a.little extra insurance is always good.
I would say it's owner preference.

 

rfarmewry:


I see that you are a hop, skip and a jump from where I am. Nice town there.
Decades ago, the old mill and adjoin shops burned. My first assignment as an entrepreneur was there. I enjoyed going there and working with some fine folks.


Don't yank the head quite yet!!!!


1. Check the valve lash. If one or both are too tight on that cylinder, they will not quite close, leak and the compression will be weak.


2. Not familiar with your prior posts. Miss on that cylinder?


3. A valve issue or a piston/ring/bore issue? Now is the time..


4. All cylinders read on WOT? Same number of cranks? Reliable guge to cylinder seal? All testers not alike.


5. All plugs out when testing?


6. Do a wet test. Add a squirt or two of engine oil to the cylinders. Retest.


7. compare the wet to the dry numbers.


8. If adding oil on the weak one improved the numbers, the issue is on the pston/ring/bore. More difficult to deal with, but doable.


Good luck


Carl

 

I'd probably consider a mild porting/ matching if you do take the head off. Don't go crazy though.

 

Carl

Thank you for the ideas...

The compression tester is brand new, WOT when testing, all plugs removed. I did not count the number of cranks but waiting for the value on the tester to settle so maybe 1 crank possibly 2 variation perhaps from cylinder to cylinder.

Main reason for testing is when starting the car sometimes starts on 4 cylinders, maybe 5 and all of a sudden realizes its a 6cyl, rough running at idle along with loss of coolant which seems to be getting worse.

Not yet tried a wet test, i will give that a go next..

Yes Petaluma is a fantastic little town (not so small anymore)

 

Compression testers:


1. Best. Has threaded adapters to allow it to be screwed into the spark plug hole. Best!!


2. A rubber cone at the end. Keep it pushed in hard during the crank. Doable, but less likely to get an accurate number.


I like and have the first type,


Comment, unasked for. Porting job not worth the effort, unless other extensive work is done to pump more air.


Good luck.


Carl

 

Carl

I have the threaded style of tester, i agree, much better than the cone type...

Wet testing the low cylinder revealed a marginal increase in pressure but not anything significant so this points to the rings being in good shape (Thank goodness)

I will check the valve clearances on the weak cylinder per your recommendations to see if anything looks questionable. If not the head will come off and i will still perform a leak test on each combustion chamber to test the integrity of the seats, if not too bad maybe re-lapping might help, if not new seats.

Thanks for the help everyone

Russell