You're welcome.
And reading about your battery, make sure the starter has full power available. Starter speed has a measurable influence, too.
Although, with all spark plugs removed, it has a much easier life to compress only one cylinder.

 

Yes... Not all 8 but 4 plugs had been removed. I've been with a good charge and good fast turnover. I am determined to get this sorted out,,, like figure out what's going on. This is the first nonMINE jaguar that I have worked on and NEVER this model. Feels like a bit of test.

Deep appreciation for all the support and suggestions.

 

Please post the readings after the measurement, I'm quite curious what the magnitude of difference is on the Jag V8.
BTW, personally I wish I had Nikasil coated liners in my 4.2 XJ8, then I would also dare to measure compression, because I could be sure that a problem can be simply cured by swapping in new piston rings. With the steel liners chance is that the cylinders need boring and honing when the piston assembly is no longer sealing. All that plus bigger pistons afterwards ... so I don't check
My old BMW R80GS bike liners with their nikasil looked like fresh from the factory after >100.000km. And they saw their share of high sulfur fuel for sure in the Middle East and Africa.
I think discarding nikasil was an over reaction and a mistake.
Just my few (euro) cent

 

Hey Aix... Will do.

I also am unafraid of the Nikisil lined. I have a 2000 Nikisil lined motor with 37k that I will be swapping into my xk8 as soon as I get a chance. I had never heard about all of the concern a issues with gas and such,,, in a sitting motor, had been out of a shell for years, I tested at 150, 140 and as high as 160lbs if I remember right. Teaspoon of oil and spun the starter. I was stoked.

My buddy did the comp test on this one, I was there, the readings were low, but I want to so it all again, and will.

 

I did not see what the other 4 cylinders had for pressure?
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I did not take them The passenger side is just easier to get to so that's where I went - for now. What does it mean if I didn't test all 8 cylinders,,, in your experience? Does it disqualify results from the 4 I did?

 

What the problem is you are ignoring the old damaged plastic timing tensioners and I think you might have jumped a tooth on the timing chain on that side of the motor.

Do not delay in replacing those as the old orange color tells us they are factory!

The other 4 cylinders will let us know if both sides of the engine have low compression. Also the throttle opening has NOTHING to do with the compression test so don't worry about what position the throttle is in when you do the test.

I always do the compression test with all 8 plugs removed just so the engine will spin as fast as possible.
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The fist thing I noticed (and was surprised by) is that, from what I can see, they are all stock tensioners - all the way down the line. I'm not ignoring them, I'm just not there yet. I haven't touched the car since that first one day. I will get back to it, soon. I will remove other four plugs, do the compression test myself, again, with the help of the suggestions here...

What the hell is all of this impatience I'm sensing? I responded to the advise about the throttle that way I did because it was a genuine positive neutral helpful suggestion. And, it does matter.

People need to chill, lol.

 

 

After reading this, I was saddling up my high horse so I could point out how blatantly wrong you were. But first I'd need some cold hard evidence so I did some research. Much to my surprise, I was less correct than usual. I'd been taught always use WOT for a cranking compression test, but I found plenty of anecdotal info that it really doesn't matter. Who'd have thunk?

From the same source (a highly respected shop teacher), I was also taught never to condemn an engine solely on a bad cranking compression test, because there were so many variables. Cranking speed is a big one, for example. If your engine passes a cranking compression test, great. If not, investigate further with a leakdown test or maybe even a running dynamic compression test. I think that's still valid advice, even though my world has been shaken...

 

Sorry if I was chewing on you. I did not mean too!

I have been on this list almost 10 years and a lot of people have needlessly destroyed their engines because they kept waiting to do the tensioners or even worse they will do the easy to get to ones on top using the "Zip Ty Wrap" method.

There is just so much wrong/BS out there because nobody seems to do any mechanic work anymore and the bare basics are now completely unknown!

Yes a leak down test is far superior BUT wait until you get people trying to that test!! I do not even bring that up unless the person is pretty advanced in his understanding of cars. There is a lot of technique in leak down tests.

Again sorry for the bad attitude!
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