Hi all,

I have a 2000 (January) XKR Convertible and upon changing some very old plugs and coils I did a cold compression test and all were 120-125 except # 8 which sounded different and was only 30psi! I added some oil, not sure how well it got in and it was 70psi. I had removed both fuel pump relays but some could have got in.

After researching the forums I read a lot about wash down and Nikasil etc. so I reassembled the engine, warmed it and pulled the fuel pump relays ran it until it stalled to clear fuel and tested just # 8 (with all other plugs in to save pulling them all) and got 120psi.

So am I ok here? Is a leak down test warranted?

Is my series 27 engine pre or post Nikasil (Its on the cusp)?

I ask as I have 300km of warranty left, lol.


Any insight is appreciated, thanks!

 

I would try the compression test again, but this time pull the injector fuse. Make sure the throttle butterfly is wide open. Nikasil was used until engines built in mid August 2001.

 

If it runs fine, don't worry about it,I went through the same thing, but my car runs like a bat out of hell.These engines are weird. Ive had different readings, different times, just gave up lol. Car purs like a kitten and you cant even hear it at idle.

Also be sure to use premium gas as it tells you too, all the 4.0 and 4.2 's love to gum up the pistons.Fuel injector cleaner helps, and marvel mystery oil in your oil after its changed,typically will free up the rings that are sticking.

 

It's more like a cat out of hell

It doesn't burn oil, purrs, and has great power and no smoke so I am inclined to agree, it was just an nikasil anomaly..

I will try marvel as there is serious gum. What about sea foam or water decarbonizing?

 

Soo, I have looked every wear and can not find in any post or in my manual what the compression should be in my XKR in PSI. Anyone?

I would think the XKR would be lower than a xk8 as it has a lower CR.

Curious what jag spec is and from someone that has tested one that has around 100,000 miles on it..

 

Anyone, please?

 

I do not know the specific psi requirements but generally they are in the 150 to 160 range with no cylinder off by more than 10%. The compressed engines have a lower compression ratio so the above might be a little high.

Measure with the engine warm, throttle plate open. I usually stick the handle of a screwdriver in the TB as it is hard to loose one of those down the intake manifold.

A squirt of oil in a suspect cylinder after an initial reading will tell you whether you have a ring or valve problem. If indications are valve a leak down test will confirm.