Hi everyone, there is so many knowledgeable people on this forum so I was hoping I might get some help.
This is my first post so here is a little background. I have a 1982 xj6 which has a misfire and idles roughly. It has been like that since I purchased the vehicle.
In addition to the misfire, the car is mysteriously losing coolant. It is a moderate amount. It is not dripping on the ground, nor is it blowing white smoke out the exhaust.
Oil and coolant do not appear to be mixing together. Also, I have done a combustion leak detection test which supposedly checks for carbon monoxide in the cooling system and it proved negative. The liquid stayed blue which supposedly means it doesn’t have a leaking head gasket. It is a cheap Amazon Combustion Leak Tester so i’m not sure how accurate it is.
I have done both a wet and dry compression tests and there is a 30 psi difference between wet and dry compression tests. That is to say all cylinders were 150 psi with the dry compression test and 180 psi with the wet compression test. The engine was at operating temperature and throttle was open during the tests. Ignition and fuel disabled.
I am getting conflicting opinions by mechanics. One Jaguar mechanic with 50 years experience says the 30 psi difference is not the cause of the rough idle. He has inspected the spark plugs and believes it to be a head gasket leak in it’s embryonic stage. Furthermore he believes being in it’s beginning stage it can be repaired with a product similar to Head Gasket Repair Sealant.
Two other Jaguar mechanics (one of which specialising in rebuilding Jaguar engines) believes the cause of the rough idle is the worn piston rings which is causing the 30 psi difference between wet and dry compression tests.
I was advised if a cylinder had coolant entering it it would be cleaner that the other cylinders which is not the case. I have inspected all cylinders with a endoscopic camera and this does not appear to be the case. All cylinders appear to be similar.
Finally i did a leak down test and found that cylinders 1, 4, 5 and 6 had 15 % leak down. Cylinder 3 had 40 % leak down and cylinder 2 had 30 percent leak down.
If i could get your input it would be greatly appreciated as I’m very confused from the differing opinions by several Jaguar mechanics.
Thanks for your time and input.