Hi gals and gents

Buddy of mine has a 1987 xjs 5.3 v12. Cylinder 1a has been diagnosed as "zero compression". Further diagnosis after removing all that stuff and getting to that plug confirms this. After putting in a table spoon or so of oil, this compression of zero jumps by a lot., which I guess points to rings. Or would oil just be getting in my gauge? Anyhow I've tried acetone and ATF to attempt for the best and free up a stuck ring, to no avail. Other cylinders read proper compression at 210.

I then proceeded to take a strong led flashlight and the cylinder wall is scored.

So here is where I am at. If its a burned valve which scored the wall it still means taking the pan off, head off, and reboring all 12 cylinders with new pistons. was prepared to take the head off but by no means am I capable of doing this additional work now that I know the wall is scored..And not prepared to have a mechanic whether jag or not do this work which is of course astronomical in price.

So what I have done is put it back together understanding its damaged state. My theory is to disconnect the fuel injector on that cylinder to avoid bugging up the cat converter and thinning the oil.

Assuming the damage has been done to this cylinder and whatever piece of valve or ring had escaped (which it has), what should I expect from doing this?

What came across my mind was o2 sensor which may pump a too rich fuel mixture...but maybe the computer isn't that sophisticated?

So in theory should my friend be okay with this approach? Disconnecting injector, adding a bit of Lucas to oil, and driving with a scored cylinder wall and either a burned valve, bad rings, or potentially both.

Thanks for the input.


J

 

Disconnecting the injector is a reasonable short term solution, but the chance of doing more damage if that ring fails totally is high, and could be catastrophic.

You are right with the injector disconnected the other cylinders will run rich.

The V12 runs slip fit liners meaning the piston and liner can be replaced with the engine still in the car, individual liner and pistons are available from Rob Beere in the UK