It was only raining a little bit this morning, and my compression tester (I wouldn't save it was especially expensive -it cost £40 rather than £15 - but the braided hose still spun in the fitting and I had to uses some pliers to remove it from the engine.. I wouldn't want to thread it into a twin cam engine.) and new feeler gauges had arrived yesterday, so I set about my investigations.
First I started the car up and ran it up to temperature at idle - It was a little lumpy when cold - then shut it off and removed all the spark plugs.
Removed fuses 1 and 11 (Main pump/ignition and in-tank pump), hooked the battery up to the C70 on some jump leads to make sure that was consistent, screwed the tester into No1 cylinder, held the throttle wide open and turned the key.
Nothing.
After a few moments of confusion, and checking which fuses I had removed, I put the gearshift back into P and tried again - at least I know the interlock works now.
Try again, throttle wide open, and cranked until the reading stabilised
No1 - 170
No2 - 195
No3 - 155-170 (was inconsistent over a few attempts)
No4 - 195
I'd have been happy with 170 across all, but apparently it can achieve 195 (which seems high to be honest, but the engine does only have 82k on it?)
I did each cylinder in turn again to be sure (and a few more on number three) with the same results.
13% lower on 1 and sometimes more on 3; I don't think that is quite what I was hoping for.
Then it started to rain so I went and hid in the shed for a bit while deciding to carry on and check the valve clearances.
By the time I got to this the engine had been cooling off for probably 3 hours. I can do it again one evening so it's definitely cold but really its the differences I'm looking at. (my gauges only go up in 0.05 increments, I should have checked that when ordering..)
1E 0.35
1I 0.5
2E 0.4
2I 0.45
3E 0.35
3I 0.5
4E 0.35
4I 0.45
Is the fact that the inlet valve clearances are bigger and out of tolerance even for a warm engine let alone cold, on the same cylinders that have the lower compression of any significance, given that the inlet valves are larger and in theory more likely to get tweaked by the dome on the top of the B200e pistons?