Club 80-90 Forums

So, following on from my previous thread (viewtopic.php?p=8313783 )

I decided to pull the heads, clean them up, reseal and refit. Cylinder 4 had leaking combustion gasket, pressurising my coolant (once hot).  All back together now with new gaskets/O-rings etc (except the lower o-ring, I left the barrels in place).

Turned it over on starter (plugs out, injectors unplugged) a bit to get oil round the system, spun freely and no funny noises (although perhaps still a mistake...), then wacked plugs in and attempted a start.  Ran really roughly, and had to open throttle to get it going at all.

Initially I thought I could mixed firing order up, but can't find anything wrong.  It was running fine before, I haven't touched timing or set up.

After a bit of web trawling I pulled the plugs and re ran compression test:

1.  225psi
2.  210psi
3.  Zero (!). (Was ~230psi before rebuild)
4.  225psi 

Pulled the rockers off to 'close' the valves, ran compression test on again, it went up to about ~160psi, so I vented and ran again....zero again.

- Could I have bent a valve in this process?  As they all had great compression before I didn't touch them and just refitted rockers as they were.
- Could I have ballsed up head fitment?  I guess it's sensible to recheck head nut Torques (50Nm IIRC).  I can't get my head around how the combustion gasket could be leaking this badly on start up.
- I have Mineral flushing oil in it at the moment, my intension was to run it briefly then drain and refill - not sure if this is relavent.

I've got a blow down tester but stupidly - no compressor to use it with.  May see if I can rig something rudimentary up with a normal tyre inflator but suspect it won't be much use.

Any suggestions welcome!

Just a thought but if you remove the rockers then no air is drawn in to compress, did you check other cylinders with rockers off or only number 3? Compression test should be done with throttle wide open to charge cylinders, most likely tappet setting on your initial test. Where is the fingers crossed emoji when you want one?

Check / reset valve clearances and check
The push rods are properly seated

Thanks guys after weimarbus post I logged off work laptop and ran outside to check...

Voila!  Refitted and reset clearances on the left bank and compression came straight back, ranging 225-240 across the board.  Happy with that.

Have started up and idled for 15-20 mins, sounds pretty noisy at the moment but i'm hoping that's just because it's been sat for a few months, plus the flushing oil.  Dumping the oil at the moment, will refill with new filter and test drive later.

Really appreciate having some where to do a sanity check - thanks all!

Now the big question is...should I bash down to the new forest in it on Thurs