It’s been a long time since I posted an update here! Lots happened over the summer; new baby (number 3), new job, and so slow pace of work on the Alpina.
Since the last post I have:
• Got the head back; needed a very slight skim to remove some fretting, pressure tested OK, new valve stem oil seals, valve seats and valves all OK
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• Cleaned up the block very carefully and cleaned out the bolt holes
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• Refitted the head; very tricky as a heavy old lump, I chose to fit the exhaust manifolds onto it on the workbench so a bit of a wriggle to get it on.
• Timed it, fitted my VANOS which had been overhauled by Hack Engineering
• Inlet manifold blasted and powder coated, looks lovely now
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• Buttoned the whole thing back up
• And it started first time! I have video proof, although it sounded like a boat engine as I only had one exhaust manifold connected to its pipe at the time.
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I felt like an absolute legend clearly, but it was not to last…
The engine stalled when I tried to rev it after a few minutes, and to cut a long story short hasn’t started since.
I’ve checked all the usual things, I don’t have any fault codes (using a proper Peake reader), fuel good, spark good, etc. The problem is one of compression. The figures I have are confusing and all bad news! Here’s what I’ve got (in psi), from a test conducted with a few ml of oil squirted into the cylinders first to help the piston rings seal after having had a lot of unburnt fuel wash them out:
1: 0
2: 32
3: 0
4: 0
5: 80
6: 125
Before the HG change they were fine on 1-4 and down on 5 & 6 with the gasket gone between those cylinders. Testing tool is brand new and seems to measure cylinder 6 just fine – and I can tell that the zero readings are right, there’s no resistance to cranking at all with the tester or a spark plug in 1/3/4.
The timing looks bang on. I set it properly with the right tools, and if it was off then I think I’d get low across the board rather than one acceptable cylinder, 2 bad and 3 appalling. Same for VANOS installation, if I’d messed it up then surely all cylinders would be down a little?
I’ve checked the valves with a boroscope. Hard to see but nothing obviously bent and all appear to be closing fully. No piston damage. Some swarf visible on top of no 3 inlet valves, which is pretty poor from the machine shop, but I can’t see it reducing compression to zero.
The cam followers all look to be in the right place, and with the lobes off the followers it looks like the valves are all retracting as they should.
Head bolts haven’t obviously loosened, but this doesn’t mean they haven’t I guess.
I need to get a leakdown test, which would pin down where the loss of compression is coming from, but I don’t have the equipment and clearly the car is a non-mover!
Anyone got any ideas whilst I try and find a leak-down tester? There’s some very experienced E36 mechanics on here I know!
Have I just installed the HG really poorly? I find it hard to believe that this could cause zero compression – poor compression maybe, but none at all?
Could a bit of swarf – or some other machine shop error – cause this? Seems less likely given that they do this for a living and I’m an amateur!