Spinning at Blyton

On further inspection the first main bearing from engine #2 that I looked at (adjacent to the failed big end if I remember rightly) turned out to be ruined. This means that it would be crank out to fix, which would make a regrind a no-brainer, plus big-end and main shells, full strip and engine flush, etc. Doing the sums suggested that I could very easily spend £1k or more fixing a £1500 engine, or replace it and sell some of the bits to make up the difference. The latter seemed like an easier, more reliable and more cost effective option, so that's the route I took.

Main bearing from engine #2.

Eventually I found an engine via Ebay, and the seller offered to knock £150 off if I bought it without going through Ebay to avoid fees... and Ebay buyer protection. Obviously I said yes and took the risk, on the grounds that I have no faith at all in Ebay's buyer protection scheme. The engine showed up promptly, although it was pretty clear that the seller's claims of driving the engine for a few months were lies - since several of the intake hoses were completely perished, I doubt it would have run at all. It was also covered in oil from various leaks. This was a bit more lying than I had anticipated from the seller (I'd expected a bit), but still, none of this is very serious, so I got it on a stand and cracked it open.

"Yeah mate, it runs really smoothly"

"No oil leaks, breaks my heart to sell it, really does"

Happily, I found more or less what I expected when I looked at the big ends - a considerable amount of normal wear on the bearings, but no sign of serious problems and (almost) no crank marks. Similarly, the mains were basically perfect (they take much less load so this is to be expected).

The only exception was big-end #1 which had a slight scratch on the crank. I umed and ahed for a while on this one but eventually decided that since the scratch was barely detectable with a fingernail, and ran straight down the centre of the bearing, there was no path for the oil to escape without building pressure and floating the crank as it's supposed to, and that it ought to really be harmless. Time will tell I suppose, but certainly there was no evidence of knocking or anything like that - the oil that came out was black but free of debris, and the corresponding bearing was worn but not excessively, and not more than any of the others. So my reading is that this has been there for a while without causing a problem.

I plastigauged a few bearings and found them to be bang in the middle of spec, which was reassuring. So I put it back together with new big-end bearings (I'd have to remove the crank to do the mains and I didn't really see the point as these looked fine and never go wrong anyway) and stronger-than-standard ARP big-end bolts (most expensive bolts I've ever bought at £8 a bolt with a total of 12 bolts).

Slightly scratched big-end.

Mains look fine.

Big end cap - no serious wear. Fractured rods, very fancy. Grass needs a cut though.

Engine on stand and crane, just in case. Good thing actually as I didn't put the stand together properly - it didn't fail but it easily could have.

Engine on stand.

Another big end bearing looking fine.

So without further ado I put it back together with new big-end bearings and main and big-end bolts and stuck it in the car, although not without replacing the flywheel with a lightened single-mass flywheel (more on this in a bit), on the grounds that if I'm going to all the effort of replacing the engine, I should at least try to improve it in some way (in addition to making it work). The flywheel was a pain in itself - I was told that standard bolts would be fine, but they turned out to be much too long for the thinner flywheel. E30 bolts didn't work as they were too short (they engaged about three threads, which I felt was a bit marginal). So in the end I bought some new E36 bolts and got them cut down by the difference in thickness, which I'm sure will do the job.

On first start I was greeted by... an awful clanking noise. I considered phoning a scrap dealer and getting them to take the car away forever but after a couple of hours of investigation and research, finally identified the cause: the engine was sat slightly differently and was touching the chassis. I got the hacksaw out and removed the offending part, and all was well. It built oil pressure without much issue, thanks to packing the pump with vaseline (there was a slight issue as the pickup pipe is held by a bracket on one of the main cap screws - when I put the main cap back the bracket moved slightly, which meant that I struggled to get the pipe right. Next time I'll put the caps on with the pump in place).

Over the next few weeks I gave it some test runs, gently building up to max revs and changing the oil a few times. Each time nothing very bad came out, and no nasty surprises occurred. However, I do regret not changing the clutch - the standard M3 clutch is unsprung, because the dual-mass flywheel absorbs vibrations. My single-mass lightened flywheel doesn't do this, so using it with a standard clutch is, I think, a mistake. At some point I need to take the engine out and replace the clutch with a sprung clutch from an M5. It's quite a lot of effort though so I'm ignoring it for now; perhaps a job for the winter.

Last weekend it got it's second track outing, this time at Blyton Park. It performed well up until lunchtime, when the heavens opened and didn't stop until the evening. I took it out anyway in the afternoon, but I can't honestly say it was particularly enjoyable, especially when the front brakes stopped working. I've since replaced the front master cylinder and will see how that goes tomorrow. Despite the missing front brakes, however, I only managed one spin in the wet, narrowly avoiding a haybale and emerging unscathed.

For once, the breakdown on the way home wasn't me (Ben's rear brake calliper fell off the Atom). A relatively painless track outing then, if spoiled a bit by the rain. Current tally: 1.5 engines per track day.