After four years of sleep...

Well there's your problem:
 

I didn't see this when I looked under the car when I was on the side of the road. I think backing off the flatbed flung it off the exhaust it was resting on. Apparently the six bolts holding the left halfshaft to the diff decided they didn't like their job and walked out; one is bent (probably the last one to go) and two had minor damage to the threads that I removed with a pass through an M8x1.25 die. No idea why they came loose, since the other three similar sets were all nice and tight. I suppose it's possible I failed to tighten them, but I haven't touched them in years as far as I recall, since I haven't done any work on the driveline.

In any case, I ordered six new ones. I'll chase the threads with a tap, clean everything, and blue Loctite the bolts in place. In the meantime, I put the three undamaged ones in temporarily so I could drive the car back into the garage. Thankfully, this seems to have been a relatively low cost failure, as nothing else seems to be damaged.

02Pilot said:

In reply to Harvey :

The smell is usually attributed to the horsehair padding they used in the seats. Since my front seats have been replaced with aftermarket units and the rear has been stripped and repadded with foam, it doesn't really have that smell any more.

That is actually really interesting. I know they did it at least until the E28 generation.

In reply to 02Pilot :

looks just like my E12 did when I was cruising Woodward with GRM Joe G a few years back.

In reply to AngryCorvair (Forum Supporter) :

You had the same failure? Any idea why these bolts back out? It would almost be easier to understand if any of the other ones were loose, but the three other flanges seem to be absolutely tight.

I've had that happen in my E28 as well, luckily I wasn't far from home and was able to limp it back after finger tightening them. For me it was on the wheel side and it damaged the drive flange so I had to replace that.

I bought a box of 25 from McMaster (so I have a spare somewhere lol) and replaced them all as the heads were starting to get wallowed out. I chocked mine up to be under torqued. I've never had it happen again since then but I did recheck them soon after install just to be sure.

I think you'll be fine with the blue loctite and torqued to spec.

It happens on early water cooled VW trans as well; I know, wrong end, but same basic idea. Blue loctite.

02Pilot said:

In reply to AngryCorvair (Forum Supporter) :

You had the same failure? Any idea why these bolts back out? It would almost be easier to understand if any of the other ones were loose, but the three other flanges seem to be absolutely tight.

In my case, wife called me to dinner before I torqued them and I just plain forgot where I left off. All four sets were loose, but the bolts on the drivers side inner backed all the way out. Only lost 1, was able to thread the other 5 back in.

Got everything put back together with the new bolts; chased the threads on the output flange, brake cleaner through the holes, and blue Loctite on the bolt threads. I found no damage, though test-fitting the bolts in the cleaned holes did not feel as precise a fit as I would have liked - I wonder if those threads were previously worn or damaged. All the other ones seemed fine and in good shape, so I have no intention of replacing them. I couldn't find a torque spec, so they got pulled what seemed like the right amount of tight. I'll keep an eye on it.

I haven't had this happen but I've read about it happening to others both on E36s and 986s. Must be a German thing. Blue loctite has always worked kept them tight for me. You should be good

again, lovely car

Even though the oil was changed just before the car was parked, that was a few years ago, so the plan was always to change it. This engine has always produced some blowby, but it seemed a bit more pronounced than I recalled from when it was last in regular use, so I decided to try a BG EPR treatment to see if I could free up the rings (I've scoped the cylinders and there doesn't appear to be any abnormal wear that I can see, so I'm guessing crud in the rings might be at least part of it). I'm always fairly skeptical of these sorts of things, but my indy has been using BG forever and has had good results, so I figured I'd take a shot.

I bought a few cans of the stuff. You dump a can in a warm engine, idle it for 10 minutes, and change the oil. It has a water-like consistency and stinks of chemicals that might actually work. It went smoothly, and while there's still blowby, it seemed a little better than before (no scientific testing, sorry), and I suspect it may continue to improve with further use if deposits have been softened. Oil pressure improved a bit, but that may just be the fresh 20w50 - spec is ~60psi @ 4k hot, and I've got 70psi, which I'm perfectly happy with.

I think I may have finally resolved (mostly, anyway) the off-idle and cruising stumble by dialing the mixture back a bit. For whatever reason, I had a sense that it was running a little rich, so I rechecked the carb balance (it was fine) and then tuned for best idle mixture at 1000rpm. Since the 40DCOEs use progression holes as well as an accelerator pump, the idle mixture affects the transition circuit as well. I need to drive it more, since every time I do I find another issue, but the light throttle situation was getting really annoying.

This seems to be turning into a sort of build/maintain/run thread, so maybe a mod could move it over to the Builds subforum? Thanks.