As promised, here are some pictures from the rebuild.
Prior to this unexpected failure, I had a box with every coolant & vacuum/intake hose piece sitting in the garage. Since I had to take the motor apart for the timing case repair, I figured I'd toss in all the other repairs with it. Every paper gasket was replaced, with both sides being coated with Permatex high-tack non-curing gasket sealer (high temp, oil & coolant resistant). I want to be DONE oil leaks & nasty filthy motor covers!
Anyway, I think a lot of coolant hoses on there were original. The throttle heater stuff was starting to leak. It is hard to see in the pic, but it is all crusty & green on the heater.
The vacuum lines and coolant bits were in sad shape. All the oil from the crankcase had done a good job of eating the rubber in there, and the over-tightened hose clamps weren't helping the semi-rotten coolant hoses.
As most M42 owners wonder, "what was BMW thinking / smoking with this idea?!"
The motor was a grimy mess from years of leaky paper gaskets. Cleaning involved scraping with a putty knife over a garbage can, and then a bath in mineral spirits, a brillo pad & an old toothbrush. That did wonders. It is so much more pleasant to work with CLEAN parts since you can actually grip them without them popping out of your fingers!
I did notice what may be a coolant leak from the head gasket. I just couldn't tell if it had been coming from the feed hose to the heater core (seemed intact), or the head gasket. I seem to recall seeing the wet spot before removing the hose, so it isn't a drop from disassembly. I looked closely at the full-sized picture, and it almost looks like the liquid ran down from the fitting. I'll just have to inspect this area in the coming weeks.
So, when I pulled the oil pan I found: 6 ball bearings, neatly stuck to my magnetic drain plug. EVERYONE should spend the $10 or whatever on one of these. It can potentially save you $thousands!
Once I removed the oil pan, I found the remains of the plastic bearing cage in 3 pieces. There were some very small chunks missing, and I assume they are in the waste oil.
I removed the timing components for cleaning & inspection. Everything seemed fine. These things have about 70,000 miles on them now, which is maybe 50% of their lifespan. All were reused (except the busted idler sprocket...that was replaced with a new one). All other sprockets & guides looked like new though.
here's another shot of the remains of the idler wheel. The spindle showed signs of damage on the race (pitting), which may have been the cause of failure. It could also have been a result of the failure. I'll never know.
My fasteners, somewhat organized. As always, cross your fingers that you don't have any left, or find yourself missing some! I later filled these cups with mineral spirits & agitated the parts with a toothbrush to knock all the crud off.
The skid plate was a disgusting mess of oil & sediment. It was almost 5mm thick in some places! I bought a giant bottle brush from the local hardware store & used it to clean the gaps in this, as well as my intake runners, using foamy engine degreaser. MULTIPLE people at the hardware store asked me if I was buying the bottle brush to clean my bong. Apparently I was one of the only people in there buying one for something OTHER than cleaning stoner-ware :p.
Nasty, nasty, nasty.
Oh boy, there's a lot of work to be done still...
The old gasket was basically baked-on. A clean, smooth & SHARP gasket scraper tidied this up.
Getting the timing case on with the head still there...this was my second time doing this, and it was as miserable as I expected. Things went badly at first when I couldn't get it lined up. Then, it STARTED RAINING! I closed the hood, cussed for about 5 minutes & then made room to push the car into the garage. Rain, in the end of May is mostly unheard of around here!
Anyway, I got some 0.005" brass shim stock from the local hardware store. I used it to slide the case under, with a little coaxing from a large clamp. Once I could get the bolts in, I let them finish the job. You MUST get the oil pump aligned with the crank prior to any of this.
I had silicone RTV on the profile gasket. It seemed like a "lubricant". Getting the brass sheet out involved removal of the kidney grille, vise grips and pulling as hard as I could manage. It was a close-call...I was pretty sure it wasn't coming out at first. So, if you do this, do what the service manual says & use some sort of lubricant on the gasket & head. Silicone engine assembly lube is probably fine.
Thermostat housing...you really really need to make sure that the bleed groove is clear! I opted to cut the gasket a little to help reduce clogging there. Also, if you use gasket sealer, apply it thinner by this groove.
Getting there. It seemed that the worst was over (and it was, for the most part).
