BMW E30 Timing Belt Pulley & Crankshaft Damage + Ghetto Repair!

Don't let this happen to you! If we hadn't found this, the engine would probably have been toast soon! In this video we discover and do our best to fix some serious damage to the crankshaft keyway, woodruff key and timing belt pulley. This is what happens if the main crank bolt isn't bolt properly torqued - it should be 410Nm (about 300 ft-lb).

In the year that we've been working on this car we've had the timing belt off four, maybe even five times., but we'd never taken off the bolt (or even checked it for that matter). Every time we put the belt back on we had trouble getting the timing marks to match up the first time. It turns out that's because the timing belt main pulley had all kinds of slop in it!

The opening clip is from just before we discovered the problem. We'd just put the timing belt on, and needed to take it off to fix a mistake we'd made installing the intermediate shaft seal. That's when we found around 5-7 degrees of slop in the timing belt pulley!

There were plenty of clues (like how easily the crankshaft main bolt came off, the issues we'd had matching timing marks, and the 'funny-looking' woodruff key). When we pulled it apart and gave it a closer look, the problems were obvious, and everything finally made sense.

Thankfully we have a 'spare engine' int the garage and the timing belt pulley and the woodruff key in that engine were perfect! Unfortunately the crankshaft keyway was damaged as well. With a drift event in a couple of days, and the crankshaft in the other engine known to have problems, we didn't have the time or the parts to fix it properly.

We test fit the new key and crank pulley and the drift was reduced to 2-3 degrees. it was also much more difficult to move it back and forth. Torqued properly, it might have been okay just like that. At least we would have been confident that the timing was correct.
We talked briefly about trying to tack weld the woodruff key in, but we were worried about all kinds of issues related to that (heat, alignment, machining it back down, and etc).

We settled on filling the gap with JB Weld because it was much better than nothing. We also made DAMN sure to get that main crankshaft bolt torqued down to spec.

Give us shit if you like, but I think, given all the factors at play, we did the right thing. Aligning the timing marks was easy for the first time!