Hi folks, i hate to mine threads but i think because of this thread the m42club has saved my engine from premature failure.
Aussie 1990 318is, 255,00 k's on the clock im going away for a trip tommorrow and wanted to make sure the car was as good as it could be.
I unbolt the lower pan and theres 4 bolts sitting there.... last time i did an oil change was at the mechanics, hes a mate of mine and i mentioned its a common thing and he said hes never heard of it and not to worry. so i sent him a pic of the bolts sitting in the pan lol he was surprised
a bit of loctite to all the bolts and all is well, like other people all the other bolts were only finger tight
thanks folks!!!! you saved me a premature engine rebuild...
but i did find 2 bits of timing chain in the pan aswell..... thats going to have to be assessed fairly quick, what are the chances of it falling apart? god knows how long its been like that for.
Good thing you checked and glad we could help.
From what I and a few others have seen, the chain breaking up is not an urgent, must fix now problem. I had a ton in mine before I had a problem. The issue is if you have those bits, PLUS the loose bolts.
It is a chain of events that creates the big problem:
First bolts come loose and some minor chain bits break off. These events are not because of each other and you may have bits in there for years or bolts in there for year, you never know.
The bolts work their way against the pump pickup.
You hit the pan on something. Speed bump, driveway, etc... Mine was a small ramp going over a fire hose when it did the damage I think. When hit, the pan flexes driving the bolt head through the pump screen. You may or may not see anything other than minor scratches on the pan. So do not count on a leak or crack.
Eventually the bolt falls out over time and chain bits get sucked through the hole into the pickup and the oil pump, which then shells (explodes). This usually will happen at a decent rpm, I was at 6k rpm.
At which point it takes about 1/2 second for the oil light to come on, and you will also hear something is wrong. You can probably get away with another 30-40 seconds before you will spin a bearing. I shut mine off immediately, like fraction of a second, but turned it back on for 10-20 seconds to make it up a hill so I could push my way home. Engine was fine. You figure the engine starts with no oil so... More than this though could mean an entire rebuild.
When this does happen and you do not spin a bearing, the parts to repair it can run into the thousands. The parts alone run nearly $1000, in fact the timing chain housing which holds the oil pump is around $300 by itself. Best thing to do is avoid losing the pump and if you do, buy a used engine to cannibalize parts or just swap the engine entirely. I found a used engine for $200, and Bmwman91 got his parts for less than that used. If you do the parts swap instead of the engine swap, be prepared, it is quite an undertaking. Probably easier to do the engine swap.
Basically as long as you do not have loose bolts in the pan, you can put off the timing chain for a bit. I would advise replacing the chain, ALL sprockets and the tensioner, regardless of its age. Be aware you may also need to replace some chain guides. These can double the cost of the job.
