Rod Knocks on my E34!

[SentinelDriver]

Hey all!

New here, even newer when it comes to DIY repairing. I found this 518i with only 130k's on it, visually in stunning condition, little to no rust.

Only thing is, the fool I bought it from had been treating it like a pizza delivery Honda, with little to no knowledge i cars, even though his uncle works as a mechanic. So I bought it cheap as hell, almost for free, and did the maintenance myself. It was low on coolant, power steering fluid, lousy rims, hell it even lacked screen wash. Worst thing was, the moron had been driving it with low oil pressure for a "little while" and now I hear this loud metal knocking sounds from the engine.

Even after filling it will oil, the sounds would still appear at starting at 2000 - 3000 rpm only getting worse when heated.


My guess is: damaged/spun rod bearing. I'll be fixing it this weekend or next week. My question is, will I be able to locate the rods from underneath, on this 518i after dissembling the oil pan? I guess I need a new set of bolts to assemble it all afterwards too! And I can't seem to find the tightening torque Nm for the rod bolts in the Bentley manual. This will be the first time for me, fixing rod bearings on a E34.



Other than that, the car drives like a tank. A very sexy tank that is, but it won't be going anywhere until it gets new bearings.
Any help would be appreciated!

Thanks!

[demetk]

If the bearing has spun, you'll need a crankshaft too.

[ross1]

If the bearing has spun, you'll need a crankshaft too.

This^ and that means engine out.
This may help when putting it back together; http://www.m42club.com/forum/index.php?topic=2247.0

[XAlt]

I'd go ahead and swap it out for something else while you're at it.

[flynfrog]

I would check it if you didn't run it that long the crank might be ok.

[kouks]

I recently had an OIL PRESSURE LOW warning but was able to pull over and get to the driveway about a block away.

After fixing the problem (a loose oil pickup tube on the oil pump), I used one bottle of LUCAS Oil Additive and Castrol 10W-40 oil and it runs like butter. Now, you may have some heavy damage if he ran it for a while, but you may try it to see if it quiets things down for a while. If the bearings can produce good oil pressure, they might still have life in them until you get a good game plan.

A member on the e38 sub-forum was having some knocking noises also, used the LUCAS and the 10W-40 and reports its quiet again.

[SentinelDriver]

This^ and that means engine out.
This may help when putting it back together; http://www.m42club.com/forum/index.php?topic=2247.0

Thanks for the link! But taking the engine out might just be way too big a job for me. I really hope it hasn't done that much damage to the crankshaft.
Otherwise I'm .... and I'll have to leave it to the professionals and pay up big time.

I would check it if you didn't run it that long the crank might be ok.

That's what I'm gonna do, because everything sounds smooth from 1000 - 3000 rpm, the knocking starts right after 3000 rpm. Could it be damaged or worn bearings only, that makes the extra gap in the rod, which explains the knocking sound?

[ross1]

Typically a rod knock is present at all RPMs. If you LIGHTLY rev the throttle is it audible? Often you'll hear it rattle a bit more on the over-run, as the revs come back down.
Whatever is going on you need to quit driving it as it's not going to get better, just more expensive.

[SentinelDriver]

Typically a rod knock is present at all RPMs. If you LIGHTLY rev the throttle is it audible? Often you'll hear it rattle a bit more on the over-run, as the revs come back down.
Whatever is going on you need to quit driving it as it's not going to get better, just more expensive.

Yes, you're right. The knocking is always audible, just not as much as when over 3000. I will need another engine.

I'd go ahead and swap it out for something else while you're at it.

Thanks for the info man. I found another fine M43 engine with 140k from a 3 series, that will fit my E34. I will still have to use my old wiring, oil pan and engine mount though.
It'll get expensive and I'll have to pay with my soul this time and I might just have the Stockholm Syndrome for this E34, but that should do it!


Thanks for the help everyone. Very much appreciated!

[XAlt]

I'd try and find an M30 or M50.

Your life will change forever, maybe.

[SentinelDriver]

I'd try and find an M30 or M50.

Your life will change forever, maybe.

Haha, that's the dream. But tax rules here in DK does not exactly make it easy for you, if you're going for that kind of performance upgrade. Not only do you have to pay extra taxation, if your performance makes up 20% more than the original, it may not even go thru' the Automobile Inspection Station, which is every two years. The law and safety rules here are extremely strict.

With that said, I think this E34, especially the 518i, is a strange bird and would need some more conversion with brakes, differential and such, if I remember correctly and my financial situation is worse than my relationship at the moment, so that won't happen.

That E34 M5 will be mine someday, just not now.