Rod Knock or not?

[f33n3y]

Hello everyone.
I have a 96 320i touring and recently i have noticed a slight knocking in the engine that increases with the revs. there is no problem with the performance but it seems to be using more oil than usual but im not sure if thats because im using 10/40 on an engine with 175k on it and its just burning away. the oil light doesnt come on or flicker.and i look after the car no thrashing the life out of it
:dunno:
any suggestions or help will be greatly appreciated:thumbup:cheers

[Pirate_copy]

Most likely a hydraulic lifter mate

Very common

[f33n3y]

Ah nice one mate :). is that a pricey job? i thought i was going to have to tat the car in after these rod knock scare stories.

[TheOnlyE36]

Most likely a hydraulic lifter mate

Very common

How have you been? Anyway back on the subject, how often do you hear about BMW 2.5 and 2.8 motors with a spun rod bearing? I just like to know. It's kinda scary thing when it comes down to low end bearing problems. I had a Dodge Stealth R/T TT with a bad rod bearing, and it is a pain in a neck.

[M-azing]

I can tell a rod knock sound if I hear it. It is a slightly dull metallic knock or tapping, rather than a crisper tick...

I was hoping mine was a lifter as well, however, it turned out that it was the #5 rod bearing, with one of the bearing pieces sliding under the other, AKA a spun bearing.

I have heard this sound many times in my life & as soon as it happened, I recognized it, but I was in denial until after a bit of investigation revealed the bad news.

To find out if you have a rod bearing going bad, you can remove one spark plug connector & start it up, rev it a bit, not too high, listen for the knocking & if it is still there, reconnect the plug & remove a different one.

When you hit the right one, if it is a rod bearing, the knocking will stop & that will tell you which rod it is.

Also, if the knocking is going at half the crank speed, it could well be a bearing, but other things can be at half crank speed too, so that is merely a clue.

If you have a stethoscope, (sure, don't we all??), with the car on a hoist & running, you can isolate where the knock is coming from more accurately, ie; from the bottom end or from up top.

If it's a bearing, you can do the work with the engine in the car, but if you need to replace the rod, the head will have to come off as well, which means you should be sending it out for machining before re-installing it.

You would replace all rod bearings & all rod bolts, as they are stretch bolts, designed for one use.

If this sounds like an expensive pain in the butt, all I can say is, uhh yup, it is.

Since I did mine, I've heard it in another car & while a few people were gathering around taking guesses at what it was, I knew right away, & when I mentioned it, no one wanted to believe it, but unfortunately, I was right again...

Good luck & hopefully it's not a bearing, but apparently it is not uncommon in these engines, more common than a main bearing from what I've been told.

If it is a bearing, look at the bright side, you'll have a set of fresh rod bearings...

[Pirate_copy]

Can be expensive to fix if the lifter is collapsed, but most people just put up with it

Try changing your oil and see if it fixes it (it may very well do)

TheOnlyE36...i am well thanks mate :thumbup:

[E36 Phantom]

It depends if it is more of a ticking or knocking. Since rod knock seems to be fairly uncommon, I'd agree with Pete on the probability of it being the lifters.
However, if it is more of a sturdy knock, you may well have it. I agree that the best idea is to just run down to your local health care/pharmacy store (not Longs or CVS) and pick up a basic stethoscope, then just lift the car up in the front and place the steth along the bottom end of the block, pay attention if the sound is particularly more clear from one cylinder or another, as that's where you have it. Also, I would NOT drive the car at all with a possibility of rod knock. Just go get a steth first and check it out.

[Pirate_copy]

Never heard of a rod bearing going on a BMW (E36 especially)

[TheOnlyE36]

It depends if it is more of a ticking or knocking. Since rod knock seems to be fairly uncommon, I'd agree with Pete on the probability of it being the lifters.
However, if it is more of a sturdy knock, you may well have it. I agree that the best idea is to just run down to your local health care/pharmacy store (not Longs or CVS) and pick up a basic stethoscope, then just lift the car up in the front and place the steth along the bottom end of the block, pay attention if the sound is particularly more clear from one cylinder or another, as that's where you have it. Also, I would NOT drive the car at all with a possibility of rod knock. Just go get a steth first and check it out.

You are so right I used to have a Stealth R/T TT. and I have to say loved that car but it's not worth of the bull **** you have to deal with!

[f33n3y]

Thanks a lot for all your help :) sorry about the delay i have to come to the mother in laws for the net as i live in the middle of nowhere :).it is like a dull knock not very loud and coming from the footwell it seems, and you can barely hear it with the bonnet up. i am going to get it looked at this week and hopefully will get to the bottom of it. its not like a solid knock just an annoying wooden kind of knocking. which now i know its there has increased in volume a million times hehe.my mrs says she can barely hear it but i think she is just trying to stop me moaning on about it :p

[Pirate_copy]

Where you based?

[TheOnlyE36]

LOL @ she is just trying to stop me moaning on about it.

[Nick325xiT 5spd]

Never heard of a rod bearing going on a BMW (E36 especially)
It happens sometimes on M50/M52 motors.

It happens most frequently on S14s (all the ****ing time), S50 Euros, and S54s.