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Discussion Starter #1 (Edited)
So I had an engine knock that came about randomly on my 122k mile 2001. Heard at idle and while driving (particularly 1500-2000 rpm) but went away with engine braking. I thought it was coming from the bell housing when I got under the car to track it down. Wishful thinking was a bad dual mass flywheel or other messed up clutch component. Took it to a very reputable BMW shop and they are saying it is coming from within the engine so they pull the oil filter and find gold metal flakes.

At this point, it would seem like I have rod knock and rod bearing issues? I don't know whether I should attempt to replace the bearings myself (at risk of not fixing or causing greater issue down the road) or what the cost for a shop to do it would be (which would be a determinant of whether I could do it). It didn't seem like this shop was very interested in selling me on the repair. They basically just said I needed a complete engine rebuild or an engine replacement. They didn't crack the engine open, mind you. I can't justify what is probably $7k-10k for either of those options on what is basically a $16k car.

My mechanical experience is healthy but I've never gone inside a motor before. What would you do in my situation? What if you had an ESS supercharger kit sitting in your closet?

Been through several of the rod bearing threads but would appreciate your thoughts.

What would you do?

Oh, here's a couple of videos:


 

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If you are certain that it is rod knock, buy a used long block from Clemster and replace it. That will be far less expensive than the other alternatives that you laid out.
 

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Many people have had knock, and the crank has been in spec and reusable. The OEM parts cost to do this job correctly is around $750, and it's not all that difficult of a repair. If you get in there and the crank is out of spec, I'm guessing you'll want to put them in the used motor from Clemster before it goes in. In any case, keep that puppy on the road :M5launch:
 

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Discussion Starter #4
Many people have had knock, and the crank has been in spec and reusable. The OEM parts cost to do this job correctly is around $750, and it's not all that difficult of a repair. If you get in there and the crank is out of spec, I'm guessing you'll want to put them in the used motor from Clemster before it goes in. In any case, keep that puppy on the road :M5launch:
What do you reckon an indy shop would charge to do the bearings ballpark? I'm waiting on one to contact me back with an estimate...but I'm fearing that will be pretty bad.
 

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George (M5Deamon) just did Christians rod bearings, reach out to him. I will be doing mine in another 20k miles or if I go FI.

Are you sure it isn't chain guides? I heard the same noise from Soemine else's M5 and it was chain guides which were fixed also by George.


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What do you reckon an indy shop would charge to do the bearings ballpark? I'm waiting on one to contact me back with an estimate...but I'm fearing that will be pretty bad.
Shouldn't be more than $2,000, some will probably bill way higher, I've heard $1,400 on the low end of the spectrum. Either way, try to get someone reputable if you don't do them yourself.
 

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Discussion Starter #7
George (M5Deamon) just did Christians rod bearings, reach out to him. I will be doing mine in another 20k miles or if I go FI.

Are you sure it isn't chain guides? I heard the same noise from Soemine else's M5 and it was chain guides which were fixed also by George.


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No idea...would the guides leave goldish metal flakes in oil?
 

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Discussion Starter #8
Shouldn't be more than $2,000, some will probably bill way higher, I've heard $1,400 on the low end of the spectrum. Either way, try to get someone reputable if you don't do them yourself.
Thank you. I think if I can get a reputable shop to do $2000 or less I will just pay them to do it.
 

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You dont know how extensive is the damage until you take it all apart = $

I was going to suggest what Rao suggested. Clemster has a low mile S62 if its within your budget i am sure he has others. Get an engine from him, transfer all of the new external parts from your engine (this is an option), change the rod's (also an option) , install the SC which sounds like its in your closet.

Once you do all that, for own educational purposes you can take the old engine apart and see WTF happened. If the block and heads are good, its a good candidate for a built motor and you can possibly re-sell it.
 

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I dont know how extensive is the damage until you take it all apart = $

I
^^very important to remember if you're not gonna pull it apart yourself. I'd probably only go the repair route if I planned on doing the work myself. If a shop gets in there an finds that the crank is out of spec, it's going to be money....and you're gonna be in the same spot you're in now.
 

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Pretty sure that is a rod knock so do not drive or start the engine until it is fixed. If you do the work yourself the cost won't be horrible, and rod bearings aren't that hard of a job, just be meticulous during the teardown and rebuild.
 

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Rod knock first shows up at around 2500 rpm so with it being very audible even at idle, and with the copper sparklies in the filter, I would be worried it has progressed enough that the crank journal is now damaged.

I like userx's idea above. If you decide to repair it yourself, buy all the parts to replace the bearings in situ. If the crank is scored, get a used engine from Clemster and put the new parts in that. It's a big job, though.

By the way, you may have to replace the chain guides as well as that may have been the starting point. They have a nasty habit of taking out the rod bearings when the plastic runners break up and the chain starts wearing aluminum off the guides.

Good luck.
 

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Not sure which shop you took it to, but contact Rated ///M on this board
http://www.m5board.com/vbulletin/members/109793-rated-m.html

He owns a shop in the Atlanta area and I have read great things about him.

Also, check to see if the noise is coming from the joint between headers and the Cats. There is a gasket there that can rust out. Bolts can also work lose. I am no expert by any means so take this for what its worth, but sounds too high pitched to me to be rod knock. Also, the noise in the video increase right where that exhaust joint is located.
 

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These straight from Clemster garage this weekend, I think he's got all your options covered. :)



 

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Engine sounds, at least in my experience, are very hard to diagnose on video. These motors make all kinds of noises and the source can be hard to pinpoint. When I hear these kinds of noises, I drop the lower oil pan to see what's in there. Failed chain guides can cause a variety of sounds. If there's no plastic chunks and you have lots of copper colored particulates, then rods bearings seem likely. It only takes 10 minutes to do this and half of that is waiting for your oil to drain. I'd be happy to sell you a good replacement motor if it comes to that, but it's always nice to know if you really need one first.
 

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Hard to tell from the videos, but if you want a rebuilt engine, we can sell you one at a very reasonable price in exchange for your engine as a core.

Thanks
-R
 

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I had a similar issue soon after I bought my car. The bearing spun but didn't trash the rod or the crank. I guess because it is softer material?

Luckily, although I'd bought the car off ebay from a shop in Florida sight unseen, the seller apologized and replaced all of the bearings for free.

Looking at the bearings it is hard to believe neither the crankshaft or the connecting rod was ruined. FWIW - I've been tracking the car every chance I get and drag racing it almost every Wednesday night. I'm sure I have at least 50 1/4 mile runs on the repair. Probably closer to 100 runs since the bearings have been changed.

Good luck and don't get discouraged!
 

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Discussion Starter #18
Thanks for all of the responses.

It seems at this time that the shop does not want the liability of doing this repair. I was told that the car would tie up a lift for too long...which is funny because wouldn't I be a paying customer as well? (I had another shop that wanted to "see" the car before they could give me a ballpark idea on the $$ involved with a rod bearing replacement (I don't know why seeing it matters for quoting me). And I had a third recommended shop tell me that they were going to estimate the cost and get back with me...never heard back.)

In any case...I'm picking up the M5 tomorrow morning and I will start by dropping the transmission to see if I was correct in my original diagnosis. At that point, if the flywheel and rotating mass of the clutch components are not the cause of the sound then I guess I will have no choice but to begin doing my own work of getting to the rod bearings.
 

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Thanks for all of the responses.

(I had another shop that wanted to "see" the car before they could give me a ballpark idea on the $$ involved with a rod bearing replacement (I don't know why seeing it matters for quoting me).

In any case...I'm picking up the M5 tomorrow morning and I will start by dropping the transmission to see if I was correct in my original diagnosis. At that point, if the flywheel and rotating mass of the clutch components are not the cause of the sound then I guess I will have no choice but to begin doing my own work of getting to the rod bearings.
Probably because they've never done the job and need to get an idea of what they're getting into :crying:

Great advice on here. Although plopping in a new motor would be the easy (although expensive) fix, it's certainly possible that the crank is in good shape despite the bearings (if that's what it is), meaning you can repair the existing motor for much cheaper than a "new" one. If the crank is trashed, perfect time to pop one in from Adam and call it good.

The good news out of all of this is that whatever option you end up going with will provide you with a "fresh" motor, which will give you peace of mind when bolting on the supercharger :checkeredflag: :cheers:
 
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