[Muz180]

My car is sitting at 135k miles and I'm getting a knocking noise that's more audible without the engine cover.. anyways I'm going to get it checked out and I'm fairly certain that it is rod knock but I was hoping u guys cud let me kno
w if there is a possibility that it's something else.. also I am on low oil right now.

[Muz180]

Checked oil filter and found some metal shavings also when I drive the noise is only noticeable at low rpms especially around 2-2.5k and I don't rlly hear anything at idle.

[mxchris727]

Yes, that's textbook rod knock. If you see shavings in the oil filter that's proof that a bearing has spun. At that point, the crank is probably scored and you are most likely better off getting a used engine installed.

[Muz180]

Would it be advisable to replace the rod bearings myself or to get a used engine and do an engine swap or have my engine repaired? And if I should buy a used motor how can I be sure of what condition the motor is in? Any help would be greatly appreciated.

[KnighTT]

Well, you have two options that involve a lot of work in both cases. One may or may not be much less expensive than the other.

Rod knock is not terribly common in n54s as I just don't see it mentioned often after years of being in these forums. Just about any engine, in any car, can get rod knock for many different reasons. It can be prevented in most cases.

The truth is, you could yank the engine and repair it but that is a incredible amount of work breaking the engine down all the way to yank the crank. I've done it on a few engines. You will need to take the crank out and have it resurfaced, if it isn't damaged beyond repair, then deal/find what other damaged may be there. Then, spec new bearings based on the new size of the crank as the tolerances have changed. I did this on a Land Rover a few years ago.

That's a lot of work and possibly a LOT of money as you will need to replace every single seal in the engine and everything else involved in the teardown and build up. Now...you may end with a bullet-prooof engine when you are done and a fresh rebuild. That's good, but that all depends on how passionate you are about that kind of thing and if you want to invest that kind of detail into your car.

Or...you can source a low cost used engine yanked from a lower mileage BMW and just swap it out. Just find an engine from a reputable source. N54's don't fetch a premium. Plus, this way gets you back on the road much faster.

My n54 has 165k miles on it and runs great. That being said, I will probably buy a used motor one day, rebuild and bulletproof it, and just swap that in for peace of mind and longevity.

[Muz180]

Originally Posted by mxchris727

Yes, that's textbook rod knock. If you see shavings in the oil filter that's proof that a bearing has spun. At that point, the crank is probably scored and you are most likely better off getting a used engine installed.

okay, thanks for the advice.

[Muz180]

Originally Posted by KnighTT

Well, you have two options that involve a lot of work in both cases. One may or may not be much less expensive than the other.

Rod knock is not terribly common in n54s as I just don't see it mentioned often after years of being in these forums. Just about any engine, in any car, can get rod knock for many different reasons. It can be prevented in most cases.

The truth is, you could yank the engine and repair it but that is a incredible amount of work breaking the engine down all the way to yank the crank. I've done it on a few engines. You will need to take the crank out and have it resurfaced, if it isn't damaged beyond repair, then deal/find what other damaged may be there. Then, spec new bearings based on the new size of the crank as the tolerances have changed. I did this on a Land Rover a few years ago.

That's a lot of work and possibly a LOT of money as you will need to replace every single seal in the engine and everything else involved in the teardown and build up. Now...you may end with a bullet-prooof engine when you are done and a fresh rebuild. That's good, but that all depends on how passionate you are about that kind of thing and if you want to invest that kind of detail into your car.

Or...you can source a low cost used engine yanked from a lower mileage BMW and just swap it out. Just find an engine from a reputable source. N54's don't fetch a premium. Plus, this way gets you back on the road much faster.

My n54 has 165k miles on it and runs great. That being said, I will probably buy a used motor one day, rebuild and bulletproof it, and just swap that in for peace of mind and longevity.

makes sense. I am trying to figure out how to access the rod bearings without taking the engine out because I do not have an engine lift, I want to do this in order to gauge the damage to the bearings/crank and decide whether or not I can fix it. But I have read multiple times that even if there seems to be no damage metal shavings could have easily spread throughout the entire engine causing wear in every component. I don't think I have the tools or nearly the amount of experience needed to tear down the entire engine and do a full inspection myself so I think my best option is to look into remanufactured engines with a warranty as I heard those can be pretty much bulletproof. Also need to figure out if I should buy an engine lift and attempt to reinstall myself or find a reputable shop. Anyways thanks for the advice, it was very much appreciated.

[mxchris727]

The metal filings will really only damage the oil pump as they get caught in the filter before the oil goes to the rest of the engine. If you are doing rod bearings alone, then you can do it from under the car. However, if the car is making that much noise than the crank is bad and will need to be refinished. The crank can only come out with he engine completely disassembled as you have to split the bedplate.
As for rebuilding vs replacing, I would just replace as you'll save some $$ and time. Make sure you can verify the VIN, service history, and ownership of the used engine.
Was yours run low on oil? The only rod knock I've seen on N54s is from that or injectors leaking fuel into the oil diluting it. These engines do not have manufacturing/oiling issues like the N55 that are starting to appear more frequently as they age.

[Boland01]

On our old E36 we had rod knock. Shut the car down in a couple blocks after it started. I can tell you the shavings got everywhere in the engine. It ruined the crank, and one of the camshafts. The oil filter will not stop the shavings from going everywhere. I'm guessing the timing chain may have carried the metal shavings into the head but I'm not sure.

We ended up taking the car completely apart, pressure washing the bare block and spending about $2K on parts. On the N54 throw in the potential damage to the turbos and I'd just look for a used engine to drop in as others have stated.

[Pladi]

TheMidnightNarwhal

[Pladi]

Originally Posted by Muz180

makes sense. I am trying to figure out how to access the rod bearings without taking the engine out because I do not have an engine lift, I want to do this in order to gauge the damage to the bearings/crank and decide whether or not I can fix it. But I have read multiple times that even if there seems to be no damage metal shavings could have easily spread throughout the entire engine causing wear in every component. I don't think I have the tools or nearly the amount of experience needed to tear down the entire engine and do a full inspection myself so I think my best option is to look into remanufactured engines with a warranty as I heard those can be pretty much bulletproof. Also need to figure out if I should buy an engine lift and attempt to reinstall myself or find a reputable shop. Anyways thanks for the advice, it was very much appreciated.

There is a member who had a seized crank due to a spun rod bearing on the N55 side of the forum. He put new bearings and is been driving it for 6000 miles. So what i am saying is its always worth trying that.. You can even measure the clearance and maybe even try to polish the crank like he did all from underneath ..


But the issue with this type of repair even if it works out 100 % is ; you are not fixing the root cause.. Unless that root cause really was that one bearing somehow.

[TheMidnightNarwhal]

If you have time and DIY I would do the polish and new bearings thing but if you don't want to fuck around definitely get a used engine.

[mxchris727]

Originally Posted by Pladi

But the issue with this type of repair even if it works out 100 % is ; you are not fixing the root cause.. Unless that root cause really was that one bearing somehow.

^+1000x

[Muz180]

Hey guys thanks alot for all ur input I'm in the process of pulling the engine rite now, still haven't ordered a used engine or figured out if I wanna rebuild tho

[Muz180]

Originally Posted by mxchris727

The metal filings will really only damage the oil pump as they get caught in the filter before the oil goes to the rest of the engine. If you are doing rod bearings alone, then you can do it from under the car. However, if the car is making that much noise than the crank is bad and will need to be refinished. The crank can only come out with he engine completely disassembled as you have to split the bedplate.
As for rebuilding vs replacing, I would just replace as you'll save some $$ and time. Make sure you can verify the VIN, service history, and ownership of the used engine.
Was yours run low on oil? The only rod knock I've seen on N54s is from that or injectors leaking fuel into the oil diluting it. These engines do not have manufacturing/oiling issues like the N55 that are starting to appear more frequently as they age.

I bought this car from my uncle for rlly cheap and they had done alot of repairs to it but rumor had it that it wasn't maintained well anyways I see that now as I owned the car for 2k miles and the engine went out on me.. I was about to do an oil change once I put on 2k miles also cuz when I asked previous owner they didn't know exactly when the last oil change was done