Oh Damn! Rod Knock.

blktoptrvl · #1 02-20-2022, 01:16 PM

OK, I am experiencing rod knock.

Has anyone tried to remove the pan with the engine (4.4i) in the car in order to replace the bearings?

Henn28 · #2 02-20-2022, 02:02 PM

Quote:

Originally Posted by blktoptrvl

OK, I am experiencing rod knock.

Has anyone tried to remove the pan with the engine (4.4i) in the car in order to replace the bearings?

I’m not sure there are any shortcuts on that job. The subframe is blocking access to the upper pan, so I’m not sure that it is possible to do the job with the motor in the car. You’d have to bring the motor up so high off the subframe that it would be only slightly more work to pull it completely. Probably less work to pull it actually due to the complexities of working on the upside down motor in the car, with limited clearance between the frame and the block and the fact that you’d need to do 90% of the work to pull it, just to get enough space between the frame and the block to work.

The diff too will need to come off, and therefore the axles so you are talking about a huge job. Unless your 4.4 has some special mods, I’d consider buying one to rebuild completely at your leasure, and then swap it in.

All that being said, what makes you think it is a rod bearing problem?

andrewwynn · #3 02-20-2022, 03:20 PM

I have a buddy that was absolutely sure his 4.4 had Rod knock.

He drove for months figuring he was just going to drive until it failed.

4 months in or so discovered he had a loose spark plug that was the whole problem.

crystalworks · #4 02-20-2022, 09:56 PM

Suspend the motor and drop the subframe. I can't imagine even BMW making it impossible to do the upper pan with the engine in the car. I know the E60 M5 guys do it this way. But they don't have AWD equipment to contend with either.

That said, it might just be "easier" to pull the engine...

Henn28 · #5 02-20-2022, 10:26 PM

Quote:

Originally Posted by crystalworks

Suspend the motor and drop the subframe. I can't imagine even BMW making it impossible to do the upper pan with the engine in the car. I know the E60 M5 guys do it this way. But they don't have AWD equipment to contend with either.

That said, it might just be "easier" to pull the engine...

That should work too. The axles would need to come out still before the subframe was dropped, and the diff would need to come off too. But that would be much easier with the axles out and subframe clear. There would be some work needed too with the steering as the rack is bolted to the subframe but the pump is on the motor. Great opportunity to refresh those crush washers, banjo bolts and double joint.

I’ve never done rod bearings. Any issues with doing them on a motor hanging above you, rather than upside down on a stand? Gravity won’t be your friend.

nick325xit 5spd · #6 02-21-2022, 07:44 AM

FYI, BMW motors generally have crank damage from spun rod bearings. Don’t expect this to solve your problem for very long.

aureliusmax · #7 02-21-2022, 01:56 PM

Quote:

Originally Posted by blktoptrvl

OK, I am experiencing rod knock.

Has anyone tried to remove the pan with the engine (4.4i) in the car in order to replace the bearings?

Once you get rod knock, the only solution is to disassemble the engine and have the crank machined and inspected along with the rods and caps matched to the new size.

Source: Two days ago I caused a bearing cap to eject out of an engine block by 'making sure' the knocking noise was actually a real engine knock. I had done one of these 'forum expert opinion repairs' which involves installing new rod bearings and a tune-up.

nick325xit 5spd · #8 02-21-2022, 02:13 PM

Quote:

Originally Posted by aureliusmax

Once you get rod knock, the only solution is to disassemble the engine and have the crank machined and inspected along with the rods and caps matched to the new size.

Source: Two days ago I caused a bearing cap to eject out of an engine block by 'making sure' the knocking noise was actually a real engine knock. I had done one of these 'forum expert opinion repairs' which involves installing new rod bearings and a tune-up.

I mean, it is actually possible to pull the panel, and inspect the crank. You can measure roundness and polish it up with emery cloth if it's still round. Or if it's a Jeep 4.0, slap new bearings in and send it. (BTDT.)

But BMWs tend to damage their cranks when this happens. And once it's out of round, it won't hold together long after you swap the bearings.

Given how cheap these engines are, it makes a lot more sense to source another engine, do the services that are much easier with the engine out, and put it in. Obviously 4.6/4.8is folks have a different situation, but there's no shortage of M62/N62B44 donors.

crystalworks · #9 02-21-2022, 02:10 PM

I have no personal experience with all that (knock on wood), but were it me... I'd throw heavy oil in it and run it until the engine decides it needs to add a window as part of a renovation project. Then swap the motor with a used one.

Everything I've heard about rod bearings (including the above) tells me that once rod knock happens... it's too late.