Rod bearings at 51k

luckyfinners · Post by **luckyfinners** » Thu Jul 06, 2023 10:15 pm

I recently took the preventative measure of replacing my rod bearings.

The car has covered 51k and has full service history. As you can see the uppers are worn, especially number 3. It looks like I changed them at just the right time.

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Money well spent and gets rid of that paranoia every time I get right foot heavy.

Mr Tidy · Post by **Mr Tidy** » Thu Jul 06, 2023 10:43 pm

That looks like a smart move!

I had mine changed at 78K and was glad I did.

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luckyfinners · Post by **luckyfinners** » Thu Jul 06, 2023 10:50 pm

How many miles have you done on the new bearings?

Mr Tidy · Post by **Mr Tidy** » Thu Jul 06, 2023 10:57 pm

I've only done just under 10K on the new bearing shells - hopefully they will last long enough for me!

buzyg · Post by **buzyg** » Thu Jul 06, 2023 11:04 pm

I can't say for sure obviously, but I think warming the oil on every journey before pressing the loud pedal is what extends the life of the shells, more than anything else. I used to change the oil every year too. If I ever buy another S54. The first job will be get them changed though, as you can never know how a car was previously driven.

Mr Tidy · Post by **Mr Tidy** » Thu Jul 06, 2023 11:13 pm

That's why I had mine replaced!

It had 7 keepers before it became mine, and the first was BMW UK so it may not have been warmed up properly before it was given the beans.

lucasxdiniz · Post by **lucasxdiniz** » Thu Jul 06, 2023 11:40 pm

For the cost of replacing rod bearings vs the cost of an engine rebuild, it's a no-brainer. Plus it does add some re-sale value to the car, so even if you're tight-fisted, you can man-maths your way around it.

I got my Z4M on a Friday, drove it home and took it for a quick spin the following day, then parked it for 3 weeks and only drove it again when I was on my way to RBM (booked bearings before I even got a Z4M!). Was I glad I did that...

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For reference, car is at 95k. They're definitely not the worst ones I've seen on forums - seen worse ones posted at ~60k . But it was the worst ones RBM had seen for a while (their words).

Mr Tidy · Post by **Mr Tidy** » Thu Jul 06, 2023 11:55 pm

They look pretty shagged!

But now they are done you have some peace of mind.

luckyfinners · Post by **luckyfinners** » Fri Jul 07, 2023 6:36 am

Mr Tidy wrote: ↑Thu Jul 06, 2023 10:57 pm I've only done just under 10K on the new bearing shells - hopefully they will last long enough for me!

I don't think I've ever seen a set of bearings that have been changed for the 2nd time, with the car being warmed up properly since the replacement (and enough mileage to wear) to see if the wear rate decreases.
Would certainly be interesting.

What run in period did you give the new bearings before giving it full throttle?

lucasxdiniz · Post by **lucasxdiniz** » Fri Jul 07, 2023 8:34 am

luckyfinners wrote: ↑Fri Jul 07, 2023 6:36 am
Mr Tidy wrote: ↑Thu Jul 06, 2023 10:57 pm I've only done just under 10K on the new bearing shells - hopefully they will last long enough for me!
I don't think I've ever seen a set of bearings that have been changed for the 2nd time, with the car being warmed up properly since the replacement (and enough mileage to wear) to see if the wear rate decreases.
Would certainly be interesting.

What run in period did you give the new bearings before giving it full throttle?

There is no running in for rod bearings. Just take it easy for 50-100 miles maybe to make sure the garage didn't screw up. Better to have the engine self disassemble at low speed should it seize up and lock your wheels.

Argenta · Post by **Argenta** » Fri Jul 07, 2023 2:26 pm

Mine were a lot worse..

XMetal · Post by **XMetal** » Fri Jul 07, 2023 3:34 pm

buzyg wrote: ↑Thu Jul 06, 2023 11:04 pm I can't say for sure obviously, but I think warming the oil on every journey before pressing the loud pedal is what extends the life of the shells, more than anything else. I used to change the oil every year too. If I ever buy another S54. The first job will be get them changed though, as you can never know how a car was previously driven.

I'm sure it helps, but not a sure thing. Mine were fairly worn when I had them swapped out at ~55k miles (all of the 50k miles were driven solely by me). Car has always been warmed prior to hitting the loud pedal. I live in sunny Southern California where the average temperature is 75F...so the engine gets up to temp fairly quickly without even trying, but still got bearing issues at such low mileage

lucasxdiniz wrote: ↑Fri Jul 07, 2023 8:34 am There is no running in for rod bearings. Just take it easy for 50-100 miles maybe to make sure the garage didn't screw up. Better to have the engine self disassemble at low speed should it seize up and lock your wheels.

I was told the same thing by my engine builder who did my rod bearings - Just take it easy for 50-100 miles or so, to make sure everything is all well. But I gave it a bit more easy miles just to be safe

luckyfinners · Post by **luckyfinners** » Fri Jul 07, 2023 3:49 pm

Interesting... Thanks

mmm-five · Post by **mmm-five** » Fri Jul 07, 2023 3:52 pm

Well...mine lasted 140,000 miles - so I must be Hoke Colburn

Combination of weekly 210 mile each way commute, weekend blasts, track days and Ring trips

JulesW · Post by **JulesW** » Sat Jul 08, 2023 7:40 pm

Interesting on the post rod bearing change process for running in. I had mine changed by an excellent Indy BMW shop specializing in M cars here in France and was told 4000 rpm limit for 1200 miles and then change the oil and filter again. A bit frustrating, but that and an Inspection 2 were the first things I did as the car had 5 previous owners and 71k miles, so it gave me a baseline to go forward with.

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