Rod bearings at 51k

Rickmitch93 · Post by **Rickmitch93** » Mon Aug 07, 2023 10:16 am

I had mine done last year. 107k miles. Excellent history. 6 worn to the copper. I can relax now lol

Wassup · Post by **Wassup** » Mon Aug 07, 2023 7:47 pm

Just had my Rob bearings changed by Darragh at Everything M3s and got lucky too as three top shells were worn down to copper, mileage 105k and impeccable service history and enthusiast owned before me.

Also changed the oil pump at the same time since BMW revised the oil pump design many times, before settling on the last iteration in 2007.

Been advised to stay below 4k revs for 1,200 miles and will be going back for a running in service as advised by Darragh.

Rickmitch93 · Post by **Rickmitch93** » Mon Aug 07, 2023 8:29 pm

Wassup wrote: ↑Mon Aug 07, 2023 7:47 pm Just had my Rob bearings changed by Darragh at Everything M3s and got lucky too as three top shells were worn down to copper, mileage 105k and impeccable service history and enthusiast owned before me.

Also changed the oil pump at the same time since BMW revised the oil pump design many times, before settling on the last iteration in 2007.

Been advised to stay below 4k revs for 1,200 miles and will be going back for a running in service as advised by Darragh.

I was told 800 miles and 4.5k revs, no harsh accelerating and don’t let the engine labour. But I’ve known people to have their shells done and put it straight on track with no issues. I’ll be dumping my oil again when it’s hit 1,000 miles. Just because I’m now Guna run millers nano drive oil

BMWZ4MC · Post by **BMWZ4MC** » Mon Aug 07, 2023 9:01 pm

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?

I changed mine at 50k miles after c. 25k miles driven by the first owner and 25k miles of spirited driving and very frequent, hard track use by me. They were all in good condition.
I’m now at 90k miles and I’m planning to change them again at 100k. In the period between 50k and 75k miles, the car saw as many track miles as it did road miles, so it will give a measure of how track use affects wear rates.

Z450 · Post by **Z450** » Fri Aug 11, 2023 10:13 am

Potentially getting at Z4MR, on 60,000 miles. Roughly what is a bmw specialist charging for a replacement?

GT Spec · Post by **GT Spec** » Fri Aug 11, 2023 1:28 pm

Wassup wrote: ↑Mon Aug 07, 2023 7:47 pm A running in service for hydrodynamic journal bearings doesn't seem logical to me at all. I would understand after a full engine rebuild due to the new piston rings 'bedding' in to the fresh cylinder hone. Unnecessary expense if you ask me.

A running-in service for hydrodynamic journal bearings doesn't seem logical to me at all. I would understand the need for one after a full engine rebuild due to the new piston rings 'bedding' in to the fresh cylinder hone. Unnecessary expense if you ask me.

lucasxdiniz · Post by **lucasxdiniz** » Fri Aug 11, 2023 9:10 pm

GT Spec wrote: ↑Fri Aug 11, 2023 1:28 pm
Wassup wrote: ↑Mon Aug 07, 2023 7:47 pm A running in service for hydrodynamic journal bearings doesn't seem logical to me at all. I would understand after a full engine rebuild due to the new piston rings 'bedding' in to the fresh cylinder hone. Unnecessary expense if you ask me.
A running-in service for hydrodynamic journal bearings doesn't seem logical to me at all. I would understand the need for one after a full engine rebuild due to the new piston rings 'bedding' in to the fresh cylinder hone. Unnecessary expense if you ask me.

I'm a Powertrain Design engineer, so I'd like to think I have a good understanding of engines and when purely considering the function of the part, I agree with you. However, I did ask the engine builders at work if I should do an oil change because of assembly lube which can linger around and clog filters if someone abuses it (conjecture). They reckoned since it's just the rod bearings, there wouldn't be enough around to a) affect the oil (when dissolving within the oil) and b) clogging up the filter (not something they've ever seen happen in engines they've built). They suggested I could change the oil filter since it's so accessible just for peace of mind.

PDJ · Post by **PDJ** » Fri Aug 11, 2023 9:52 pm

lucasxdiniz wrote: ↑Fri Aug 11, 2023 9:10 pm They suggested I could change the oil filter since it's so accessible just for peace of mind.

I change my oil filter every 2 to 3 thousand miles between oil changes, for around £10 to £15 it is cheap insurance for the engine.

PDJ · Post by **PDJ** » Fri Aug 11, 2023 9:54 pm

Z450 wrote: ↑Fri Aug 11, 2023 10:13 am Potentially getting at Z4MR, on 60,000 miles. Roughly what is a bmw specialist charging for a replacement?

£1200

But as you have the oil pump and relief valve (one unit) out add the cost of an oil pump as this is what kills these engine if it sticks open.

Simon 3.2M · Post by **Simon 3.2M** » Sun Aug 13, 2023 2:46 pm

There’s no need to run the engine in post bearing change.

S54 PILOT · Post by **S54 PILOT** » Sun Aug 20, 2023 1:41 pm

129k miles bearings same condition as OP

My tech said that they will look the same right after 20k no matter the miles on the car.

: photo_2023-08-20_08-36-39.jpg (161.2 KiB) Viewed 549 times

Mr Tidy · Post by **Mr Tidy** » Sun Aug 20, 2023 8:33 pm

They probably wouldn't look pristine after just 20K, but the third from bottom in your photo looks much worse than any of mine did after 78K miles.

But at least new ones give you some peace of mind.

S54 PILOT · Post by **S54 PILOT** » Sun Aug 20, 2023 8:40 pm

No, its just light situation, 3rd one looks exactly same as on OP picture

Mr Tidy · Post by **Mr Tidy** » Sun Aug 20, 2023 8:50 pm

S54 PILOT wrote: ↑Sun Aug 20, 2023 8:40 pm No, its just light situation, 3rd one looks exactly same as on OP picture

Fair enough - mine looked much like that too!

beanie · Post by **beanie** » Mon Sep 04, 2023 1:53 pm

Just to add to the data, I’ve just had mine done at 75k.

: 47D9F210-7D06-4660-A964-007730712BB7.jpeg (171.51 KiB) Viewed 409 times

I’ve owned the car for 10 years and from 30k to 75k and I’ve been ultra diligent in keeping the revs and load low during warm up. Looking at the pics, I could probably have got a fair few more miles out of them but as we all know, the cost of misjudging this is high.

On another note, Redish have been fantastic-my sump had a repair done a few year back thanks to the threads being stripped by an unknown monkey. Unfortunately this has not been done perfectly so has meant a new sump has had to be ordered. Not a cheap or easily found part but communication and their willingness to help has been second to none.

If anyone for any reason someone wants a Z4m sump with a less than perfect repair then let me know. I’ll hopefully be picking the car up in the next day or two so be quick or I’ll just leave it for scrap. They’ve said it might be possible to use a timesert but because of the previous repair they weren’t convinced it would hold.

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