MidnightRun's ride: BMW Z4 3.0si Sport E86 - NOT BROKEN!

Mainly with the DPF not warning when it’s clogged and diesel getting in to the oil.

Other than that I loved the look and the space and how it drove. More power than my 1.6 TDI Octy.
I've read that's mainly on cars that are short-use predominantly and lacking in regular maintenance. Apparently if you're a driver who doesn't do at least a motorway run per day of use, you should look to replace oil every 6k miles or 6 months. I'll do that anyway - an oil change between each 12-monthly regular service. It's a fantastic car so far. Booked in to my local to fix a tyre pressure sensor issue and a faulty drivers window switch, plus a rattle I've noticed in certain cornering conditions (potentially a top mount or a CV, not 100% sure).
 
What sort of economy are you getting? I just got my best ever in a short 30 mins run in the Octy today. 72.9 mpg :)
 
What sort of economy are you getting? I just got my best ever in a short 30 mins run in the Octy today. 72.9 mpg :)
I've only driven it home from picking it up on Sunday and was averaging 56mpg, 47mpg is the car's average on the computer.
 
So, its been a while, but I have a sad update...

About 2 months ago I took my car in to work. On the drive in in the morning, about 500m from the office, I noticed a noise come on suddenly - a sort of high pitched whining sound that went up and down with the engine revs. It wasn't a belt, but something more mechanical in sound. I pulled in to work and the engine sound rough, so I turned off the engine and started messaging a friend who's pretty hot on these engines. His thought was a belt had slipped or the chain had gone.

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I had to get home at lunch time, I had something important I couldn't miss so I decided to try the car to see if it was drivable. To my surprise, it started easily and there was no weird sounds or anything, so I decided to risk it and drive it home. Weirdly, exiting the driveway at work, the brakes felt solid and were nearly non-responsive. Not good! I took the approach of driving incredibly cautiously and slowly and gave acres of following distance to any cars ahead on the drive.

I made it most of the way home when I was rolling along slowly on a dual carriageway up a hill and the red oil light came on as the engines started feeling really lumpy and rough. I panicked and limped it about a mile up the road into a lay by where I stopped it and turned it all off and made some phone calls.

My friend who I'd been messaging earlier came along and helped me remove the oil filter cover to check if the oil filter had collapsed (something that had happened to a friend's car previously with similar symptoms). The filter was in tact, but full of swarf!

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We replaced the filter with one he had with him, closed everything up, and called a vehicle recovery truck. They dropped the car at a local mechanic for them to look into it and see what they could do.

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Their verdict was the oil pump had failed and the engine was a write-off. They weren't keen to do the investigative work or any rebuilds, so I shifted the car to a mechanic I've used in the past who was keen to take on the work. It sat around for a while while he cleared out a backlog of jobs, and finally he removed the engine.

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He has reported back that the likely scenario that led to this chain of events was the nut that holds the sprocket on the oil pump stripped or sheared off, getting sucked into the engine. Both the sprocket and the nut are MIA.

Current state:

The engine is being stripped to investigate the extent of the damage and make sure the block can be saved and rebuilt.

If it can't be saved, I'm in the difficult position of needing to source a replacement engine. I've looked into it, and they're not easy to find unfortunately. The engine is a N52B30K, which is an upgraded version of what was the original N52B30 in the Z4 series, and features a host of upgrades. I've found older engines with higher mileage, but that's not exactly ideal. I might end up rebuilding a donor engine by stripping it down to the block and replacing all the components with the upgraded parts from the K engine.

Either way, it's eye-wateringly expensive (yet still less than a brand new block from BMW) and a very sad and unlucky thing to have happened!

Watch this space!
 
So, its been a while, but I have a sad update...

About 2 months ago I took my car in to work. On the drive in in the morning, about 500m from the office, I noticed a noise come on suddenly - a sort of high pitched whining sound that went up and down with the engine revs. It wasn't a belt, but something more mechanical in sound. I pulled in to work and the engine sound rough, so I turned off the engine and started messaging a friend who's pretty hot on these engines. His thought was a belt had slipped or the chain had gone.

View attachment 1151290

I had to get home at lunch time, I had something important I couldn't miss so I decided to try the car to see if it was drivable. To my surprise, it started easily and there was no weird sounds or anything, so I decided to risk it and drive it home. Weirdly, exiting the driveway at work, the brakes felt solid and were nearly non-responsive. Not good! I took the approach of driving incredibly cautiously and slowly and gave acres of following distance to any cars ahead on the drive.

I made it most of the way home when I was rolling along slowly on a dual carriageway up a hill and the red oil light came on as the engines started feeling really lumpy and rough. I panicked and limped it about a mile up the road into a lay by where I stopped it and turned it all off and made some phone calls.

My friend who I'd been messaging earlier came along and helped me remove the oil filter cover to check if the oil filter had collapsed (something that had happened to a friend's car previously with similar symptoms). The filter was in tact, but full of swarf!

View attachment 1151286

We replaced the filter with one he had with him, closed everything up, and called a vehicle recovery truck. They dropped the car at a local mechanic for them to look into it and see what they could do.

View attachment 1151287
View attachment 1151288

Their verdict was the oil pump had failed and the engine was a write-off. They weren't keen to do the investigative work or any rebuilds, so I shifted the car to a mechanic I've used in the past who was keen to take on the work. It sat around for a while while he cleared out a backlog of jobs, and finally he removed the engine.

View attachment 1151289

He has reported back that the likely scenario that led to this chain of events was the nut that holds the sprocket on the oil pump stripped or sheared off, getting sucked into the engine. Both the sprocket and the nut are MIA.

Current state:

The engine is being stripped to investigate the extent of the damage and make sure the block can be saved and rebuilt.

If it can't be saved, I'm in the difficult position of needing to source a replacement engine. I've looked into it, and they're not easy to find unfortunately. The engine is a N52B30K, which is an upgraded version of what was the original N52B30 in the Z4 series, and features a host of upgrades. I've found older engines with higher mileage, but that's not exactly ideal. I might end up rebuilding a donor engine by stripping it down to the block and replacing all the components with the upgraded parts from the K engine.

Either way, it's eye-wateringly expensive (yet still less than a brand new block from BMW) and a very sad and unlucky thing to have happened!

Watch this space!
Oh man, that's really unfortunate. Back when I was looking at Z4s I was looking at the pre-facelift models (unfortunately, that meant no coupes) specifically because I was nervous about the "K" engine due to their relative rarity. Hope you can get it all back together, those Z4 coupes are really really neat cars with one of the best looking interiors BMW has ever done. I wonder if anyone has done an S65 (or N62?) swap in those cars? Seems like it would be a great fit, less weight out in the nose.
 
Oh man, that's really unfortunate. Back when I was looking at Z4s I was looking at the pre-facelift models (unfortunately, that meant no coupes) specifically because I was nervous about the "K" engine due to their relative rarity. Hope you can get it all back together, those Z4 coupes are really really neat cars with one of the best looking interiors BMW has ever done. I wonder if anyone has done an S65 (or N62?) swap in those cars? Seems like it would be a great fit, less weight out in the nose.
I have considered the S65 swap but it'll cost nearly three times as much, and this is more than I can afford in the first place. Let's not write it off as an option though!
 
UPDATE!

It's been a long minute, but I thought I'd share an update, nearly a year late...

At the start of November '22 I picked up my Z4 with it's freshly rebuilt N52B30k engine and proceeded to slowly run it in. The run-in process was a simple case of keeping RPM below 3k and not doing anything silly with driving - basically driving like a grandad until everything had settled back into place properly. After about 6 weeks I'd covered the 600 miles needed for a first oil change, and booked in with the mechanic who oversaw the rebuild and fitted the engine for me. I was on over 800 when I finally got the car to him, so he decided to skip the 1,000 mile oil change and do it all in one. He was really happy with the state of the oil and the overall running condition, so off I went and proceeded to enjoy my car for the remainder of the year!

I managed to put on over 2,000 miles, which is more than the previous three years combined!! It's just past it's annual check-up and had a full service back at the same mechanic. Failed an MOT on a dodgy rear tyre a couple of days ago but that's now sorted and she's all good and back on the road!

That said, I'm heading away for a month in a week, so I'll be pulling the battery out, putting it on trickle charge in the garage and leaving her un-taxed for December...
 
UPDATE!

It's been a long minute, but I thought I'd share an update, nearly a year late...

At the start of November '22 I picked up my Z4 with it's freshly rebuilt N52B30k engine and proceeded to slowly run it in. The run-in process was a simple case of keeping RPM below 3k and not doing anything silly with driving - basically driving like a grandad until everything had settled back into place properly. After about 6 weeks I'd covered the 600 miles needed for a first oil change, and booked in with the mechanic who oversaw the rebuild and fitted the engine for me. I was on over 800 when I finally got the car to him, so he decided to skip the 1,000 mile oil change and do it all in one. He was really happy with the state of the oil and the overall running condition, so off I went and proceeded to enjoy my car for the remainder of the year!

I managed to put on over 2,000 miles, which is more than the previous three years combined!! It's just past it's annual check-up and had a full service back at the same mechanic. Failed an MOT on a dodgy rear tyre a couple of days ago but that's now sorted and she's all good and back on the road!

That said, I'm heading away for a month in a week, so I'll be pulling the battery out, putting it on trickle charge in the garage and leaving her un-taxed for December...
I still look at and appreciate these Z4 coupes every time I see one. Such a great little car.
 
I have to say, until recently I hadn't realised how (relatively) 'cheap' non M Z4 Coupes were. I'm about to hand over 8 grand to Munich Legends for repairing and rebuilding my E90 320si engine, and a friend pointed out that for similar money I could get into a Z4 3.0 Coupe. I was sorely tempted, they are great looking cars.
 
I have to say, until recently I hadn't realised how (relatively) 'cheap' non M Z4 Coupes were. I'm about to hand over 8 grand to Munich Legends for repairing and rebuilding my E90 320si engine, and a friend pointed out that for similar money I could get into a Z4 3.0 Coupe. I was sorely tempted, they are great looking cars.
You definitely should have... 😉
 
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