Ap bbk

[BMWZ4MC]

Sorry to hear that Tom. Interestingly, mine has started to overheat in traffic too. The first time was at the top of a slip road after a long, constant 70mph on the motorway. The amber temperature light came on until I moved off again. The next time was a few weeks later in heavy traffic and that time I briefly saw the red temperature warning light. Driving in little or no traffic, it behaves completely normally but the cooling fan seems to be working earlier and harder. In retrospect, the cooling fan might have been kicking in earlier than usual for several months now.
I’ve had one episode of very low coolant, but I too have had a slow leak for years and I assumed I simply forgot to top it up. Most concerning, the oil level is slightly high on the dipstick. However, the last oil change was done by a garage as a part of an Inspection service, so I cannot be sure that they didn’t overfill it.
I’ve been too busy with work to start investigating, but my thoughts are head gasket (unlikely since it was replaced 40k miles ago), thermostat (probable), water pump, or a damaged radiator from debris being thrown up on track days. I’ll probably start with a new thermostat and expansion tank and see if that fixes it.
I remember mmm-five writing that he’d had a ‘complete refresh of the cooling system’ during one of the many rounds of Trigger’s Broom work on his car, but I didn’t ask him at the time what precipitated that decision or what he replaced.

[TomK]

I’ve been too busy with work to start investigating, but my thoughts are head gasket (unlikely since it was replaced 40k miles ago), thermostat (probable), water pump, or a damaged radiator from debris being thrown up on track days. I’ll probably start with a new thermostat and expansion tank and see if that fixes it.

Well I appear to have dodged a bullet. I refilled the coolant and replaced the expansion tank cap, all seems resolved. No over pressurisation and I logged water temps at constant ~80c for half an hour or so. Working theory is that the reservoir got so low that I created an airlock. Of course the underlying issue of where the coolant is going is a concern but it's been like that for 7 years at least, I just need to check the level more often
I hope your issue is something as simple as this Richard. I've just booked a trackday for monday to prove/disprove my theory, wish me luck

S2000 race here. I left a lot on the table compared to dave, but it is his car. Will try man up a bit for snetterton in a few weeks time!
And seeing as this thread is completely derailed by now a link to my rear interior. Any advice on trimming/fabrication welcome thanks.
viewtopic.php?f=2&t=93757&p=2004113#p2004113

[TomK]

Well I'd call that a success! 300 miles completed, lots of 8k revs obtained and no sign of the poor s54 which must have got very hot being bothered at all Now my rod bearings will probably s**t their pants
Lesson learnt.. check your fluids
Here's some celebratory s54 goodness, the new 4.44 FD is hilarious, I'm not sure it is faster but it sure feels it.

[BMWZ4MC]

Excellent news, Tom. It’s great when a potential disaster turns out to be a simple and cheap problem to fix.
It’s winter here, and mine seems to have stopped overheating (for now). Interestingly, an Indy checked for error codes when I had it serviced recently and they found that the cooling fan is not working. They left the car running for a while and couldn’t provoke overheating or get the fan to activate (the ambient temperature was around 10C at the time).
I’ve bought an E60 cooling fan and shroud assembly for considerably less than the Z4-specific complete assembly and I’ll swap the new motor into my existing shroud when I have time. The motor is not available as a separate item, so this is the most cost effective way. This thread gave me the idea: viewtopic.php?t=127626

Fingers crossed that will solve my problem. However, I have a clear memory of hearing the fan running whilst the car was overheating, so I’m suspicious the problem is as simple as a faulty fan.

Very entertaining videos, as always

[Rickmitch93]

I was close to pulling the trigger on some ap racing that came off a e46 m3. Will they not bolt striaght on to my car then?

[BMWZ4MC]

I was close to pulling the trigger on some ap racing that came off a e46 m3. Will they not bolt striaght on to my car then?

Shimming it with washers will make it fit (as above). Don't assume that will be the case for all E46 M3 BBKs though - the Alcon set up intended for the M3 and M3 CSL will not fit our cars.

[BMWZ4MC]

Excellent news, Tom. It’s great when a potential disaster turns out to be a simple and cheap problem to fix.
It’s winter here, and mine seems to have stopped overheating (for now). Interestingly, an Indy checked for error codes when I had it serviced recently and they found that the cooling fan is not working. They left the car running for a while and couldn’t provoke overheating or get the fan to activate (the ambient temperature was around 10C at the time).
I’ve bought an E60 cooling fan and shroud assembly for considerably less than the Z4-specific complete assembly and I’ll swap the new motor into my existing shroud when I have time. The motor is not available as a separate item, so this is the most cost effective way. This thread gave me the idea: viewtopic.php?t=127626

Fingers crossed that will solve my problem. However, I have a clear memory of hearing the fan running whilst the car was overheating, so I’m suspicious the problem is as simple as a faulty fan.

Very entertaining videos, as always

Swapping the E60 cooling fan motor into the E86 ///M shroud was extremely easy and it's fixed my overheating issues. Having fixed my SRS warning light too recently, my Zed is unusually trouble free at present (except for the huge stone chip in the windscreen that will necessitate a replacement before the next registration safety check).

[Rickmitch93]

I was close to pulling the trigger on some ap racing that came off a e46 m3. Will they not bolt striaght on to my car then?

Shimming it with washers will make it fit (as above). Don't assume that will be the case for all E46 M3 BBKs though - the Alcon set up intended for the M3 and M3 CSL will not fit our cars.

Ah right I had no idea. I just assumed it would fit due to running e46 m3 front callipers, csl discs. Learn something new every day lol. Is it safe to use washers?

[BMWZ4MC]

Mine have survived lots of heavy track use in ambient temps of up to 35C without any problems.

[Mr Tidy]

I’ve bought an E60 cooling fan and shroud assembly for considerably less than the Z4-specific complete assembly and I’ll swap the new motor into my existing shroud when I have time. The motor is not available as a separate item, so this is the most cost effective way. This thread gave me the idea: viewtopic.php?t=127626

I wish I had read that before I had a new fan fitted to my car last year!

[BMWZ4MC]

I feel your pain - the cost to have it fitted in Australia would have been extortionate and there were no S54 fans in the country anyway, necessitating slow importation from Germany with associated taxes / duty etc. I think the total fitted cost would have been several thousands of dollars.
The E60 fan was much cheaper and available immediately in Aus, and the labour was free! It took me an hour to swap over and fit.

[Mr Tidy]

The cost here wasn't as painful as that - I got it supplied and fitted for £600.