Z4 3.0 M54 heating and cooling issues. Advice welcome!
Discussion
Hi I’ve just bought a Z4 with some issues and want to start fixing it up. One of the issues it has is the engine overheats very quickly. From cold start to the needle creeping up to the top of the gauge happens within about 15 mins. This is a very recent issue and it was not driven once it got hot so I’m hoping the engine will be ok once it’s sorted.
The radiator fan isn’t working but there is no heat coming into the car either. The interior fans are fine but the air is cold even when the engine is warmed up, so I couldn’t divert any heat from the engine into the cabin.
I am hoping for the thermostat being the issue as I am wondering if it is stuck closed then maybe water isn’t circulating. Wondered if it could be the waterpump too/instead although there was no noise from it. However I am open for any input from people familiar with this engine.
Thanks in advance.
The radiator fan isn’t working but there is no heat coming into the car either. The interior fans are fine but the air is cold even when the engine is warmed up, so I couldn’t divert any heat from the engine into the cabin.
I am hoping for the thermostat being the issue as I am wondering if it is stuck closed then maybe water isn’t circulating. Wondered if it could be the waterpump too/instead although there was no noise from it. However I am open for any input from people familiar with this engine.
Thanks in advance.
The first question is - how did it end up like this? Did it just break one day or was someone tinkering?
They are a pain to bleed and an airlock can cause some of the symptoms you've mentioned. Ideally if tricky you want to raise the front on a jack. Or if your lazy, just park on a hill and bleed...
Thermostats aren't that expensive but I'm not convinced that's the problem. Fairly easy to take out and test in a pan of boiling water if you want to know for definate? But once the ~18 year old gasket is disturbed you probably want to replace it anyway...
They are a pain to bleed and an airlock can cause some of the symptoms you've mentioned. Ideally if tricky you want to raise the front on a jack. Or if your lazy, just park on a hill and bleed...
Thermostats aren't that expensive but I'm not convinced that's the problem. Fairly easy to take out and test in a pan of boiling water if you want to know for definate? But once the ~18 year old gasket is disturbed you probably want to replace it anyway...
I do have a steep drive so if I bleed it I’ll make sure to do it nose up.
As far as how it happened, it wasn’t driven much by the previous owner since the weather got cold. He came it to try it one day and found the battery was knackered. Replaced the battery and found when he ran the car after that the radiator fan didn’t come on when AC was engaged and the heater wasn’t working either. That is what I was told, obviously I can’t confirm it’s exactly what happened but that’s the information I have been given.
Just wondering how an airlock would happen on a previously working car? Is that possible?
As far as how it happened, it wasn’t driven much by the previous owner since the weather got cold. He came it to try it one day and found the battery was knackered. Replaced the battery and found when he ran the car after that the radiator fan didn’t come on when AC was engaged and the heater wasn’t working either. That is what I was told, obviously I can’t confirm it’s exactly what happened but that’s the information I have been given.
Just wondering how an airlock would happen on a previously working car? Is that possible?
Edited by Douglas Quaid on Saturday 27th January 20:32
The radiator fan isn’t coming on even when the engine gets hot. The fan should come on when the AC is engaged as far as I’m aware and that isn’t happening either so something isn’t right.
I’m not sure whether the heating inside the car is linked to that or not as it could be two separate issues that have gone wrong at the same time.
All of the rest of the electrics work fine. Not to sound like an idiot but what is transport mode and how would I check?
I’m not sure whether the heating inside the car is linked to that or not as it could be two separate issues that have gone wrong at the same time.
All of the rest of the electrics work fine. Not to sound like an idiot but what is transport mode and how would I check?
So far I haven’t done any of those things as I haven’t actually collected it yet so it’s not on my drive. That will be the first thing I want to do but I just wondered if the symptoms sounded obvious to anyone here before I did that just in case someone else has had these same issues.
Edited by Douglas Quaid on Saturday 27th January 21:31
Douglas Quaid said:
Hi I’ve just bought a Z4 with some issues and want to start fixing it up. One of the issues it has is the engine overheats very quickly. From cold start to the needle creeping up to the top of the gauge happens within about 15 mins. This is a very recent issue and it was not driven once it got hot so I’m hoping the engine will be ok once it’s sorted.
The radiator fan isn’t working but there is no heat coming into the car either. The interior fans are fine but the air is cold even when the engine is warmed up, so I couldn’t divert any heat from the engine into the cabin.
I am hoping for the thermostat being the issue as I am wondering if it is stuck closed then maybe water isn’t circulating. Wondered if it could be the waterpump too/instead although there was no noise from it. However I am open for any input from people familiar with this engine.
Thanks in advance.
M54 stats generally stick open when failed and it sounds like yours is fubar. Poss air lock too. But it could be that it's closed/partially closed and not allowing flowThe radiator fan isn’t working but there is no heat coming into the car either. The interior fans are fine but the air is cold even when the engine is warmed up, so I couldn’t divert any heat from the engine into the cabin.
I am hoping for the thermostat being the issue as I am wondering if it is stuck closed then maybe water isn’t circulating. Wondered if it could be the waterpump too/instead although there was no noise from it. However I am open for any input from people familiar with this engine.
Thanks in advance.
Replace the stat & water pump at the same time IMO (Wahler stat and MEYLE water pump from BMWmotormec) and then refill / bleed the system proper. As said above, with the nose up. Heaters set to max temp, low speed etc. You need Comma G48 coolant
Edited by d_a_n1979 on Saturday 27th January 22:32
Douglas Quaid said:
Thanks for that, I was struggling finding a decent parts website. Will get on it as soon as I’ve picked the thing up.
No worries; these are my go'to's for parts:BMWmotormec:
https://www.ebay.co.uk/str/bmwmotormec
C3BMW:
www.c3bmw.co.uk
Carpartsinmotion:
https://www.ebay.co.uk/str/carpartsinmotion?_trkpa...
Carpartscentre:
https://www.ebay.co.uk/str/theno1carpartscentre?_t...
Autodoc:
www.autodoc.co.uk
Try and stick with the OE/OEM brands (Febi Bilstein, Wahler (stats etc), Lemforder, TRW etc & the likes of Meyle & Moog have done me fine for years too; both well made with zero issues form me personally) - all my M54 E39s had these parts & they're all going strong still!
Your first job is to remove the bleed screw and slowly add coolant, heater set to hot and engine doing 2500 rpm until it starts coming from the bleed hole (and hot heater) in order to cure an air lock. I've never had to jack a BMW up to do this. Very often these issues are simply a low coolant level.
The Z4 is basically an E46 so you have old E46 problems. Pre E46 BMW's had a simple, effective electric fan with two speeds and a switch on the rad. That was too simple and reliable so it was redesigned with a fan unit with a speed resistor pack on the motor, plus another relay clipped onto the cowling, plus a signal wire from the engine ECU. Any one of these can fail but you can quickly remove the fan and check the condition of the wires where they enter the resistor. It's common to find a corroded broken wire. A relay is a tenner secondhand on ebay and checking continuity on that stupid signal wire (very thin gauge) not impossible.
It could be that the car overheated and blew the head gasket - that's game over for an M54. Maybe the water pump had shed it's plastic impeller vanes although that was nowhere near as common as folk would have you believe. A water pump is 40 quid new, Circoli, Borg Warner etc. Very simple to replace.
I'd start as suggested by bleeding the cooling system.
The Z4 is basically an E46 so you have old E46 problems. Pre E46 BMW's had a simple, effective electric fan with two speeds and a switch on the rad. That was too simple and reliable so it was redesigned with a fan unit with a speed resistor pack on the motor, plus another relay clipped onto the cowling, plus a signal wire from the engine ECU. Any one of these can fail but you can quickly remove the fan and check the condition of the wires where they enter the resistor. It's common to find a corroded broken wire. A relay is a tenner secondhand on ebay and checking continuity on that stupid signal wire (very thin gauge) not impossible.
It could be that the car overheated and blew the head gasket - that's game over for an M54. Maybe the water pump had shed it's plastic impeller vanes although that was nowhere near as common as folk would have you believe. A water pump is 40 quid new, Circoli, Borg Warner etc. Very simple to replace.
I'd start as suggested by bleeding the cooling system.
Heater set to hot and blower on isn’t going to do a lot as the fans inside the car are blowing ice cold even when the engine warms up. I’m really hoping it’s not got a blown head gasket/warped head as that would kybosh it pretty effectively. I’m trusting the guy (perhaps naively) to not be lying about the interior heating, overheating engine and non working radiator fan issue being only a very recent issue and he’s not driven it round with the temp maxed out. He said he didn’t but I’m essentially crossing my fingers I guess.
If not then it’s potentially an expensive gamble but that’s the way it goes sometimes with secondhand cars I’m telling myself.
If not then it’s potentially an expensive gamble but that’s the way it goes sometimes with secondhand cars I’m telling myself.
Douglas Quaid said:
Heater set to hot and blower on isn’t going to do a lot as the fans inside the car are blowing ice cold even when the engine warms up. I’m really hoping it’s not got a blown head gasket/warped head as that would kybosh it pretty effectively. I’m trusting the guy (perhaps naively) to not be lying about the interior heating, overheating engine and non working radiator fan issue being only a very recent issue and he’s not driven it round with the temp maxed out. He said he didn’t but I’m essentially crossing my fingers I guess.
If not then it’s potentially an expensive gamble but that’s the way it goes sometimes with secondhand cars I’m telling myself.
Having the temps to max and blowers on low opens the heater matrix to allow full circulation; so it won't produce any heat until the engine is up to tempIf not then it’s potentially an expensive gamble but that’s the way it goes sometimes with secondhand cars I’m telling myself.
It sounds like this isn't going to happen as the stats more than likely buggered and needs replacing; so do that first and then see how you get on
Buy a sniffer test off Amazon and take that with you; do that FIRST before anything else to see if there's a HG issue. If there is, walk away
Hi chaps, well it is not as simple as I had first hoped. I have been waiting for tyres so haven’t used the car much but have noticed it’s dropped some mayo on the drive. Checked the header tank and some coolant has gone. I can’t really tell from the dipstick how much oil has dropped but there must be a bit. Now I can’t imagine how it would be mixing oil and water to make the mayo unless the head gasket has gone and it’s leaking out somewhere.
I haven’t put it on a ramp, I’ve got it in with the mechanic i use who’s a good guy so just waiting for the bad news. There isn’t any other way this could be happening is there?
It seemed to drive alright but I haven’t really given it a proper run at any speed out as it had old knackered tyres on that I didn’t trust, so I have just pootled locally rather than thrashing it.
Any input or insight good or bad appreciated.
I haven’t put it on a ramp, I’ve got it in with the mechanic i use who’s a good guy so just waiting for the bad news. There isn’t any other way this could be happening is there?
It seemed to drive alright but I haven’t really given it a proper run at any speed out as it had old knackered tyres on that I didn’t trust, so I have just pootled locally rather than thrashing it.
Any input or insight good or bad appreciated.
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