Hot temp/pressure issues; thoughts? 3.0i

bigwinn · Post by **bigwinn** » Mon Jul 18, 2022 9:06 pm

Yesterday John and I replaced his expansion tank as it went pop on his 3.0

Today the second hand one did exactly the same

Now, are we either really unlucky and a third new one will be OK, or there is something causing the issue further up the food chain?

Other things of note are that the fan isn't running, compared to my 3.0 which spins up from engine switch on

Second question is what stops the fan from running?

We have swapped the fans over, so thats not the issue. We have bridged the green wire and still no change.

Engine doesn't show high temp on the gauge at all

What are peoples thoughts?

Cheers

Stuart

bigwinn · Post by **bigwinn** » Mon Jul 18, 2022 9:17 pm

Will swap the temp sensors out to see if that’s a cause

Rockhopper · Post by **Rockhopper** » Mon Jul 18, 2022 10:17 pm

I’d do a sniff test to rule out head gasket failure.

Chris_D · Post by **Chris_D** » Mon Jul 18, 2022 10:52 pm

I was advised years ago by a garage that replaced the expansion tank on my E36 coupe (M52TuB25) when it popped, to slightly under-fill or keep the coolant at the lowest allowable level in order to compensate for pressure buildup during the summer months and warm temps.
Have done that for 15 years now and never had an issue.
Just a thought.

bigwinn · Post by **bigwinn** » Mon Jul 18, 2022 10:53 pm

Chris_D wrote: ↑Mon Jul 18, 2022 10:52 pm I was advised years ago by a garage that replaced the expansion tank on my E36 coupe (M52TuB25) when it popped, to slightly under-fill or keep the coolant at the lowest allowable level in order to compensate for pressure buildup during the summer months and warm temps.
Have done that for 15 years now and never had an issue.
Just a thought.

Cheers Chris. We did top it off tbf

AveZ4coop · Post by **AveZ4coop** » Tue Jul 19, 2022 9:32 am

Rockhopper wrote: ↑Mon Jul 18, 2022 10:17 pm I’d do a sniff test to rule out head gasket failure.

I would check this too. Seems a bit suspect that the second tank failed so quickly. I hope you get it resolved.

Zulu4 · Post by **Zulu4** » Tue Jul 19, 2022 9:41 am

Hi Stuart,
This guy had a similar problem with the fan not coming on. Turned out to be the fan controller (which is on the fan unit itself).
https://www.bimmerforums.com/forum/show ... 005-Z4-2-5

bigwinn · Post by **bigwinn** » Tue Jul 19, 2022 9:42 am

Zulu4 wrote: ↑Tue Jul 19, 2022 9:41 am Hi Stuart,
This guy had a similar problem with the fan not coming on. Turned out to be the fan controller (which is on the fan unit itself).
https://www.bimmerforums.com/forum/show ... 005-Z4-2-5

Thanks Rob will have a read

bigwinn · Post by **bigwinn** » Tue Jul 19, 2022 9:44 am

Zulu4 wrote: ↑Tue Jul 19, 2022 9:41 am Hi Stuart,
This guy had a similar problem with the fan not coming on. Turned out to be the fan controller (which is on the fan unit itself).
https://www.bimmerforums.com/forum/show ... 005-Z4-2-5

If the fan control module is on the fan we have swapped these over already- but there is always the possibility that both may be faulty

enuff_zed · Post by **enuff_zed** » Tue Jul 19, 2022 9:47 am

bigwinn wrote: ↑Tue Jul 19, 2022 9:44 am
Zulu4 wrote: ↑Tue Jul 19, 2022 9:41 am Hi Stuart,
This guy had a similar problem with the fan not coming on. Turned out to be the fan controller (which is on the fan unit itself).
https://www.bimmerforums.com/forum/show ... 005-Z4-2-5
If the fan control module is on the fan we have swapped these over already- but there is always the possibility that both may be faulty

Or the supply to it?

bigwinn · Post by **bigwinn** » Tue Jul 19, 2022 9:48 am

enuff_zed wrote: ↑Tue Jul 19, 2022 9:47 am
bigwinn wrote: ↑Tue Jul 19, 2022 9:44 am
Zulu4 wrote: ↑Tue Jul 19, 2022 9:41 am Hi Stuart,
This guy had a similar problem with the fan not coming on. Turned out to be the fan controller (which is on the fan unit itself).
https://www.bimmerforums.com/forum/show ... 005-Z4-2-5
If the fan control module is on the fan we have swapped these over already- but there is always the possibility that both may be faulty
Or the supply to it?

Yeah I’ll get a multimeter over the feed pins good call

Where is it fed from? DME?

enuff_zed · Post by **enuff_zed** » Tue Jul 19, 2022 9:53 am

Newtis seems to show a power feed and a feed from the DME, but just to a big block labelled fan? No other controller?

enuff_zed · Post by **enuff_zed** » Tue Jul 19, 2022 9:57 am

It shows Fuse 61 feeding power to the fan

bigwinn · Post by **bigwinn** » Tue Jul 19, 2022 9:59 am

Thanks Martin

enuff_zed · Post by **enuff_zed** » Tue Jul 19, 2022 10:01 am

Not just a big fat airlock stopping circulation? If coolant isn't flowing through the rad or past the temp sensor then it could be the block is getting hot on its own and creating extra pressure.

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