E91 - 330D - coolant temperature

[Tony B2]

What sort of coolant temperature would you expect in normal operating conditions - either in urban traffic, or motorway speeds?

I have just started monitoring mine, as fuel consumption has been getting worse and worse over the last year or so (used to get 43mpg on a long motorway journey). Currently getting 33 mpg with a 50/50 mix of urban and motorway.

At the moment urban coolant temperature is 69C, which seems a bit low to me, and is presumably contributing to the extra consumption.

Ambient was 10C for the last run.

[657]

Approx 90C

I’d guess you need both front thermostats. If you have a DPF it won’t be regenerating at less than 75C iirc. I have a E60 535d and when the thermostats are shot it is nigh impossible to get above 75C. High load and not so high revs or speed do help, but aren’t really practical unless towing. Fuel consumption does suffer. Easy DIY.

[sortedcossie]

That'll need both stats changing for sure. If you want to fit and forget then use gen BMW thermostats.

[d_a_n1979]

sortedcossie said:

That'll need both stats changing for sure. If you want to fit and forget then use gen BMW thermostats.

^^^ This

I was told the temps should be 88-90ºc for normal running on OEM BMW stats

[657]

Genuine BMW is only fit and forget … for a while

[Tony B2]

657 said:

Approx 90C

I’d guess you need both front thermostats. If you have a DPF it won’t be regenerating at less than 75C iirc. I have a E60 535d and when the thermostats are shot it is nigh impossible to get above 75C. High load and not so high revs or speed do help, but aren’t really practical unless towing. Fuel consumption does suffer. Easy DIY.

Thanks for responding.

You say "both front thermostats".

I have looked on realoem.com but can only see a single thermostat?

https://www.realoem.com/bmw/enUS/showparts?id=UY92...

[sortedcossie]

There is a main one, and an EGR one.

[d_a_n1979]

Tony B2 said:

657 said:

Approx 90C

I’d guess you need both front thermostats. If you have a DPF it won’t be regenerating at less than 75C iirc. I have a E60 535d and when the thermostats are shot it is nigh impossible to get above 75C. High load and not so high revs or speed do help, but aren’t really practical unless towing. Fuel consumption does suffer. Easy DIY.

Thanks for responding.

You say "both front thermostats".

I have looked on realoem.com but can only see a single thermostat?

https://www.realoem.com/bmw/enUS/showparts?id=UY92...

This is what you need: https://www.ebay.co.uk/itm/126204938436?itmmeta=01...

Mahle are OE for the M57; Febi for the N47/N57

[Tony B2]

d_a_n1979 said:

Tony B2 said:

657 said:

Approx 90C

I’d guess you need both front thermostats. If you have a DPF it won’t be regenerating at less than 75C iirc. I have a E60 535d and when the thermostats are shot it is nigh impossible to get above 75C. High load and not so high revs or speed do help, but aren’t really practical unless towing. Fuel consumption does suffer. Easy DIY.

Thanks for responding.

You say "both front thermostats".

I have looked on realoem.com but can only see a single thermostat?

https://www.realoem.com/bmw/enUS/showparts?id=UY92...

This is what you need: https://www.ebay.co.uk/itm/126204938436?itmmeta=01...

Mahle are OE for the M57; Febi for the N47/N57

Many thanks, this is very useful.

Is there a secondary temperature reading (i.e. not just main coolant temperature) that I can use to diagnose whether this thermostat is also faulty?

I have the BMW Drive Analyser app (and dongle) which I can use to check various parameters - I forget which ones are logged without actually getting into the car, and the weather is dire here at the moment!

[d_a_n1979]

Tony B2 said:

d_a_n1979 said:

Tony B2 said:

657 said:

Approx 90C

I’d guess you need both front thermostats. If you have a DPF it won’t be regenerating at less than 75C iirc. I have a E60 535d and when the thermostats are shot it is nigh impossible to get above 75C. High load and not so high revs or speed do help, but aren’t really practical unless towing. Fuel consumption does suffer. Easy DIY.

Thanks for responding.

You say "both front thermostats".

I have looked on realoem.com but can only see a single thermostat?

https://www.realoem.com/bmw/enUS/showparts?id=UY92...

This is what you need: https://www.ebay.co.uk/itm/126204938436?itmmeta=01...

Mahle are OE for the M57; Febi for the N47/N57

Many thanks, this is very useful.

Is there a secondary temperature reading (i.e. not just main coolant temperature) that I can use to diagnose whether this thermostat is also faulty?

I have the BMW Drive Analyser app (and dongle) which I can use to check various parameters - I forget which ones are logged without actually getting into the car, and the weather is dire here at the moment!

You can access the hidden menu on the cluster to see what the temps are; but IIRC it's just the one temp

TBH for their cost and not a lot of time to fit them; top up the system and re-bleed; it makes sense to get them done as they'll probably outlast your ownership

I had weird temp issues on a previous E65 730D Sport in 2018; swapped the stats over to the ones I linked to; car ran sweet as a nut after that

[Tony B2]

d_a_n1979 said:

Tony B2 said:

d_a_n1979 said:

Tony B2 said:

657 said:

Approx 90C

I’d guess you need both front thermostats. If you have a DPF it won’t be regenerating at less than 75C iirc. I have a E60 535d and when the thermostats are shot it is nigh impossible to get above 75C. High load and not so high revs or speed do help, but aren’t really practical unless towing. Fuel consumption does suffer. Easy DIY.

Thanks for responding.

You say "both front thermostats".

I have looked on realoem.com but can only see a single thermostat?

https://www.realoem.com/bmw/enUS/showparts?id=UY92...

This is what you need: https://www.ebay.co.uk/itm/126204938436?itmmeta=01...

Mahle are OE for the M57; Febi for the N47/N57

Many thanks, this is very useful.

Is there a secondary temperature reading (i.e. not just main coolant temperature) that I can use to diagnose whether this thermostat is also faulty?

I have the BMW Drive Analyser app (and dongle) which I can use to check various parameters - I forget which ones are logged without actually getting into the car, and the weather is dire here at the moment!

You can access the hidden menu on the cluster to see what the temps are; but IIRC it's just the one temp

TBH for their cost and not a lot of time to fit them; top up the system and re-bleed; it makes sense to get them done as they'll probably outlast your ownership

I had weird temp issues on a previous E65 730D Sport in 2018; swapped the stats over to the ones I linked to; car ran sweet as a nut after that

I do still have a comprehensive BMW warranty on the car. Thermostats should be covered by this. The only problem is the dealer has to test and agree with my diagnosis. And they are getting very tight with claims.

I have been quoted £377 (P&L) to change the main thermostat (presumably one, not two), outside of the warranty.

Time to do some data logging....

[Twolane]

Just changed both thermostats on my 120d, noticed the heater wasn't getting hot enough and mpg getting worse.
Checked the running temp with the hidden menu and it was only 50C.
Fitted both coolant and EGR stats, just generic ones from a motor factors, not OEM.
Heater now works great and mpg has gone from 36 to 44 for the same journey.

[d_a_n1979]

Tony B2 said:

d_a_n1979 said:

Tony B2 said:

d_a_n1979 said:

Tony B2 said:

657 said:

Approx 90C

I’d guess you need both front thermostats. If you have a DPF it won’t be regenerating at less than 75C iirc. I have a E60 535d and when the thermostats are shot it is nigh impossible to get above 75C. High load and not so high revs or speed do help, but aren’t really practical unless towing. Fuel consumption does suffer. Easy DIY.

Thanks for responding.

You say "both front thermostats".

I have looked on realoem.com but can only see a single thermostat?

https://www.realoem.com/bmw/enUS/showparts?id=UY92...

This is what you need: https://www.ebay.co.uk/itm/126204938436?itmmeta=01...

Mahle are OE for the M57; Febi for the N47/N57

Many thanks, this is very useful.

Is there a secondary temperature reading (i.e. not just main coolant temperature) that I can use to diagnose whether this thermostat is also faulty?

I have the BMW Drive Analyser app (and dongle) which I can use to check various parameters - I forget which ones are logged without actually getting into the car, and the weather is dire here at the moment!

You can access the hidden menu on the cluster to see what the temps are; but IIRC it's just the one temp

TBH for their cost and not a lot of time to fit them; top up the system and re-bleed; it makes sense to get them done as they'll probably outlast your ownership

I had weird temp issues on a previous E65 730D Sport in 2018; swapped the stats over to the ones I linked to; car ran sweet as a nut after that

I do still have a comprehensive BMW warranty on the car. Thermostats should be covered by this. The only problem is the dealer has to test and agree with my diagnosis. And they are getting very tight with claims.

I have been quoted £377 (P&L) to change the main thermostat (presumably one, not two), outside of the warranty.

Time to do some data logging....

Ah… In that case I’d be getting them to sort it.

Don’t let them know you’ve used a code reader; they don’t like that. But you’ll find the temp display in the hidden menu. Use that, take pics when you know the car should be at full temp & then pass it to them to fix.

I’ve had a fair bit of warranty work done on my F31 in 2023; zero issues with the claims, I just paid the excess etc

[657]

Good luck getting them done under warranty. I got a “we don’t have a protocol for checking those”. This was from a very proactive dealership, which had sorted quite a few niggles under warranty.

Yes the second one I was referring to is the egr thermostat. If you have an automatic there’s one in the gearbox too. The other two have so far solved my issues. I’m on my third or fourth set now, mind I’ve owned it since 09 and there’s over 300k on it. I’ve tried dealer supplied and OEM aftermarket and cannot detect any difference in longevity. Whoever does it make sure they use proper coolant.

As I referred to earlier, your DPF will not regenerate at those low temps, which will create a bigger headache if not sorted.

[Tony B2]

d_a_n1979 said:

Ah… In that case I’d be getting them to sort it.

Don’t let them know you’ve used a code reader; they don’t like that. But you’ll find the temp display in the hidden menu. Use that, take pics when you know the car should be at full temp & then pass it to them to fix.

I’ve had a fair bit of warranty work done on my F31 in 2023; zero issues with the claims, I just paid the excess etc

They should not be too upset about me reading codes and data - I bought the dongle/app from them (BMWDrive Analyser) - a really nice device, and the app has excellent functionality.

[Tony B2]

657 said:

Good luck getting them done under warranty. I got a “we don’t have a protocol for checking those”. This was from a very proactive dealership, which had sorted quite a few niggles under warranty.

Yes the second one I was referring to is the egr thermostat. If you have an automatic there’s one in the gearbox too. The other two have so far solved my issues. I’m on my third or fourth set now, mind I’ve owned it since 09 and there’s over 300k on it. I’ve tried dealer supplied and OEM aftermarket and cannot detect any difference in longevity. Whoever does it make sure they use proper coolant.

As I referred to earlier, your DPF will not regenerate at those low temps, which will create a bigger headache if not sorted.

Understood on the DPF threat.
I will be going in to see them tomorrow!

[d_a_n1979]

Tony B2 said:

d_a_n1979 said:

Ah… In that case I’d be getting them to sort it.

Don’t let them know you’ve used a code reader; they don’t like that. But you’ll find the temp display in the hidden menu. Use that, take pics when you know the car should be at full temp & then pass it to them to fix.

I’ve had a fair bit of warranty work done on my F31 in 2023; zero issues with the claims, I just paid the excess etc

They should not be too upset about me reading codes and data - I bought the dongle/app from them (BMWDrive Analyser) - a really nice device, and the app has excellent functionality.

There are folk on here who have fallen foul of admitting they've read their own codes when it came to BMW warranty and the work was refused... Worth bearing in mind

TBH the stats aren't expensive; I'd still be tempted to get them sorted myself

[Tony B2]

d_a_n1979 said:

There are folk on here who have fallen foul of admitting they've read their own codes when it came to BMW warranty and the work was refused... Worth bearing in mind

TBH the stats aren't expensive; I'd still be tempted to get them sorted myself

I used to do loads of work on my cars, so have the tools. But not much motivation these days!

As the car is under warranty, I would be more concerned about invalidating the warranty by doing the work myself, than the use of a BMW sold dongle, which provides lots of operating data. It is not what I would call a code reader.

I had to order the Dongle from BMW on-line and it was delivered by my local dealer.

It would be a bit unreasonable now for them to complain about me using it!

[d_a_n1979]

Tony B2 said:

d_a_n1979 said:

There are folk on here who have fallen foul of admitting they've read their own codes when it came to BMW warranty and the work was refused... Worth bearing in mind

TBH the stats aren't expensive; I'd still be tempted to get them sorted myself

I used to do loads of work on my cars, so have the tools. But not much motivation these days!

As the car is under warranty, I would be more concerned about invalidating the warranty by doing the work myself, than the use of a BMW sold dongle, which provides lots of operating data. It is not what I would call a code reader.

I had to order the Dongle from BMW on-line and it was delivered by my local dealer.

It would be a bit unreasonable now for them to complain about me using it!

Agree; that's fair enough

As you said; deffo worth asking them to fix the issue

Let us know how you get on

[Tony B2]

I have been monitoring data in the last few days, a couple of observations:

1. Yes - coolant temperature is taking a long time to get up into the mid 80s - typically only achieved at motorway speeds, at least 20 minutes from switch-on
2. The catalyst temperature also seems low - in traffic, hardly ever stirs above 200C, but once at m/way cruising speeds it varies between 300 and 400, and is very throttle sensitive.

What is normal for cat temperature?

Car is booked into dealer next Monday.