[Johnnybhoy7]

Looking for some help from the very helpful people on here! Cars struggling to get past 70 degrees. Both thermostats were only replaced 6 months ago and replaced glow plugs whilst work was being done. Only fault codes showing on my car are for 'air boost temperature sensor' and 'glow plug 1'. Would replacing the air temperature sensor and the glow plug relay potentially solve my problems? Any help appreciated

[Digitalize]

Thermostats are gone again. Pretty much the only cause.

[Johnnybhoy7]

Originally Posted by Digitalize

Thermostats are gone again. Pretty much the only cause.

Really do you think so???? Need to check n see if I have warranty. Only was fitted 6/7 months ago

Could it potentially be something like a coolant sensor? Or is it the thermostat itself that picks up the temperature?

[Aragorn30d]

were the stats genuine?

The thermostats control the temperature by regulating water flow thru the radiator. They're self contained mechanical devices so theres no ECU interaction with them.

The coolant sensor measures the water temperature and feeds it to the dash cluster and ECU.

[Johnnybhoy7]

Originally Posted by Aragorn30d

were the stats genuine?

The thermostats control the temperature by regulating water flow thru the radiator. They're self contained mechanical devices so theres no ECU interaction with them.

The coolant sensor measures the water temperature and feeds it to the dash cluster and ECU.

My cars been running for 20 minutes. Only town driving and it's only getting up to 61 degrees. Mpg although not bad isn't great at 35.1mpg. Is it possible thst the boost temperature sensor is causing this? No?

[Aragorn30d]

No its nothing to do with the boost temperature sensor.

Probably the main stat with the temp that low.

[Johnnybhoy7]

Originally Posted by Aragorn30d

No its nothing to do with the boost temperature sensor.

Probably the main stat with the temp that low.

How quickly should my car heat up?

[Aragorn30d]

Depends on the outside temperature and engine load.

Should be at or near 90c after 20mins of driving around though.

Mine is most of the way there after 5-10mins

[mistryn]

When fitting the egr and main stat always use genuine BMW parts, may be ££ worth bit more. I've heard handfull of cases where stats were brought from euro car parts or gsf and they failbafter few months

[Johnnybhoy7]

Originally Posted by mistryn

When fitting the egr and main stat always use genuine BMW parts, may be ££ worth bit more. I've heard handfull of cases where stats were brought from euro car parts or gsf and they failbafter few months

I don't think it was a genuine part. Won't make that mistake again

[Johnnybhoy7]

Getting fault code A6D1 short circuit additional water pump. Could this be the cause??

[Aragorn30d]

nope, that just does additional circulation when the engines off for the REST function.

[chrissyw]

Got my main stat from BMW for £45+ vat.

[Digitalize]

As said that's a 'spare' water pump that is for the REST function, and potentially if the car is still hot when turned off.

At 70c max I'd say both are gone.

EGR is very easy to do yourself, to the point where if a garage is doing the man stat, they'll do the EGR one for free.

[chrissyw]

With a new EGR stat I couldn't get mine above 78c.

New main stat took it up to 90c

[Johnnybhoy7]

Originally Posted by chrissyw

With a new EGR stat I couldn't get mine above 78c.

New main stat took it up to 90c

Probably replace both. Both were only replaced in April

[Somerset Jim]

Originally Posted by Johnnybhoy7

Probably replace both. Both were only replaced in April

I'd do both. I've just changed both stats in the last month for the second time in a year. Second time lucky though!

[Johnnybhoy7]

Just looking for a final opinion before I go spend best part of £200 again. Mpg plummeted to 27.1mpg, it is all around town but still seems catastrophically low. Is it only the thermostat that could cause this or is there any other suspects? And is there no way of checking the thermostat except for the temperature? Thanks guys for all the help

[Digitalize]

Well you can pull the thermostat off, boil it in a pan of water with a thermometer in and see when/if it opens and closes, but if you're doing that you may as well change them.

Just bad luck but nothing else can cause it to run cold, other than thermostats stuck open, even if for example your fan was always running, the thermostats would shut to keep the engine up to temperature.

MPG will be because it's running cold, and it will be even worse now the weather is getting colder.

You could block the vents in front of your radiator with some cardboard/tape and test it to see if the temps increase. Just cardboard/tape all the front bumper openings and go and drive it. Should also increase in temp when sat idling, but obviously slowly as there's no load.

[Johnnybhoy7]

Originally Posted by Digitalize

Well you can pull the thermostat off, boil it in a pan of water with a thermometer in and see when/if it opens and closes, but if you're doing that you may as well change them.

Just bad luck but nothing else can cause it to run cold, other than thermostats stuck open, even if for example your fan was always running, the thermostats would shut to keep the engine up to temperature.

MPG will be because it's running cold, and it will be even worse now the weather is getting colder.

You could block the vents in front of your radiator with some cardboard/tape and test it to see if the temps increase. Just cardboard/tape all the front bumper openings and go and drive it. Should also increase in temp when sat idling, but obviously slowly as there's no load.

Thanks digitalize for the quick reply. I'm considering just taking the hit and replacing the main thermostat see how that goes. At one point sitting idling it almost did get up to temperature but as soon as I started to drive the temperature plummeted. It was idling for a long time but I was waiting on someone so was sat still. I tried taking it on the dual carriageway to put a bit more strain on the engine and the temperature went down again. It sounds like it's stuck open doesn't it?

[Somerset Jim]

Originally Posted by Johnnybhoy7

Thanks digitalize for the quick reply. I'm considering just taking the hit and replacing the main thermostat see how that goes. At one point sitting idling it almost did get up to temperature but as soon as I started to drive the temperature plummeted. It was idling for a long time but I was waiting on someone so was sat still. I tried taking it on the dual carriageway to put a bit more strain on the engine and the temperature went down again. It sounds like it's stuck open doesn't it?

That is most definitely the thermostat. Both of my previous 330d's did exactly that when they needed the stats changing.

[Johnnybhoy7]

Originally Posted by Somerset Jim

That is most definitely the thermostat. Both of my previous 330d's did exactly that when they needed the stats changing.

I thought that myself Jim just because both thermostats are only 7 months old I tried to rule out any other possibilities. Was a euro car parts one so I've leaned my lesson. Go get BMW one tomorrow n get fitted n let yous know how i get on