XSeries-forum

[quote="Alan Gunn"]
Just had mine done this morning and now running at 90/91 on the dual carriageway  .
Got to the garage at 9am car went on the ramp about 9.10am and i was driving away at 10.30.
Can't say what the price would be as i get m8s rates and i paid £20 labour bought the part myself.
Just a note it only lost about 3 ltr of coolant.
[/quote]

Was it an oem part? What did it cost?

It was this one the same as i put on my 320d 5 years ago so got the same again.
https://www.ebay.co.uk/itm/BMW-E53-X5-3 ... 0011.m1850

Had OEm thermostat fitted today. nit much better. Took it out on to the motorway and as soon as it hit 72c the temperature suddenly dropped, like the thermostat had just opened, and went down to around 60c. Took it back to the garage. I thought maybe the reading on the hidden menu was maybe just under reading and reporting 72c when maybe it was 92c. However , they had an infrared gun and pointing it to the water pipes they got within a degree of the reading on the hidden menu

Bear in mind the car has just had a new radiator, fan, water pump and thermostat fitted. I had the same low running temperature issue before the thermostat was fitted.

So Ive just done a simple google search on "What causes an engine to run cold" and it states that , aside of the thermostat it could be a coolant fan really. admittedly the search was generic and not BMW specific, but could this be the case? If not Im at a complete loss as are the garage as to what is happening?

Could it be a coolant fan relay?

As far as I'm aware you have a viscous fan, so no electrical relay. Unless for some unknown reason at a set temperature the DDE is switching on the A/C fan. Easily enough to check by switching of the A/C and let the engine idle and see if the A/C fan comes on at around the same time as your temperature drops ie around 72c. If you've tried this then obviously ignore.

Smee
Mine was doing that up to 72 then you could see the temp needle drop.
Well i first noticed the needle drop then i went to the hidden menu and could see the temp hit 72 then drop.
New stat in yesterday and temp just goes up to 88 and slowly climbs to 89/91 constant well that was over around 9 miles after getting up to the 89/91.
Strange this 72 mark on both yours and mine.

Yep and im on my third stat

So here's a theory. The car has a coolant temperature sensor which (maybe) thinks the car is hotter than it is and opens the thermostat?
So, ..... question ... what actually triggers ghe thermostat to open, because in the good okd days in nineteen canteen, we didnt have sensors on cars. So what makes it open/close?

I have the same engine in my E83 3.0d and have changed the thermostat. The thermostat is rated at 88 degs C
The thermostat solely uses water temperature to heat up the wax in the thermostat causing it to open at 88 degs
Some BMW's have a heating element built in to the thermostat, it is controlled by a module on the car, this circuit can manipulate when the stat opens by the heater warming up the thermostat causing it to open.
These thermostats have a cable/ Multiplug that attached to the thermostat housing.
Mine didn't have one, and it was listed for E53 diesel as well

[quote="henrym3"]
As far as I'm aware you have a viscous fan, so no electrical relay. Unless for some unknown reason at a set temperature the DDE is switching on the A/C fan. Easily enough to check by switching of the A/C and let the engine idle and see if the A/C fan comes on at around the same time as your temperature drops ie around 72c. If you've tried this then obviously ignore.
[/quote]

Yes it is a viscous coupling so youre right, but no ive not tried that. Do you mean the ac fan comes on in the car? Should the ac button be on or off?

Absolutely, the V8's stat tend to be opened by the DME which send a voltage to the heating element in the stat they open at over 100c. You have a normal dare I say old school stat opened by water temperature. I know you are on your third stat but the garage guys proved via the IR gun that the stat had opened way before the 88c

[quote="Horizon"]
I have the same engine in my E83 3.0d and have changed the thermostat. The thermostat is rated at 88 degs C
The thermostat solely uses water temperature to heat up the wax in the thermostat causing it to open at 88 degs
Some BMW's have a heating element built in to the thermostat, it is controlled by a module on the car, this circuit can manipulate when the stat opens by the heater warming up the thermostat causing it to open.
These thermostats have a cable/ Multiplug that attached to the thermostat housing.
Mine didn't have one, and it was listed for E53 diesel as well
[/quote]
Yes mine did t have it as I watched the garage fit it and it was also rated to 88c but that's 3 from 3 suppliers - including bmw, they cant all be defective surely. I had the problem before I changed it so that would be 4 thermostats not working?

have you got or can get any of the old stats, if so get the kettle on and heat up some water, need to have something to measure temp of water in kettle, pop the stat in on a bit of string and see what temp it opens at.

Will do

[quote="Smeeagain"]
[quote="henrym3"]
As far as I'm aware you have a viscous fan, so no electrical relay. Unless for some unknown reason at a set temperature the DDE is switching on the A/C fan. Easily enough to check by switching of the A/C and let the engine idle and see if the A/C fan comes on at around the same time as your temperature drops ie around 72c. If you've tried this then obviously ignore.
[/quote]

Yes it is a viscous coupling so youre right, but no ive not tried that. Do you mean the ac fan comes on in the car? Should the ac button be on or off?
[/quote]

At idle, im lucky to get it to even 60c let alone 72c. What is the DME?

Smee
This must be doing your head in as it's getting to mine.
All we have is an old fashioned wax-stat type thermostat that opes at a set temp.
If it doesn't open at that temp then it's faulty in my book.
It's a shame that it is in the position it is on the car and such an over priced part.
Somebody must make the actual thermostat why can't we just buy that part instead of paying for a big lump of plastic as well.