Coolant thermostat

[X5Sport]

DME = Digital Motor Electronics.  The engine’s ‘brain’.  Called the DDE (Digital Diesel Electronics) on our oil burners, but it is the same thing.

[Smeeagain]

Yes its doing my head in big time. I get on very well with my local garage and they are going to give me the old part to test. They have also said that they are prepared to remove the BMW one to let me test that too. Whilst the evidence points to the thermostat everyone Ive spoken to says its just not possible to have had four defective ones
If i test the old ones and they are defective then fine, but if they operate as they should then Ive no idea where to go next.

[Smeeagain]

[quote="X5Sport"]
DME = Digital Motor Electronics.  The engine’s ‘brain’.  Called the DDE (Digital Diesel Electronics) on our oil burners, but it is the same thing.
[/quote]

Aha! And does the DDE on an E53 control the water temp in any way?

[Smeeagain]

So ive been to the garage and retrieved the first and second thermostat to test them, which I'll do next week. The original had been binned and the oem is currently on the car.

I had a four hour motorway drive today, and the temperature hits a max of 66c then would drop back gradually to 58c and then back up to 66 and so on

Smee

[henrym3]

In answer to your DDE question. No it does NOT in any way control the opening of the thermostat. Your's is just a normal stat, opened by the water temperature, I know I said heat a kettle but bearing in mind the actual size of your stat with all that plastic around it, it would probably be easier to put it in a saucepan full of water then heat the pan on the cooker. Be easier to keep tabs on the temp' as it heats up. Will be really interesting to hear the results.

[Smeeagain]

Thanks, will post the results next week. I have a temp probe so can measure it accurately. Do you think it is possible that Ive had three consecutive defective thermostats????

[henrym3]

Only if your the unluckiest man in the world, however I can't see why/how this problem can be fixed if it's not the thermostat.

[Alan Gunn]

Many years ago i had a full box of spark plugs and every one was faulty.
That caused a lot of head scratching i can tell you.
Suppose you could get a batch of anything that are faulty.
But in your case you have had stat's from different places (i think).
:'( :'( 

[Smeeagain]

One from ECP, one from Andrew Page and one from BMW. They look identical as though they have come from the one manufacturer with the exception that the BmW one has their logo on it, so if they do all come from the one manyfacturer then the tooling has been modified to allow for an insert to add the logo, at the very least indicating a different batch for the housing but the gubbibs ie the wax operated working batch may well cone from the same batch
Smee

[Smeeagain]

[quote="henrym3"]
Only if your the unluckiest man in the world, however I can't see why/how this problem can be fixed if it's not the thermostat.
[/quote]

Could there be an airlock or physical blockage anywhere else in the ststem that is in some way could be impacting upon all of this?

[X5Sport]

It could, and you do need to physically check what the stat you have is really doing.  Is it actually opening at 88°C or well below?

If it is on temp then the block is hitting temp but the flow via the coolant loop is slower meaning more time to cool - which could give a cooler radiator. 

I don’t know where the gauge temp sensor is located.  If the sensor is on the rad and the garage are checking the rad then both could be being fooled and the issue is elsewhere.

What’s the oil temp doing?  It should be somewhere around 100°C.  My car varies between ~95° and ~105° and takes about 15 miles to come up in the current air temps - much longer than it does on warmer days.

[Smeeagain]

I havent yet checked the temp they open at, but will do so. Ext week. The garage checked top and bottom end with an infra red gun. Can i access oil temp somewhere on the hidden menu?

[henrym3]

The list of things the hidden menu tell's you doesn't include oil temperature, at least my list doesn't. I have an oil temperature gauge where most people have the fuel consumption gauge and the highest it goes is around 90/95c and normally takes some time to get there. 

[Smeeagain]

[quote="X5Sport"]
It could, and you do need to physically check what the stat you have is really doing.  Is it actually opening at 88°C or well below?

If it is on temp then the block is hitting temp but the flow via the coolant loop is slower meaning more time to cool - which could give a cooler radiator. 

I don’t know where the gauge temp sensor is located.  If the sensor is on the rad and the garage are checking the rad then both could be being fooled and the issue is elsewhere.

What’s the oil temp doing?  It should be somewhere around 100°C.  My car varies between ~95° and ~105° and takes about 15 miles to come up in the current air temps - much longer than it does on warmer days.
[/quote]

What did you mean when you say both could be being fooled? Surely the thermostat opens at a certain temp or it doesnt, which I hope to be able to check tomorrow

[X5Sport]

The thermostat should open at a certain point, and it may be so doing.  It will react to the temperature where the stat is, but if the sensor (and garage measuring point) are elsewhere (such as the radiator itself) then the coolant will be at a different temperature simply because that’s how the system (and a radiator) works.

Hence needing to physically check the stat to see what it is doing.  If it is opening well below 88°C then it’s faulty.