AlexAdams

Agreed new thermostat sounds faulty. I had a new pattern part main thermostat fail after 4 months and only a couple of thousand miles so faulty as supplied is not out of the question. Ps) your 2L should warm up more quickly as it's more stressed, has less thermal mass and less coolant than the 6 cyl variants.

Tigr

Sounds like the EGR thermostat you installed is still bad...

On my car, besides the main water-pump, I have second small electric one. Check if that one is running in your case. Also, set the temperature in the "air-conditioning" to maximum in the car, with fans running, and then try again to let the air out from the system at the EGR Thermostat screw. If you had not done like this, then there is still air in your system.

Lenniz

I'd like to shed some light on how crucial this little fix actually is, and how much damage it can actually cause in the long run.

May of last year my turbo died. Alright I thought, easy fix. After a close inspection my EGR was black as the night, DPF and Cat was clogged up, intake manifold had a layer of 1cm with soot. And while I have resolved all those issues and replaced my turbo and removed all the filters/egr etc, both me and my mechanics still hadn't found out exactly WHY this happened, I regularly do long trips (4-5 times a month) so the DPF and cat shouldn't be as clogged up as it was.

Anyways, while my car is running great now I still couldn't figure out the high fuel consumption (1,1l/100km, before around 0,8-0,9 city driving, occasional heavy foot) so that's when I found this thread (and others) and decided to check my coolant temperature in the hidden menu, and behold, after an hour of driving I my temps vary from 52-64c, with the highest I've seen is 70c when idling for 2 hours, and then immediately lowering to around 54-55 the moment I start driving again. Outside temp around -4c.

So in total the labour and parts I replaced has cost me around 4k EUR.. yeah, get it fixed ASAP if you have a diesel and want it to last.

I have had my car in to three different garages including an 8 hour trip to a BMW dealership and not a single one has checked out the thermostats.

Waiting for the new thermostats now, will post an update on the fuel consumption as soon as they are installed.

Lenniz

An update as promised... New stats installed, temperature is now 88-94c (highest I've seen) and the fuel consumption almost gave me a heartattack, down from 1,1-1,2l/10km to 0,7-0,8/10km!

All in all, great success and after 10 months of problems I can finally check my car out of death row

Tomba_530d

Hello people,

I'm new here and have similar issues as you have experienced.
My problem: running a 2006/09 530d 231bhp version. Replaced both thermostats in the past for both BEHR replacements (2 times). After 1,5 - 2 year the engine temperature took ages before heating up (I tuned my car myself and found the curve which moves the stripes above the engine speed meter -> E6X only). I set 3000rpm (minimum possible) to 60°C and 4700 rpm to 85°C (on stock 75°C is set as 4600rpm-> 530d/535d = 4800rpm IIRC). It normally always gets to 4700rpm/85°C after 5-10 minutes driving. When it didn't I replaced the EGR and main thermostat at once.
Unfortunately the main thermostat came in as a MAPCO variant which I wasn't keen on but the EGR thermostat came as a BEHR one. Although that I replaced it for the MAPCO (main) the engine warmed up perfectly for a week. During the next week I had the opportunity to drive my car fast for a couple of minutes (+200km/h). The day after the warm up issues arise again. Since the main thermostat was not from BEHR I decided to replace it AGAIN.

Before the thermostat was replaced the water pump was replaced as well at 300.000km (currently 330.000km) ,bearing noise and leakage caused the coolant level warning sign. In the mean time I replaced all belts and bearings. The engine really sounded as new again, no belt noise or anything. Since I only changed the main thermostat by then it didn’t warmed up fast and only to 70-75°C. Only when I floor it, it would go to 80-83°C. But once I drive moderate and keep engine speed high the coolant temperature falls back quite easy to 77-80°C (to much coolant flow through radiator I suspect…).

Too identify which thermostat was faulty I decided to put a clamp on the hose from the EGR thermostat. This way it would be blocked and it should avoid cooling down. During a test drive the temperature behavior didn’t change. So I removed the clamp from the hose and this time I used a larger clamp to “cut” the hose towards the lower point of the radiator. This way it would not be possible to cool down through the radiator. Don’t worry I checked the temperature while driving! But it didn’t raise as much as 90°C during fast driving. Higher compared to normal but not overheating as I would expect.
I’m quite stuck at the moment. I can replace both thermostats again and see what happens. But this would be the 3rd set in short time. Or the quality sucks or the temperature sensor circuit is not correct.

I checked ambient and coolant temperature today before starting the car. Car was shut down 18:00 yesterday and started 09:00 this morning (15 hours off cool down). Ambient temperature 16°C coolant temperature 22°C.Does anyone of you ever thought of the temperature sensor? I looked at ETK/realoem and they list additional new terminals and wires for the sensor once ordered. Although no water can spill easily in that spot (back on the cylinder head). I might have a feeling the sensor might be broken or corrosion on the terminals/contacts. These sensors are NTC, high resistance at low temperature (guess ->~2.5-3.5kOhm) and low resistance at high temperature (guess ->~250-350 Ohm). In the case of a resistance in the contacts from let’s say 25-35 Ohm (just guessing) this resistance doesn’t make a huge impact on low temperatures as the resistance of the sensor is high to. But on high temperatures it could lead since the resistance is quite low compared to low temperatures. (1% at low temps, 10% at high temps).

To check which thermostat is broken, have some of you ever check temperatures before/after EGR thermostat? Clamped it? If the EGR thermostat is clamped and it doesn’t heat up should the main be the defective part? Is there a chance of clogged pipes/hoses? I’m tempted to buy original BMW products although they are BEHR, I’m doubted that the spare markets does get equal products somehow (new thermostats seem to fail very often from aftermarket sources).

What do you people think -> replace the main thermostat again?

Best regards,

Tomba

ripley

I think what you need is a publisher.

FormerE30Owner

You mean "editor". A publisher wouldn't publish that!