35d worsening gas mileage - solved- thermostat/fan/EGR cooler - DIY with pics

[Ozer]

Nope, as far as i know mine is stock and temps are around 84c degrees

[asilee]

Originally Posted by Ozer

Nope, as far as i know mine is stock and temps are around 84c degrees

Go figure. some people complaining at 60-70k miles and others dont have any issues well over 100k.

[02Coastie]

Thanks to the OP and everyone who posted to this thread. We just picked up a 2010 35D and I immediately checked for this issue. Even with extended driving, the temps never get above 71deg C. As the car is in California and under the 70k extended emissions threshold, I took it to the dealership to get checked out. While they found some other faults with the SCR system and replaced those already, it seems they are dragging their feet on the thermostat. They claim "these diesels take a long time to warm up" etc. Can anyone point me to official factory tech specs that indicate what the normal operating temp is supposed to be? I've searched a number of threads and have only been able to find people using the 88deg C marking on the thermostat as "proof." Anything that will help me "educate" the dealership would be great!

[noodle654]

I managed to catch a regen while driving today. Got some data from BMWhat. I have a question about regenerations in this car. I see a lot of people saying that regeneration won't occur if the car doesn't get to 75C...the whole active vs. passive. My engine coolant rarely gets above 71C...but I still get pretty consistent regens according to the data. Today it was 25F (-4C) outside.

My car average regeneration is 444KM or 275 miles. Today it occurred at 400,000 meters or 250 miles. The car was definitely not running very hard and was only running for 30 minutes around town errands (30-50mph roads, not much stopping). But I did see the temps go up, car mpg dropped considerably, and soot level (in grams) started to drop as regeneration kicked in.

Soot mass was 3.74 grams when regeneration started. Engine temp was 71C, and went up and stayed at 76C for about 15 minutes of 30-55mph driving. Once regeneration was complete temp dropped to 71C.

Maybe my car is an anomaly (knock on wood)? Anyone else not having regen problems with high mileage X5s?

[ninja_zx11]

Originally Posted by noodle654

I managed to catch a regen while driving today. Got some data from BMWhat. I have a question about regenerations in this car. I see a lot of people saying that regeneration won't occur if the car doesn't get to 75C...the whole active vs. passive. My engine coolant rarely gets above 71C...but I still get pretty consistent regens according to the data. Today it was 25F (-4C) outside.

My car average regeneration is 444KM or 275 miles. Today it occurred at 400,000 meters or 250 miles. The car was definitely not running very hard and was only running for 30 minutes around town errands (30-50mph roads, not much stopping). But I did see the temps go up, car mpg dropped considerably, and soot level (in grams) started to drop as regeneration kicked in.

Soot mass was 3.74 grams when regeneration started. Engine temp was 71C, and went up and stayed at 76C for about 15 minutes of 30-55mph driving. Once regeneration was complete temp dropped to 71C.

Maybe my car is an anomaly (knock on wood)? Anyone else not having regen problems with high mileage X5s?

The minimum threshold for regeneration is 60℃ not 75℃ and if coolant temperature remains below 60℃ then it would throw thermostat malfunction code.

[Doug Huffman]

Originally Posted by 02Coastie

[ ... ]They claim "these diesels take a long time to warm up" etc. Can anyone point me to official factory tech specs that indicate what the normal operating temp is supposed to be? I've searched a number of threads and have only been able to find people using the 88deg C marking on the thermostat as "proof." Anything that will help me "educate" the dealership would be great!

Here is the technical literature on BMW's that I know of. It's about a thousand pages without much organization and no index. Descriptions of the diesel engine's starting sequences imply some NOT as being when adjustments for starting are terminated. I do not recall a positive statement of normal operating temperature.

https://drive.google.com/folderview?...&usp=drive_web

https://drive.google.com/folderview?...&usp=drive_web

MCPOCG Al Thiele BMCM is neighbor.

[Beemerboie]

So I did all this work on main this week and the only thing didn't change from before is the smell. Main is a diesel and I get the smoke smell inside the cabin and The shop told me I'm getting smell inside my cabin because of the egr cooler Leake but I replaced with a new one and I'm still getting a bit smell. I have no clue where that's coming from. I also changed the thermostat once the egr cooler being replaced. Now my worries are how do I get the codes off. I was expecting to go off automatically but I don't know if that's possible. Can someone tell me what else is the parts i can check to change the smell.

[02Coastie]

Originally Posted by Doug Huffman

Here is the technical literature on BMW's that I know of. It's about a thousand pages without much organization and no index. Descriptions of the diesel engine's starting sequences imply some NOT as being when adjustments for starting are terminated. I do not recall a positive statement of normal operating temperature.

https://drive.google.com/folderview?...&usp=drive_web

https://drive.google.com/folderview?...&usp=drive_web

MCPOCG Al Thiele BMCM is neighbor.

Thanks for the link! I've used some of the items in there to support my case, but I fear it may be a lost cause. I'm going to try and present a temp log to the SA, but it seems their position is: No Code, No Problem.

I bet the Master Chief has some pretty amazing stories. It was a very different service back then! As a prior BM myself, glad to serve in his legacy.

[sgrice]

Beemerboie - Exhaust smell in the cabin is getting a bit off topic from thermostat function, so further lengthy discussion would probably be best on a different posting. Nonetheless, though, I would say that if your EGR cooler is OK, then look at these 2 posts for further possibilities.

The first link is here, and I particularly recommend looking at post #9 with the melted exhaust gas pressure line. I seem to recall some other posts about other exhaust gas pressure sensor lines coming loose near the dpf, but I can't find those at this time.

The second link is here, and details what I found in my car (I post as stevieg on bimmerfest). Be aware that no disassembly is required to look at the two bolts that loosened up/fell out on my upper/small/high pressure turbo. Pop the hood and look on the passenger side (US car) and make sure there's no soot on the side of the upper turbo, and look in the gap between the heat shield and the turbo to make sure your bolts are in place. You'll only be able to see two of the three bolts without removing or loosening the heat shield, but between the presence/absence of soot and the two bolts - that should be enough to see if a leaky turbo is the source of the smell.

Hope that helps.

[Beemerboie]

Thanks a lot for the reply with the links it actually helped me I'm gona try once I get a time. @sgrice