[JT8Diesel]

So I have a 2010 335d. Coolant temps are 65-75°C, never higher than 75°C.

It seems that every online DIY, Bentley, etc. references the non-diesel thermostat.

Does anyone have links / info to change the thermostat?

[TorqueAddict]

Using search helps. BTW following are the threads that i found searching the forums:

http://www.e90post.com/forums/showth...ght=thermostat

http://www.e90post.com/forums/showthread.php?t=1008568


Also try: Link

[nicklockard]

I'm about to do it myself. Looks like it's right under the vacuum canister. I read here it's a much easier job if you remove the EGR cooler first to gain access. A search of youtube vids turned up some polish video which doesn't seem too far off the mark, and some X5D how-to vids as well: https://www.youtube.com/results?sear...m57+thermostat

Biggest difference being theirs have the secondary EGR t-stat which North American models don't. So ignore that part.

[JT8Diesel]

Thanks for the link.

I'd searched in this forum, and the main DIY forum without any luck. I hadn't thought to search the UK forum though.

[335dsleeper]

It's a very simple job. It looks a bit intimidating at first but, once you drain your coolant, its rather straight forward. Pull the EGR cooler like nicklockard suggested, just be careful with the erg coolant lines. They can become brittle and crack. Pull the cooler and the 4 10mm bolts are right there. Swap it out, reinstall the EGR cooler and top off your coolant. done and done

[BB_cuda]

Per yozh's unfortunate experience, for cooler removal be careful with the bolts that attach to exhaust manifold. He broke off one of the OEM bolts when he was loosening them. He had to drill it out. I dressed those bolts with antiseaze when putting them back in.

[335dwanted]

I documented my experience here:

http://www.e90post.com/forums/showthread.php?t=1191391

So I replaced my thermostat on my '09 335d on Sunday of this past weekend (72K miles on the odometer).

Before replacing my thermostat temp was running between 168F and 174F and sometimes into the high 180Fs during regens.

After replacement my temps have jumped up between 190F and 199F during normal/typical operation, it will spike into the low 200s if I get on it or spiritedly climb a hill.

I have no opinion on fuel economy yet; not enough miles.

Process was simple enough:

1. Put the front up on jackstands
2. Drop the under car tray.
3. Try to drain coolant - Since the rad petcock is apparently hidden by the intercooler and I did not want to try and remove that, I was planning to pull the lower radiator hose but could not find that either. I did pull a hose near the bottom of the radiator going to what I think is either an oil or trans heat exchanger. Unfortunately that only drained a quart or so of coolant. Pretty much got a mess of coolant splash from all the other parts as removed. Note that all the coolant line connections are fastened with the wire clips that slide out to free the hose/pipe.
4. Remove Air box + snorkel in front/top of underhood + air supply pipe running to turbos. The turbo supply pipe has one bolt on the body of the pipe (not near the inlet or the outlet of the pipe). The pipe connection at the turbo is just a press fitting but you will need to release the crankcase breather hose+heater clip.
5. Remove EGR Cooler; I disconnected at EGR valve, at exhaust manifold and two bolts holding body. I also pulled the two coolant lines (expect more coolant spilling unless you were able to drain system better than I) but left the vacuum lines connected. It easily pivoted out of the way.
6. Remove Thermostat housing; I removed the 4 bolts, then I released the clips on the two hoses connected to the thermostat housing. The larger pipe is flexible and can be pushed out of the way (if you did not drain the system well be ready for a big splash when you disconnect this pipe or when you dislodge the housing itself after removing bolts). The other hose is a rigid plastic pipe (I think it is the heater piping) which is a bit tricky since that pipe is rigid and the thermostat housing will not easily slide sideways (the thermostat itself protrudes into the water pump housing limiting sideways movement). I did loosen the nearer of two bolts securing the heater pipe, but it is real fiddly located just underneath the EGR valve with very little room to maneuver. A ratcheting box end wrench would be your friend here but I don't have any. Once you can get a little movement of the rigid pipe you can get the thermostat housing off the ridged pipe an free to remove.

As they say, installation is just the reverse of the above. I did grease the O-Rings (one on the heater pipe and one on the thermostat housing) to help things go back together. Torque the thermostat housing bolts to 10 NM.

I needed precisely one gallon of coolant to replace what I lost; I caught roughly 80% of this amount in my bucket, the rest on the floor of the garage. I think I read somewhere that coolant capacity is between 8 and 9 quarts so I replaced roughly half.

[nicklockard]

This turned out to be a good thread. If you guys need a moderator to highlight nuggets of DIY wisdom and post as stickies I can help.

[JT8Diesel]

Job done.

I was four hours start to finish, with a couple stops to look a couple things up.

The job was "basically" as advertised with a few differences. Most guides seem to be from Euro cars that have the EGR thermostat that we don't have. They also seem to have the ATF reservoir on the passenger side and some other slight air duct differences.

I replaced about half the engine coolant, I would have liked to have drained it, but didn't want to get too involved with intercooler, etc. There is a lot of grime / soot on the passenger side pipe of the intercooler, and on the top side of the under engine tray. I'll need to get that sorted at some point also.

[nicklockard]

I concur with TdiWanted's summary. Took me about 3.5 hours to complete job. I also replaced a vacuum diaphram and wanted to replace red boost hose o-rings (unscucessful).

Highlight on TDIW's point number 6: there is a bolt (10mm I think) just underneath the EGR valve which holds the rigid "Y" shaped plastic pipe. If you just loosen it by 6 threads or so using open ended wrench, without removal, it makes pulling that heater connection off of the old thermostat housing (and installing onto new one) a bit easier. Gives just a tad of clearance and wiggle room needed. I would not recommend removing it, because replacment would add a lot of time. There is NO clearance to re-thread it back in.

I lost ~5.5 L (didn't pre-drain or anything). I refilled it to a slightly higher coolant mix ratio for higher boilover protection. Went on a test drive after burping system (very easy), car hods 92-95C. My brand was the 'genuine BMW' which I believe is a Behr sourced part. I did not use ramps or remove bottom pan (don't have tools for it), or I would probably not have lost as much.

[Mark M]

Looks like this job is in my future too. Coolant temps hovering around 70 degrees max.

Thanks for the diy tips.

Update:
I did this job last night. Not hard at all just tedious and takes time to get everything else out of the way. Tip, get 4 new 10mm bolts for the tstat. They thread into soft aluminum and the old bolts looked rough. I wish I had fresh bolts last night, I reused them but am not happy with they they felt threading in. I also used loctite blue.

Car is not fully back together yet. I'm doing the glow plug module tomorrow. Fun.