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Discussion Starter · #1 ·
I have enjoyed my 335d since taking delivery 10 days ago with one big exception. Why would I have what appears to be an intermittent overheating problem? On two occasions after driving modestly, (really! I AM breaking it in...), upon turning off the engine, there was a noticeable burning smell either from the engine compartment or under the vehicle itself. Additionally, soon after turning the engine off, the engine cooling fans turned on and ran for about 15-20 minutes. This has now happened three times in our cool autumn northeast weather (50-55 degrees), but has shut down normally all other times I have driven it (no burning smell, no fans running). The dealer has "checked it out" and found nothing wrong, nor is there any indication on the computer of overheating having taken place. There is no temperature gauge on the car as you may know, but the idiot light does not come on. I told the dealer today about the most recent episode, and he looked at me like a deer caught in the headlights and can offer no explanation. Hard to believe this is "normal" on this car. Can anyone shed some light on this issue?
 

· BMW Fahrer
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The fan running after you shut the car off is not indicative of any malfunction. Not sure if the 335d has the same electric water pump as the 335i, but if it does, I think that can also kick in after you shut the engine down.

Both the 335i and 335d are twin turbo and generate a LOT of heat...


On the other hand, the funky burned smell after getting out of the car typically has nothing to do with the engine overheating. It usually is just some of the undercarriage protection goo melting/hardening along the exhaust path. Could also be a little brake pad smell thrown into the bouquet (and if you had a manual tranny some clutch essence as well).

If the smell doesn't go away in a few weeks, then it warrants careful investigation - but not before.
 

· 40 Oz. to Freedom
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The fan running after you shut the car off is not indicative of any malfunction. Not sure if the 335d has the same electric water pump as the 335i, but if it does, I think that can also kick in after you shut the engine down.

Both the 335i and 335d are twin turbo and generate a LOT of heat...

On the other hand, the funky burned smell after getting out of the car typically has nothing to do with the engine overheating. It usually is just some of the undercarriage protection goo melting/hardening along the exhaust path. Could also be a little brake pad smell thrown into the bouquet (and if you had a manual tranny some clutch essence as well).

If the smell doesn't go away in a few weeks, then it warrants careful investigation - but not before.
+1. You're probably just smelling residual cosmoline (or whatever they use these days) burning off as well as other VOC's fresh from the build process. Should go away soon. As long as your engine temp does not get abnormally high you should be fine. It was a smart move to ask the dealer but they are probably right.
 

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I have enjoyed my 335d since taking delivery 10 days ago with one big exception. Why would I have what appears to be an intermittent overheating problem? On two occasions after driving modestly, (really! I AM breaking it in...), upon turning off the engine, there was a noticeable burning smell either from the engine compartment or under the vehicle itself. Additionally, soon after turning the engine off, the engine cooling fans turned on and ran for about 15-20 minutes. This has now happened three times in our cool autumn northeast weather (50-55 degrees), but has shut down normally all other times I have driven it (no burning smell, no fans running). The dealer has "checked it out" and found nothing wrong, nor is there any indication on the computer of overheating having taken place. There is no temperature gauge on the car as you may know, but the idiot light does not come on. I told the dealer today about the most recent episode, and he looked at me like a deer caught in the headlights and can offer no explanation. Hard to believe this is "normal" on this car. Can anyone shed some light on this issue?
This is a perfectly normal smell when the car is new. My car has alsmost 3K on it now and no smell. The fan does sometimes run for a bit after you turn the engine off but that is also nothing to worry about.

My car runs as low as 187 degrees and has gone as high as 208 degrees only once in the summer. It averages in the mid 190's now.

Don't bother looking for the temp reading. It is a feature on the BMW Performance steering wheel only. Unfortunately it does not give you oil temp on the diesels but it does on the gas cars. go figure! :dunno:
 

· Freude am Diesel Fahren !
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328 Posts
It's the exhaust system...

From the owner's manual:

Pages 115-116
Diesel particulate filter
The diesel particulate filter collects soot particles and burn them periodically at high temperatures. This cleaning process take several minutes. During cleaning, you may notice that the engine temporarily runs less smoothly and that a somewhat higher engine speed is necessary to achieve the accustomed performance. Also, noises may be heard and a slight amount of smoke may emerge from the exhaust, even for a short period after the engine is switched off.

Could this have been the source ?

I down-loaded the manual - and the pdf makes it easy to search questions like these!

Congratulations on your new diesel BMW !!
 

· BMW d Driver
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1,136 Posts
I had the same thing. Dealer said that it is first off the shipment wax/spray burning off and some of the new car break in stuff burning off.

Second, it can be the Particulate Filter burnoff as Rob referenced.

I would not worry too much. I had it happen the first time and I thought the brakes were on fire it was smelling so bad and so hot, the few times since it has done it mostly it just smells a bit hot and the fan runs.
 

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I encountered this problem when I picked up my new 335d last Saturday. I first noticed it right after leaving the dealership, and then it seemed to go away after a few minutes. I smelled it again the next day and was getting a little concerned that the car was running hot until I ran a search and found this thread. The smell now seems to have gone away, so I thought I would add to the knowledge base on this issue. Thanks to the Bimmerfest community for all of the great information over the years.

By the way, I'm loving the new 335d!
 

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335d overheating?

I had the exact same issue-a strong smell of high temperature "something" in the engine compartment accompanied by the fan running for 4-6 minutes after the ignition was turned off. The smell was strong enough to enter the passenger compartment-my wife and I thought initially there was a house fire nearby. This occurred at about 4400 miles on my new 2009 335d. The fan had never run before after turn off even after 50-75 miles of high speed driving, so I was concerned when it occurred after a low-speed 15 mile round trip to the airport.

My usual BMW mechanic, though unfamiliar wit the 335d, thought it imprudent to drive the car without an engine temperature readout. And since there is no temp gauge...I called the selling dealership's service department. They had no ideas as to what might be causing the smell and had it flat-bedded to them for a checkout. As luck would have it I was leaving for a Florida vacation at 5 am the next morning, so it was a huge headache!

After having the car for 3 days the dealer reported that they could find no fault with the car. I insisted they investigate further, saying I was not imagining what had occurred and was afraid I would damage the car if the "problem" weren't fixed. After 2 more days the dealer advised that what we had smelled was probably the diesel engine's "purge cycle" - which now seems correct based on the information from the Owner's Manual posted above.

You would think that an authorized BMW dealership would have ready access to this information and be able to diagnose the issue over the phone. Would have prevented a lot of inconvenience and hassle. I am not impressed with the dealer training for this new BMW diesel! (they also recommended non-runflat snows which were a disaster and had to be junked after 10 days of use at a cost of over $1000 including shipping, mounting and unmounting charges. But that's a separate story.)

That said, the 335d is the best, funnest BMW I have ever owned! Unbelievable torque and fuel economy around 42-44 on my highway work commute. A very fun car to drive. I've owned three 3-series, two 5-series and two 7-series over the years. My very first BMW was a 2002i bought in 1972 under the European Delivery Program.

I've loved them all but the 335d is my favorite.
 

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I have not encountered this issue since my last post. I now have over 1000 miles and all of my overheating smell issues occurred in the first few hundred miles.

Still loving the 335d.
 

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Just had this for the first time on my 2010 335d. The smell was very noticeable and the fan ran for a good 20 minutes after I shut it down. We had an immense amount of rain today... it was right after a very easily driven 6 mile drive home from my office. I now feel reassured it was nothing to be concerned about.
 

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I started to worry until I saw this thread! It happened to me today after 2k miles. Fan ran after shut off after 2 10 mile trips. The garage smells like burnt marshmallows now! I started to look under the hood and noticed something odd.
There is a hose coming out of the air box going towards the turbos and it leads nowhere, it is just cutoff. I opened the airbox and noticed an electrical device at the base of the hose. The only explanation I can think of is that its a heat sensor or its a switch that allows heat to come in to the airbox during cold starts. :dunno: I don't think its related to the overheating issue, but its something odd I noticed.

Here is a picture of the hose
 

· Speed Demon
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Checking now...brb.


 

· BMW d Driver
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I think it is just how it measures air flow.

Here is the Diagram from Real OEM:
http://www.realoem.com/bmw/showparts.do?model=PN73&mospid=51054&btnr=13_1191&hg=13&fg=20

Notice it is called a "Hot-film air mass meter". That then brings up this info:

K&N said:
Hot Film

Hot-film MAF sensors function much like a hot wire sensor, and used a centrally-heated film or metallic grid-type element. One side of the film encounters cooling airflow, while the shielded backside maintains a consistent temperature, and the current differential between the two is measured and relayed as a square-wave digital frequency output, between around 30Hz at idle and 150Hz at wide-open throttle. Hot film sensors tend to be more robust and less susceptible to contamination than hot-wire types.
Source
 

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I think it is just how it measures air flow.

Here is the Diagram from Real OEM:
http://www.realoem.com/bmw/showparts.do?model=PN73&mospid=51054&btnr=13_1191&hg=13&fg=20

Notice it is called a "Hot-film air mass meter". That then brings up this info:

Source
Well that's a good thing if it's less prone to clogging than a standard MAF (wire-type) I had to constantly clean my maxima's MAF or else CEL would regularly come up. Ironically it was oil from the K&N filter lol.
 

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And I thought the 335d was the second coming. :tsk:

Looks like the 328i is still the vehicle to buy if you want a trouble-free BMW.
 

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And I thought the 335d was the second coming. :tsk:

Looks like the 328i is still the vehicle to buy if you want a trouble-free BMW.
Yes, the 328i is more likely going to have a more trouble-free experience due to it's NA simplicity. No, it didn't have enough power for me as it basically felt the same/slower than my E46 330i. Also can't stand the "rubbery" getrag manual that BMW puts in the 328i. Also the slower shifting GM steptronic is another let-down. Why can't BMW standardize and use the superior ZF trannies that they reserve for their higher-end 3 series?
 

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The part I'm referring to in the top corner of the air box is NOT the MAF sensor.

This part is not referenced in the diagram in the link you posted. I'll try to post pictures of inside the airbox when I get a chance. You all should check your airboxes as well. You'll be surprised to find a thick foam like layer before the paper filter and a heavy netting before the MAF sensor adding to the restriction.

The hose is #6 in this diagram, no mention of the base


Code:
No.	  Description		Supplement	Qty		Part Number	Price	Notes
01	Intake muffler		            	  1		13717811905	$300.56+core
02	Air filter element		    	  1		13717797465	$55.40	+core
03	Spring clip		L=42MM	              3		13711716113	$1.16	
04	O-ring			92X6MM	  1		13717794556	$5.63	
05	Decoupling element		    	  2		13717539911	$5.73	
06	Hose		                           	  1		13717803343	$32.93	+core
07	Hex bolt with washer	M6X25-U1-ZNS3  2	07119903851	$2.42	
08	Rubber Mounting			   1		13717801429	$0.91	
09	Grommet				           1		64126910076	$1.50	
10	PLUG-IN CONNECTION BRACKET	   1		61139123604	$1.98
 
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