[335D Alpha Pappa]

Originally Posted by TYS335D

Thank you very much BB_cuda, bvanlieu and QUIKDZL for adding your thoughts and suggestions to the discussion.

I emailed my dealer to share the information that I found on this forum about thermostats, and I received a reply today. Please bear in mind that my dealer has been taking excellent care of my BMWs for 32 years. I understood from them that they have received some recent communications from BMW about thermostats, although I do not know the details. They agreed that replacing the thermostat would be a good next step. The bad news is that their estimated cost of replacing the thermostat is $930, and replacing it is not certain to fix the problem.

The situation brings me back to my thoughts as I started this thread. Is it possible to keep the engine and emission systems reliable and functional, or do they just get out of order and never work right again no matter what you do? Does one get to a point after 120,000 miles or so where these cars are no longer economically feasible to keep on the road? My 335d has been well taken care of, always worked on by authorized BMW dealerships, and not driven particularly hard. At 125,000 miles, I’ve never had to replace the brake pads or rotors, for example. Many of the miles have been highway miles.

I am still deciding whether or not to fork over the $930 to have the thermostat replaced. As much as it would cost, it’s still vastly less expensive than buying a new car. Also, I really don’t like the electric power steering systems that seem to come on every new car.

I’ll let you know how it turns out. Thank you again for sharing your thoughts.

TYS335D

You have been a BMW customer for 32 years and you are having sticker shock? Take it to a VW dealer and let them change it, their hourly rate is much less than BMW and they are used to working on german cars. It is just a t-stat. Seriously, it should cost between 400-500 at a stealership for this change.

Here is why T-stat temps are important:

"Regeneration is started during the next drive as soon as the coolant
temperature reaches a value of at least 75°C and the exhaust-gas temperature before catalytic converter a temperature of at least 240 °C. Additionally, the fuel tank must contain at least 10 litres.

The optimum effect of the regeneration is achieved when the vehicle is operated for approximately 20 minutes at a constant as possible speed of at least 60 kph after regeneration has started. Experience shows that the best regeneration results are obtained from cross-country driving."

"If a regeneration drive is terminated early, regeneration is continued in the next driving cycle as soon as the coolant temperature again reaches a value of at least 75°C and the exhaust-gas temperature before catalytic converter again a temperature of at least 240 °C.

When the diesel particulate filter is very blocked with soot it is possible that the regeneration request may be blocked after a short time or not enabled. Should this happen, it is necessary to regenerate the diesel particulate filter in an approximately 30-minute motorway or cross-country drive with a speed as constant as possible. The service function "Regeneration particulate filter" must then be repeated.

From time to time furthermore, if the diesel particulate filter is extremely clogged with soot the exhaust gas backpressure can be so high that there may be problems in achieving the cutoff speed. This degrades the ability to carry out the exhaust gas backpressure check in many cases. A clean
egeneration neutralises this problem in many cases and lowers the exhaust gas backpressure.

During the regeneration phase when the engine is running, from time to time the display of regeneration active jumps to regeneration not active. This behaviour is identified exclusively on a stationary vehicle with a running engine. This behaviour does not generally impair the planned regeneration procedure."



For longevity, around 200,000 km (125,000 miles) you will get a DPF warning that it must be replaced due to soot accumulation. It is a calculation based on how many grams remain after each regeneration.

"The diesel particulate filter retains all
particles. These include non-regenerative
particles, such as oil ash, swarf and additive
residues. The non-regenerative particles
gradually lead to a blockage of the diesel
particulate filter over time. Over a distance of
1000 km, approx. 0.6 grams of powder ash are
deposited in the rear third of the diesel
particulate filter.
The diesel particulate filter is therefore subject
to a replacement interval. The replacement
interval can be anywhere between 160,000
km and 220,000 km."

[floydarogers]

So, about 2 months ago, BMW replaced my NOx sensors again, on the 2/24 BMW parts warranty (after they had been replaced by the NOx sensor extended warranty on 3/15/2016). Probably they replaced good NOx sensors (at the direction of BMWNA), so when the SES came on again after a couple weeks, I recorded the codes (4D16, 46A4, 4D17) and drove it for a few weeks - sometimes these things go away after a regen or two, as you probably all know.

But, after a couple longer trips and they didn't go away, I took it in this week to BMW Bellevue (while expensive, they're pretty much the only game in town when it comes to M57 stuff - neither of my two indies that I use know these engines well) and had them spend some money on diagnosis. After $250 initial, and another $200 on drive/monitor (my tank ended up almost empty after two drive/monitors), they came up with a new one on me.

They said that the EGR valve was sticking just a bit, which was causing problems with regens and the SCR tests during regens because too much O2 was in the exhaust stream. Well. Don't know what to say, but it's plausible I suppose (I'll have to review the training docs' chemical reaction stuff.) So, at the direction of BMWNA (the SA appeared to open a PUMA for me, what with my notorious reputation? ), they replaced the EGR (the old one - which had been replaced by the first recall back in 2011 - with a brand new one and off I go. Cost to replace the EGR was $377 parts $428 labor.

SA said that the old one wasn't choked like some CBU related ones were (so I'm happy with that report). But the charge, after $450 diagnosis and labor and parts, was around $1800. So this is really a cautionary tale of what these things cost to maintain after warranty. That brings my total costs for this 335d to $14582.50 (sans tires). I did get a $200 discount because of my BMWCCA membership!

They also did the DPF clean procedure - forgot about that, cost was almost $600.

2010 335d delivered on Nov 1 2009, 127200 miles.

(I'm sure that some of youse guys will laugh at me for my "keep it stock" proclivities, but keep it light, please. <insert "prayer" smiley> )

[dmanb2b]

Originally Posted by floydarogers

(I'm sure that some of youse guys will laugh at me for my "keep it stock" proclivities, but keep it light, please. <insert "prayer" smiley> )

Quite contrary. Thanks for sharing your experience so that others in same situation may benefit

[cm335d]

I wonder if the EGR could have been cleaned up so that it didn't stick? Do you happen to have any pics to share of the removed EGR valve?

[floydarogers]

Originally Posted by cm335d

I wonder if the EGR could have been cleaned up so that it didn't stick? Do you happen to have any pics to share of the removed EGR valve?

Sorry, not. SA said he didn't think the CBU was causing it to stick.

Just did a 595 mile trip, no SES. 38 mpg going east, 36 mpg back into the winds.

Forgot in original post that they also did the DPF clean procedure, cost was almost $600.

[TYS335D]

Thanks very much floydarogers, dmanb2b, bvanlieu, Persian Whisperjet, RED-d, 335D Alpha Pappa, and cm335d for your thoughts and, 335D Alpha Pappa, the very detailed explanation of the regeneration process and the diesel particulate filter. I have an update on my situation.

I had the thermostat in my 335d replaced today right at the estimated cost of $930. The good news is that the coolant temperature is up around 87C to 91C and it stays there except that it did drop to about 85C just briefly when I coasted down a half mile-long hill. I also noticed that the radiator fan revs up when I start the car after it sits for a few minutes, something that it used to do but hasn’t in recent months. The engine may be a little less intrusive in the interior when I’m idling at a traffic light, but I can’t be absolutely sure on that point. Someone did say that it would be smoother at the correct temperature.

The bad news is that the Service Engine Soon light came back on about 40 miles after I picked up the car with the new thermostat. I don’t know the code numbers, but the BMW flowchart directs the technicians to replace the NOx sensors as a next step, and I do have complete confidence in them. The cost of replacing the sensors is a couple of thousand dollars as I understand it, and replacing them may reveal other expensive problems. It turns out that my NOx sensors and the SCR convertor were replaced about 40,000 miles ago. It makes you wonder if another component that isn’t working right - like maybe the thermostat - has caused the replacement sensors and convertor to fail prematurely.

As an aside, my loaner car today was a 340. Other than the very smooth, powerful BMW 6 cylinder engine, I wasn’t terribly impressed. I wouldn’t pay $60,000 for a car with cheap feeling vinyl seats and a wind whistle in the driver’s side door. In almost every respect, I’d much rather have my 335d than the 2018 340, and therein lies my conundrum. I can’t find a new car that I’d rather have than my 335d, even as much of an expensive nuisance as it’s become.

Thanks again to everyone for sharing all of your knowledge and advice.

[335dsleeper]

$930 for a thermostat? Jesus! That’s criminal!

[bimmerdiesel]

Same boat... I am at 95k miles and no mods yet. I have been getting emissions related codes. I m on edge. Going to get it checked out soon. Currently inclined to get rid of emissions equipment.

[Yozh]

Originally Posted by 335dsleeper

$930 for a thermostat? Jesus! That’s criminal!

Insane. It’s a 1hr job for a qualified technician. Ok may be 2hrs with EGR cooler in the way. Insane.

[Yozh]

Originally Posted by TYS335D

The bad news is that the Service Engine Soon light came back on about 40 miles after I picked up the car with the new thermostat. I don’t know the code numbers, but the BMW flowchart directs the technicians to replace the NOx sensors as a next step, and I do have complete confidence in them. The cost of replacing the sensors is a couple of thousand dollars as I understand it, and replacing them may reveal other expensive problems. It turns out that my NOx sensors and the SCR convertor were replaced about 40,000 miles ago. It makes you wonder if another component that isn’t working right - like maybe the thermostat - has caused the replacement sensors and convertor to fail prematurely.

I believe there is a function in settings where they can reset NOx sensors. May be adaptations. I also, would start with cleaning of the metering valve. But I would definitely not pay through my nose for it.

[Mark M]

If your nox sensors were replaced in the last two years they should be covered under Bmw parts warranty. Look into it.

[TYS335D]

Thank you 335dsleeper, bimmerdiesel, Yozh and Mark M for your posts. I thought I would share my results from replacing my thermostat last Saturday.

I agree that $930 is a hefty price to pay for replacing a thermostat, but I really have no complaint about the transaction itself. I made the decision to replace the thermostat, the dealer quoted the $930 cost to replace it in advance, I agreed and had them do the repair, the actual cost was exactly what was quoted, and as far as I can tell the work was done perfectly. As I recall, the cost of the thermostat itself was about $96, which is the normal high price that you pay for genuine BMW parts from an authorized dealership.

The technician reset the Service Engine Soon light, and I had high hopes that it would not come back on. Unfortunately, it did after about 30 miles. I used the hidden menu to check the coolant temperature after the repair, and with the new thermostat it runs promptly up to around 88C and stays at that temperature plus or minus about 4 degrees. So, there was a problem with the thermostat that got fixed, but clearly there are other problems that are causing the Service Engine Soon light to come on.

I had an experience 3 years ago with a message on the dashboard telling me that my 335d would not restart after 200 miles (not 1,000 miles) because it had incorrect diesel exhaust fluid in it. That happened about 500 miles from my destination which was Lincoln, NE. I had to be very careful to not shut off the engine out of habit, like at a fuel stop or rest area, but I was able to drive the whole 500 miles to the BMW dealer in Lincoln without shutting off the engine. So, now when I see the Service Engine Soon light on, I wonder how long it will be until I get a message like the one I mentioned above telling me that the car won’t start again. Because of those experiences, I now restrict my use of the 335d to local trips only.

Thanks again for the wealth of knowledge that you’ve shared on this thread.

TYS335D

[rbreding]

JR has a "keep stock emissions" tune that disables the nox sensors, DEF system, and egr but keeps the DPF active. Bump In performance and eliminates all the failure points. Passes emissions too.

[335_The D]

So I just purchased a 335d with 60k on it. The bimmer threw a light within a few days and got the entire cbu issue cleaned at the dealer including inside the heads. I was given the option to purchase an ext warranty to 100k for 5 grand. Would it be better to do the deletes or do the warranty now that everything is spotless??