Carbon Build Up - How Common is it? - The Unofficial BMW M5 Messageboard (m5board.com)

chunpng · 26th July 2005, 20:44

Hi,

I just read some threads/posts about carbon build-ups in the engine head. Evidently, dealers are charging $5k-$8k to fix it. I did a search and nothing shows up as a specific thread. How common is this in the S62 engine? Also, besides the SES light and or failing smog, are there other symptoms? Now that we have some M5s with higher miles, it'd be good to know.

I know the Porsche Carrera has this carbon build-up issue and throws the SES lights. Typically one would replace/rework the valve guides to fix that. How does one fix that problem in the S62 engine? Is there any recommended practice to minimize the build-up in the first place?

Personally, my own M5 had 67k miles and had no smog probelms or SES lights associated with this issue. Also, other E39 series cars, is this an issue with them?

Thanks for the education, as always.

CP

basil · 26th July 2005, 21:12

I too have been wondering the same thing. I might be facing this issue.

I wonder if there is a correlation between abnormal carbon build-up and those of us with high oil consumption S62 engines.

It seems that some of us are having powerloss issues (perhaps with pinging) and have not been able to remedy the problem even after changing MAFS, O2's, cam sensors, etc. .

BKH · 26th July 2005, 23:57

Quote:

Originally Posted by basil

I wonder if there is a correlation between abnormal carbon build-up and those of us with high oil consumption S62 engines.

I've seen the heads off twice in my low-mileage 11/99 build M5. Both times I've been surprised at the carbon buildup, that despite using the best gasoline as well as occasional "complete fuel system cleaners" prior to oil changes. My service department says that it happens across all model lines but agrees that the high oil consumption of the early models may contribute to this situation. Of course I now have have an '05 block so we'll see what happens...

HDClown · 27th July 2005, 00:12

People have told me that giving your car the "red line treatment".. driving it up to red line a few times every once and a while helps with burning off carbon buildup? Is that just an old urban legend or is there any truth to it?

mottati · 27th July 2005, 00:34

Pong,
I think the s62 carbon build up problem is similar to that with the porsche. Carbon clogging the the smog ports eventually causing the ses light. From what i've heard, performance is not effected, just the smog pump and ses light.

Not sure about how common it is, there've been a few posts here and i've seen a couple on other boards, so it doesn't seem very common. I would imagine that a car with higher oil use would have more carbon deposits, so perhaps they go hand in hand. i'm at 66.6k right now, no issues (as far as i know!). My plugs look pretty good last time i took them out.
Mike

Joe H · 27th July 2005, 04:34

Carbon build-up problem was apparently only present on the 2000 and earlier years. BMW supposedly made changes to the design that fixed this problem, so it should not be an issue for 2001 and newer models.

See this thread.

I am in big trouble with this one!

Joe

mchin · 27th July 2005, 19:22

Hey HDclown I subscribe to the same "red line treatment" school of thought. I will occasionaly make a red line run with the impression that this somehow clears the intake passages.

I think my belief stems from the old days when my friend's father would "blow out his carburetor" in the old oldsmobile V8 by dropping down a gear in the automatic transmission and flooring it. You would inevitably see a cloud of black smoke coming out of the pipes.

I am fairly certain I am doing more harm than good but its nice to keep the old traditions going.

later.

Michael

gsfent · 27th July 2005, 19:26

Quote:

Originally Posted by mchin

Hey HDclown I subscribe to the same "red line treatment" school of thought. I will occasionaly make a red line run with the impression that this somehow clears the intake passages.

I think my belief stems from the old days when my friend's father would "blow out his carburetor" in the old oldsmobile V8 by dropping down a gear in the automatic transmission and flooring it. You would inevitably see a cloud of black smoke coming out of the pipes.

I am fairly certain I am doing more harm than good but its nice to keep the old traditions going.

later.

Michael

When I had my car dynoed, the first couple of runs did in fact produce some black smoke out of the tailpipe. Clearly, the old methodology still helps. That is why a few runs to redline, properly done, under load are probably good for the engine. Best would be a track day!!

Regards,
Jerry

boplaw · 2nd August 2005, 22:29

Well, the old carbon build up bug just bit me.

My service advisor just called me and asked how long she could keep the car. I said what's up? She said the SES light is on because the of the carbon build up on the heads, blah, blah, blah. And although my car is a CPO it would not be covered under warranty and my new car warranty ran out a couple of months ago.

BUT!! The BMW reps were at the dealership today and they said they would pay for it this one time "as a good will gesture".

I feel so loved

.

ard · 2nd August 2005, 23:46

Quote:

Originally Posted by boplaw

because the of the carbon build up on the heads, blah, blah, blah. And although my car is a CPO it would not be covered under warranty

Well, THAT'S a concern.... any explanation as to why the warranty doesn't cover it? If you do get a chance to query the SA once the work is done it'd be useful to know where BMW is on this issue... what is the final $$ count for this fix?

A

louv · 2nd August 2005, 23:57

Quote:

Originally Posted by boplaw

...
BUT!! The BMW reps were at the dealership today and they said they would pay for it this one time "as a good will gesture"...

I'm fairly sure (based on zero actual data) that when BMW does something as a "Good Will Gesture" they either already know that they have a systemic, wide-spread problem (see: Pixel failures in Instrument Cluster), or they need to do research on the problem and your car is being used for that research.
Just my opinion.