FAQ on Carbon Build-Up Issue (First Attempt) - Page 13

Riley6 · 27th August 2005, 07:57

I purchased an 00' about 6 weeks ago with 61K miles. This issue is a major concern of mine, as I don't have or ever want 8K lying around just for a "cleaning". Although I have seen no signs of carbon build up - no SES light, no cold engine hesitation, etc. Prevention was not discussed much so I am wondering if I should begin taking measures now to prevent it ie fuel additive periodically, auto-rx, etc? Oil consumption is unknown as I have put less than 1K miles on it. And I always drive like a bat out of hell so babying it is not an issue for me

LLcoolM5 · 28th August 2005, 13:17

Well,

I decided to not to try and clean the smog ports (not enough time) on the heads this weekend but I instead changed the plugs (very easy DIY'er) on the M5 and 740iL and found some interesting information and as a added bonus, got rid of the cold running hesitation problem!!. The reason I am posting this in this carbon build-up string is because this may or may not be characteristic of cars suffering from carbon build-up. Obviously, I am a M5 owner suffering with the carbon build-up issue so I thought I would share this. The pictures below were meant to show there is a trend that developed on my plugs (pictures don't do a job of showing this). The plugs that were at the front of the engine (near radiator) had the largest amount of oil fouling with the oil fouling decreasing and you went back in cylinders towards the firewall. The pictures where meant to show how the oil coated the plug threads more completely and thicker in the front cylinders versus the rear cylinders. Also both rear cylinders on each side had the largest amount of ashing, with enough deposits to block and or occlude several of the outer electrodes from the center electrode. According to several different plug reading charts and my interpretation of these spark plug color charts (http://www.centuryperformance.com/spark2.asp) I suffer from ash carbon deposits and fouling (especially on rear cylinders) from the burning of oil (duh), and straight out oil fouling on the front cylinders which is typical of early production M5's. Supposedly my plugs were 25K old (who knows if previous owner was telling the truth) so this wasn't the best news for me. All I know the plugs may be the original ones (I hope so). I was just concerned about the difference in plugs from front to back. Why are the front plugs having more oil on them and the rear plugs are plugged with carbon deposits??

After changing the plugs I didn't notice that much high rpm gains, but the hesitation and resistant acceleration from a cold start was gone!!

LL

[img]file:///H:/DCIM/100PENTX/IMGP0960.JPG[/img]

LeatherMan · 28th August 2005, 22:32

I have a horrible stumbling/hesitation problem during warm up and even during regular driving. I am changing my MAFs as soon as the parts arrive for DavidS, but maybe I will do the spark plugs in the mean time. What spark plug did you go with?

Eric

ELEVENS · 28th August 2005, 23:37

Quote:

Originally Posted by LLcoolM5

[font=&quot]...t I instead changed the plugs (very easy DIY'er) on the M5 and 740iL and found some interesting information and as a added bonus, got rid of the cold running hesitation problem!!...

Wow, those plugs look terrible! No question that the car will run better with new plugs!!!!

How much time does the plug change take?

Do you recommend ordering anything ahead of time (other than the plugs), such as gaskets?

How much oil does your M5 burn?

How many miles on your M5?

What model year?

Sorry for all those questions, but I was a bit startled by the looks of those plugs. Thanks for the pics.

-Bill

LLcoolM5 · 29th August 2005, 00:47

Quote:

Originally Posted by ELEVENS

Wow, those plugs look terrible! No question that the car will run better with new plugs!!!!

How much time does the plug change take?

Do you recommend ordering anything ahead of time (other than the plugs), such as gaskets?

How much oil does your M5 burn?

How many miles on your M5?

What model year?

Sorry for all those questions, but I was a bit startled by the looks of those plugs. Thanks for the pics.

-Bill

How much time does the plug change take? It took me about 1.5 hours. I could only wish-changing plugs on my American sports cars (Mustang, Trans Am) were this easy when I was growing up. I would almost cry when I had to try and get out that last plugs near the firewall on those push rod V-8's. With the directions below there is nothing special that has to be removed or no special body contortions or excessive amount of swearing for this job. This is one nice engineering design of BMW on how simple it is to change plugs.

Anyhow, here is a link to great directions (http://www.bimmerboard.com/forums/posts/4789) with easy to understand pictures! The directions are for the 4.4-liter engine that comes in the 540 and 740's. The only real difference in the directions and the pictures are the electrical connections to the Bermi coils are horizontal instead of vertical, and the space we have to work with is much smaller. No special tools needed. The tools you need (from my memory) is a 5/8" spark plug socket, a long socket extension with a "wobble joint" at the end, a 10 mm socket for the 2 small screws that hold on the valve outer cover and the Bermi coils over the plugs, and a torque wrench capable of tighten the spark plugs to 23 Nm. I did one side at a time to ensure I didn't loose anything or mix anything up. What ever you do, don't drop one of the 10 mm nuts down into the head. Be very careful screwing them on and off.

Do you recommend ordering anything ahead of time (other than the plugs), such as gaskets? Just the plugs (went OEM: NGK Pt 4 prong NGK part number# BKR6EQUP). I was going to go with iridium plugs but read and heard to many supposed "horror" stories that the iridium electrode can fall out into the cylinder, so I wimped out and went OEM. The stories may or may not be urban legends, but I have enough M5 problems right now to add that thought to my stress levels. But.......if you want to be totally prepared... sometimes the valve cover gasket will leak oil and you could change the gasket once you get the plugs out. I checked mine and had no leaks on the M5, but the wife's 740iL had some small oil leak around the valve covers. So sometime in the future I will be doing the gasket repair on the 740iL.

Here are two links (again for e38's) with the instructions on how to replace the gaskets (if you feel up to it): http://e38.org/images/TIS/valve_cover_replacement.jpg
http://home.comcast.net/~snyderwc/vcgaskete38.html
http://bimmer.roadfly.com/bmw/forums...4306850&page=1

How much oil does your M5 burn? Right now it is burning about a 1 liter / 1000 miles. I am constantly running this car real hard and never take it on longs trips, just 1/4 blasts all around town and the routine 40 mile round trip each day to work, so that may have to do with some of the oil consumption and destroy the theory that running it hard will get rid of carbon deposits.

How many miles on your M5? 106,876 on a 2000 M5 with a 12/99 build date.

LLcoolM5 · 29th August 2005, 00:57

Quote:

Originally Posted by LeatherMan

I have a horrible stumbling/hesitation problem during warm up and even during regular driving. I am changing my MAFs as soon as the parts arrive for DavidS, but maybe I will do the spark plugs in the mean time. What spark plug did you go with?

Eric

Leatherman,

I have two brand new MAF's, 02 sensors and thought the same thing that the new MAF's would hopefully stop the rough and stumbling acceleration in the morning, Luckily for me changing my plugs helped my problem. It was confirmed again this morning when I left for church.... no more hesitation. I wish you the same pleasure!!! It pissed me off every morning that the car would run like this for 1/2 mile,I wasn't happy that this was "normal" for some M5's.

DavidS · 29th August 2005, 15:15

I want to add a few points:

1. All hardware in the M5 is metric. You want a deep 16 mm socket for the spark plugs.

2. There are often oil leaks from the timing case into the spark-plug wells. Check with a flashlight if there is oil before removing the plugs. If there is oil wipe it up with some paper, and the with some cotton buds.

(If there is a lot of oil, you need to get the timing case gasket changed. That is a pro job, as the Vanos units need to be remved.)

3. Each of the two spark plug covers is held in place by two dome nuts. The left rear one is very tricky to get in place when reassembeling everything.
If you drop it, it will land on the bottom engine cover. Unless you have the car on a lift, making retreival easy, you may find having a spare one practical. This is a cheap part, perhaps $1 or so.

BMW part number 11 12 1 747 162 "Cap nut with rubber sealing".

4. This is a thread discussing various spark plugs in the S62 engine:

Spark Plugs: Denso Iridium or NGK Iridium?

David

ELEVENS · 29th August 2005, 16:25

Thanks LLCoolM5 and DavidS for all that useful info. about plugs and plug replacement.

Regarding those pics of the oil-fouled plugs. I'm wondering why the plugs towards the front of the motor would be less fouled... I've seen the opposite on Chevy small block V-8s, where oil pooling in the heads after shutdown would provide an opportunity for worn valve seals (on the rear cylinders) to suck oil, especially on startup.

Are we pretty sure that the piston ring/cylinder bore is generally the cause of excessive oil consumption on the S62 and not the valve seals? Just checking, as the valve seals are probably cheaper to fix than rebuilding the bottom end.

Lobo · 4th September 2005, 19:19

Quote:

Originally Posted by LLcoolM5

All,

What year models are affected: 2000 and 2001, may have hit a 2002.

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.

so, is it 2001, maybe 2002 and before? or have they cleared the 2001?

thanks

rudy

KevinM · 4th September 2005, 20:49

Like many posting here, I am looking for any help preventing this issue. As Shadowman points out (thanks!) it may not be an issue for many of us. However, if there is a good way to help prevent carbon build up that is not too difficult or expensive, I am interested.

So far, some are using Auto-Rx, which I may try as well. I have heard good things about a product called BG 44K (http://www.bgprod.com/;). Anyone else hear about this product or have experience with it?

Thanks.