Carbon Build Up - HELP!

[Ohmess]

I recently pulled off the Weber DGAVs and intake manifolds to make way for a set of three Weber DCOEs. When I look into the head, I see a fair bit of carbon buildup on the number three intake valve. The other valves are not that pretty either.

This is what has me concerned (Number 3):

One of the first things I did when I got my 72 3.0 CS was to adjust the valves. In the process of doing this, I found that one of the bolts was stripped and was not holding the eccentric in place properly. I replaced the bold and nut and properly adjusted the valve clearance. The stripped bolt was on the number 3 valve.

Is this something that can this be addressed with Techron or LiquiMoly Ventil Sauber, or is more extensive work required?

Here are the valves in order:

Number 1:

Number 2:

Number 3:

Number 4:

Number 5:

Number 6:

 

[Sven]

You could do a compression test to compare cylinders. A leaky valve would show itself. If the compression is ok then maybe a worn valve stem guide or seal allowing oil to drip through to the back side of the valve. With the head off I have been able to wiggle open valves (i.e. indicating a worn guide). You might be able to reach in and grab the stem with your fingers to see if you can move it side to side.

Oil coming in through the intake via the valve cover breather (not sure how that is connected to the DGAV's).

Or are you just trying to clean up the black stuff?

 

[Stevehose]

I had carbon buildup so I bought a can of BG ISC Induction System Cleaner and put it into a spray bottle and applied it directly to the valve and let it soak then hit it with some bronze gun cleaner brushes on a rod then repeated untl clean. You can put each cylinder at TDC to keep crap from going into the cylinder then separately clean the end of the valve when open.

The stuff is nasty so use in a well ventilated area with gloves but it dissolves the carbon when other stuff did not.

 

[Ohmess]

Thanks guys.

I did a compression test a year ago and obtained the following: 182.5, 180, 178.5, 175, 180, 182.5. Those are straight readings (average of two) at 50 degrees, dry sunny day, no elevation correction (I live roughly 400' above sea level). I have not driven the car much since then.

These results seem quite good, and this is a reason I would rather not pull the head. (The other reason being I want to drive my car!)

So, whilst contemplating this carbon thing, I figured out my heater core shut off and started thinking about where my vacuum distribution block will go:

 

[Peter Coomaraswamy]

Chris, everything on the outside looks great! I can tell you have been hard at work. I'm just thinking here, you can clean off the valves as mentioned below but with those compression numbers I think you're in good shape. I would get those carbs tuned up and start driving her- it's that time. Don't look for too many problems/projects at one time have some fun with her this summer and if the head needs work, that's what your winters are for Although heads and blocks can cause problems on these cars generally they are bullet-proof; your head is an '86 I think, so a good year for longevity. After zooming around with you last year I know you really like driving so take Annabelle out for the summer and have some fun!!!

 

[Stevehose]

Looks good, I would kill for those compression numbers. How old is your starter? While carbs are off consider replacing it with the smaller, stronger version that can be unbolted with a socket wrench easily? You won't want to replace that later with all the carb stuff on.

Just my help in spending your money

PS I will be making your gaskets this weekend.

 

[Ohmess]

Steve - I looked into one of those little starters, but I have already swapped my original starter for the starter you see in the pictures. Peter gave it to me when I was in TX, and when I opened it up, brushes look great and the bearings were smooth. So, I cleaned the commutator, lubed it up, reassembled and testing it on the bench. I am thinking it is hard to justify hunting down another starter when I had such a nice one on hand. Obviously, if I misjudged the longevity of that thing I will be kicking myself.

Peter -- yes, she looks quite different than she did on your lift in TX. As you know, she's got great bones. I am looking forward to riding her hard.

 

[m5bb]

Actually those valves look very normal.
You are making way too much out of a little carbon on the back of the valve.
If you want to see a really badly carbon coated valve do a Google search and hit the photos section.

What you don't want is so much carbon that the valve won't close properly.
I have seen that.
Your compression numbers tell me you have a healthy head and it doesn't have leaking valves.
A leak down test would totally confirm that.
You also do not want carbon build up on the top of the pistons. Read on......

With that said.
I have been using a product called Seafoam for years.
You can put it in your gas a few times and clean up those valves.
You can also directly inject it into a engine although with the Webers I'm not quite sure how I would do that.
It worked well on my 312K 533i that has never had the head off.

The worst thing for an engine is first, driving short distances where the motor never gets to operating temperature and second driving around with the rpm under 3000 RPM all the time and maybe lugging it down by not downshifting when you should.
Don't be afraid to put the pedal down and shift at 5000.

Every time I drive my S38 M5 I make sure ( after complete warm up) that it gets at least a couple full throttle runs to 7000. The ECU is set to cut the ignition at 7200. Banging the rev limiter.
There is no carbon in that motor.

 

[Ohmess]

Thanks a ton Gary - one of the reasons I pulled the auto and replaced it with the 5 speed was that she upshifted readily and thus aways seemed to be lugging along at less than 2500 rpm in town.

I am going to forge ahead once my intake gaskets arrive.