Carbon buildup

JohnByers · **Posted:** Thu Dec 15, 2011 10:25 pm

Car:

'03 Mercury Cougar 2.5 V6 w/89k

Problem: car was brought to me with a slight miss. Poor fuel economy, hesitation etc.

Car needed several things. Complete tune up, filters, egr valve, and IM upper gasket.

When I removed the upper plenum the carbon build up was excessive. Like 1/4" thick of nastiness. On the lower half of the manifold it has the flaps and they were sticking badly. I removed lower portion and have tried soaking in parts washer, carb cleaner, pb blaster. I can't get those flaps completely freed up, they still "stick."

Thoughts?

RichardNuss · **Posted:** Fri Dec 16, 2011 6:29 am

I saw a Crown Vic 5.0L with buildup inside the intake manifold when I worked as a mechanic in high school. We sent the manifold to the machine shop to have it "hot tanked". They supposedly "tanked" it for 3 days and there was still crap in the manifold. The owner got tired of waiting and had us put it back together the way it was.

I think we should have used some mechanical means to scrape or brush that crap out of there. I don't know what, but maybe like engine cleaning brushes (they have a flexible shaft) spun in a drill. Could have gotten the majority out, and then had it hot tanked. My guess is that the machine shop did not really spend as much time on this manifold as they said they did, but who knows?

Of course this older model Ford (how long ago was high school?) didn't have intake flaps. So it wouldn't matter if we had removed some material in the process, slightly altering the internal diameter of the intake.

On your flaps, can you feel carbon buildup around them? If so, I wouldn't be afraid to use a wire brush or something to try to remove the carbon. You could start with something brass so it's softer. Do the flaps actually seal to the intake when closed, so that you need to worry about removing a small amount of the ID of the intake around them?

And can you dis-assemble the flaps from the intake, so that you can try hot tanking it (or does it have rubber seals that would be hurt if you hot-tank it while assembled)? Intake manifold buildup is a common problem in some VW TDIs after some miles, and those folks recommend just getting the intake tanked, and it cleans it up.

This was caused by a combination of oil vapor and EGR, right? Does this car have a PCV valve on it (I mostly work on old crap, so I'm not sure if all newer cars do)? If so, make sure you check that too, in case it is bad and contributing the problem.

Jason Mauldin · **Posted:** Fri Dec 16, 2011 8:41 am

What cars was that engine used in?

How much do the junkyards want for a manifold that was pulled from a low mileage engine.

JohnByers · **Posted:** Fri Dec 16, 2011 9:38 am

That's a good question. Would have to do some searching...

Ryan Holton · **Posted:** Fri Dec 16, 2011 9:42 am

Mopar Combustion Chamber Cleaner works like a champ on that stuff.

Vincent Keene · **Posted:** Fri Dec 16, 2011 9:55 am

Ryan Holton wrote:

Mopar Combustion Chamber Cleaner works like a champ on that stuff.

Are you sure? I would think Motorcraft Combustion Chamber Cleaner would be required for a Ford. Oh wait, I'm confusing this with a krautmobile. :lol:

Arthur McDonald · **Joined:** Fri Aug 29, 2003 1:54 am **Posts:** 2052

Jason Mauldin wrote:

What cars was that engine used in?

Ford Contour/Mercury Mystique.

I recall finding a thick layer of the black goop in the upper intake manifold of my '90 5.0 when I pulled it to replace a leaky valve cover gasket. Used throttle body cleaner to get some of it out. At least cleaning the gunk away from the EGR turned the CEL off for a few weeks.

What are intake manifold flaps? Some kind of check valve?

Vincent Keene · **Posted:** Fri Dec 16, 2011 10:36 am

Arthur McDonald wrote:

What are intake manifold flaps? Some kind of check valve?

Your Mustang has them. They look like this:

JohnByers · **Posted:** Fri Dec 16, 2011 11:01 am

Vincent Keene wrote:

Arthur McDonald wrote:

What are intake manifold flaps? Some kind of check valve?

Your Mustang has them. They look like this:

yep, my understanding is it helps with bottom end torque...

Ultrasonic cleaning has been mentioned. Just got to find out if anyone in the Goldsboro area has such a rig...

Also heard soaking in ATF as well.

Jason Mauldin · **Posted:** Fri Dec 16, 2011 11:07 am

if it's a composite type manifold, I would be careful about the chemicals that you soak it in. Although I have no guidance on what is or isn't acceptable.

Chris Halweg · **Posted:** Sat Dec 17, 2011 12:18 pm

Wire rotary brush?

JohnByers · **Posted:** Sat Dec 17, 2011 1:50 pm

Tried that. It's all metal o I think I am going to find a machine shop with one of those ultrasonic parts cleaner as was suggested on another forum. Will report back with results.

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Carbon buildup

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