Question : Lots of sludge in intake manifold

[LifefulDeath]

Today I replaced to MAP and noticed a lot of build up on the inside of the peice the MAP mounts to. I could also see it on the inside of the manifold. So I stuck my finger in and pulled out a bunch of black, sticky, chunky sludge. I'm not sure if it's coming from something internal and being sucked back into the manifold through the MAP vac lines from some where else

The rough idle has gotten to the point where the tach and the oil pressure gauge bounce together. Four beats and revs up like "put put put put rev up, put put put put rev up".

I'm gonna open her up in the morning and clean it. See if I can't find where it's coming from. Don't know if I should try sea foaming the vac lines or not.

If anyone's got some input. Please, let me know. Thanx

[SappySE107]

Its the EGR polluting your intake manifolds. Its eaiser to run some GM Top Engine Cleaner through the engine to clean it out.

http://60degreev6.com/forum/f86/using-gm-top-engine-cleaner-t35230

[55trucker]

I suppose if you wanted to get a little on the anal side......and you really doooooo want to pull off the plenum & the intake manifold.. send them out to a machine shop and have then *tanked*.....you'll be sure that the inside as well as the outside will be spotless.

[LifefulDeath]

lol Well I'm not gonna get that into it, but I pulled out about a gumball sized chunk of crap out of the plenum. I just figured, if it's that bad there, what's the rest look like.

Thanx guys

[LifefulDeath]

So, I haven't done the top engine cleaner, yet. I remembered when I replaced the TPS sensor I put sea foam in the oil and it ran great for 2-3 weeks. I tried it again and ran some through the vacuum line on the intake. No change. The car even died when I took it out. There is no vacuum on the cruise control soloniod, what so ever.

That write up says to use the fuel pressure regulator vac line. Um... where is the fuel pressure regulator? Or can I just use any small vac line? Like the one off the MAP sensor...

[WrathOfSocrus]

The rough idle has gotten to the point where the tach and the oil pressure gauge bounce together. Four beats and revs up like "put put put put rev up, put put put put rev up".

That lope at idle sounds like a low vacuum issue. People with large cams tend to have a lopey idle and lower vacuum from the valve overlap. There could be a disconnected or cracked hose. Sometimes the hose appears to look solid and then by giving it a slight bend will reveal a rather large crack. I have come across 3 vehicles with that issue so far this winter alone.

As for the seafoam, I read it was good to use the brake booster vacuum line. It's roughly the size of the top of the seafoam can. I've heard stories of people putting it in and getting large clouds of garbage coming out the exhaust. I personally haven't seen that but my intake was more varnished than gunked up. I used the seafoam on the trans and had miraculous results. It went from slipping to accidentally laying some rubber on the test drive.

I guess it is possible that one of the vacuum ports on the intake got sludged up but the lopey idle sound more like a leak than a clog. If your intake has so much sludge in it that you can stick your finger in and pull out a wad of goo I wouldn't recommend the seafoam. All of that sludge is going to fly into your injectors, valves, and piston rings. A good degreaser should take care of the thicker gunk and a paint stripper will remove the varnish that the degreaser doesn't remove.

[LifefulDeath]

lol I've fixed 3 lines in the few months I've had the car. Thought I had them all...

Lately the idle has been dropping insted of revving... It bounces for a bit then drops like a rock while stopped at lights. Not just the idle. The oil pressure does the exact same thing the tach does. Today while at a long light I shifted into neutral. Just to see what would happen while the idle was dipping and it died.

The vac lines from the intake to the valve covers are fine. As well as the PCV line. The EGR line is good. There is no vacuum on the HVAC/ cruise control lines.

Where does the HVAC attach into the vacuum system? Then I could just start there and move in.

[LifefulDeath]

Found it! The rear vac line to the MAP. I found a patch in it and followed it back. Sure enough, it was melted. Replaced it and took her out. Cruise works. Vents work. Still a little bit of dancing in the tach. I'll reset the ECM in the morning. To cold out now lol

Thanx again guys

[HayesPerformance]

As a side point,

One way to REALLY cut the sludge down I have found on ANY vehicle is installing a oil catch can/oil seperator. I empty the one in my car at least once a month and you would not believe the crap that it catches from going into your intake. I'll take picture and post them next time I empty it.

I have it installed before the PCV valve and it stays perfect! Where I live it can get VERY cold and I found that when it is around -15 (and way lower) for awhile, it catches EACH WEEK a huge amount of oily condensation in the catch can.

I use them in my vehicles and the intakes, etc stay SO CLEAN!!!

By the way, BE VERY CAREFULLY if you buy the cheap ones cause they often DON'T hold vacuum, you need to "seal" the joints, etc with silicone and check with a vacuum gauge.

[90coug]

my 3.4dohc contained a lot of sludge, I found out that the throttle body gasket had gone and the car was eating coolant (why there was so much sludge in the intake) Once fixed the sludge stopped forming and the car didn't smoke white

[SappySE107]

There isn't a throttle body gasket on 91-95 and there is no coolant going through the gasket on the 96-97. The motor wouldn't have black sludge from coolant anyway.

[90coug]

Sappy, you can edit my posts all day if you want. IMO you only did that beacuse you knew you were wrong. Why is it the same thing, forum to forum? Some moderator controls everything you say.

Anyway, here is the picture of the throttle body gasket, you will see the pocket below the big hole where the coolant flows.

[SappySE107]

You wanna edit posts, ill do the same. I have about had enough of the newbie DOHC owners giving me attitude.

If there is coolant going through the 96-97 TB, then I am sorry. I only tore mine off once but I don't recall coolant going through the arm anywhere. Im not tearing it off my car again to check. Regardless, how does ingesting coolant equal black sticky chunks?

[90coug]

You wanna edit posts, ill do the same. I have about had enough of the newbie DOHC owners giving me attitude.

If there is coolant going through the 96-97 TB, then I am sorry. I only tore mine off once but I don't recall coolant going through the arm anywhere. Im not tearing it off my car again to check. Regardless, how does ingesting coolant equal black sticky chunks?

Coolant + dirt + oil + gas, I'm assuming can cause black sticky goo. I'm sure the coolant isn't the only culprit.

[SappySE107]

thanks for the gasket, that clears it up. Like I said, I have only done one.

Fuel is not in the upper intake or TB. Oil is there from the PCV and EGR is on so those 2 things equal the culprit. Coolant wouldn't help but it wouldn't be black.

I removed your post with attitude because im sick of newbies talking shit. If I wanted to control what was said, it would be simple. I co-own the site. To you its about being right. To me its about having the facts.