Intake plenum cleaning

[IronEagle]

I have a 1992 lumina base sedan with a 3.1L MPFI V6 on a 3 speed autmatic transmission. I was cleaning my EGR and throttle body with some carb cleaner and noticed the in a lot of carbon residue on the top of my intake plenum when I reached my hand wear the throttle body bolts up. Is there a way to clean that out?

[GabsOlds]

When you do the lower intake gasket, you can hit it with brake cleaner while you have it off the car. 

[IronEagle]

So basically take the inatake plenum off the car and spray it with brake or carb cleaner?

[GabsOlds]

Yeah mon! That would be the way I do it. Remember to clean off the old paper gasket real good before you put the new one on. 

Edited August 26, 2018 by GabsOlds

[IronEagle]

What paper gasket? The throttle body one?

[GabsOlds]

3 hours ago, IronEagle said:

What paper gasket? The throttle body one?

No. The upper intake to lower intake. On the 3.4L, it's paper, and there's on 1 gasket. I dug around on the internet, and I found out that yours has 2, and they come in paper as well as other materials. So, whatever yours is, make sure your clean the mating surfaces thoroughly. 

[55trucker]

16 hours ago, IronEagle said:

I have a 1992 lumina base sedan with a 3.1L MPFI V6 on a 3 speed autmatic transmission. I was cleaning my EGR and throttle body with some carb cleaner and noticed the in a lot of carbon residue on the top of my intake plenum when I reached my hand wear the throttle body bolts up. Is there a way to clean that out?

You're going to find that the carbon residue will be everywhere inside the runners, you pull off the plenum & take it into a machine shop & have them *tank* the plenum, it will come back to you clean as a whistle.

[IronEagle]

Is there anyway I can do this myself? This is the only way I get to work. How can I do this "tank" thing myself?

[Imp558]

You can't hot tank it without a tank. You can however hose it down with solvent  (I like scrubbing bubbles bathroom cleaner personally but it may take something more aggressive to cut carbon) and blow it out with the pressure washer at the car wash.

[IronEagle]

A mechanic I know said I should soak it for an hour in carb cleaner, but I think i am going to get a new one. I probably going to both this weekend.

[Imp558]

Try to clean it first, it's only a few bucks for a can of engine cleaner. I've had luck soaking them in my parts washer and using wire brushes too, a bucket of diesel would cut it for a soak. That's what's in my parts washer. 

[IronEagle]

What kind of container can I put my intake plenum in to soak in carb cleaner. It pretty gunked up on the inside.

[55trucker]

11 minutes ago, IronEagle said:

A mechanic I know said I should soak it for an hour in carb cleaner, but I think i am going to get a new one. I probably going to both this weekend.

It would take a considerable amount of carb cleaner to immerse an entire plenum casting.

As suggested you can try the diesel bath method, but ultimately the aluminum *hot tank* will deliver the best results. Carbon buildup inside the plenum & the lower intake is something you can't escape, as long as EGR's & PCV's exist there will be this by-product.

[GabsOlds]

How about undiluted simple green, in a regular 5 gallon bucket, or a plastic tub. That stuff is serious! I've seen it cut through some tough stuff at work. It starts to bubble as soon as you immerse parts in it. Buy 2 gallons of simple green and empty into a plastic tub (storage tubs would work very well). Then let the intake plenum soak in it. No water. 

 

Edited August 27, 2018 by GabsOlds

[rich_e777]

13 hours ago, IronEagle said:

Is there anyway I can do this myself? This is the only way I get to work. How can I do this "tank" thing myself?

Purple Power is relatively cheap and one can get a 2.5 gal jug for about $20 at Autozone. Fill up a plastic storage tote and toss the plenum, valve covers, brackets, bolts etc whatever metal pieces that have no electronics or bearings on it to soak over night. Worked fine for me but just make sure you rinse good.

Simple green or the ZEP brand industrial degreaser at Lowes/Home Depot works good to the same way as mentioned.

[mfewtrail]

Just clean the throttle body + egr passage, and call it a day. You're not going to make any noticeable improvement in anything from removing the carbon buildup inside the plenum.

[Imp558]

2 cans of scrubbing bubbles knockoff from the dollar store, car wash. $5 and done in a few minutes.