Intake manifold cleaning

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On-the-car spray-in products Thanks to Bill Cleary.

The PCV system for the SHO engine can cause the intake plenum to become coated with a dirty oil film over time. This film can cause decreased flow and a concomitant power loss. There are several different ways to clean the plenum. Here's two.

All of these products are available via wholesale only (you have to get them from a garage).

BG Air Intake System Cleaner (PN# 406-8). The first product is a spray can that has a cleaner and lubricant so it's nicer to your throttle body than straight Gumout.

BG Fuel Injection System Cleaner (PN# 210). Get a can tap (like an A/C freon can tap) and open a non-pressurized can of Fuel Injection System Cleaner. Take the end of the hose (attached to the can tap) and attach it to the vac. port that's right after the throttle body. The hose has a .025 orifice and lets the Fuel Injection System Cleaner vaporize into your manifold over the course of about 10 mins (12 oz. can).

BG-44K Fuel Additive (PN# 208). For the finale, shove a can of BK44 into your gas tank and away you go! The results on my car were noticable on the ride home: smoother idle, better sound.

The garages get these things pretty cheap (~$7-$10 for all three)

Hand cleaning Thanks to Russell Thompson. I took it upon myself to clean the intake manifold on the car today.It's a relatively straightforward task (see Removing the intake manifold), but I learned a few things today that I'd like to pass on.

I used the Helm manual as a guide, and it's pretty good, but it missed a few brackets and bolts you have to remove. I've heard Ted and a few others say it's a 10 minute job to get the thing off. It took me every bit of 30 minutes the first time (I'll explain that in a minute). Just when you think you've disconnected everything, surprise, you missed a vacuum line, or a coolant hose, or something. It's MUCH heavier than I expected it to be.

Well, I finally got it off and it was filthy. I've only got 36k on the car, and that manifold was nasty! I used 2 cans of Gumout intake cleaner ('cause it claims it won't harm the finish). I squirted a bit into each of the 12 runners, picked the whole thing up, rolled it around sothe stuff went everywhere, and dumped it. Then I wiped into each runner with a soft cloth, and repeated the above process. I also cleaned the gaskets, wiped off the top of the motor, and sprayed and wiped the runners leading to the valves.

I had a problem putting it back on. Actually, it went on fine, took about 15 minutes. The car started immediately, spewing smoke from the Gumout. The smoke cleared after about 20 seconds, and the beast was idleing(?) like a champ. It was at this point I noticed the coolant running between my feet. There are 3 coolant lines that you undo. Two are easily accessible, one is underneath the manifold, and I couldn't get to it with the manifold on. Guess which one I forgot to re-connect....

The second time the manifold came off in 10 minutes. I re-connected my line, put everything else together, and torqued everything down in another 10. This is not a difficult job. I topped off the coolant, and went for a ride. Throttle response feels crisper. I don't know if there's any difference or not, but it certainly feels that way.

I spent about 3 hours on the whole project. The next time I do it it'll take me 45 minutes. Will it make any difference in performance, mileage, durability, etc? I dunno, but I'll sleep easier tonight knowing that my baby's breathing thru a clean intake tract. Speaking of which, has anyone put a filter in their PCV line to reduce the amount of crud that gets pumped into the manifold?