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dumb engine cleaning question

Oct 30, 2001
Glen Burnie, MD, USA
1986 Bright Red Coupe
Today one of my mechanics told me to buy a couple bottles of GM "Top Engine Cleaner" to clean the deposits out of the engine. However, his instructions were to "find a good vacuum line, pour the stuff in, and let it soak."

Something seems a bit odd about that... can I just take off the MAF and bellows and pour it straight into the throttle body?

The directions on the can are for carbuerated models: take off the air cleaner, start the engine, pour most of the bottle in until the engine starts to choke, then quickly dump the rest in and let it stall. Then let it soak, put the air cleaner back on, and rev the heck out of it.

Any suggestions?
Another way to go

Small hose & funnel
Open the throttle plates
(engine off & hot)
Shove hose 1/2 way down plenum

Pour stuff into funnel connected to hose.

Ta Da

Thanks - that makes sense.

Weekend project... along with replacing an oddly noisy PCV valve (I realize that a rattle is normal when you shake one, but this sounds like a paint can shaking in my engine!)

get a gm valve the after market one are notorious for rattling not calibrated correctly
get a gm valve the after market one are notorious for rattling not calibrated correctly

And that's exactly what I did, at the same time I picked up the engine cleaner. Mechanic said the same thing you did. Good advice...
Welp, did the cleaning today. As it was snowing heavily, I did the whole thing in the garage - which now smells of engine cleaner, even though the door was open. Was never able to actually stall out the engine with the stuff, but poured two bottles in through the throttle plate while the car was running, then shut it off and let it sit for a while before restarting it and revving the heck out of it.

Got cleaner spit out the tailpipes. Is this normal???

Also took off the distributor cap and cleaned the contacts, plus the tip of the rotor, and removed the screens from the MAF.

Car at least idles better, but it'll be a good couple of days before I can drive it again and see if any real difference was made. Might also change the plugs out while I'm playing.

Thanks for the help, folks...

Did ya

clean the IAC motor?

Will help the idle situation as well.

Re: Did ya

vigman said:
clean the IAC motor?

No... didn't know it existed :( I'll check my Haynes.

And here I thought I'd be getting a LESS-complicated motor than my Subaru one. Guess there's something to be said for 100% computer control.


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