De-carbonizing an engine-internal

[talon2swords]

Ok, I've read various methods on the internet about using GM top end cleaner.

Right now I have one can of the liquid stuff and one can of the spray stuff.

On a 3.1l or similar engine, I was thinking about unbolting the upper intake manifold and pouring about 1/6 of a can of liquid cleaner into each cylinder intake in the lower intake, maybe then spray the upper valve stems/seats as best I can in those passages, put the upper back on and then letting the whole thing sit over night. (or should I turn the engine a few times, then let it sit?)

Then crank it up, let it blow out, then change the oil.

Is this a bad idea? I was looking for an "easy" way to get carbon buildup outta an engine (without removing spark plugs, etc.) Thanks.

[Superdave]

back in the 80's we'd just drip a little water down in the carb.. that would make the engine squeeky clean in a hurry.


the problem with dumping it down the runners is that one or more of the intake valves will be slightly open and just let the stuff dump into the cyl.. so that valve will still be dirty. I think that stuff works best in a hot engine..


I'm guessing the best method is the famous GM Smoke Screen.. get the engine to full operating temp, pull a vacuum line and stick it in the bottle of cleaner.. then try your hardest to keep the engine running.


*edit..

"WOT till the can is empty then let it stall and sit overnight. Gotta fuck with the throttle so it'll run and drink it down" - Frank in the V6 IRC chat

[Z26-T]

http://www.beretta.net/board/ib3/ikonboard.cgi?act=ST;f=9;t=455

[talon2swords]

I read somewhere about someone recommended not pouring the GM top end cleaner down the brake booster line, as it made the engine sieze up (hydrolock I think?). I'll have to look for the article. Maybe it was just that too much was added at one time, but it still sounds scary.

[ForcedFirebird]

Drippng tranny fluid in there will do the same thing, only it's combustable

[1988GTU]

First of all, what made you want to do this? If the engine has been maintained most of its life it should be fine for the rest of its running life.

[IsaacHayes]

Mine looks pretty damn clean without ever doing anything to it. The pistons look black but smooth from what I can see in the spark plug hole.

[geoffinbc]

Agreed. I would be worried about all the shit leaving the engine at once and clogging up the cat converter. I would think a slow acting cleaner like one you add to the gas would be better. You can add seafoam to your gas.

[sprucegagt]

Just don't add Seafoam through a vacuum port! This engine can run backwards if you add too much.

[Superdave]

Just don't add Seafoam through a vacuum port! This engine can run backwards if you add too much.

um.. what?

[sprucegagt]

It's true. I added to much through the PCV port that caused the engine to stall and then run backwards. I knew it was running backwards because of the air coming out of my CAI.

[IsaacHayes]

LOL !!!!

[geoffinbc]

No it will not run backwards. There is no way for it to build compression and fire if it does. Only a 2 stroke can run backwards or forwards. However with pressurized oiling it will quickly be ruined.

Air may have come out of you intake if it coughed back through the throttle body.

[sprucegagt]

It didn't cough, unless a cough can last for about 7 - 10 seconds. It diesel'd the entire time and rattled the valves like crazy. This happened about a year ago and I thought that I did trash the bearings.

[geoffinbc]

Yea it could make a dieseling sound from the liquid being in the cylinders. But if it were actually turning backwards no compression would build and nothing would happen it would just sit dead.