joeg26er

Well, I did a compression test twice on my engine and got 206/200/204/205 with the throttle plate wide open.

The egine has 125,600 miles on it and some are saying that these readings are high because of carbon
deposits.

I have heard that you can put ATF in the engine and intake to clean out the carbon deposits.
Would this cause my engine to run better or worse?

I would think that the carbon has filled in any gaps and made a better seal where it was needed?

rainforest

well yeah it will run better if you have excessive carbon deposits. Carbon deposits will possibly help cause pre-ignition and detonation.

virginia_dude

Excessive deposits would only hurt, the ECU will retard timing to control detonation and you lose power, you'll only hear the rattle if its gotten real bad, beyond what the computer can control. As far as what works, I've heard a strong MIST of water will do it. Don't stream water in, you'll hydro lock it aand bust things. I would think the ATF would not do good things to the CAT or the oxygen sensor. I've heard MOPAR Combustion chamber cleaner is good. then you've got the B&G motor vac which if you believe Pat Goss is good. But then he gets paid to promote them.


[Modified by virginia_dude, 10:14 AM 2/6/2002]

SpooN Man

Lots of carbon can improve your compression test values. clean it and see

FSTASNTZ

I use the MOPAR stuff. Get a couple of cans of it if you have never done it before. And, do not have anyone stand behind the car, unless you really dislike them...


Jason

virginia_dude

Measured compresion values don't mean much. Carbon buildup is the cause of preingnition. And Knocking. Two things that will lighten your wallet when you damage your motor. If you want higher compression, get your head shaved. Carbon buildup is not a good thing to have.

joeg26er

How can I tell for sure if i have "excessive" carbon deposits?
Would I have to take my engine apart?

Anyone vouch for this water mist method?

Thanks for any help you can give.

-TJ

Be careful using any fuel addatives to clean carbon deposits.
Last year I thought it would be a good idea to use some Gumout Regane fuel system cleaner. Unfortunately, it worked too well. All the crap in the intake manifold/runners on my D15B2 washed down and adhered itself to the tops of the intake valves. All was well until I shut the car off. The next day, I went to start it - it never started again. The carbon crap that washed onto the intake valves solidified and caused the intake valves to not seat - no compression. That prompted an emergency DPFI to MPFI swap - easier to put in a spare motor than pull the head, clean valves.....

-TJ

racerxadam

i've heard of the water method. the idea is based on observing a car that has a blown head gasket. if you look in the cylinder that has the leak that will be the cleanest cylinder. the water cleans out the carbon deposits. if your going to try it don't do it at higher than idle rpm and don't mist too much cause water can't be compressed.

martini

sounds like water injection. Lots of peopl use that. Not only will it decrease the chance of detonation by absorbing some of the heat in the combustion chamber, it will also "steam clean" your combustion chamber.

it would take quite a bit of injecting the water to clean it properly. I still suggest some ATF or Sea-Foam.

virginia_dude

I would think ATF would carbon things up worse, or plug the cat. But a clean engine will run better than a very dirty one in any case. Carbon deposits creat hot spots that cause pre-ignition and detonation. The knock sensors won't be telling the computer to retard ingnition timing, You'll be able to run a lower octaine gas and make more power in the same time. If you hear the engine knock with the recomended octaine fuel in it you really need to take care of it. The computer can only do so much to stop it. You would already be losing power before you even knew you had a problem.


[Modified by virginia_dude, 10:05 AM 2/7/2002]


[Modified by virginia_dude, 10:06 AM 2/7/2002]

SoloSol

we have a bg carbon cleaning system that the dealership uses. it uses compressed air, chemicals with the engine running

virginia_dude

A thought about the ATF method. Your intake right up to the head is dry, no fuel. ATF lining that will collect any dirt and dust that gets past your air filter and build up. That can not be a good thing either. Think about it, nothing to flush the atf out of the intake, short of removing it and cleaning it.