Additive to clean piston crowns of carbon

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Hello all,
I have a 1997 Firebird Formula, the last year for the GEN II LT1 5.7L 350. It has reached 151k miles on the clock. Although it has run very well I had to change head gaskets. I noticed the piston crowns are all about equally coated in a relatively thin layer of carbon but I made no effort to clean off while it was apart. While the heads were at a machine shop for pressure testing and a light milling I decided (rather unwisely) to test the fuel injectors and did so with Rubbing Alcohol thinking that would be harmless enough. How seriously wrong I was! Even though I drained all alcohol from the fuel rail after testing and it sat for a couple of weeks little did I know it had corroded the injectors to the point they don't actuate anymore. After I got a no-start upon re-assembly I tested them with no fluid to see if they would click and got nothing from them. Lesson learned. A new set is on order.

I really don't have a need to clean injectors but want to clean up the combustion chambers. I don't expect to get them squeaky clean but any improvement is something. To this end I ordered 6 cans of GumOut Multi-System Tune Up because it contains PEA which is supposedly effective at carbon cleanup.

Can anyone validate the claim of PEA's effectiveness? Is there something on the market that is better? What would be a reasonable application interval of such a additive?
 
It's difficult to say PEA would "clean" the tops of the existing carboned up pistons to any useful degree. It will reduce the problem as you go and clean it a bit but the sure solution is to remove the heads. Then clean everything and start using PEA on a regular basis.

Putting anything more "severe" in a running engine must be done with care and still the results might be less than expected. You can try fizzing water into the intake track a very little at a time but be careful. Then there are the canned wonder additives but again, results may vary and disappoint.
 
Thanks for your reply OneEyeJack,

On-going cleaning is what I'm interested in. Not expecting miracles. I have access to a tiny lighted camera that can go into a spark plug hole for a look-see later on to check the progress. Gotta love those high tech toys. I'll check to see if there's any progress after I've gone through those 6 cans I ordered. I suppose I'll use it every other tankful. With the new injectors it will be back on the road late next week. I have two other vehicles in rotation every week but I'll be driving the Firebird much more for a while so I can change the oil and filter again after 300 miles. Will go easy on it. Breaking in new roller lifters, pushrods, and rockers.
 
Originally Posted By: Donald
Water?


Yup
smile.gif
 
GM/ACDelco has a product available that specifically and effectively cleans piston crowns of carbon deposits.
It's available from dealerships and parts houses as "Upper Engine and Fuel injector Cleaner," PN 88861803.
It was formerly packaged as "Top Engine Cleaner."

Per TSB #10-06-01-008G usage instructions are as follows:

1. Remove the spark plugs and ensure that none of the pistons are at top dead center (TDC).
2. Clean the pistons by putting 118-147 ml (4-5 oz) of Upper Engine and Fuel Injector Cleaner, GM P/N 88861803 (in Canada,
use 88861804), in each cylinder. Allow the material to soak for at least 2.5-3.0 hours, but no more than three hours and then
remove the cleaner. A suggested method of removing the cleaner is cranking the engine over. Make sure to unplug the
ignition coils and fuel injector before cranking the engine over. Also make sure that the painted surfaces are covered so no
damage is done.
Important: Ensure that the engine cleaner is thoroughly removed before reinstalling the spark plugs. Failure to do so
may result in a hydro-lock condition.
3. Reinstall the spark plugs. Replace the spark plugs if necessary due to excessive carbon deposits.

07856fe5-cb83-4607-8d89-5e95078f0c8c.jpg


Good luck with it!
 
Originally Posted By: BrocLuno
Originally Posted By: Donald
Water?


Yup
smile.gif



x2

I like to take a one-liter soda bottle, drill a 1/8" hole in its cap, fill with water, and squeeze to squirt it in. Run the motor at 2500-3000 RPMs and get 'er in the intake.

If you get a smoke show, you're doing it right.

Have the air cleaner/ hoses handy so you can slam it back together while it's idling and take it out on the road to clear the last of it out.
 
Water carefully used should work. But i have to ask, is it really a problem? If it is a light thin coating, perhaps its normal. I get the clean engine thing, but the engine burns hydrocarbon fuel. I'd not do much more than a light water treatment. Some techron now and then, with an Italian tuneup.

You don't want the cure to be more harmful than the symptoms.
 
Yeah the carbon just bothers me. I had a family friend who owned Dixi Propane company in North Charleston. He had a Lincoln Continental 2-door with a 460 in it converted to run on propane (as well as a GMC delivery truck). The car had a long propane cylinder in the trunk. He always said you couldn't win a race with it. After it passed 120,000 miles I was there when they took the heads off that thing and I was astonished to see the pistons perfectly shiny, clean as a whistle and looking brand new. I wonder why propane burns so clean and why gasoline less-so?

My LT1 pistons look to have a double coating of carbon, one thin one over another thin one. I've typically used regular unleaded though premium is recommended. It has never pinged on me running regular.
 
If it doesn't ping, it's fine. In fact, carbon deposits I've read can actually raise the compression ratio a tad which gives a slight increase in power.
 
Originally Posted By: Drew99GT
If it doesn't ping, it's fine. In fact, carbon deposits I've read can actually raise the compression ratio a tad which gives a slight increase in power.


I read somewhere that a thin layer of carbon insulates the piston top and gives a bit more power since you're not loosing heat to the piston.
 
Originally Posted By: Surestick
Originally Posted By: Drew99GT
If it doesn't ping, it's fine. In fact, carbon deposits I've read can actually raise the compression ratio a tad which gives a slight increase in power.


I read somewhere that a thin layer of carbon insulates the piston top and gives a bit more power since you're not loosing heat to the piston.


That layer of carbon can interfere with the normal transfer of heat to the oil and cooling system and cause hot spots. It's probably better to have the engine work as designed and not have carbon build up anywhere on the valves, pistons or anywhere else in the combustion chamber.

Using a PEA based fuel additive is a good idea for just about everything it touches on the way through the engine. These new gasoline formulations are excellent but with the increasing performance requirements to meet emission standards and the more complicated fuel systems to meet these requirements a little extra caution is a good idea.

It's interesting to watch the progress being made to solve carbon problems with the new GDI engines.
 
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