geolab

I had some time to kill yesterday and was next to a car accessories mall.
I strolled inside feeling I had to purchase something.

My engine has had a rehab at porsche 10000 km before.
They changed all the seals.
Changed all the oil and fuel hoses.
Distributor caps and heads were changed for sure, they were new when I took the car.
In the changed parts box, I saw plenty of lifters, I do not know if they changed ALL the lifters. etc. AND THE ENGINE PINGS A LOT ON LOAD NOW.

I try a lot of porsches often, and porsche mechanics try my car.
The verdict they say is that my car's engine is very fast, responsive, agile compared to other 993's, but it pings.

I think I need to change the spark plug cables, (I changed all sparkplugs myself, light greyish pink on all after 10 years)
Maybe change the distributor belt, or check if porsche did change mine.

So here is the story,
In the mall, I searched for something to clean the carbon build-up on pistons, because
carbon build-up on pistons do make the engine ping.
I did not find anything.
I found a similar product to techron, to dehumidify the gas tank and clean the injection/intake valves. I purchased it.
Filled the gas tank with the stuff.
Drove for half an hour.
Thought of soaking the pistons with this stuff, so I unplugged both distributors, pushed on the
gas pedal. and cranked the car.
WELL THE ENGINE RAN FOR A FEW SECONDS.

Now I know it could only be the carbon that ignited the gas.
Does anyone know of a product to decarbonize the pistons a tad without dismantling the engine?
Did any try some sort of thing?
yes I googled and googled to no avail...

Robin 993DX

Continue to use techchron type of product along with your gas when you fill up and try to drive the car as hard as you can after warm up. That's was the excuse I have always used when pulled over by a police office for speeding. "Oh officer I was trying to blow all the carbon build up out from the engine!"

geolab

Droving on the autobahn around 5000 rpm for a few hours doesn't help, I wish I could come across Merlin the
enchanter and he could remove that carbon

Garth S

There is a combustion chamber cleaner/conditioner sold here by GM/AC Delco called Cleens (#993026 aerosol,#992872 liquid) that actually works to decarbonize the motor: I've used it successfully on domestic V8's that locked exhaust valves open due to dislodged carbon .... but never on a Porsche.
After stalling out a warm, running engine with this cocktail, let it sit several hours: when restarted, you could fill a city block with billowing white smoke .... so centre-ville Paris may not be the place to experiment ...

geolab

THAT looks promising, a fast google and I found the GM tsb on the proceedure.
Looks like some guys induce water after inducing the cleaner. I know water will crack loose the heated carbon.
I am not sure though which is the PCV valve, any ideas?

AM993

Check out www.terraclean.net/home.html
Maybe you can find something similar in France. Or you can send your car to Canada and I will take good care of it

Jukelemon

Well, if you are going to go that route, then I wpuld also suggest an old timers method on domestics and older cars. I have sone this sucessfully, without damage on older FJ40 that had 200k + on the engines.

You can mix a 50/50 solution of water and brake fluid. Put it in a spray bottle. Have a person idle the engine at 3500-4000 rpm and spray the solution into the intake WITHOUT the filter being present. It WILL smoke and BOG.

The solution will "boil" the valves and clean them. I have seen before and after pics-it is pretty impressive.

Now, I personally woudl NOT do this to a Porsche BUT there is 0 logical validity to my statement i.e. a Porsche engine could react in the same manner as a domestic in this case. BUT I am not going to try and find out.

I would guess that the solution mentioned above has very similar additives as the one I mentioned-just packaged and sold.

brucec59

What's worse - carbon buildup, or breaking loose chunks of carbon buildup? Not trying to be a smartass, but I'd be really afraid of getting a piece of that gunk in an oil passage or elsewhere.

RallyJon

Pardon the noob question, but where between the combustion chamber and the exhaust would a carbon chunk have access to an oil passage?

JasonAndreas

Just remember that anything you pour into and hope to let soak inside a horizontally opposed six cylinder will just leak out the exhaust valve unless you manually turn the engine over for each cylinders compression stroke. From experience I can tell you that Techron does nothing for the pistons or cylinders inside a 3.6l. It might work on the injectors but that is it. The same applies to Seafoam, btdt. It makes a great smoke show but when I looked at the top of my pistons and the valves I didn't see any noticeable differences.

Steve Weiner-Rennsport Systems

Jason is right on!

Thus far, there are no chemicals that will remove the built-up carbon on pistons and chambers.

We've used Techron, Lubro-Moly, and MotorVac to successfully remove soft carbon from injectors and the backs of intake valves but these products-services have no effect on piston crowns or combustion chamber surfaces.

We use a soda blaster to remove these carbon buildups when the engine is apart for a valve service and its very effective on pistons as well.

I'm sure I'm dating myself, but I used to use water poured into the throat of a carburetor (running at 2K RPM) to remove carbon and you always ran the risk of getting a piece of that hard stuff trapped between a valve and its seat. It worked very well but it carried some risk. I've heard of people doing this on MFI'ed and carbureted 911's but I wouldn't take the chance.

geolab

I hate taking the engine apart only for the carbon, then again, it was only a matter of time.

David Schiff

Jukelemon and Wennersport are corrct.
H20 + C= co, co2 so2 etc etc and it does work.
water/steam over hot carbon "sublimates" the carbon into gaseous components and i have used this for years on other carsBUT the water should be hot to avoid thermal shock to valve seats/cast manifolds.
The gasification of carbon in solid form has been well worked out and used in Blast furnaces for years to produce water gas, a flammable, epa horrible mixture of sulfur, co co2 etc etc to add to the heat of the incoming fuel charge.
if we could get hot moisture/steam into the passages of the sai they would be cleaned, if they were patent.
ds
I have thought this is the soln for the SAI
I would induce a water aerosol into the pump but i dont know how to run the pump at will. I must be on when the engine is warm and run for a period of time

FGL28

On Wheeler Dealers last night Edd China did a DeCarbonization on an XK8 with a "new" system. Does it work?

sonny1

Water Injection.,cheers.
Sonny1.


OTE=geolab;3939506]I had some time to kill yesterday and was next to a car accessories mall.
I strolled inside feeling I had to purchase something.

My engine has had a rehab at porsche 10000 km before.
They changed all the seals.
Changed all the oil and fuel hoses.
Distributor caps and heads were changed for sure, they were new when I took the car.
In the changed parts box, I saw plenty of lifters, I do not know if they changed ALL the lifters. etc. AND THE ENGINE PINGS A LOT ON LOAD NOW.

I try a lot of porsches often, and porsche mechanics try my car.
The verdict they say is that my car's engine is very fast, responsive, agile compared to other 993's, but it pings.

I think I need to change the spark plug cables, (I changed all sparkplugs myself, light greyish pink on all after 10 years)
Maybe change the distributor belt, or check if porsche did change mine.

So here is the story,
In the mall, I searched for something to clean the carbon build-up on pistons, because
carbon build-up on pistons do make the engine ping.
I did not find anything.
I found a similar product to techron, to dehumidify the gas tank and clean the injection/intake valves. I purchased it.
Filled the gas tank with the stuff.
Drove for half an hour.
Thought of soaking the pistons with this stuff, so I unplugged both distributors, pushed on the
gas pedal. and cranked the car.
WELL THE ENGINE RAN FOR A FEW SECONDS.

Now I know it could only be the carbon that ignited the gas.
Does anyone know of a product to decarbonize the pistons a tad without dismantling the engine?
Did any try some sort of thing?
yes I googled and googled to no avail...[/QUOTE]