Carbon cleaning the 4.2L LL8. Experiment

zaid3ssaf

Well-Known Member
I have recently performed carbon cleaning on the pistons and valves using a method recommended by @MRRSM and I figured to document the experience for those who would like to pursue this in the future. The method involves pouring AcDelco Top engine cleaner in the spark plug holes. This is NOT a guide, nor do I pretend that the performed method is the flawless.

Required tools/materials:
  1. 10 mm socket, 13mm socket ,5/8' spark plug socket, ratchet, and suitable extensions.
  2. AcDelco Top Engine cleaner (PN: 10-3015 ), 2 x 32 oZ cans
  3. Shop towels
  4. Optional: seafoam, new spark plugs, new oil.
  5. Borescope (optional) for your own satisfaction
Procedure:

Soaking​
  1. With a hot/warm engine, remove the resonator.
  2. Drain the engine oil (refill with cheap organic oil). I reused my old oil after the procedure since it only had 300 miles.
  3. Remove the ignition coils and remove the spark plugs. Make sure the engine is not very hot when removing the spark plugs.
  4. Pour about 10 oz of Acdelco Top Engine cleaner in each cylinder
  5. Replace the spark plugs. This way the warm vapors inside the cylinders are not escaping to the atmosphere, and it gives the valves a better chance to decarbonize with hot vapors.
  6. Let soak for 3 hours. DO NOT CRANK THE ENGINE with the solvent soaking or you will HYDROLOCK it by bending the pistons.
Draining​
  1. After 3-4 hours of hot soak, remove the spark plugs
  2. Cover the spark plug holes with shop towels to prevent splashing, or alternatively, cover the rest of the engine bay with plastic
  3. Remove the fuel pump relay
  4. Crank the starter motor for 10-15 seconds and watch the fireworks
  5. Using a vacuum, clear the rest of the cylinders of residual solvent and carbon chunks. I Used a brake bleeder hand pump and collected the solvent.
  6. Optionally, refill the cylinders with Seafoam and let soak for an hour. Repeat the draining procedure. This way, more of the carbon chunks are suspended in (and removed with) the Seafoam and are less likely to clog your Catalytic converter. I haven't done this because I forgot to grab seafoam.
  7. Perform the draining very well to minimize the risk of HYDROLOCKING. Replace spark plugs, ignition coils, fuel pump relay, and oil.
  8. Fire it up and enjoy the smoke show!
Results:

Pistons:​
Before​
1605988226391.png 1605988255005.png1605988274674.png 1605988297442.png
After​
(I drove the truck for 200 miles before taking these pictures. Immediately after the cleaning the I can see 80% of shiny metal on all pistons)​
1605988502358.png 1605988531191.png
1605988747812.png
Residual fluid (not absorbed by shop towels)​
1605988815541.png1605988835540.png
1605988860818.png
*Weight of carbon residues (not absorbed by shop towels) after hand pumping the residual solvent is 3.25 grams​
Filtered by class 1 filter paper in the lab.​
I forgot to do to a compression test before and after. However, the truck does idle more smoothly with better pedal response. Additionally, the dieseling sound that the truck had on idle became less pronounced. After driving 200 mile, I took the spark plugs and cleaned them but they can be replaced if desired.

*Room for improvement:
Fitting an a balloon using fittings on the spark plugs holes and cranking the starter (with solvent inside). This way, the solvent can splash against the valves and clean them while having enough room to go out of the engine into the expandable balloon without hydrolocking.
 

BrianF

Well-Known Member
Thanks for sharing!! Yes, the good old piston soak. From what I gather, these are almost mandatory on some older Toyota oil burners. Not only do they clean the crown but cleans up the rings and can improve oil consumption.

As I read this, I think when I do my plugs next I should do this. Can only make things better.
 
OP
zaid3ssaf

zaid3ssaf

Well-Known Member
Thanks for sharing!! Yes, the good old piston soak. From what I gather, these are almost mandatory on some older Toyota oil burners. Not only do they clean the crown but cleans up the rings and can improve oil consumption.

As I read this, I think when I do my plugs next I should do this. Can only make things better.
I had borescope pictures before driving and they look pretty clean. I hear that doing this would also clean up the ridges on the oil rings. Next time I will try to do this with Marvel Mystery Oil. Its less potent than AcDelco TEC but also much cheaper.
 

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