Black stuff on the pistion...

[ToRqUe]

I recently was cleaning out my OS .18 and my TRX 2.5. I Have ran around a half a gallon through my .18 and the pistion and sleeve is in great shape amd alot of compression and i really didnt have to do anything major to clean it. My TRX 2.5 has a gallon throught it and the pistion has turned black and so has the top of the sleeve and around part where the glow plug come out. I figured where the black was where the combustion was happining but why is it pitch black ??? i tried 2 get it off but it wont come off. I compared it to the pistion that came w/ my Hot Bodies Tornado. And the Hot Bodies' pistion if still silver and it has has around 5 gallons through it. What could this black stuff be ??? Am i running bad fuel ??? I used Top Fuel for this engine only , the hot bodies engine got Blue Thunder and the OS .18 got O'Donnell.

 

[bigfreak]

The Top fuel probably uses a lot of caster oil. It notorious for getting the inside of your engine all gummy. I've always used race fuel with synth lubes so I donno how to clean it up or even if you should. My gut says that denatured alcohol might help get rid of it. You could also try WD40, brake cleaner and acetone. Just don't get cheaky and try like an SOS pad, sandpaper or anything else that would remove metal material.

good luck.

 

[CorradoPsi]

the black stuff your seeing is built up from combustion. it can be cause by many, and a combination of things. your engines compression (how many shims are in it), fuel type used, how much fuel its ran, plug type, typical engine temps, etc. basically if its not thick enough to scratch off, its not anything to worry about. you typically get blackened parts when your compression ratio isnt high enough. you can try either removing 1 thin shim from the engine, or try a higher nitro content fuel, dont do both though.

 

[olds97_lss]

I just thought the black stuff happened when you ran too hot too often.

 

[jon2]

I just thought the black stuff happened when you ran too hot too often.

I am with you on this one. Numerous times I have had the same discussion at my LHS and that is the biggest reason if not the Only reason. Normally on the TRX2.5 it will be a common thing to see as that engine loves to run in the 250's to 290. DOn't know why but they do at least for me they did. just had to use finger control and ARO after each run and let it cool at BDC(Bottom Dead Center)

Jon

 

[CorradoPsi]

well if its a case thats common with the trx 2.5 and overheating. add a thin shim to the engine. you would be surprised at how drastic the temps drop from this small change.

 

[Rolex]

I agree with the overheating causing the black build up. Do what everyone at the track running a 2.5 did. Get an aftermarket cooling head. The stock head on that engine is the pits.

 

[jon2]

I agree with the overheating causing the black build up. Do what everyone at the track running a 2.5 did. Get an aftermarket cooling head. The stock head on that engine is the pits.

On my old 2.5 I got the Mutant Head from Hardcore Racing and that thing rocked!!. Temps still hovered in the 260's to 270's when I pegged the throttle a lot but not like the stock head on the 2.5.

Jon

 

[GRESSMASTER]

carbon built up dude--sand blast it

 

[jon2]

be careful when sand blasting as you score the piston at all and you can end up having compression issues. I don't recommend the sandblasting unless you know exactly what you are doing.

Jon