10 replies to this topic

[BiBiBiB]

Hey guys, Ever since a very long highway trip my 1275 has started to diesel. It seems to be getting worse. I apply the in gear method to shut the engine off which works fine, though of course I want to have the underlying problem fixed. We're having the mixture and timing checked, although initial attempts show no improvement. I have a sneaking suspicion that there may be some afterglow going on, caused by carbon built up. I will be doing a endoscope inspection this weekend to determine it for sure. 

 

Question: what is the best professional and reliable method for decarbonizing an engine?

 

I've read up about the water vapor method but for obvious reasons I want to do it properly, ideally without having to take the head off.  Could you advise on methods or substances for getting the job done properly.  

Edited by BiBiBiB, 14 March 2023 - 08:55 AM.

[BaronVonchesto]

Unfortunately the best way to decarbonise is to take the head off. Nothing like mechanical disturbance to knock off the sticky carbon off the pistons.

 

I'e heard good things about using water vapour, but never did it often enough to know how effective it is. I had done it a handful of times since rebuilding my engine. and recently i took the head off again and there was some rather sticky carbon on both the valves and pistons.that needed a lot of wd40 and scrubbing to get rid of.

[BiBiBiB]

Thanks. Ill need to bite the bullet and take the head off.

To inquire further, anyone have experience with companies that provide cleaning services by means of hydrogen and oxygen gases?

[andyapanel]

Head gasket failure cleans the two pistons pretty well, though it is a bit drastic.

A good old fashioned decoke is what you need, if you think that is the cause of your deiseling.

Check timing.

Good luck

[weef]

Here is an old trick for a quick decoke using about half a litre Redex and a wide open space, preferably in the middle of nowhere.

Get the engine up to working temperature, remove the air filter element, up the idle with the carburrator screw to a really fast idle, slowly pour the Redex into the air intake being careful not to stall the engine, ignore the copious ammounts of smoke from the exhaust, wait till the smoke clears then reinstate all to normal. Now take for a spirited drive to clear any residue.

If there are no concerned citizens nearby you will not have to explain to the fire brigade what you were doing.

[DeadSquare]

Here is an old trick for a quick decoke using about half a litre Redex and a wide open space, preferably in the middle of nowhere.

Get the engine up to working temperature, remove the air filter element, up the idle with the carburrator screw to a really fast idle, slowly pour the Redex into the air intake being careful not to stall the engine, ignore the copious ammounts of smoke from the exhaust, wait till the smoke clears then reinstate all to normal. Now take for a spirited drive to clear any residue.

If there are no concerned citizens nearby you will not have to explain to the fire brigade what you were doing.

 

And keep using the Redex

[imack]

Here is an old trick for a quick decoke using about half a litre Redex and a wide open space, preferably in the middle of nowhere.
Get the engine up to working temperature, remove the air filter element, up the idle with the carburrator screw to a really fast idle, slowly pour the Redex into the air intake being careful not to stall the engine, ignore the copious ammounts of smoke from the exhaust, wait till the smoke clears then reinstate all to normal. Now take for a spirited drive to clear any residue.
If there are no concerned citizens nearby you will not have to explain to the fire brigade what you were doing.

It's a long time since I last squirted redex down a carb and watched the world dissappear in vast clouds of white smoke.
Nobody took any notice years ago. Loads of fun!

[Stevie W]

Also used to pour a little Redex down the spark plug holes and leave it to soak for an hour or so, this supposedly cleaned or softened the carbon buildup on the piston tops. 

Then replace plugs and as already said start the engine and drive until the clouds of smoke clear, ah the good old days!!!!

 

Cheers, Steve.

[Designer]

Lets upset The Mayor of London, forgotten his name   , Drive to the edge of the ULEZ stop apply the Redex in the cylinders and then proceed.        

[panky]

I have heard about water injection using the vacuum line for the dizzy advance. Pull it off the dizzy and plonk it in a container of water with the engine running, might be an idea to use clear pipe so you can see how much is being drawn in.

I've never tried it myself but it sounds feasible - as long as you don't suck too much in.

Edited by panky, 18 March 2023 - 05:15 PM.

[ThermalEvent]

An old boy I use to work with used a spray bottle (window cleaner type one) with plain water and mist water into diesel engines by hand to decarbonise them. Had to also rev them at the same time or else they would bog down. If its not "misting" you could risk hydrolocking! Not sure how this would work with a carb'd engine though.