Discussion
Ok so my Audi has a bit of a cold it seems
Driving along the past week and its driving like a new car even though its 8 year old
Then seems like go off a cylinder and the shine light flashes off and on the. If I stop the engine and start up its back to driving perfectly again.
Took it to my local inde who said it was probably a sticky valve and put some mysterious liquid in the fuel tank
The liquid worked and he said to bring it back Friday for a decoke. I remember seeing it done on wheeler dealers a while ago
Anyone have this done and is it a good fix ?
Driving along the past week and its driving like a new car even though its 8 year old
Then seems like go off a cylinder and the shine light flashes off and on the. If I stop the engine and start up its back to driving perfectly again.
Took it to my local inde who said it was probably a sticky valve and put some mysterious liquid in the fuel tank
The liquid worked and he said to bring it back Friday for a decoke. I remember seeing it done on wheeler dealers a while ago
Anyone have this done and is it a good fix ?
Decoke would mean taking the head off, cleaning it all up and refitting. A big job and I'd epxect 300 quid or so (a rough guess).
My advice would be to drop the oil and fill it up with new, don't change the filter. Take it for a good Italian tuneup, use plenty of throttle and all the rev range. Do 50-100 miles or so of pretty hard driving so the engine gets good and hot.
Come straight back home and drop the oil whilst it's still hot or very warm. If it comes out dark, do it again. Then replace both filter and oil, I am very sure you'll see an improvement.
If it's a petrol engine, use diesel engine oil only for the above flush - it has more detergents in it and will clean the inside of the engine better than a petrol oil.
My advice would be to drop the oil and fill it up with new, don't change the filter. Take it for a good Italian tuneup, use plenty of throttle and all the rev range. Do 50-100 miles or so of pretty hard driving so the engine gets good and hot.
Come straight back home and drop the oil whilst it's still hot or very warm. If it comes out dark, do it again. Then replace both filter and oil, I am very sure you'll see an improvement.
If it's a petrol engine, use diesel engine oil only for the above flush - it has more detergents in it and will clean the inside of the engine better than a petrol oil.
LeoZwalf said:
Decoke would mean taking the head off, cleaning it all up and refitting. A big job and I'd epxect 300 quid or so (a rough guess).
My advice would be to drop the oil and fill it up with new, don't change the filter. Take it for a good Italian tuneup, use plenty of throttle and all the rev range. Do 50-100 miles or so of pretty hard driving so the engine gets good and hot.
Come straight back home and drop the oil whilst it's still hot or very warm. If it comes out dark, do it again. Then replace both filter and oil, I am very sure you'll see an improvement.
If it's a petrol engine, use diesel engine oil only for the above flush - it has more detergents in it and will clean the inside of the engine better than a petrol oil.
Trouble with the above is that generally a decoke takes place to clean all the carbon build up off the valves, and unless the valve stem guides and piston rings are shagged there should be no oil on the valve heads them selves, just carbon from the combustion process, so dropping the oil as many times as you like won't achieve any results .... My advice would be to drop the oil and fill it up with new, don't change the filter. Take it for a good Italian tuneup, use plenty of throttle and all the rev range. Do 50-100 miles or so of pretty hard driving so the engine gets good and hot.
Come straight back home and drop the oil whilst it's still hot or very warm. If it comes out dark, do it again. Then replace both filter and oil, I am very sure you'll see an improvement.
If it's a petrol engine, use diesel engine oil only for the above flush - it has more detergents in it and will clean the inside of the engine better than a petrol oil.
We had issues years ago when vauxhall decided not to leave enough clearance on the valve stem guides on the twin cam 1.4 and 1.6 corsa and tigra engines, used to bind the valves up to the point they would stick open on cold starts and run rough to the point they would be open enough to drop compression down enough so it wouldn't start, first fix was some chemical drawn into the inlet at around 2000rpm, used to work for a short while and would fill the workshop up with thick grey smoke, but eventually the symptoms would return and it was head off time to ream out the guides, must have cost vauxhall a pretty penny that with the amount of heads removed under warranty .
I believe the same thing happened to Ford 4 valve engines when they first introduced them. Obviously, the factory development drivers would thrash the daylights out of them, and keep the valve stems hot. When Mr & Mrs bumble got their hands on them, and never went above 2000 rpm, the valves stem didn't get hot enough to burn off the carbon, hence it would build up, and eventualy make the valves stick open. Thrashing them regularly was the simple solution, but I believe Ford shortend the valve guides to reduce the heat extraction rate from the valves, making them run a bit hotter.
amusingduck said:
rhinochopig said:
Just run three or four tanks of v power through it on some long runs. The detergents in both the petrol and diesel variants are very effective.
All fuels have detergents as standard anyway?e.g. http://cars.aol.co.uk/2011/04/25/behind-the-scenes...
The OP makes reference to the 'Wheeler Dealers' decoke which involves connecting up a machine and running a detergent through the injectors while running the engine at fast idle. Removing the head and 'decoking' in the old-fashioned sense is a thing of the past with modern unleaded and injection/ignition technology.
This one http://terraclean.co.uk/ ooooo nano tech, means you cant see if its worked cos its too small
HustleRussell said:
. Removing the head and 'decoking' in the old-fashioned sense is a thing of the past with modern unleaded and injection/ignition technology.
As long as everything is running ok I'd agree to a point ..... valves still accumulate carbon build up even with detergent fuels, if the engine is not running correctly, poor ignition for example this build up will be more excessive.rigga said:
HustleRussell said:
. Removing the head and 'decoking' in the old-fashioned sense is a thing of the past with modern unleaded and injection/ignition technology.
As long as everything is running ok I'd agree to a point ..... valves still accumulate carbon build up even with detergent fuels, if the engine is not running correctly, poor ignition for example this build up will be more excessive.I agree with the 'italian tune-up with v-power' people. It's the cheapest and simplest solution to try before anything else.
rigga said:
I think there was a few law suits floating about concerning various fuel company's, shell being one I recall concerning valve issues and running problems back then too.
Different issue than detergents, the fuel was essentially too good for some engines and some valves burnt out, particularly vauxhalls I seem to recall. Was it Formula Shell? That was rocket fuel.jshell said:
Different issue than detergents, the fuel was essentially too good for some engines and some valves burnt out, particularly vauxhalls I seem to recall. Was it Formula Shell? That was rocket fuel.
Kinda shows your age if you remember Formula Shell 
It was reported to affect Cavaliers especially but at the time I was in the RAF and they had literally thousands of them running on Formula Shell exclusively and didnt have any issues
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