Engine running on
- Thread starter Duane
- Start date
Gargo
Active Member
The quick answer, put it in gear and dump the clutch.
Don't let it happen, it causes damage to the engine.
It sounds like the car has been sitting for a while; conduct a good service first, that may cure it.
Things like spark plug gaps and condition, ignition timing, carbs running too lean at idle or rich etc can cause a hot spot in the combustion chamber that will act as igniter for the dieseling. If you let it happen it can start to destroy the head gasket, the damaged gasket will start to glow (burn) and act as a wick to increase the problem. It can even pit the castings, which again cause a local hotspot and on it goes.
So, new plugs, new fuel (super unleaded) check timing, check carb mixture at idle (not too rich, not too lean).
Good petrol will have anti knock additives which may help.
If it is still happening, stop the engine by stalling rather than the ignition key. At that point I'd lift the head to check and renew the gasket, while cleaning the carbon deposits from the combustion chamber.
G.
Don't let it happen, it causes damage to the engine.
It sounds like the car has been sitting for a while; conduct a good service first, that may cure it.
Things like spark plug gaps and condition, ignition timing, carbs running too lean at idle or rich etc can cause a hot spot in the combustion chamber that will act as igniter for the dieseling. If you let it happen it can start to destroy the head gasket, the damaged gasket will start to glow (burn) and act as a wick to increase the problem. It can even pit the castings, which again cause a local hotspot and on it goes.
So, new plugs, new fuel (super unleaded) check timing, check carb mixture at idle (not too rich, not too lean).
Good petrol will have anti knock additives which may help.
If it is still happening, stop the engine by stalling rather than the ignition key. At that point I'd lift the head to check and renew the gasket, while cleaning the carbon deposits from the combustion chamber.
G.
johnsimister
Active Member
My 2000 TC, now bored out to 2200 so 9:1 compression, has been doing this although less so on 99-octane super unleaded than on 97-octane (which ought to be fine for a 9:1 four-cylinder P6). The engine is recently rebuilt and should have minimal carbon deposits. Fuelling and ignition timing (the latter using the correct 2200 TC distributor to match the rebore and compression ratio) are spot on. I have found a cure, I think, but will need another tankful of 97-octane to be absolutely sure. The cure, brought on by thoughts that modern fuels are more volatile than 60s/70s fuels and perhaps more readily lit by hotspots in the combustion chamber, is to fit spark plugs one grade cooler: NGK BP8ES (equivalent to Champion N6Y) instead of the usual BP7ES (equivalent to the factory-spec N7Y). Could be worth a try. Certainly the engine is running very nicely at the moment.
John
John
mikecoombs
Active Member
Check and see which direction the engine is turning when it runs on. Quite often its backwards....
Check your idle mixture and particularly the off idle mixture as running lean is a cause. Wrong needles can also mess up the idle but thats a professional job to fix
Inlet manifold leak is also a possibility.
Then I'd try one grade HOTTER plug first or switch to Iridium plugs if you can get them. If the inside of the engine is new/clean, the plug is most probable culprit but it can be just dieseling where the blow bye from the new rings is self igniting. If it does run in reverse you may well have an exhaust full of fuel and oil which diesels. Before buying new plugs I'd file the ground terminal corners off to a rounded end; not top and bottom surfaces just the two vertical right angles at the end of the electrode
In terms of how to stop the engine; try full throttle first (no ignition and it won't do anything but backfire if its running backward), then putting it into gear with the brakes fully on hard (kinda risky but normally works) or get someone to block the end of the exhaust (don't use your hand) and /or spraying/misting water on the steel parts of the exhaust (only exhaust) to cool the gas inside.
M
Check your idle mixture and particularly the off idle mixture as running lean is a cause. Wrong needles can also mess up the idle but thats a professional job to fix
Inlet manifold leak is also a possibility.
Then I'd try one grade HOTTER plug first or switch to Iridium plugs if you can get them. If the inside of the engine is new/clean, the plug is most probable culprit but it can be just dieseling where the blow bye from the new rings is self igniting. If it does run in reverse you may well have an exhaust full of fuel and oil which diesels. Before buying new plugs I'd file the ground terminal corners off to a rounded end; not top and bottom surfaces just the two vertical right angles at the end of the electrode
In terms of how to stop the engine; try full throttle first (no ignition and it won't do anything but backfire if its running backward), then putting it into gear with the brakes fully on hard (kinda risky but normally works) or get someone to block the end of the exhaust (don't use your hand) and /or spraying/misting water on the steel parts of the exhaust (only exhaust) to cool the gas inside.
M
roverp480
Active Member
I had trouble with a brand new Land Rover running on back in the middle 1970's. Garage couldn't cure it and I mentioned it to one of Land Rover company engineers at a meet he was at and he advised slowing down the tick over speed to the minimum the engine would tolerate without stalling, ignoring the service data idle speed. Problem solved
Demetris
Well-Known Member
Indeed, the higher the idle speed, the more prone engines are to running on. I remember MG Metros, they had a wild(ish) camshaft, and in order to bring HC emissions at idle to a reasonable level, the idle speed was fairly high. Of course this in its turn caused running on problems, and as a solution they fitted a solenoid valve, that vented the inlet to the atmoshere when the ignition was switched off. It worked very well.
Speedfreak
Active Member
I was once told cleaning the flame trap helped with running on….I always keep mine clean….not sure if It’s fact or fiction.
can’t hurt however I guess..l
can’t hurt however I guess..l
*update*. car now running again.Mine does the over run sometimes but never realised it had such harmful consequences. Time for a full service. Once I get the car running again.
and running on
waiting for warmer weather to start longer jobs as I have to work outdoors.
Will review the running-on situation next.
new plugs, Not sure I have any new plugs
new fuel (super unleaded). - can add fuel - if I dare a trip to the filling station.
check timing, Static timing or with a strobe thingy ( never done either task)
check carb mixture at idle (not too rich, not too lean). suppose this needs a probe in exhaust?
sdibbers
Well-Known Member
If you haven't checked your timing I'd be inclined to say that's your first place to look. if its too advanced it can cause a major hotspot on the piston crown that will certainly cause running on. Do you notice pinging when driving?
nor sure I have noticed pinging ( pinking ? ) noise while driving, but there are so many noises.
The door cards are not fitted, along with much other trim. Engine seems to make the right nosies when tootling about.
sdibbers
Well-Known Member
Bugger! I’ve lived in the colonies too long!