17 replies to this topic

[Sunshine]

I don't really know how to explain this one, but will try:

A couple times now, when I have turned the igniton off to park the car, it has coughed a bit, shuddered then the engine turned off. It's not been everytime, but did it to me twice this morning. The engine was properly warmed up too. It is worrying me and I have no idea why it is doing it.

Any help would be great since cowboy is away for 2 weeks now. Hopefully it is something that I can fix (pretty good with tools - at least change change a tire and most small things like that)

It is a Mayfair 988 Automatic, 85-86.


Thanks!!

[Guess-Works.com]

It's what's called run-on (dieseling), which is caused by pre-ignition... This is a symtom of a number of things but the most common in Minis is the engine is getting a little to hot, and there is still enough fuel in the system to ignite without the aid of the spark....

Check your coolant level, and also check the mixture (fuel/air) is not too week as this will also cause a the engine to run hot...

The other thing is that it could just be the cold weather which is play silly B's with the carb.

[Sunshine]

i can check the coolant.. all the fluid levels were topped up last weekend, but it won't hurt to check them again.


i'm not sure if it is running hot since the temperature gauge hardly ever moves.. but know when engine is warm by how she runs and sounds.


as for the cold, might have to get her a thicker blanket to tuck her in with... i guess she doesn't like the pink flannel sheet i'm using now

[Jackman]

I have had that problem since i bought my mini, we have tried to fix it but cant seem to get rid of it fully, it can also be due to a carbon buildup in the engine (not sure about that though) it is seeming to get worse now its cold but i get around it if it wont stop by putting it in gear and then lifting the clutch and then it stops but not very nicley. Any helps on getting rid of it fully will be nice.

[TimS]

on the injection cars they have an anti run on valve! its a very common probalem in cars that are non inection and itsnt really something to worry about! and sometimes can be really hard to get rid of, even sharp edges in the combustion chamber can cause it, though this is rarer than igntion timing, and fuel mixture out

[marksmini]

i had this problem a while ago

found it to be a carbon build up, abd when the engine is very hot, the carbon glows and when the engine if jurned off the carbon keep it running,



aint RED X good for clearing that sort of problem up?

or as guessworks says it could be due to your mixtures incorrect

[Jordie]

mine does it. probally no water in mine, i must keep a check on it.

Sometimes its short other times abit longer.

[Dan]

It's not the injection cars with anti run-on valves it's RSP Coopers and ERA Turbos. Injection cars don't need them 'because there's no way that fuel can be drawn through after the injection is turned off.
The extra heat won't show up on the coolant gauge usually, as it is getting hot because it isn't being cooled properly so the coolant doesn't heat up. It is the heat which remains in the combustion chamber which causes the problem. This extra heat can be held in the exhaust valves or piston crowns(both of which are effectively uncooled), or as has been said a build up of carbon or another foreign body in the chamber which retains heat. Check the oil and water levels, also there are various products which you can chuck down the carb to clear the carbon without removing the head, some of which work quite well. If that doesn't work it probably just needs a tune up, as Guessworks said it could be running slightly lean or the ignition timing is off. Or you could have the wrong plugs fitted, they need the correct temperature range.
Sometimes the required tuning level of the engine will mean that it always generates a lot of heat, as in the ERA or RSP. In these cases Rover chose to put in a purge valve which vents the inlet to atmosphere once the ignition is switched off, leaning out the charge. The Turbo's also ran special liquid metal cored exhaust valves to help them remain at a sensible temperature. Other cars (such as performance Vauxhall engines) use oil jets in the crankcase to cool off the piston crowns from below as they travel down the cylinder.

Out of interest does it still run-on if the heater valve is open while running? Because with this closed heat builds up around cylinder 4. And I assume you close the choke before stopping the engine.
And Flappy sorry to disagree but it is something to worry about. If it goes on for more than one or two revolutions, particularly on an older engine the mill is basically running with barely any oil pressure. And detonation is always a bad thing anyway.

[dklawson]

I don't mean to sound rude or anything, but I'm always amazed when this problem amazes people. Admitedly it isn't expected on "newer" cars, but on anything old with a carburetor it's going to happen sometime. As Dan said, injected cars don't have the problem because the fuel supply completely dries up when the key is turned off.

As mentioned above you can sort it out by getting rid of sources for hot spots in the combustion chamber. Depending on how much time, effort and money you want to spend you can: set and check points gap, timing, fuel adjustments, and decarbonize the combustion chambers.

DON'T let your car diesel like this as it's bad for the crank. However, stopping the dieseling is as easy as this: When you're going to switch off the engine, put the car in 4th gear. As you turn off the ignition slowly release the clutch pedal. The engine will stop immediately. It's an old solution to an old problem.

[Guess-Works.com]

I must admit, when mine does it, I dump it in gear aswell, but shortly after plug in the cyrpton and check the tuning/mixtures.. and its normally about this time of year when the cold sets in, cold air takes up less volume therefore your mixture will weaken ever so slightly, not sure this is the cause, but it's the best thought I've had today ( which says something ! :erm: )

[Jackman]

Im living with mine, dosent bother me at all, just reminds me that its old and just like a woman. Tempramental, by the way my car is called Jynx (guess why if u want lol)

[marksmini]

old and just like a woman

:grin: :grin: :grin: :grin:

[vasi]

This problem is also common on cammed engines. It happened on my last GT, and happens with this one too. Both have silly cams. I just go full right foot just as I'm turning the engine off to stop it from running on.

[TimS]

Dan dont be sorry to disagree, i completly agree with ur comment!lol mistake on my behalf, best think b4 i post next time

[vasi]

my car is called Jynx (guess why if u want lol)

Because the first three letters of the reg are JNX, like mine?