19 replies to this topic

[wkd_lil_law]

Hey everyone,

 

I am not mechanically minded so sorry my explanation is not very technical.

 

My '91 mini mayfair (Manual, 1 litre) over the past couple of months got stuck at high revs whilst on the motorway, both times shortly after it had started raining.

I managed to make it home both times by driving at 40mph which kept me at 3.5 on the rev counter.

 

On the advice of my friend who said it was the throttle cable sticking, i got a new one put on a couple of weeks ago, and was fine up until yesterday.

 

2 days in a row from start to end of my 5 min journey to work, stuck at high revs again.

However on the way home around 5/6pm .... all is well.

I noticed that these 2 mornings have been cold and wet with dew, and the drive home was sunny and dry.

 

Another friend has told me tonight that actually it sounds like the clutch is sticking?

Haven't read anything so far that links my issue, and rain to a clutch problem.

 

Thanks

 

 

[Cooperman]

I think your friend means 'the clutch is slipping'.

If you were pulling 3500 rpm at 40 mph then there is a problem with the clutch. On a '91 Mayfair 3500 rpm in top should be at least 65 mph, or were you in 3rd gear.

Can't see why it should be a wet weather issue.

More information is needed here if we are to help.

[wkd_lil_law]

Thank you so much for your reply.

 

When we got it (my car was rescued from a field where it had been left for sometime) the clutch had seized but friends sorted it. 

Its been a couple of years since then, and i've not noticed any other issues.

Yes normally id say 3500 is when im at least 60mph.

 

Strangely the first time it happened i pulled over in a service station and when i got moving again it returned back to normal, seemingly of its own accord.

 

I am aware the engine is moving around a little recently, so I need to get some mounts ASAP.

 

Sorry i'm not giving you any mechanic info here, just what i have experienced.

[dyshipfakta]

Sounds like clutch arm is seizing and releasing every so often. Sometimes it sticks and slips the clutch others it works ok. Needs sorting and get as much grease into it as possible. I dare say if you have slipped it that badly there won't be much of the clutch left.

[ger]

If you are getting high revs whilst stationary and foot off the accelerator pedal could this be due to something sticking in the carb?

 

Ger

[Cooperman]

If the revs don't match what the road speed should be at those revs it will be a clutch issue.

[carbon]

The symptoms described by OP sound a bit like carb icing up. The ice build-up around the throttle shaft holds it open.

 

If you stop and wait for about 5-10 mins it warms up and the ice disappears.

 

This can happen in cold and damp weather if the carb inlet is not picking up warm air from the exhaust manifold. I've had this happen with a 998 running HS4 carb with the inlet trumpet moved to pick up cooler air.

 

If it happens again, and you can safely pull over to the side of the road, lift the bonnet and look at the carb, if there is a lot of condensation or even frosting on the carb near the throttle then it is probably icing up.

[wkd_lil_law]

Thank you I will get the clutch checked out as soon as poss.

 

Mostly it seems to happen WHILST driving, but did go into high revs recently when i just reversed off the drive, I think it was at 2500rpm still when foot was off the accelerator.

 

I'll go with clutch and go from there, and let you know what happens!

 

Thanks all so much, I need to learn a bit about my car if i am going to keep it long term aye!

 

Now I'm hoping to find a good mechanic in herts or npton!

[wkd_lil_law]

The symptoms described by OP sound a bit like carb icing up. The ice build-up around the throttle shaft holds it open.

 

If you stop and wait for about 5-10 mins it warms up and the ice disappears.

 

This can happen in cold and damp weather if the carb inlet is not picking up warm air from the exhaust manifold. I've had this happen with a 998 running HS4 carb with the inlet trumpet moved to pick up cooler air.

 

If it happens again, and you can safely pull over to the side of the road, lift the bonnet and look at the carb, if there is a lot of condensation or even frosting on the carb near the throttle then it is probably icing up.

 

Oh really! Thank you, maybe that makes sense now it is getting colder, although it happened twice in summer so very unlikely for it to be cold enough I guess

[dyshipfakta]

Still doesn't explain how you were doing 60 and revving the nuts off of it unless you were in the wrong gear of course.

[carbon]

 

The symptoms described by OP sound a bit like carb icing up. The ice build-up around the throttle shaft holds it open.

 

If you stop and wait for about 5-10 mins it warms up and the ice disappears.

 

This can happen in cold and damp weather if the carb inlet is not picking up warm air from the exhaust manifold. I've had this happen with a 998 running HS4 carb with the inlet trumpet moved to pick up cooler air.

 

If it happens again, and you can safely pull over to the side of the road, lift the bonnet and look at the carb, if there is a lot of condensation or even frosting on the carb near the throttle then it is probably icing up.

 

Oh really! Thank you, maybe that makes sense now it is getting colder, although it happened twice in summer so very unlikely for it to be cold enough I guess

 

I have been re-reading your first post. If the engine is just running at higher speed that you would expect when you're driving along, then it's unlikely to be the carb icing up.

 

If you're running at 40mph in top gear and the rev counter is showing 3,500rpm then it is much more likely to be because of clutch slipping.

 

At 40mph in top gear would expect to see no more than about 2,500rpm on the rev counter.

[nicklouse]

I would find a mechanic and get them to take it for a drive with you.

[gazza82]

Slipping clutch is easy to diagnose. Drive it slowly and get into as high a gear as possible as quickly as possible. Then floor it.

 

If the car picks up steadily and accelerates, it's probably isn't the clutch

 

If the rev counter shoots up and the car slowly increases speed (or doesn't!) clutch is foobarred ..

[tiger99]

If you have correctly described the problem it isn't carb icing. Please do not be misled by utterly incorrect advice. It MUST be the clutch as the relationship between engine revs and road speed is incorrect, as is correctly explained above.

Whether it is a simple external problem or a need for complete clutch replacement can only be determined by careful examination.

If you do get carb icing, it may be weather dependent, but it will be a severe power loss, usually accompanied by rough running, and is usually short duration as engine heat shifts the ice eventually. The revs and roads peed will remain consistent.

Best get it looked at by a Mini expert, although people on this forum can guide you through a diagnostic process.

[carbon]

If you have correctly described the problem it isn't carb icing. Please do not be misled by utterly incorrect advice. It MUST be the clutch as the relationship between engine revs and road speed is incorrect, as is correctly explained above.

Whether it is a simple external problem or a need for complete clutch replacement can only be determined by careful examination.

If you do get carb icing, it may be weather dependent, but it will be a severe power loss, usually accompanied by rough running, and is usually short duration as engine heat shifts the ice eventually. The revs and roads peed will remain consistent.

Best get it looked at by a Mini expert, although people on this forum can guide you through a diagnostic process.

Agree that the OP's problem is unlikely to be carb icing, more likely to be clutch. Said as much above.

 

But carb icing does not always give a severe power loss. My experience with the carb icing up on a Mini has been with throttle not closing properly and as a result engine speed going high when taking it out of gear.