Car reving its balls off.

[Rob.]

1.9Diesel Mk1. Every now and again it red lines its self. and nothing i can do will stop it reving.
I instantly thought head gasket. Checked the compression all are fine. But changed it any way as I had a spare laying about.
But it still revs to red line on its own every now and again what could it be ??

1. Revs as high as it can on its own.
2. Even turning engine of it stays on and revs.
3. New head gasket.

 

[LegoHead]

burning oil maybe?

 

[Luke.]

sounds like the engine is running up!

check the oil level as it could be overfilled causing the car to burn the oil and rev up!

can cause serious damage so check it asap!

how did u manage to stop it?

stall it?

 

[Russ_16v]

dervs when revving high can suck oil through and will continue to run on oil, so id say either too much oil, or a breather prob maybe?

 

[Rob.]

sounds like the engine is running up!

check the oil level as it could be overfilled causing the car to burn the oil and rev up!

can cause serious damage so check it asap!

how did u manage to stop it?

stall it?

just checked oil and its normal level.
stuck it in 5th and dual carriage it all way home. when i got home it turned off fine. lol.

 

[rich_1989]

try checking the stepper motor, its a box linked to the throttle which controls the ilde running speed of the engine, sometimes they go mental and need replaceing, could also lead to damage of fuel potentiometer

 

[Rob.]

it seems as soon as these is any kind of power going to the wheels it stops reving its balls off.

 

[rich_1989]

it will do coz the stepper motor will only adjust th idle to compinsate for power steering air con etc, but some times it goes crazy! and needs replaceing, when the cars in neutrol ther is nothing stopping the revs jus gradually pickin up, but with it in gear it hardly affects it about 2k revs

see if you can find wher the throttle cable connects and find a little black box with a metal pin stickin out the back on a spring, if this can be pushed in much, you have found ya prob

 

[Rob.]

it will do coz the stepper motor will only adjust th idle to compinsate for power steering air con etc, but some times it goes crazy! and needs replaceing, when the cars in neutrol ther is nothing stopping the revs jus gradually pickin up, but with it in gear it hardly affects it about 2k revs

see if you can find wher the throttle cable connects and find a little black box with a metal pin stickin out the back on a spring, if this can be pushed in much, you have found ya prob

stepper motor ? On a diesel ???

 

[rich_1989]

not 100% but the principle is the same, when things like a/c are run with the engine idleing it puts strain on the engine, the throttle on a diesel is usually cable so will have the same kind of mechanism, check wher the cable connects to the throttle itself and snoop around, if ther is a thottle quadrant check behind the flat part of it, ther should be a pin which is spring loaded and will push the quadrant open abit, which is all it needs to build up revs when it not in gear, if this is the case, nip down the scrappy and rip one off there or you will be lookin arround the 100 quid mark. its not the easyest thing to detect is the stepper motor and to be honest, the fuel potentiometer has somthing to do with it as i had change this too.

 

[Djw John]

If you do need to get the engine to stop put it into 5th and just sidestep the clutch forcing it to stall, better than a blown up engine!

 

[rich_1989]

^ or just turn the key?

 

[mattjk]

^ or just turn the key?

What I was thinking too lol!

 

[Rob.]

If you do need to get the engine to stop put it into 5th and just sidestep the clutch forcing it to stall, better than a blown up engine!

Thats what i had to do last night

^ or just turn the key?

What I was thinking too lol!

Because its a diesel. The Cam belt is still turning the fuel pump so the engine is still getting fed. turning the ignition off will only stop the electric.

 

[mattjk]

Fair point!

 

[Brasseye]

leaking inlet manifold ?

 

[Rob.]

leaking inlet manifold ?

Wouldn't that course different things to happen then reving its balls off on its own ?

Like would judder alot as to much air in fuel mixture.

 

[Djw John]

Last time I heard of it was too much oil in the engine

 

[tim124]

try checking the stepper motor, its a box linked to the throttle which controls the ilde running speed of the engine, sometimes they go mental and need replaceing, could also lead to damage of fuel potentiometer

its a mk1 diesel, they dont have any electrics at all, just 12v feel to the manual fuel pump

 

[tim124]

People are just guessing, badly.

its a mk1 diesel, it doesnt even have a throttle butterfly so it just has an open manifold...

it will only rev if fed with more fuel, diesel/oil. So either engine oil is getting in or the diesle pump is broken.

As you have done the headgasket and you say the oil level and compression is fine, i would say its the diesel pump

 

[Sym0n]

When was the last time it was serviced? The Mk1 derv engine is pretty simple, so I'd drop the fluids and change your filters first. If the problem is still occurring then, as tim124 says, check/and or change your derv pump.

 

[tim124]

I have a 1.9d car sitting in essex with a fully functional pump on it if youre interested

 

[rich_1989]

Fair point!

yep i stand corrected keep 4getin its saitan fuel