Thread: Power Surging

I'm assuming it's a manual, if so clutch may be slipping, Regards Frank.

Thanks for the reply.
Yes it is a manual. I thought it could be the clutch to, but i have been telling myself it couldn't be as it is almost brand new (about a thousand or so of mostly easy driving kms on it)...

I would think you would smell a clutch if it was slipping.
Could it be fuel pressure related or even fuel filter blocking the flow?
Does it happen when your under high revs but low load?

Im thinking it could be a lack of pressure and not fueling properly under load.

Thanks for the suggestions.
I have put in a new fuel filter a while ago and it made no difference.
No it doesn't appear to happen under high revs when there is low load. I haven't noticed it surging when i rev it right up sitting still, only when the vehicle is actually moving has it ever done it.
Could this surging be the gear box?
I originally thought the injectors must be blocked up and the engine couldn't get enough fuel when under load. But i cant hear the engine change note when the surging happens. I put through some fuel injector cleaner anyway but that made no difference also.
The symptoms do sound like the clutch, but with a new clutch and no burnt smell it shouldn't be the problem.

if it was clutch slipping the revs would change up and down. sounds to me more like a fuel issue or spark issue. dont know much about the v8s but seems like any petrol engine problem like that, unless its an auto (which you mention isnt).

on another note the clutch can still slip even if new, if things like rear main are leaking etc. if that was case you probably wouldnt smell burning, or not usual burning. but as mentioned above doesnt sound to me like clutch.

sorry i cant help more. id take advice from one of the guys here with the v8s. im sure they can help you narrow it down.

Originally Posted by Finnius

Could this surging be the gear box?

I would not think so.
A faulting gearbox would be very noisy and clunky i would imagine.
(unsure if a dry gearbox would do this however.... Low or no oil i mean.....)
Its always a possibility i guess? I cant say i have ever ran a manual gearbox dry to know. I suspect dry bearings would squeal like a shot pig though.

I have had many clutches go in the past and they have always been consistent in the way they feel. Slipping is quite obvious and not like surging at all.
Rather like your getting bogged where the revs increase due to reduced friction between the clutch and pressure plate and loss of momentum as the effect.

Rear main dripping onto the clutch could definitely cause a slipping clutch feel.
Should be easy to illuminate that one however.

It is a disco so wait 2 days and it will be dry of oil so drive then to test HAHAHAHA Joke joke on that one.

Beyond that i keep thinking of surging as a fuel related thing.

Another thing to note is if the clutch was slipping the revs would increase then level but if its lack of fuel the revs would drop then level out.
Which of the 2 does it do?

From your OP it sounds like the latter where the revs drop out then raise.

not sure how the disco v8 engines work but on my old r31 skyline i was getting surging because the distributor shaft started seizing. it is driven by teeth on camshaft so in the end it chewed all those and the car stopped. replaced the whole engine because it was cheaper and easier at the time. and what a great engine the new one was.

but yea at first the symptons were surges which would be always at particular rev range or speed. i forget which. eventually got worse till the car just came to halt. luckily near home.

not saying thats your problem but apart from fuel issue could be electrical or firing issue? agree with Damink does not sound clutch related.

id expect if the gear box was causing issues it would be loud and youd be bouncing around a bit when the surges happened. my lt230 bearings were almost collapsed and you could hear it. constant whining in sync with engine.

I will take it for another drive tomorrow and take note of a few things mentioned i should check.
The owner before me said he went through a couple of ignition control modules in the time he owned it. Could a faulty module be the cause?