Occasional stiff clutch = ?

[GQGasPig]

Hi All,

I have a manual '91 GQ petrol/gas wagon with 280,000km on the clock. Occasionally when you press the clutch to change up gears the clutch feels stiff/hard for a moment then returns to normal. This has just started happening on the way home from our most recent trip. This does not appear to be happening when changing down gears. It does not matter if the engine is hot or cold.

I have checked the clutch fluid and it is between the min and max levels and I have not been able to find any leaks around the clutch fluid unit thingy (the name of it escapes me) or any were else for that matter.

I have had the GQ for close to 7yrs now and in the last 2yrs it has done 1 5,000km and another 2,000km trip which we just finished 2 days ago. On these trips we have been towing one of those 1 tonne big ass Jayco offroad camper trailers at highway speeds.

Any thoughts on what the problem may be?

Cheers

GQGasPig

[henry]

Mate my GQ does it sometimes. Ive found it to be a lack of vacuum in the clutch vacuum booster. Mine does it when ive been on full throttle or close to it. The reason why it does not happen on down shift is you have maximum manifold vacuum when the throttle is shut. There is a one way valve in the line to the booster, my guess is that it could be failing.

Hope this helps, Nik.

[j-top paj]

i was thinking vaccum too

[Sexy Fingers]

Mate my GQ does it sometimes. Ive found it to be a lack of vacuum in the clutch vacuum booster. Mine does it when ive been on full throttle or close to it. The reason why it does not happen on down shift is you have maximum manifold vacuum when the throttle is shut. There is a one way valve in the line to the booster, my guess is that it could be failing.

Hope this helps, Nik.

Mines done 298 000km's and it does it too. I'm very sure it is a vacuum problem also

[marin]

yep, both my shorties have done this, accelerate hard away from the lights, and the next gear change the clutch is stiff as.

lack of vacuum for sure. I remember somebody on here adding another vaccuum tank and getting rid of this problem.

marin

[GQGasPig]

Thanks for the replies.

Two more questions.

1. If it is the one way valve as Nik and others have said, will the valve eventually fail altogether and leave me clutchless?

2. Has anyone tried to replace the valve only and if so what cost was involved (parts and labour) or do you need to replace the clutch booster as well?

Cheers
GQGasPig

[chimpboy]

The vacuum only provides assistance, so it would not see you losing all clutch control.

A one way valve is a very cheap item, replace that and the vacuum hoses and see how you go.

[henry]

Like chimpboy said you wont lose the clutch altogether, it will just be hard to push in, like it is when you have no vacuum assistance.

[j-top paj]

try doing it with the engine switched off.
if it feels the same then i think you have your answer