Difficulty shifting gears

I'm having a few issues changing gears in my '91 gq Td42.
It shifts fine when cold, after about half an hour or so of driving it becomes very hard to change gears (this problem comes and goes) with the engine of I can change no problem.
It does not grind except trying to get into reverse.
Double clutching does not help, nor does pumping the clutch pedal.
The clutch is not slipping, however I think it may not be releasing properly, not sure how this could be affected by different temperatures though.
Could this be caused by air in the clutch lines?
I have changed the gearbox oil, the problem is the same.

So i'm thinking the problem could be
-I'm in need of a clutch bleed.
-Clutch fingers worn.
-synchro problems.
-or a buggered gearbox?

I'd be checking out the diaphragm in the clutch booster. problem is not the gearbox.
As you said it could be air in the system. could even be adjustment.
Cheers, the ferret.

Cheers mate, I'll have a look into it tomorrow, I hadn't considered the diaphragm!

Quote:

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Originally Posted by thebeatjackson

Cheers mate, I'll have a look into it tomorrow, I hadn't considered the diaphragm!

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Could even be a lack of vacuum, are the brakes working ok?
Cheers the ferret.

No actually, the brakes could certainly be better!
The friction point for the clutch is very close to the floor too.

I mean they stop the car, there's plenty of meat left on them, but there's no way i'd be able to do an emergency stop, worse than your standard 4wd truck brakes.

Although the brake pedal is firm before I start the car, then goes soft (i.e normal, not spongy like there's air in the lines) when I start the engine. Would that indicate that there is no vacuum leak?

The brake pedal will drop once you have vacuum, normal.
Friction point close to floor with clutch means clutch adjustment (not applicable in your case) probably worn clutch plate.
Start saving for a clutch overhaul, sorry to be the bearer of sad tidings

Sadly, your's truly, the ferret.

Does sound like your clutch is worn , but check that your clutch is getting full travel on the fork and that the clutch line is not cracked and master and slave cyliners are all good before changing the clutch.
How did the oil look when you changed it in the gbox?

pretty clean when I changed it, no metal filings either.

are you running the correct gearbox oil, it should be a friction modified oil (VMX 80)

This is the oil I'm using.
http://www.nulon.com.au/products/Gea.../#.T4JF1_Drq5I

G`day mate
check the hydraulics first. with the engine off bleed the booster by pumping the pedal a few times until the pedal is firm to push to the floor, if it has a small amount of free travel then is firm to push to the floor then the hydraulics are more than likely ok and your problem is the clutch it`s self.
If it`s the clutch it could be a number of things.
1 a cracked fork
2 a cracked diaphragm spring
3 a broken pressure plate hold back clip there are 3 or 4 of these can`t remember off hand
4 a broken fulcrum ring
all of these require box removal
hope this is of some help

if the clutch has a soft line, ie rubber hose , check to see that its not bulging under presure too...

should be using a gl-4 oil in a patrol gearbox. vmx-80 and vmx-m work well

Quote:

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Originally Posted by pearcey

G`day mate
check the hydraulics first. with the engine off bleed the booster by pumping the pedal a few times until the pedal is firm to push to the floor, if it has a small amount of free travel then is firm to push to the floor then the hydraulics are more than likely ok and your problem is the clutch it`s self.
If it`s the clutch it could be a number of things.
1 a cracked fork
2 a cracked diaphragm spring
3 a broken pressure plate hold back clip there are 3 or 4 of these can`t remember off hand
4 a broken fulcrum ring
all of these require box removal
hope this is of some help

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Seems to be in the hydraulics from this test, pumped the cluch pedal for about 2-3 minutes with little to no change in firmness.

Quote:

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Originally Posted by billyj

should be using a gl-4 oil in a patrol gearbox. vmx-80 and vmx-m work well

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cheers, I'll change it again, do you use the 80 or the m is there much of a difference between them?

Quote:

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Originally Posted by thebeatjackson

Seems to be in the hydraulics from this test, pumped the cluch pedal for about 2-3 minutes with little to no change in firmness.

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If there is no fluid leak the mater can be bypassing internally
Start the engine hold the clutch down with the car in gear for a minute or so and if the car starts to slowly creep away then the master is bypassing
If it is the master fit a new one don't re kit the old one as the have a special coating on the bore and honing removes this and premature wear becomes a problem

Quote:

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Originally Posted by pearcey

...
Start the engine hold the clutch down with the car in gear for a minute or so and if the car starts to slowly creep away then the master is bypassing
...

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I haven't tried this yet, but I do remember it doing something like this when sitting at traffic lights.

Quote:

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Originally Posted by thebeatjackson

I haven't tried this yet, but I do remember it doing something like this when sitting at traffic lights.

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Any dout change the master not that expensive and cheaper than pulling the box.

very strange, does it always shift easy when cold? I wonder if the throwout bush is stuffed?

Quote:

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Originally Posted by Richo460

very strange, does it always shift easy when cold? I wonder if the throwout bush is stuffed?

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Always shifts beautifully when cold (so far), which is why I didn't immediately assume it was in the clutch or spigot bearing.

thats a weird problem you have there. I reckon it would be worth while changing the clutch fluid if you haven't done already. Is it hard to get out of gear or hard to get in gear or both? If it doesn't grind or clunk then i would think the box is ok, grinding into reverse is normal as it doesn't have a syncro but all forward gears do. Is there any clutch fluid loss?
In the clutch master cylinder there is a seal that may be leaking, but leaking back to the resovior not onto the ground so it may not be disengaging the clutch properly, can't see how this would be temperature related either though, its a tricky one. Always start with the easy and cheap things to fix and check first. lol

my missus 4x4 had a problem like that but it turned out that she had piss all oil in the gearbox.

well guys ive had the same issue appear in the last 2 weeks. Just popped up one day, but mine is very hit and miss. Not just when hot, and is hard to change up or down sometimes..
ill try the cylinder first, but clutch has got nearly 1/2 million on it so might change it out soon to be sure..

I'd say your clutch has given its all Kallen and its having a bit of a rest

Well not really.. poped the bonnet to check for leaks from the cylinder.. couldn't see any. Popped the lid of the fluid tank aaannnnndddddd...
No fluid... :o

So ill top it up, and look for leaks..
What is the preferred clutch fluid for Nissan?

Kallen Westbrook
Owner of
Westy's Accessories

Ok, dot 4..
Will I have to bleed it now? Or are they self bleeding?

Kallen Westbrook
Owner of
Westy's Accessories

My clutch was a pain to get into 2nd or 3rd and once I replaced the clutch I have no problems at all.... I have also replaced slave cylinder..!!!

had the same thing in the nav it was the master leaking on itself but yours kal you got an external leak

have you tried adjusting the clutch pedal at the master and at the pedal stop