Can't select gears in GU

[4by]

Hi all,

Vehicle: 4.2 GU turbo diesel. 145,000 k's

Problem..... It's very hard to select gears when idle.

When the car is warm, after a 10 min drive if I take my foot off the clutch for a few seconds at idle, it is very hard to select gears.
If I stop with my foot on the clutch I get all gears no problem.
When its cold I can select gears.
I have just changed the oil to Castrol Syntrans synthetic and its still the same.

I don't think its the clutch or bleeding is needed because it works great when cold, when moving, slowing down or leaving my foot on the clutch when idling. But, I'm no mechanical expert, so I can be proven wrong........

Any ideas is appreciated because its a pain in the butt to drive.

[ACH]

4by,

the box in your GU is derived from trucks so it's not a smoothy by any stretch...but you probly know that!

At 145 thou I wouldn't expect your synchros to be shot, and these boxes are as tuff as. But it's possible...

Is the Syntrans stuff recommended by Castrol? FWIW I use Penrite oils in the motor and drivelines.

It could still be your clutch tho'...

[stack]

had the same problem got 175,000 on the clock i changed to a heavier oil and it fixed the problem,

[4by]

had the same problem got 175,000 on the clock i changed to a heavier oil and it fixed the problem,

Hi Stack, Do you remember what grade of oil you used?

I wan't to make sure I put the right grade in before I throw out the $110 syntrans oil.

[fnqcairns]

4by mine does it too - I think, are you talking about hard to select 1st at the lights sometimes, more-so when warm but can get better when hot? I was looking into synthetic also but mainly for the longevity of the box and less so the hard change problem.
I agree with you it is nothing to do with the clutch it's a red herring, I personally think it is a quirk of these boxes after a bit of wear and tear it becomes worse.
With other boxes I have used selecting reverse then straight into 1st helps due I understand to them being on the same layshaft but I could be wrong.
Just a thought give the ep additives in the synthetic a thousand Km or so to start working and see how you go, I understand they can take a while to build up.

cheers fnq

[4by]

It's not just 1st gear fnq, its pretty much any gear when standing still.

It's bloody annoying when the lights change and you sit there trying to jam it into 1st and the car behind you is blasting his horn........

The only way to prevent it is by leaving your foot on the clutch.

It's something that needs to be resolved.

[fnqcairns]

Ok all gears, and the gate is closed even on second gear and even on 3rd?
In mine sometimes the gate will close on 1st then in the same predicament as you (at the lights) I try 2nd which is also closed. Then I try 1st again but without the rush using constant pressure but not being stupid about it and it will often (not always) slide through. I have yet to try any of the other gears in a rush
My problem after a highway run seems to do it less.

My clutch is in perfect order also.

Your problem may be worse than mine but mine can be pretty bad sometimes if I forget which car I am driving, fast selction snaps the gate closed -try this as it works well for me to get around the situation, when sitting at the lights in neutral with foot of the clutch then the light turns green put your foot on the clutch, then dont rush, really! dont rush the stick, in easy time find the 1st gear gate, dont snatch it just use even constant pressure and ease through, it's all in the timing between clutch and gate. Slow it down.

This works for me, if I rush and the 1st gears gate is found almost as soon as the clutch hits the floor I will have problems.
I suspect it gives a shaft inside the gearbox 1/2 second to spin down a bit to allow easier selection, dont know but makes sense to me (why thicker oil might cover up the problem??).

These gearboxes simply cannot be rushed, sort of fits well with my td4.2 non turbo engined LWB and I suspect our gearboxes are identical.

Not being a smart arse about any of this but practice it, slow stick movements through the gate, it shit's me too but if yours is like mine, i can go back and forth 5 times between 1st and 2nd with no luck in a rush and it will be 2nd that I finally get with rushed force. Doing it the slow and steady way I will only have problems if I forget and rush.

Be interested to hear if it works for you also.

cheers fnq

[4by]

Thanks fnq,

I only have a basic understanding of mechanics and your explanation and help is great.

I'm about to go out, so i'll give your scenario a try and report back tomorrow.

Muchly appreciated.

[4by]

Hi fnq,

Your remedy seems to work. Nice and slow.
It's not that I'm rushing or trying to be quick, which makes me think there still is a problem. I drive all my 4wd's and cars the same. Ive never had a problem with my old GQ or 3.0 GU, but I think they had different boxes. It just can't be right having to select 1st that slowly. If every Nissan 4by was like that, nobody would buy them.

It's still the odd time I get caught out at lights and try and select 1st and can't get it in.....
Its a pain remembering to always make sure you slowly select 1st gear.

Still, there must be a reason on why this is happening, and some way of fixing the problem. I still consider this to be a problem.

This happened once before after Nissan changed the oil at 80,000k's and they had no idea of the problem. I drove to Cape York the next day and had no problem. Nissan again changed the oil at 105,000k's (different dealer) after fixing 5th gear, and it was all good then.

Thanks again for your help fnq, at least now I can still comfortably drive my 4by. Still have to find a fix.

[HL]

It's not just 1st gear fnq, its pretty much any gear when standing still.

It's bloody annoying when the lights change and you sit there trying to jam it into 1st and the car behind you is blasting his horn........

The only way to prevent it is by leaving your foot on the clutch.

It's something that needs to be resolved.

If thats' the case, put it in reverse and floor it. That will stop the horn.

Cheers

[fnqcairns]

HL

4by Thanks for the feedback, I think you are right it's not normal although these boxes are closer to truck boxes, they are simply slow. It's a real pain when in 4wd and need to snatch 1st -it ain't going to happen!

My gearbox is really tight due to an easy life before I owned it there is 0 slop anywhere actually in the whole drive train. I put my problem down as exacerbated by this if the car was used as a 4wd and not almost totally a mums taxi I suspect the problem would be better than it is now due to wear.
It's possible you will without thinking end up halving the time it takes to grab 1st at the lights as you adapt the procedure to suit your car.

Consider giving the synthetic oil and its form of pressure additives a chance to work. It may improve yet? I will soon be changing mine to the same oil I think.

Looking to delay ending up with a loose box as long as possible and what bloke is going to argue with that!


What if anything happened after 105k to cause the problem again? I am at a disadvantage as the oil is still the same oil I bought the car with, it is just about due.

cheers fnq