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Discussion Starter #1
OK, I’ve had this intermittently now for 2 years and had it in to be checked twice but, as it wasn’t recreated under test, I’ve not had a diagnosis. However it’s got far more regular today. Typically the day before I planned on a 700 mile round trip!!!!!

When I’m coasting there’s a knocking coming up from what feels like the gearbox (I feel it through the clutch too). The severity is varied but always noticeable and disappears as soon as I put anything on the accelerator.

Just sitting on the drive there with the engine ticking over and there’s very little knocking but when I dip the clutch slightly the knocking starts (if I push to the floor it goes away again).

I’m not expecting a diagnosis but has anyone any idea what this is? I’m thinking clutch (replaced about 40k ago) and hoping not gearbox.

I’ve had diagnosis of “stone stuck in the engine tray” and “exhaust starting to go” previously but that seems unlikely given what I’ve described.
 

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Have you checked the propshafts? The uj's, especially the rear joint on the front can give trouble.

Other than that, probably the gearbox. The good news is that they are pretty cheap secondhand.
 

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Discussion Starter #3
Thanks for getting back so quickly man.

I have to hold my hands up to being a novice so I’ve crawled about underneath looking for something obvious but actually checking anything. I put a bit of trust in the mechanics to check these things.

What should I be looking for in the things you suggest?
 

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Thanks for getting back so quickly man.

I have to hold my hands up to being a novice so I’ve crawled about underneath looking for something obvious but actually checking anything. I put a bit of trust in the mechanics to check these things.

What should I be looking for in the things you suggest?


Check for movement in the joints by trying to turn it while holding one side still. There should be no play at all.
 

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Discussion Starter #5
Thank you guys, I’ll try to have a look before I head off today. If it is the UJ’s, Milner have them for £12 each but I’m thinking 2 years worth of rattling about will probably have damaged the knuckle too so replacing the lot might be a good idea?
Found a couple of options;
Milner have a complete after market (£155)
Billcar have a complete Nissan (£330)
Would the OEM necessarily be the better option?

Look like just a flanged connection at each end so should be easy enough to change out. Am right in thinking this or is there more to it? Thinking I should probably replace the bolts too if I’m going down that route.

Off now to prep my wife’s (mug smaller) car for the journey now...............
 

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Thank you guys, I’ll try to have a look before I head off today. If it is the UJ’s, Milner have them for £12 each but I’m thinking 2 years worth of rattling about will probably have damaged the knuckle too so replacing the lot might be a good idea?
Found a couple of options;
Milner have a complete after market (£155)
Billcar have a complete Nissan (£330)
Would the OEM necessarily be the better option?

Look like just a flanged connection at each end so should be easy enough to change out. Am right in thinking this or is there more to it? Thinking I should probably replace the bolts too if I’m going down that route.

Off now to prep my wife’s (mug smaller) car for the journey now...............
Honestly if your unsure get somebody who is to do it !!! the bolts can be awkward !!! I wouldnt be swapping the shaft without being 100% sure its the shaft.Certainly changing the UJ is not a novices job.
It certainly sounds like a joint but cant understand how it has held on for 2 yrs without it ending up in the road.
 

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Discussion Starter #7
It certainly sounds like a joint but cant understand how it has held on for 2 yrs without it ending up in the road.
I don’t do a lot of miles so I can only assume that’s why it’s lasted.

Didn’t get a chance to look properly this morning so it’ll be a few weeks before I can do anything about it now anyway.

Thanks again for the advice.
 

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Check both the front and rear prop UJ, as even when in just 2WD the front prop will spin.
I replaced all 4 of mine.
This video shows excessive play in the rear/front UJ.
Just grab the prop near the Uj's and waggle it about, if you have any movement (other than the tiniest amount, almost nothing) then they need changing.
https://youtu.be/m7gCc2zFKJE
 

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Check both the front and rear prop UJ, as even when in just 2WD the front prop will spin.
I replaced all 4 of mine.
This video shows excessive play in the rear/front UJ.
Just grab the prop near the Uj's and waggle it about, if you have any movement (other than the tiniest amount, almost nothing) then they need changing.
https://youtu.be/m7gCc2zFKJE
That video in my experience wouldnt be typical of UJ wear . The knocking sound the OP is experiencing will be coming from rotational wear with the needles wearing and cracking up so when under load there is no knocking because of the torsional loading however when free wheeling the play causes the knocking. It will be evident by grabbing both sides of the joint and checking for rotational play which should be totally non existent. Have seen many uJs that dont have any sideways movement as demonstrated by the video yet are shot. Usually this type of wear will first manifest itself as an unknown squeak when coasting,however the OPs will be past this point if its the UJs.
 

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Discussion Starter #11
Thanks for all the advice gents, always grateful for the help.

Still away at the moment but I’ll try to check on Monday then go from there.

I’ll post the (hopefully) final conclusion when I get the work done.
 

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Oh. I may be about to say the dumbest thing today, possibly ever, but does the D40 not disengage the front hubs when in 2WD?
 

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Oh. I may be about to say the dumbest thing today, possibly ever, but does the D40 not disengage the front hubs when in 2WD?
I think it's more that the transfer box is not engaged when in 2wd, so no actual drive from the box, however the front wheels still rotate the front prop.
 

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Yep, up until a couple of decades ago various 4x4s were often fitted with automatic free wheeling front hubs. This meant that the front prop, diffs and driveshafts din't turn unless 4x4 was engaged at the transfer box.
Due to the hub design from the D40 onwards this isn't possible.
 

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Yep, up until a couple of decades ago various 4x4s were often fitted with automatic free wheeling front hubs. This meant that the front prop, diffs and driveshafts din't turn unless 4x4 was engaged at the transfer box.

Due to the hub design from the D40 onwards this isn't possible.


Hmm, more recently than a couple of decades I think. I’m pretty sure many current IFS off roaders still have automatic hubs - and the 70 Series Land Cruiser still has manual ones! (Actually now I think they’re “auto” and “locked”, but you still need a wheel brace to change them.)

I must say I’ve not paid much attention to my truck. I’ll mark the front shaft tomorrow and go for a drive.
 

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Discussion Starter #20
OK, been under the truck this morning and U joints all seem fine (absolutely no rotational or lateral play).

However, on the front prop there is rotational play between the front (thick) section and the back.

Also noticed that the shaft doesn’t run straight between U joint connections, by that i mean there’s an angle at the point the front and back section meet. Are these meant to be floating or should it be a rigid connection right through?

Had a look for anything loose while I was there but saw nothing.
 
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