Nissan Patrol Vibration

Hi, I have a 1995 Nissan Patrol SLX GR SWB its a 4.2 Diesel and all
seems to be in shape BUT has a horrible low rev vibration which
dissappears as soon as you are above 1000rpm (ONLY WHEN YOUR MOVING NOT
STATIONARY)

However I removed the rear prop and drove in 4wd (well front wheel
drive) and the vibration dissappeard - However I replced the rear prop
with a new one and the vibration came straight back????

I've taken the Vehicle to the Nissan Dealer in Trowbridge Wilts (They
knidly charged me £50 to tell me they can't work out what it is and
fobbed me off to go elsewhere!)

I've also checked all the exhaust system nothing wrong there and all
the gearbox mounts etc seem OK.....

I'm tearing my hair out and no one seems to have any idea, I can't
believe I'm the only person to have had this as its certianly very
noticable!

Please Please Please someone help - any ideas more than welcome
(Although I dont wanna sell it thanks



All the brakes/steering etc are sound as a pound, and the suspension
feels/looks good??? - I've also jacked the vehicle up and run it on
axle stands but without the initial load you dont seem to get the
fault??


Thanks guys and gals

Dave

Einstien wrote:
> Hi, I have a 1995 Nissan Patrol SLX GR SWB its a 4.2 Diesel and all
> seems to be in shape BUT has a horrible low rev vibration which
> dissappears as soon as you are above 1000rpm (ONLY WHEN YOUR MOVING NOT
> STATIONARY)
>
> However I removed the rear prop and drove in 4wd (well front wheel
> drive) and the vibration dissappeard - However I replced the rear prop
> with a new one and the vibration came straight back????
>
> I've taken the Vehicle to the Nissan Dealer in Trowbridge Wilts (They
> knidly charged me £50 to tell me they can't work out what it is and
> fobbed me off to go elsewhere!)
>
> I've also checked all the exhaust system nothing wrong there and all
> the gearbox mounts etc seem OK.....
>
> I'm tearing my hair out and no one seems to have any idea, I can't
> believe I'm the only person to have had this as its certianly very
> noticable!
>
> Please Please Please someone help - any ideas more than welcome
> (Although I dont wanna sell it thanks
>
>
>
> All the brakes/steering etc are sound as a pound, and the suspension
> feels/looks good??? - I've also jacked the vehicle up and run it on
> axle stands but without the initial load you dont seem to get the
> fault??
>
>
> Thanks guys and gals
>
> Dave
>
rear diff?

Possibly, BUT I took it to a transmission specialist and theythought it
would be very unlikely that the rear diff would only vibrate at low
speed like that, and be silky smooth at speed???

I did replace the diff oil and there where no signs of burnt or poluted
oil, and no excess of bits on the magnitic drain plug?

Is there any way to test the rear diff?

Einstien wrote:
> Possibly, BUT I took it to a transmission specialist and theythought it
> would be very unlikely that the rear diff would only vibrate at low
> speed like that, and be silky smooth at speed???
>
> I did replace the diff oil and there where no signs of burnt or poluted
> oil, and no excess of bits on the magnitic drain plug?
>
> Is there any way to test the rear diff?
>

It sounds to me like a dodgy bearing somewhere between the
the transfer box and the rear diff inclusive. It only
happens under load, so I'm pretty sure its in the drive
train, not suspension or anything else.

What about some of the bearings? It might also be in the
transfer box, rather than the diff. It be that when you
unload the bearings and gears by taking the propshaft off,
that you stop some worn parts rubbing together.

I'd check your t'box oil and see what's in that.

Also, you could jack the vehicle while in RWD, take off the
prop shaft, run the engine in gear REALLY slowly and see if
you can feel anything on the end of the prop shaft. Make
sure somebody is nearby to turn off the engine very quickly
if you need them to.

You might also be able to turn the t'box output shaft with a
wrench and see what you can feel.

Get a magnetic telescopic retriever and go fishing in the t'box?

No other suggestions I'm afraid except opening up the t'box
and rear diff housings and having a good look.

Tim

"Einstien" <[email protected]> wrote in message
news:[email protected]...
Hi, I have a 1995 Nissan Patrol SLX GR SWB its a 4.2 Diesel and all
seems to be in shape BUT has a horrible low rev vibration which
dissappears as soon as you are above 1000rpm (ONLY WHEN YOUR MOVING NOT
STATIONARY)

In no particular order.

Engine dynamic balancer/crank pulley.
Propshaft. A new unbalanced one is not unknown.
Bearing in gearbox, especially the transfer box. Is the transfer chain
driven with an offset between the rear and front?
Free wheel hubs.
Diffs or axle drive shafts.

If it is the dynamic balancer then it will get worse and probably throw
fanbelts at high revs.

Huw

Guys,

Thanks - I'm not convinced it's anything in the Engine as it only
happens when your moving - If I add load to the engine by trying to
pull away with the hand brake on it doesn't do the vibration...

As for the Prop, I've tried 2 and had mine tested, so definatly not the
prop.... I suspect as you lot suggest the fault lies either in the
transfer box or the rear diff, my question is =

How do I work out which one is at fault? - Obviously both still turn
when you drive in front wheel drive, but neither the rear output or the
input to the diff have any load?? I cant feel any play on either
flange???

Help... And Thanks in advance!

Dave

The other thing is I cant believe I'm the only person to have
experienced this.... I did find another post on Google Groups, BUT no
answer, just another person saying "Yeah I have the same fault" -
Shouldn't Nissan have had some knowledge of the fault?????

"Einstien" <[email protected]> wrote in message
news:[email protected]...
> Guys,
>
> Thanks - I'm not convinced it's anything in the Engine as it only
> happens when your moving - If I add load to the engine by trying to
> pull away with the hand brake on it doesn't do the vibration...
>
> As for the Prop, I've tried 2 and had mine tested, so definatly not the
> prop.... I suspect as you lot suggest the fault lies either in the
> transfer box or the rear diff, my question is =
>
> How do I work out which one is at fault? - Obviously both still turn
> when you drive in front wheel drive, but neither the rear output or the
> input to the diff have any load?? I cant feel any play on either
> flange???
>
> Help... And Thanks in advance!
>
> Dave
>

The most practical course of action is inaction until it gets worse and is
easier to diagnose. It's a damn machine you see. It is prone to malfunction.

Huw

Indeed possibly doing nothing was the best plan - however I think the
vehicle is going to shake itself to bits, so.......

I changed the transfer box over the weekend (boy are the nuts on the
end of the main shaft in the transfer box on tight!!! ) AND the
vibration was exactly the same......

My question is - what in the diff could be causing this??? I still
cant help feeling that bearing in mind it is so rev related its more in
the engine????

"Einstien" <[email protected]> wrote in message
news:[email protected]...
> Indeed possibly doing nothing was the best plan - however I think the
> vehicle is going to shake itself to bits, so.......
>
> I changed the transfer box over the weekend (boy are the nuts on the
> end of the main shaft in the transfer box on tight!!! ) AND the
> vibration was exactly the same......
>
> My question is - what in the diff could be causing this??? I still
> cant help feeling that bearing in mind it is so rev related its more in
> the engine????
>

In your last post you said "I'm not convinced it's anything in the Engine as
it only
happens when your moving - If I add load to the engine by trying to
pull away with the hand brake on it doesn't do the vibration..."

I still think it may be harmonics but I am not experiencing what you are so
can only take wild guesses. Certainly if it was a four cylinder then there
could be crank balancer problems which would be more severe and consistent
than a harmonic balancer problem on your 4.2.
You should be able to isolate the vibration by its speed. Is it relative to
revs in isolation or to revs which vary by gear selected or is it relative
to road speed only or to road speed and gear selected.
Use a simple process of elimination and if that fails.......the only course
left is to tear your hair out by the roots.

Huw

Huw