P38 Strange vibration just started

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kooky_guy

kooky_guy

Well-Known Member
Posts
2,410
Location
Sandhurst, Berkshire
Hi Guys,

Just noticed an annoying vibration on my 98 4.6. Under load, it's fine, but on overrun and light throttle there seems to be a vibration as though I'm driving over a lightly corrugated road.

It doesn't do it all the time and I only really noticed it last night and this morning.

Any thoughts? Tyres are all good and it doesn't feel like wheel vibration anyway, more like in the drivetrain.

Guy
 
goonarmy said:
worn ujs, damaged prop?
Click to expand...

I was kind of hoping it might just be something like that (instead of gearbox, diffs etc). Do they cause this kind of symptom though? It just seemed a bit odd that it doesn't do it under load and that it's suddenly started.

I'll have to get under it at the weekend and have a good heave around. Is that still the accepted procedure for UJ testing?

Is it the p38 that has the rubber doughnut thing on the props that is prone to perishing? If so, is there any particular method to test it?

Guy
 
kooky_guy said:
I was kind of hoping it might just be something like that (instead of gearbox, diffs etc). Do they cause this kind of symptom though? It just seemed a bit odd that it doesn't do it under load and that it's suddenly started.
Click to expand...
yep thats wot me 110 did nd a noise started juyst before it failed
 
The vibration has got quite bad now.

It's only really doing it on hard acceleration and overrun. It's making some very odd noises too - occasional scraping, squeaking and the odd groaning noise.

Does that sound like a UJ? I had a quick waggle of the front prop earlier and it seemed to be ok. I'm away at the moment and it's too muddy here to get underneath it properly but I'm just after suggestions for when I get home.

As I mentioned previously, the vibration sounds and feels very much like I'm driving over a corrugated road surface.

It's all happening at once now too. I'm getting the pressure switch EAS fault every other day, some pikey in a transit smashed my mirrror this afternoon, the battery died thursday and I can't select 1st in low range! Waaaahh!!

Where's my matches?

Guy
 
Last edited:
Could be yer Viscous Coupling in the transfer box ..... Mine "Juddered" abit & I found a seized VC ... Still not fixed it though .. just dropped out the front prop ( I can go Sideways round corners now .... ( Oh the JOY of a "Powerslide" in a p38!!)
 
the hooded claw said:
Could be yer Viscous Coupling in the transfer box ..... Mine "Juddered" abit & I found a seized VC ... Still not fixed it though .. just dropped out the front prop ( I can go Sideways round corners now .... ( Oh the JOY of a "Powerslide" in a p38!!)
Click to expand...

Gawd I hope not. Ah well, back at home sometime tomorrow and got the rest of the week off so I should be able to do some checks weather permitting.

Silly question, but with the VC test, I know it needs to be in neutral but does the handbrake need to be on or off?

Guy
 
No problem to have hand brake on once its the front wheel you jack up. The hand brake acts on the rear prop shaft so will actually help your test.

My money is on worn out UJ's though. Both of mine have done this to warn of impending failure. I ignored it with my old 200tdi and my brother had a drive shaft try and come up through the floor to him!!! Thankfully I learned the lesson with the P38 and replaced UJ's as soon as problem occurred.

If it is UJ then you have to ask yourself why? with 200tdi it was combination of VC and lack of grease. P38 it was purely down to lack of grease.
 
Ok, just tried the VC test and I can just about turn one of the front wheels. It's VERY stiff though. Good job my tyres have got decent tread on them.

To me, there seems to be a lot of movement backwards and forwards on the wheel as I turn it one way then the other. Is that normal?

Guy
 
Have you examined the driveshafts while rotating the jacked wheel? Thats the first place to go if you've got excessive movement, next diff and then transfer chain.
check along the driveline to see where the excessive play starts.
 
do ya grease ya propsujs?Id change them cos its cheapest n easiest.Mine got really noisey on me 110 just before they failed
 
SpudH said:
Have you examined the driveshafts while rotating the jacked wheel? Thats the first place to go if you've got excessive movement, next diff and then transfer chain.
check along the driveline to see where the excessive play starts.
Click to expand...

Good point. I'll give it a good going over when I get home.

I've not greased the UJs - I assumed that was all done at the last service. If I end up having to do this kind of thing myself then what's the point in having it serviced?!

I'm a bit limited as to what I can do with it here on oliday.

Guy
 
Right, finally managed to get underneath it and I suspect that both UJs on the front prop are knackered - I assume there should be no movement at all? They both move up and down a bit.

There doesn't seem to be any movement at all on the rear prop UJs, so I assume this is the case.

There is a little bit of rotational movmement in the front prop as well which I'm not sure is correct. Something in the gearbox end makes a little clunk each time I rock it back and forth. Should there be any rotational movement allowed on the front prop?

I don't spose it's worth trying to grease them now since they're obviously knackered already but what sort of grease should they have? Is the prop the same stuff?

Guy
 
kooky_guy said:
Right, finally managed to get underneath it and I suspect that both UJs on the front prop are knackered - I assume there should be no movement at all? They both move up and down a bit.

There doesn't seem to be any movement at all on the rear prop UJs, so I assume this is the case.

There is a little bit of rotational movmement in the front prop as well which I'm not sure is correct. Something in the gearbox end makes a little clunk each time I rock it back and forth. Should there be any rotational movement allowed on the front prop?

I don't spose it's worth trying to grease them now since they're obviously knackered already but what sort of grease should they have? Is the prop the same stuff?

Guy
Click to expand...

General purpose grease. If there is movement in front prop at gearbox end. Check if drive flange is tight. Front drive flange connects directly to viscous coupling there should not be any movement in that. Unless you apply force to turn it. Any play must be in flange or centre diff viscous
couples to. It depends on how much play we are talking about.
 
wammers said:
General purpose grease. If there is movement in front prop at gearbox end. Check if drive flange is tight. Front drive flange connects directly to viscous coupling there should not be any movement in that. Unless you apply force to turn it. Any play must be in flange or centre diff viscous
couples to. It depends on how much play we are talking about.
Click to expand...

Cheers Wammers.

Not much play - I just wasn't sure there should be any. Think I'm going to get a garage to do the joints so I'll ask them to check it at the same time.

Since the prop is rotating slightly, that means there must also be play at the front diff end. Again, should there be?

Pretty sure the UJs are the source of the vibration now but it's worth me checking these other things out while I'm at it.

Guy
 
kooky_guy said:
Cheers Wammers.

Not much play - I just wasn't sure there should be any. Think I'm going to get a garage to do the joints so I'll ask them to check it at the same time.

Since the prop is rotating slightly, that means there must also be play at the front diff end. Again, should there be?

Pretty sure the UJs are the source of the vibration now but it's worth me checking these other things out while I'm at it.

Guy
Click to expand...
Do the ujs ya self.Cheap n easy.Use busters guide.Grease gun and grease from halfords will be fine probbaly ep2 lithium grease
 
kooky_guy said:
Cheers Wammers.

Not much play - I just wasn't sure there should be any. Think I'm going to get a garage to do the joints so I'll ask them to check it at the same time.

Since the prop is rotating slightly, that means there must also be play at the front diff end. Again, should there be?

Pretty sure the UJs are the source of the vibration now but it's worth me checking these other things out while I'm at it.

Guy
Click to expand...

Slight play in diff is usual after a few thousand miles. Comes from slop of planet and Sun wheels and slight wear in splines of halfshafts. Most of the play you feel in a diff is this and not the crown wheel and pinion. If there is no noise when driven then it should be ok.
 
SpudH said:
Have you examined the driveshafts while rotating the jacked wheel? Thats the first place to go if you've got excessive movement, next diff and then transfer chain.
check along the driveline to see where the excessive play starts.
Click to expand...

Interesting. I tried the VC test yesterday and I thought it passed. The wheel was very very hard to turn, but I did turn it.

I've just tried it again on the opposite wheel and either I'm being feeble after spending the day clearing the garage out or something is wrong.

Just how much effort should be required to turn one wheel? It is in Neutral with the handbrake on.

Looking at what's going on with the excessive movement, it all seems to be in the front UJ. One of the garages I spoke to sugggested just greasing it, but there doesn't seem to be a grease nipple on the front one - I was just trying to rotate it to check. Also there is a LOT of movement. The wheel rotates an inch either way and all that movement seems to be being taken up by the play in the front UJ. Both of the garages I spoke to seem to want silly money to do the joints for me.

I really don't want to try doing the joints myself - I tried doing them on al old Rover of mine years ago and completely screwed it up so it's put me off for life!

I note that Island 4x4 do a complete front prop for £89.99. Anyone got any experience of these? Seem to me this might be the best option, but I'm worried about the VC now.

Apologies for dragging this thread out, but I really do appreciate everyone's input.

Guy
 
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