vibration/rumbling under acceleration on 1988 3.5 efi auto

my rrc 1988 3.5 efi auto has developed a nasty vibration under acceleration, it starts just above 2000 rpm and is at its worst around 3000.

the vibration stops as soon as i let off the gas regardless of road speed which leads me to believe its not too much to do with the drive system/shafts etc.

i am confused as the engine revs ok with no load.

this problem has arisen after greenlaning, i have cleaned the vehicle and had a look underneath and cant see anything untoward going on.

i was wondering if anyone else has experienced this and/or could point me in the right direction of investigation.

Thanks

Possibly engine mounts

V8 Bruiser said:

my rrc 1988 3.5 efi auto has developed a nasty vibration under acceleration, it starts just above 2000 rpm and is at its worst around 3000.

the vibration stops as soon as i let off the gas regardless of road speed which leads me to believe its not too much to do with the drive system/shafts etc.

i am confused as the engine revs ok with no load.

this problem has arisen after greenlaning, i have cleaned the vehicle and had a look underneath and cant see anything untoward going on.

i was wondering if anyone else has experienced this and/or could point me in the right direction of investigation.

Thanks

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if your motor revs freely under no load conditions i think you will find that the problem IS transmission related either gearbox/transfer box , props , or diff , a failing pinoin bearing will give the symptoms you describe , i suggest you look closely at the transmission mate...............sorry!!!
rick.

check yer prop uj's

clutchdust said:

check yer prop uj's

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Yeah i'll 2nd that, had the same on my disco at 2000 revs, turned out to be a nakered uj on the front prop

Torque rod bushes? If range rovers have such a thing.

Had the same thing going on with my old volvo, changed the torque rod bushes, problem solved.

Stu.

i would go for bushes or UJ too, get under it and look at the UJs you shouldn't have any slack/play on them as you twist and turn them with your hand

Dopey said:

i would go for bushes or UJ too, get under it and look at the UJs you shouldn't have any slack/play on them as you twist and turn them with your hand

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its better to actually remove the props when checking them for wear because once removed they can then be rotated through their axis and any tight spots are easily felt ( obviously there should`nt be any ) this cannot be done whilst they are fitted on the vehicle , and such wear can also produce the symptoms you describe .
rick.

If your going to take it off, then do that and give it a drive, if it has stopped the vibration then you'll have cracked the problem, for short periods it isn't a problem to drive around like that, but don't go driving around at 90 mph like that, be a little sensible about it and it should be fine just leave it off for a few days until you have replaced it (get new bolts and nylocks though they do stretch and its good mechanics to do so)

You can just change the UJs its easy enough, but fiddly and you need a #1 (big hammer) so its not a gentile job, get GKN Hardy Spice UJs there one of the better makes, but if your got the £££ then get a prop because to be honest the jobs a pain in the ass

Dopey said:

If your going to take it off, then do that and give it a drive, if it has stopped the vibration then you'll have cracked the problem, for short periods it isn't a problem to drive around like that, but don't go driving around at 90 mph like that, be a little sensible about it and it should be fine just leave it off for a few days until you have replaced it (get new bolts and nylocks though they do stretch and its good mechanics to do so)

You can just change the UJs its easy enough, but fiddly and you need a #1 (big hammer) so its not a gentile job, get GKN Hardy Spice UJs there one of the better makes, but if your got the £££ then get a prop because to be honest the jobs a pain in the ass

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if you use a big hammer to change your u/j`s mate its no wonder you find its a pain in the ass , as for exchanging the prop........... why at worst it may need a balance , not a fortune , over the years ive must have changed hundreds of u/j`s not just in cars and 4x4s but also heavy commercials and plant equipment and tbh in all that time ive never had to use a big hammer , a press is the best method by far , i know most on here would not have access to such kit but , in realality you dont need one for any 4x4 u/j once the circlips are out the u/j can be removed quickly and easily useing a copper hammer , and best pushed back in useing a decent vice and a socket to push the bearing cup home , its not that hard to renew both u/j`s from start to finnish in half an hour per prop .
rick.

I don't have a good vice (other than smoking drinking and girls, but that’s a different thread yea?) I don't have a copper hammer, and i have never changed a prop on a RR either, but i have changed plenty on my SII and i have used a hammer because i had to, getting them in is easy, getting them out is a pig, its a job i don't like and can think of better ones to do, ralko bushes are a pain too, so is changing a gearbox, some jobs i don't like, some i don't mind doing, that’s why i think its a pain in the ass, is that fair enough?? I built my SII up in the front garden from the chassis up (ok i was an idiot for striping it down in the first place) took me 2 years, no garage or air tools etc, but i do with what i have i’m no mechanic, and i don't pretend to be one, but when someone asks for help i will try and help, but i’m not a total fool and have a C&G (Distinction) in mechanics, and the advice i gave him was good advice

ok dopey put yer toys back in yer pram mate i was`nt having a go at you ( you would know if i was ) i was just trying to point out theres more than one way to skin a cat , ive been a hgv mechanic for more than 37yrs and also have c+g and also maybe enough certificates and other such like to repaper your living room , when it come to the stick and lift mate they arnt worth diddly , also you dont need to preach to me about doing jobs outside and making do with whats available at the time , you may find i just have the edge on you there !.
we all share a similar interest in our vehicles and, just the same as you i was also trying to give the guy some good well meaning advice , so is that fair enough for you !
rick.

i have checked the props and the uj's on the vehicle and they feel pretty solid. gave them a good greasing while i was there. the vibration is still present albeit not quite as bad, i think. its hard to tell!
will try getting them off one evening this week, is it as simple as unbolt and drop out or shall i allow a good few hours?

Its about a 10 min job or less some bolts are hard to get at, helps if you have a thin socket too, snap-on is ideal they have thin walls on them, remember which way it came off!!! some put them back the wrong way around (Or try to)