Birty Dastards Jeep Club

Tech Forum => Workshop => Topic started by: 249raf on January 07, 2010, 06:48:58 PM

Title: I donno what it is do you?
Post by: 249raf on January 07, 2010, 06:48:58 PM

Hi Guys ive got a 93 YJ4.0  and ive got a strange issue.

A couple of weeks ago i went through a big puddle and the motor started running rough, it started a gentle judder on acceleration which gets more pronounced as the revs build, aah damp in the HT leads i thought, so i gave them all a liberal dose and went on holiday for Christmas.

Got back this week and thought, sleet, snow,  i best use the jeep

In 4 wheel drive mode the car drives normally as it always has, put it into 2 wheel drive and the judder and vibration starts again, it feels like she's running on 5 cylinders, put it back into 4 wheel and its all smooth again, put it in Nuetral and it purs like a kitten

im confused


ian

Title: Re: I donno what it is do you?
Post by: Panic mechanic! on January 07, 2010, 07:24:58 PM

what speed does the judder come in at?

Title: Re: I donno what it is do you?
Post by: 249raf on January 07, 2010, 07:38:55 PM

from around 10 mph but it feels the same in each gear so im not sure its speed related

ian

Title: Re: I donno what it is do you?
Post by: Panic mechanic! on January 07, 2010, 07:47:44 PM

make sure your vacuum disconnect on the front axle is unlocking , you can get a vibration from the front axle  if it isn't disconectiong properly , when in 4wd you won't get it as the shaft is being driven by the engine.

Title: Re: I donno what it is do you?
Post by: 249raf on January 07, 2010, 07:55:49 PM

thanks, matey

Title: Re: I donno what it is do you?
Post by: 249raf on January 07, 2010, 08:24:12 PM

Quote from: Panic mechanic! on January 07, 2010, 07:47:44 PM

make sure your vacuum disconnect on the front axle is unlocking , you can get a vibration from the front axle  if it isn't disconectiong properly , when in 4wd you won't get it as the shaft is being driven by the engine.

How can i check the vacuum disconnect is working, it does sound like thats the problem

Title: Re: I donno what it is do you?
Post by: Panic mechanic! on January 07, 2010, 08:38:12 PM

you can  pull off the vacuum lines and feel for suction in each of the lines as the  transferbox is selected between 2wd and 4wd, in 4wd your whole front axle is driven , when you select 2wd the disconnect unlocks the front off side drive shaft and  allows the centre diff to free wheel as it were, not being driven it will turn either slowly or possibly not at all so no problem, if it has not released  it will spin the diff and the front propshaft as well, as none of these items are balanced it can cause a  feeling of judder/vibration when the vehicle is in motion.
It may not sort your problem but its a recent phenomina I have found on other jeeps sites and seems quite common