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1999 3.5 Six and 5 spd manual jumps out of 4 WD high

rgouinrgouin Posts: 3
edited March 2014 in Isuzu
I have a 1999 Trooper 3.5 Six with a 5 speed manual and manual Aisin hubs. I am having problems with the 4 WD. When I engage the 4X4 dash switch in 4 WD High, it constantly jumps out of gear. However I have no problems with this jumping out of gear when it is in 4 WD low. The 4X4 has not been used that much. I am wondering if anybody else out there has had similar problems, and what might be the cause as well as what did they do to correct the problem. All replies requested and welcomed.


  • Does the transmission jump out of gear when in 2wd Hi?
    Just curious about how the transfer case gear selection can effect the transmission gear selection. Is there different loading in the drivetrain? Maybe when in 4wd hi turning both front and rear axles gets stress between them and puts a twist on the whole drivetrain which the transmission is sensitive to? Are there drive train mounting point that have worked loose enough to allow this possibility of twisting? All I can guess that is different in 4wd Hi vs Lo is the amount of torque on the transmission is higher, if you are on good traction such as pavement in 4wd the differences in front and rear axle speeds like when turning a tight turn can place a lot of torque on the transfer case and transmission until a wheel slips to release the torque.
  • No not at all. The 2WD drive operates perfect. I drive it every day and have taken it on a 500 mile trip. I did get in a rough area that required 4WD but ahd to use the low range. I am wondering if it might have a problem in the vacum system or maybe there is a promblem with a vacum switch. Any thoughts on this idea. I have ask the local Isuzu service shop and the said that I might check this out as to a vacum switch, but I have no idea where to start on this area..
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