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View Full Version : Jimmy 4x4? Issues


rraasch04
08-27-2007, 03:58 PM
Hey,

I have a 1991 GMC Jimmy that does some wierd things every once in a while. While driving, usually only happens when traveling around 55-60mph, all of a sudden there will be a humming noise from the front end. That's when I hit the brakes and it gets louder and louder until about 45-50 then "pops" and stops. I then can re accelerate up to about 60 and it's fine. Seems to be very spiratic sp? and does it sometimes while other times it does not for several trips.

So, my only thought would be that the 4 wheel drive is engaging and then as I slow down it disengages. That is about the only thing I can think of, but now idea on any solutions.

Anyone else ever seem to have any of these symtoms? Or any suggestions on fixes, or just wait until the 4 wheel drive completely goes out and not worry about it?

Thanks for reading the longest post i have ever posted on this site (and it's not even about my GA!) :)

99GrandAMSE
08-28-2007, 06:39 PM
... how does that year engage the front axles, vacuum? ... if so, check for leaks and or condition of the vacuum motor :shrug:

RazorDX
08-28-2007, 07:04 PM
If it's the same as my Blazer, it's done by mechanical switch.

99GrandAMSE
08-28-2007, 07:24 PM
I wasn't sure as I know various 4x4s that year used vacuum