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Guest Message by DevFuse

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89 GL wagon: Where are the vacuum actuator and 4wd vacuum switch located?

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3 replies to this topic

#1 kdr


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Posted 22 April 2004 - 10:19 PM

OK. I have a nasty vibration that begins at about 20 mph and peaks at 35 mph, resolving into a dull roar by the time I reach 55 mph. I've replaced tires and struts, didn't help. Oddly, the vibration will dissappear if I switch to 4wd and accelerate. When i stop accelerating the vibration returns. It is always present in 2wd. One of the univeral joints on the drive shaft (from the transfer case to the rear diff) is a bit loose, but not bad and I reckon the shaft isn't turning in 2wd anyway so this is (maybe?) not the problem. I understand there is a vacuum switch for the 4wd and an actuator but I can locate neither. Could this be teh source of teh vibration, as if somhow the car is running somewhere between 2wd and 4wd? Where are these vacuum bits? Help! I have to take the old girl to Maine (from Maryland) in June and would like to have some idea what is going on here. Thanks.

#2 Snowman


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Posted 22 April 2004 - 10:50 PM

I would actually suspect the loose U-joint in this case. The shaft is turning in 2wd, as it is still connected to the rear wheels, however it is spinning free of the tranny with no load. I would venture to say that when in 4wd, the shaft is loaded, and with pressure on the joint, it can't vibrate back and fourth.

As to the possibility of the transmission running "between 2wd and 4wd", I sort of doubt this is the case, but I know very little about the pushbuttion 4wd trannies, so feel free to correct me anyone. Usually when the 4wd controller goes out, it just stays in 2wd. Also, I think that if it was stuck in between or something like that, there would be a lot of gear-grinding sort of noises, not a vibration.

#3 calebz


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Posted 22 April 2004 - 11:09 PM

I agree with snowman. I would also check rear axles just for giggles.

BTW, the actuator solenoids are on the drivers side strut tower, near the fuel filter. The actuator diaphram is on the side of the tranny... I really don't see how they could be your problem though

#4 kdr


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Posted 23 April 2004 - 05:27 PM

Thanks all. I suppose a drive shaft replacement is in order.



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