4wd A.d.d.

[lincolnchuck]

My problem is when i put it into 4WD the front axle is not locking in. The front driveshaft spins when shifted into the 4WD. I have auto hubs but the wheels arent locking in. So I did some troubleshooting with the two hoses going to the driveshaft. When i disconnect the red marked hose and connect it to a vaccum on the engine then the 4WD locks up and the 4WD works. I hook up the blue marked hose to the vaccum and the 4WD disconnects. So then i hook the hoses back up to the ADD to see if it will work the factory way and it doesnt. SO is the ADD bad or is it the vaccum tank by the front right fender. i am so confused. my ride is a 1995 T4R V6, with IFS, w/auto locking hubs.

 

[fourwd1]

The ADD system doesn't have auto hubs, it has drive flanges (kind of like manual hubs that are always locked). Maybe a PO added them?

If in your tests you were using a vac source other then the normal one for the ADD system (which it sounds like you did), then yes the vac tank/line could have a leak somewhere. The vac switches on the ADD system sound like they are working OK.

 

[lincolnchuck]

JUst so i understand the 4wd hoses are connect to a unit that is bolted over the passenger side fender. There is a red and blue electronic thing. i traced the hose to the vaccum tank and there are no holes. the only why i could find out is to put a vaccum tester on it.

 

[lincolnchuck]

so i think the vsv might be broken. i was reading on another forum site and it said that i could just leave the hose that locks in the front diff. on to a vaccum line off the engine and do away with the VSV. is that true? Also could i disconnect the vaccum tank and run a line to the VSV to see if it will work?

 

[fourwd1]

Look here and here for some info that will help.