Another mini truck owner friend came to visit me yesterday and we went for a ride in my 91 S83p through my woods on my logging trail the day after a rainstorm. At the end of the trail were some rain filled ruts left by a jumbo loader. My rear wheel was spinning in the rut mud. I was stuck. I was in LOW, which I always assumed was 4WD, but neither front wheel was turning, just the rear tire was spinning. I had to get the skid steer and pull myself out with a chain, a bit embarrassing since I'm sure it would have extricated itself if the front wheels were really in 4WD. Later I raised the dump bed and my friend moved the lever from HI to N to LO and I watched the mechanism in the back as the cylinder went out to an intermediate position and out about an inch. I've been assuming for a couple years that when I was in LO I was really in 4WD, but it took that mud hole to show me that I've been fooling myself all along. Can anyone tell me what things to check first and any potential/likely reasons and fixes? When I'm in HI and press the button on the lever, the green 4WD dash light goes on, as well as when in LO, so that was enough to trick me into thinking I had been in 4WD in the past. Any ideas? Thanks.
There should be a vacuum servo on the front Diff. Check to be sure the vacuum tubes are intact - can you see it move when you activate the 4WD button - engine running of course ?
Thanks, I'll go out and try to get oriented and look for the vacuum servo and take some photos. It would be very convenient and probably cheap if the problem was just a broken hose.
trying to sort out the front differential vacuum servo mysteries After I learned what I should look for first, I found a post by fupabox that told me where to look. I discovered two things that were not right. One was a disconnected wire from the front differential servo. I could not plug them together again, apparently when the body was lifted 2 inches with blocks, the wires were no longer long enough to connect. If that wire does anything useful, I'll have to splice in a couple inches to make the male and female connector parts reach each other. I found the two hoses coming from the vacuum servo. One of them travels up to a cluster of vacuum hoses and is connected up there and looks okay. The other hose goes from the servo body to a retainer clip and then ends and connects to nothing. I could not see immediately where that hose was supposed to connect to. I could not tell if it was now too short after the lift, what its normal length was, or if it was normal or cut off. What is it supposed to connect to? The actuator on the servo does not look like it has moved in a while and has a rusty cotter pin. I'll try to clean it up a bit and lubricate and then if I get the wire and hose reconnected (assuming I can figure out where the hose is supposed to connect to) I can see if that servo is moving.
It's a good idea to replace any vacuum tube that you don't know the age of.They cause more problems on these little trucks than any other single item.Best part is they are cheap.
I'll be happy to replace the hoses... but I need to figure out where the free end of one of them is supposed to plug into. I haven't located a diagram or schematic yet.
I just looked at mine, and I traced that hose to the furthest rearward port, directly in front of that green plug in one of your pictures. (Below and to the right of the shifter under the drivers seat) it looks like there two ports facing down, it goes to the back one. I think the wire is just a ground. I doubt it is causing any issues, but you may as well hook it back up... Do you happen to have any pictures of how the steering is setup with your "body lift"? I've been thinking about doing it on mine, but I haven't decided how I want to tackle that part of it. Any modifications to the front control arm mounts?
I soldered in a 4" extension to the separated wire (most definitely a ground wire, since it was connected to a bolt going into a solid casting) and then it was long enough to reconnect. I tried an angled mirror and flashlight and fished around with my fingers for quite a while trying to find any nipple that might accept a vacuum hose in the general area that the tube pointed when in the clip, but couldn't detect anything in the failing light even with a flashlight. I stuck my camera in there and fired away with the flash on hoping to find some clues. in my photos I put bit of red tape on the end of the disconnected hose so it would be evident in the photos. I kept the few photos that showed the green plug you mention and the disconnected tube marked with red tape. I never felt with my fingers anything to plug into but at least now with your kind help I know where to look... and see if the hose is still long enough to reach there. The photos I had that were in the right general direction to show part of the green plug and the open red taped end of the disconnected tube don't really show any open port near the green plug, too much stuff blocking the view, so tomorrow I'll just keep feeling around near the green plug for anything that seems like a possibility. I pulled out the servo's actuator by the cotter pin and it does move, so I know it isn't completely stuck. Aaron, regarding the lift, John the welder at JD Minitrucks extended the steering column a couple inches and used mostly 2" square tubing all the way around to lift the whole body. I put 2" lift kit spacers for the struts. I should have photos of most of it someplace if I can dig them out. I'll have to see if they include the end of the steering column. Otherwise I'll take some new ones for you of the steering column extension.
Aaron, initially I was having trouble interpreting your description of the correct port for the vacuum hose. Eventually the thing that I thought was some sort of "knob" for that green electrical plug turned out to be some sort of plastic cap covering over a port that had a little quarter inch of rubber hose left on it. I took my old hose, which was about 13 inches, into the parts store and asked for a new one, but 24 inches long. The old hose was about 2 inches to short to reach the port above the green plug, perhaps because of the lift. I put the new hose on the servo port and the other end on the port above the green plug, started the engine, put the stick shift in neutral and the range lever in HI and pressed the 4wd button. I had previously put some oil on the cotter pin and that joint. I could hear some faint click and some vacuum sounds, but the actuator didn't seem to move. I thought maybe it moved a millimeter or so, but I'm not sure if that was wishful thinking. How much travel is there supposed to be in that actuator when the 4wd button is pushed? What am I supposed to see happen exactly? I don't think it is going into 4wd. I drove it around and tried the button but nothing seemed to change. Some photos below, did I actually get the other end of the hose where it was supposed to go?
I took a couple pictures to better explain where the hose goes. The arm on the actuator has about an inch of travel I believe... it was early in the morning here when I took these pics, so I didnt want to start the truck and take pictures in its on and off positions. (Slight exhaust leak on mine, and the rest of the family is still sleeping...) It's a lot easier to see where the lines go if you remove the 1 10mm bolt under the drivers seat and drop the vacuum assembly down. Here's some pictures... I'm pointing right at the hose that goes to your front diff actuator in the one pic. You will hear a faint click from the rear actuator, as well as one from that front one. If the front wont move all of the way, you might try taking out the cotter pin and manually moving it back and forth to help free it up. Good luck!
4WD working now!!!! Thanks for all the help! Aaron, that photo saved the day! I took out the 10mm wrench, looked at the cluster, finally figured out the right angle to look at it from, and then I saw the offending open port. The thingy I put my hose on at first by the green plug needs to be left open (the reason for that cap thing I suppose keeps dirt out or something). I plugged my hose to the right place, put it back together, started it up, and the actuator worked! Took the truck out on the woods train just after the thunderstorm filled all the muddy ruts with rainwater and it sailed through everything without getting stuck! I have a small video that of the actuator working but you can't attach videos directly here, only still images.
yes, all is well with the 4WD assuming I can find the little cap on port I wrongly put the hose the first time. My kids were playing in the cab and I think they may have borrowed it. I'm not even sure what those things are called or if they have any filtering function, it seems they must have some function of allowing air to move into the port but protect it from dirt. Hard to look for a replacement on ebay or amazon or the local parts store if you can't guess what they are called with success.
It is called a VSV ( Vacuum solenoid valve ). I had some trouble finding one for my fuel vapor system. so they may be hard to find. I would think that a filter off any VSV should do, or just make one from a bit of open cell foam - it is just to keep chunks out of the valve. Bob Jonah
I guess I'll give one more attempt at locating it where the kids were playing before the lawn mower finds it. I have to keep the cab locked usually because they find it irresistible. Thanks for the nomenclature Bob!
