Need help with 89 chevy 4wd front end [Archive] - MyTractorForum.com - The Friendliest Tractor Forum and Best Place for Tractor Information

: Need help with 89 chevy 4wd front end


aguysmiley
12-11-2005, 06:25 PM
Has anyone here ever had the front differential apart on one of these Chevy's? I believe they used this front end from 88 to 98.

I lost 4wd this summer in my truck. It started blowing fuses when shifted into four wheel. Yesterday I crawled under there and determined that the actuator on the front end was bad, causing the blown fuses. So I replaced it with a new one. No more blown fuses, but it's still not engaging the front end. I have tested the new actuator and it is definately working. I've got in there and pushed against the piston that the actuator pushes against, and can't get the front end to lock in. I can feel something rub in there when I push the piston in and rotate a tire by hand.

I've never had one of these apart...yet. I would like to know how this system works. I'm guessing there is a clutch pack in there that is tightened by the actuator? I bought one of those vehicle specific manuals today. That was a waste of money.

Could any of you explain to me what's inside of that differential? My problem is definately in there somewhere. Everything up to that point is working the way it should. I should also note there are no unusual noises anywhere, nor were there any when 4wd first quit working, just blown fuses.

sixchows
12-11-2005, 06:46 PM
Ken
What manual did you buy? I have a Chilton manual for 88-98 chevy/gm full size trucks.

slipshod
12-11-2005, 06:59 PM
Your Chevy has a ridgid mount front differential that powers two half shafts. If you have not used the four wheel drive since summertime and just fixed the electronic accuater control you may have a water problem not allowing the unit to go into gear. Before I tore it apart I would get the truck insind and totally defrosted, then try to engage the unit. I own an 88 and one winter I had similar problems, but not the blown fuses, just would not engage. The truck got warm the unit work. Since then I have been better about keeping fresh fluid in it.My truck now has over 300,00o on it and that unit has not been apart, I have changed out the universals, half shafts, and hubs, but not done any repair on the differential.

aguysmiley
12-11-2005, 07:00 PM
I bought a haynes. Covers 88 to 98 chevy trucks. All it has in it about the front end is how to remove and replace. Does your manual have a blown up diagram by chance?

aguysmiley
12-11-2005, 07:04 PM
Your Chevy has a ridgid mount front differential that powers two half shafts. If you have not used the four wheel drive since summertime and just fixed the electronic accuater control you may have a water problem not allowing the unit to go into gear. Before I tore it apart I would get the truck insind and totally defrosted, then try to engage the unit. I own an 88 and one winter I had similar problems, but not the blown fuses, just would not engage. The truck got warm the unit work. Since then I have been better about keeping fresh fluid in it.My truck now has over 300,00o on it and that unit has not been apart, I have changed out the universals, half shafts, and hubs, but not done any repair on the differential.

Well it's been in my garage and thawed since Friday night. Not the warmest place, but the snow and ice is long gone. I would think the problem would be something like what you are saying. Seems more like something is stuck instead of broken.

case220
12-11-2005, 09:11 PM
Does it lock in while driving? Sometimes if not used often they tend to take a while especially cold. Front diff's on these have a sliding gear to couple the right shaft together. No fiber clutch's. If you need manual I should be able to hook ya up w/ repair procedures. Will see what I've got. Will get back to ya late tonight or tomorrow. Does your 4X4 indicator light turn on? Do you know for certain that it isn't locking in or are you just going by the indicator light. There's a switch screwed into the front diff that turns that light on and off. I would drive it around a little w/ the t-case locked in and see what happens. If you don't hear any strange noises and fluid is good you should be ok to drive. If you were checking to see if it locked in with only the left side off the ground then you wouldn't have know for sure as it should be an open diff and the right side is what locks together.

aguysmiley
12-11-2005, 09:34 PM
This thing has always taken a bit to engage and disengage. It's definately not engaging the front end. I've driven it up and down my driveways several times. Rocked it back and forth for I don't know how long. Drove it down the road for about 10 miles. Ran it in gear with all four wheels off the ground. Nothing. No light, and no front wheel drive. It's real easy for me to feel when the front end is working, especially in my icy drive, but there is nothing happening up there.

I can't imagine there is anything seriously wrong in there. It worked great until that activator went bad this summer. Is it possible that that sliding gear could be stuck somehow? Gummed up from not being used in so long, or sludge maybe?

This summer I was working for a small excavating company, and had to drive through a creek everyday to get there. After reading Slip's post, I went out and changed the fluid in it. There is no water in it. It has a slight metallic tinge to it, but no chunks of any kind. Really didn't look to bad.

case220
12-11-2005, 11:00 PM
http://service.gm.com/engif/000/000/344/344345.gifHere's what ya got. Ill see if I can find yer e-mail and send ya repair guide.

case220
12-12-2005, 09:22 AM
Hey Smiley, check yer e-mail for repair guide and let me know if ya got it and if it helps.

aguysmiley
12-12-2005, 07:14 PM
I'll check in my mail. Thanks for your help.

This morning I decided to run in 4 high on my way to work to see if it would ever engage. About half way there it went in. I've worked it in and out several times today and it seems to be working fine.

I'll save that manual though for future reference. Hopefully I'll never need it.
Thanks again.

slipshod
12-12-2005, 10:59 PM
That sounds familiar!