4wd question

[s15jimmy]

I have a 1994 Jimmy with 4.3 Vortec and around 179k miles. I have a problem and I need some input as to whether or not this can be done.

For those of you familiar with this particular year, on the 4WD system there is a vacuum actuator under the battery. This part keeps breaking and Im tired of having to go buy one every time I leave it in 4wd without taking the vacuum off. My question is this: I know in earlier years of the Jimmy/Blazer that they had a center console shifter. Is it possible to retrofit or put in a manual shifter instead of relying on the stock vacuum system?? Im sure finding one of the center consoles and shifter would be no problem in a junkyard locally. Im just curious if anybody else has attempted this or has done it and how it can be done. Something has to give here. Im tired of losing my 4wd. Its snowing today and hubby needs to take it but now 4wd is not working, so now has to take our diesel (block heater not working but has not been replaced yet). Please help!

 

[Molson02536]

I have a 1994 Jimmy with 4.3 Vortec and around 179k miles. I have a problem and I need some input as to whether or not this can be done.

For those of you familiar with this particular year, on the 4WD system there is a vacuum actuator under the battery. This part keeps breaking and Im tired of having to go buy one every time I leave it in 4wd without taking the vacuum off. My question is this: I know in earlier years of the Jimmy/Blazer that they had a center console shifter. Is it possible to retrofit or put in a manual shifter instead of relying on the stock vacuum system?? Im sure finding one of the center consoles and shifter would be no problem in a junkyard locally. Im just curious if anybody else has attempted this or has done it and how it can be done. Something has to give here. Im tired of losing my 4wd. Its snowing today and hubby needs to take it but now 4wd is not working, so now has to take our diesel (block heater not working but has not been replaced yet). Please help!

The floor shift works in the same manor, there is a vacuum switch on top of the transfer case that is activated when you put in to 4wd. The electronic and manuel type of system works the same way.

You can convert your vacuum system to a mechanical system with the use of a cable and keep is locked in the on position. You can run the cable into the cabin or just leave it in to the engine bay to activate your front axle to lock.

Just make sure your 4wd is in the off position when your driving on dry pavements so you don't burn out your transfer case and front differential. I had the same issues with my 1996 Jimmy 4wd when my vacuum switch (which was always going bad) and my front axle was locked up for about a year and i had no issue.

I eventual changed my transfer case and replaced it with a AWD transfer case and have my front axle locked mechanically. Here is a link that shows you how to convert your vacuum system to mechanical with a cable.

http://diamond.site90.com/html/actuator.html

Good luck and keep us posted on how your project turns out.

Molson02536

 

[s15jimmy]

Molson, thanks so much for responding! What you provided helped me a great deal. Unfortunately, I keep having problems connecting with the link provided, so will have to try that at a later time. Turns out the actuator under the battery was okay (the diaphragm had not split) and all the lines were hooked up. I forgot to mention that my uncle replaced all the vacuum lines last year but I guess I have a vacuum leak somewhere still because its not working and the heat is stuck on the defroster. The driveshaft is engaging, but the 4wd is not kicking in. Any ideas?

When looking for an AWD transfer case, which one did you get? I may eventually do this depending on how much the t-case is. Did you have to do much retrofitting?

My parents use to have an 86 2-door Jimmy that I loved because of the center shift 4wd and even though it works under the same premise, it only malfunctioned once because of a bad switch and that was about a year before the head gasket went after 200k+ miles. It didnt have much power (had a 2.8) but it would go ANYWHERE you wanted to go. Same goes for this one when the 4wd works. I got the EGR issue figured out (needed revised gasket) and drive this daily. I really need to get this thing fixed.

 

[Molson02536]

Molson, thanks so much for responding! What you provided helped me a great deal. Unfortunately, I keep having problems connecting with the link provided, so will have to try that at a later time. Turns out the actuator under the battery was okay (the diaphragm had not split) and all the lines were hooked up. I forgot to mention that my uncle replaced all the vacuum lines last year but I guess I have a vacuum leak somewhere still because its not working and the heat is stuck on the defroster. The driveshaft is engaging, but the 4wd is not kicking in. Any ideas?

When looking for an AWD transfer case, which one did you get? I may eventually do this depending on how much the t-case is. Did you have to do much retrofitting?

My parents use to have an 86 2-door Jimmy that I loved because of the center shift 4wd and even though it works under the same premise, it only malfunctioned once because of a bad switch and that was about a year before the head gasket went after 200k+ miles. It didnt have much power (had a 2.8) but it would go ANYWHERE you wanted to go. Same goes for this one when the 4wd works. I got the EGR issue figured out (needed revised gasket) and drive this daily. I really need to get this thing fixed.

Cut and past the link to your search and hope that will help with the link.

Check your Vacuum line from the passenger side of your intake. The lines tee off at the back of the Distributor and replace any rotted and damaged Lines and tee. There will be a line for your cruise control, HVAC, and your 4WD.

As for the transfer case. I used one from a 91-94 Olds Bravada, Borg Warner 4472 with the front drive shaft cause they came with CV joint as to U joints in your Jimmy.

Keep us posted and keep up the good work.

Molson02536

 

[s15jimmy]

Problem found!

I feel like a real simpleton right now. Turns out the rubber diaphragm on the actuator under the battery had a small tear in it almost too small to be seen. Looks like the washer that they use on the underside had sharp edges and cut through it. Its rigged now so that I can use the 4wd and I have ordered an Airtex/Wells (arent these made by Wells?) actuator. Any thoughts on this brand? Not sure how much better it will be, but worth a try at least until I figure out when I want to convert. Still plan on converting to a manual though. It will be much simpler. Took some zip ties (go ahead and laugh!) and pulled the cable to engage the front diff so I have 4wd ability until my new part arrives. All I have to do is push the button. Just have to watch my speed until I get my new part.

Molson, thanks for all your help and suggestions. Its good to know that there are still good people out there willing to help out. Ive been working on vehicles since I was about 15, but there is so much to learn. Its amazing how much you can learn from a forum. Learned a lot about my diesel (6.0) from forums.

Stay tuned for updates. If anybody else has suggestions, feel free to chime in. If you know common problems, etc., chime in. Ive already experienced the whole EGR issue firsthand, but solved it.

 

[s15jimmy]

I found my problem and I feel like such a simpleton. It was the actuator after all. It had a small cut in the rubber diaphragm almost too small to see. Apparently the washer that they use in the bottom has sharp corners and cut through. I have already ordered another actuator, an Airtex. Any thoughts on this brand? Are these made by Wells? Any better than Dorman? I surely hope so! Ive already been through 4 actuators in the last year.

I want to see what the Airtex actuator does before I make a final decision about converting to manual, which Im sure I will probably do anyways. Managed to rig the 4WD cable with zip ties (go ahead and laugh!), so I have 4wd capability if I need it, at least until my new part comes in. Will continue to update so stay tuned.