Transfer case vacuum switch

[drdd]

Hello all! It's been awhile since I've been on the boards here.

Well, my 97 Jimmy has the classic "tranny fluid in the vacuum ball" along with some weird defrost vent behavior. Anyhow, looks like I'll be replacing the transfer case vacuum switch.

Any suggestions for doing this on a 97? special tools or tricks? gotta pretty much do it by feel right? cuz I can't see anything around the T-case.

after I replace the switch, I need to drain and refill Tranny and drain and refill T-case. Then I'll blow out all vacuum lines with air and let drain if necessary. Anything else?

EDIT: also, how do I know if the problem is the vac switch or the seal btwn tranny and T-case ??

[MT-2500]

Originally Posted by drdd

Hello all! It's been awhile since I've been on the boards here.

Well, my 97 Jimmy has the classic "tranny fluid in the vacuum ball" along with some weird defrost vent behavior. Anyhow, looks like I'll be replacing the transfer case vacuum switch.

Any suggestions for doing this on a 97? special tools or tricks? gotta pretty much do it by feel right? cuz I can't see anything around the T-case.

after I replace the switch, I need to drain and refill Tranny and drain and refill T-case. Then I'll blow out all vacuum lines with air and let drain if necessary. Anything else?

EDIT: also, how do I know if the problem is the vac switch or the seal btwn tranny and T-case ??

If getting transmission/transfer case fluid in vacumn lines go for a transfer case vacumn switch.
If the vacumn lines have fluid in them best to replace them because fluid in them makes them swell up and get soft and not hold vacumn on ends/or come off on ends.
If seal is leaking between transmission and transfer case it lets fluid out of transmission and ets it go back into transfer cae causing it to over fill.
Is your transmission getting low and or transfer case over full?

On replacing transfer case vacumn switch sometimes lowering transfer case helps give a little more finger working room to get to switch.

Also if ball vacumn ball or front axel pancake or switch and line have fluid in them they need cleaned out.
Also ckeck vacumn lines to heater controls and or switch.
Good luckm and let us know how it goes.

[old_master]

Transfer case vacuum switch is a 10 minute job to replace. Gotta do it by feel alone. Reach over, (from rear of vehicle to front) the frame crossmember, unplug the vacuum connector, (pulls straight off) use a deep well socket and a flex head 3/8" drive ratchet.
http://www.oreillyauto.com/site/c/de...eyword=600-500

As for the lines, transmission seal and transfer case seal, MT hit the nail on the head!

[drdd]

Thanks All.

Easy job. I got the T-case vacuum switch out with just a 7/8 wrench. 5 minutes tops.

I took off the vacuum ball and applied a hand-vacuum pump to get out any fluid. This got most of it, but I let it drain over night just to be sure. I blew out all the vacuum lines with compressed air (gently). I had some extra hose so I replaced a few of the lines (the ones that were easy to get to

I bought the switch new from the dealer ($45). It didn't come with an o-ring so I bought one at the hardware store. It's a #54 o-ring (11/16 x 9/16 x 1/16).

The hardest part was getting the new switch to catch the first thread.

My tranny fluid was not low so I think it was just the switch, not the seal btwn trans and t-case. I'm gonna test drive it a little and re-check the fluid levels just to be sure.

Thanks again guys!

[MT-2500]

Originally Posted by drdd

Thanks All.

Easy job. I got the T-case vacuum switch out with just a 7/8 wrench. 5 minutes tops.

I took off the vacuum ball and applied a hand-vacuum pump to get out any fluid. This got most of it, but I let it drain over night just to be sure. I blew out all the vacuum lines with compressed air (gently). I had some extra hose so I replaced a few of the lines (the ones that were easy to get to

I bought the switch new from the dealer ($45). It didn't come with an o-ring so I bought one at the hardware store. It's a #54 o-ring (11/16 x 9/16 x 1/16).

The hardest part was getting the new switch to catch the first thread.

My tranny fluid was not low so I think it was just the switch, not the seal btwn trans and t-case. I'm gonna test drive it a little and re-check the fluid levels just to be sure.

Thanks again guys!

You are welcome and thanks for posting back how it went.
Good Luck.

[drdd]

Well, the test drive was no good. Trans wasn't shifting right.

I opened the top fill bolt on the T-case and tons of fluid came pouring out.

Guess it's time for a new seal ...

[MT-2500]

Originally Posted by drdd

Well, the test drive was no good. Trans wasn't shifting right.

I opened the top fill bolt on the T-case and tons of fluid came pouring out.

Guess it's time for a new seal ...

Yes. you need a transfer case/transmission seal.
But.
Before you drive it any more check transmission fluid level.
Transmission not shifting right and.
Over full transfer case says under filled transmission and if drove much with transmission fluid low a burnt up transmission.

Before you proceed with transfer case seal make sure you transmission is working good with no slippage and codes.

[drdd]

When I opened the t-case, it seemed like a few gallons of fluid came out. So now the trans and t-case are about empty.

Can I refill transmission at the dipstick and then check for operation as you suggested? Is that enough to test it, or will it just flow into the t-case?

I guess what I'm trying to ask is, how can I check the transmission for proper operation and no codes, if there is a seal leak?

[MT-2500]

Originally Posted by drdd

When I opened the t-case, it seemed like a few gallons of fluid came out. So now the trans and t-case are about empty.

Can I refill transmission at the dipstick and then check for operation as you suggested? Is that enough to test it, or will it just flow into the t-case?

I guess what I'm trying to ask is, how can I check the transmission for proper operation and no codes, if there is a seal leak?

Fill both to the full before driving.
Then test drive for transmission operation'.
Then re check transmission level.
If low refill and rechck transfer case level.

Usually it takes time for seal to leak fluid into transfer case.
But keep a close eye on it untill fixed and even after fixing.