NP205 Leak and Speedo Recalibration

[AHowe88]

Well it appears I am leaking where my speedo connects to the Tcase. I found this little write up, on how to fix it: http://coloradok5.com/forums/showthread.php?t=269149

Seems pretty self explanatory, but I'd like to take this opportunity to recalibrate my speedo, with the calibration box pictured in the above link.

I found one here (search for: #54RA2)
http://www.transmissioncenter.net/sp...n_______va.htm

A few questions:
- When I take this apart, do I need a catch pan, or should there be no oil?
- Does anyone have any experience with the speedo calibration box, good or bad?
- Where else should I check for leaks? I'm nervous this isn't the only leaky spot...

[Dale99]

My speedo gear was stripped out so I can help on some of this.

Yes you will need a catch pan. Even though the fill level is below this, it seems it likes to splash oil there, and it does stay! I tried tilting the truck, didnt help.

I was also leaking at the rear seal where the driveshaft goes in, as well as one of the gaskets for that same housing. All of mine were able to be done while still in truck.

[cleszkie]

When I swapped out my speedo gear, only a small amount of oil came out, so you will need a small catch can. New o-ring and no more leaks from the speedo gear housing.

However, I have found that most of these NP205 cases also leak past the threads of the various access cover bolts. Some of the bolts thread into "blind" holes that do not penetrate the case. These are not the problem. The problem are the bolts that thread into holes that are tapped right through the case. Hot, thin oil will make its way past the bolt threads and onto your driveway, no matter how much silicon you put on the gaskets. I used to try putting a dab of silicon on these bolts before I installed them, but that never seemed to last. The absolutely best way to stop the leaking is to use a white teflon thread sealant paste on the bolts before installation. Its sold at every auto parts store. Since I did this, absolutely no leaks from my NP205. Don't forget to apply it to the fill and drain plug threads too.

[my90k5]

Thank's cleszkie for that bit of advice. I'll use your advice when I assemble my trany and transfer case.

[AHowe88]

Originally Posted by Dale99

My speedo gear was stripped out so I can help on some of this.

Yes you will need a catch pan. Even though the fill level is below this, it seems it likes to splash oil there, and it does stay! I tried tilting the truck, didnt help.

I was also leaking at the rear seal where the driveshaft goes in, as well as one of the gaskets for that same housing. All of mine were able to be done while still in truck.

Thanks! I'm new to working on transmissions. Did you have a write up for the rear seal replacement, or were you just doing it based on your own knowhow?

Thanks for the tip on teflon tape.

[cleszkie]

AHowe88 -

Not teflon tape. Teflon paste. The paste never hardens, and seems to work more consistently than tape.

[AHowe88]

Well I found the other source of my leak. Just in front of where the fill pipe drops into the transmission pan, there is a plug I had nothing connected to the plug, but it was a small three pronger. When the truck was sitting, there was no leak, however when it was put in gear, it would puke out of this plug.

Can anyone tell me what this plug is for?

[Bigdav160]

Remove it and put in a pipe plug. That switch is not needed.

[AHowe88]

Originally Posted by Bigdav160

Remove it and put in a pipe plug. That switch is not needed.

That's what we did. What was it for?
Posted via Mobile Device

[jaros44sr]

Originally Posted by AHowe88

That's what we did. What was it for?
Posted via Mobile Device

Can post up a pic, never knew a transfer case to have a switch

[AHowe88]

Originally Posted by jaros44sr

Can post up a pic, never knew a transfer case to have a switch

I didn't take any, and the plug has since found a new home in the trash.
Posted via Mobile Device

[cleszkie]

Someone correct me if I am wrong her, but that switch on the transmission was part of the timing control system (TCS) that was part of the original emissions control equipment. It prevented the use of the vacuum advance before the tranny/engine was up to operating temperature.