servo seal?

[holshotracer]

i have a leak right now and it looks like it coming from the servo closes to the motor. is there a seal that could be replaced? when parked over night there is about a 1/4 of a quart of atf on the ground.

 

[Glacier991]

The cover that slides into that servo bore has an O-ring on it. That is the OD servo. That sounds like a lot of leakage though.... sure that's the source?

It can be reaplaced but in reality you really damn near need to drop the CAT to do it... though it CAN be done without removing the CAT.

IF that was it, that is a job I mightly GLADLY pay someone else to do.

 

[BrooklynBay]

You might as well replace the entire servo in addition to the O ring while you are doing this. There are 2 servos on that side. You could upgrade to the larger servo, and cover or keep the stock size. The larger servo would make a more positive shift engagement since it holds more fluid, but you might have to compensate by using a large ratio boost valve to prevent a fill time delay. Check the modulator at the same time. You might have this leak being caused by heat from the catalytic converter. Install a heat shield if you don't already have one.

 

[Glacier991]

Good point BB.

 

[Bent Bolt]

Heat shield is sooooo important for these trucks!!!!! As BB said, if you are doing one, do both while you're there.

 

[Glacier991]

And as was suggested, do the OD to a ZC servo with matching cover and the intermediate to an AB servo with a matching cover.

 

[holshotracer]

its coming out to the servo. i thought it was the modulator because i change it just after it bought the ex. its not leaking there because theres no fuild above the servo cover.
about how much would a larger servo cost? one other ? this wouldn't have any effect on the one-two shift. i replaced the modulator and still having problems with it shifting.

 

[BrooklynBay]

Check the price on WWW.TransmissionPartsUSA.Com. I think the servo, and cover should be around $20. There are a few kinds of modulators, and hardware available. Do you have a link to a picture of the one you used?

 

[holshotracer]

the modulator that i used came out of my spare trans that i have sitting in my garage. it was the same as the one that i pulled out. i made sure that the spring and little rod were put back in. i looked at the post about changing the modulator before i did it. i'm not worried about the 1-2 shift as much as the leak right now.

 

[Glacier991]

I understand. But so long as you are going to have then access to the servos, this is a good time to simply add the upgrade while you are at it. The ZC will not affect the 1-2 you're right, but a slipping OD is a common problem and a little more "hold" is not a bad thing. In any event.... the cost is cheap and heck, why not?

 

[holshotracer]

well i decided to change the servo.it took me about 2 1/2 hours to do with most of that going to getting the exhuast off. i put in a stock servo because i was getting sick of the puddles that the tanny was leaving.
i noticed tonight on the highway before i changed the servo i was running at about 700 rpms higher than normal in OD. could this be because the servo leaking?

 

[BrooklynBay]

Did you replace both servos? Did you mix the springs from both of them? Where did you buy them?

 

[holshotracer]

i only replaced only the od servo. i used one out of my spare tranny. i know that i should of got a new one but no one had one in stock and i want to get the leak fixed soon because it was getting worst. the leak is gone and it shifts into OD fine. it i have to do it again it should be easier beause the biggest problem was taking the exhuast off. now i have to figure out the 1-2 shift problem.

 

[ff2024]

Will the Sonnax boost valve compensate for the larger OD servo?

 

[BrooklynBay]

It should. I recommend the high ratio boost valve with the O rings.

 

[ff2024]

BrooklynBay, I don't think that it comes with O rings?

 

[BrooklynBay]

They make them with, and without O rings.

 

[Glacier991]

In the 1st Gens the boost valve uses O rings. The 1-2 shift is all about the intermediate servo - the one you DIDN'T change. If your OD servo was fried, I bet you your 1-2 shift issue is a fried intermediate servo. IF you go back in, PLEASE take my advice and replace the OD with a ZCservo and make sure that your intermediate is an AB?

 

[holshotracer]

the one that i replaced was a AB, winch i replaced with a AB. the other one is a BB. i'm going to order the both servos and upgrading them. is this the boost valve i need?

56947-02K A4LD Large boost valve kit with o rings
High ratio .338" diameter, used in 4.0L models. Restores line pressure boost. This is a direct replacement part. No machining required

also what part# sould i get of the servos and covers, i don't see the ZC on transmissonspartsusa site. one other ? does the boost valve come with instutions?

 

[Glacier991]

All you need to convert the intermediate from a BB to an AB is to move your new OD over into that bore. The servo and cover are a matched set, and the bores (OD and Intermediate) are identical.... so you have 50% of what you need. Now all you need is the ZC servo and matching cap for the OD.
Transmissionpartsusa has them, search under 5R55E though - they were NOT A4LD parts, but ARE backwards compatible.

That is the boost valve you need. The spool is anodized a pretty purple color, but to my knowledge that is just a coincidence and not part of some color coding scheme.