Moparts

A904 Line Pressure Issues

Posted By: GOAT Duster

A904 Line Pressure Issues - 07/27/19 11:33 PM

My Transmission was recently rebuilt and has a used throttle body. I have a TCI torque converter. It is all behind a 360. Oh yeah and a Lokar kickdown cable. (I know I know, I read the reviews and will likely be changing it out for the Bouchillion one or stock one.
So here is the problem: I have reverse and 1st gear...no upshift. I did some testing: fluid is full, line pressure is at 80psi in 1st gear @ 1000 rpm which is high from what I am reading, should be around 54 to 60 rising to 90 to 96 when throttle lever is moved. It doesn't increase as the throttle linkage is moved. This led me to check my line pressure in drive at 1600 rpm at the front servo release port. Nothing, nota, no reading what so ever, even when the throttle position linkage is moved.
Please if anyone has experienced this or knows what could be the problem please advise.
Posted By: RapidRobert

Re: A904 Line Pressure Issues - 07/28/19 12:47 AM

trans was OK before the rebuild? (other than needing rebuilding). did the rebuilder note any specific part changes (valve body etc). this is more of a BTT for ya.
Posted By: GOAT Duster

Re: A904 Line Pressure Issues - 07/28/19 12:56 AM

Trans had a broken valve body, so a used one purchased online was put in it. Trans was given to me in the broken state, so I am not sure of what else may have been wrong. Since condition was unknown a rebuild was decided on. I was thinking that the throttle position lever was put in wrong since it doesn't do anything. Or maybe the valve body was bad...it was used after all. Problem is the trans was redone over a year ago and sat for the past year until the project picked up again.
Posted By: RapidRobert

Re: A904 Line Pressure Issues - 07/28/19 01:29 AM

I'd wait for Kunkel & Transman to chime in but if it was me I'd wanna do something with/about the VB (the brain) AFTER pulling the pan & seeing if the throttle pressure linkage etc looks right. (not my area just thinking out loud).
Posted By: John_Kunkel

Re: A904 Line Pressure Issues - 07/28/19 04:43 PM

Disconnect the Lokar cable at the transmission lever and push the lever full forward. If it will upshift with the cable disconnected, the problem is in the cable installation/adjustment. If it still won't upshift the problem is internal.
Posted By: RapidRobert

Re: A904 Line Pressure Issues - 07/28/19 07:16 PM

John you're the man (as always).
Posted By: GOAT Duster

Re: A904 Line Pressure Issues - 07/28/19 11:52 PM

Still no shift with cable disconnected...would you suggest starting with the vavlebody since it is the easiest to get to? Was thinking of adding a Transgo TF-2 shift kit in the future anyways.
Posted By: UCUDANT

Re: A904 Line Pressure Issues - 07/29/19 01:16 AM

popcorn

Attached picture 60778879_597561864100079_7354178806229237760_n.jpg
Posted By: moparx

Re: A904 Line Pressure Issues - 07/29/19 02:59 PM

did you disassemble & clean the valvebody before installation ? if so, maybe one of the check balls got placed in the wrong position or omitted.
if not, there may be a sticking valve or "???" inside the valvebody.
in either case, i would remove the valvebody, disassemble & clean, then inspect closely to see if anything may be suspect. then proceed accordingly with what is found.
beer
Posted By: John_Kunkel

Re: A904 Line Pressure Issues - 07/29/19 05:14 PM

Before removing anything, I would check the governor pressure, no governor, no upshift. It's fairly common to have a governor failure right after an overhaul due to improper assembly of the governor.
Posted By: GOAT Duster

Re: A904 Line Pressure Issues - 07/30/19 01:06 AM

John_Kunkel, Thanks for your assistance thus far. I never thought to check the governor pressure. Unfortunately that wasn't the problem, it acted just as you described it would. I guess in reality that is fortunate not unfortunate. LOL While checking tonight I put the gauge back on the kickdown band plug and did notice that the pressure gauge did move ever so slightly when it is first put into gear but then stayed at zero. Not sure if this gives you any more to go off or not. At this point do you think that removing the throttle body and giving it a good cleaning to ensure there are no sticky check balls, ect… is worth a shot?
Posted By: GOAT Duster

Re: A904 Line Pressure Issues - 07/30/19 01:07 AM

Love it Bob, what's the color scheme for this one?
Posted By: GOAT Duster

Re: A904 Line Pressure Issues - 07/30/19 01:09 AM

moparx...thinking you might be onto something there. Looking more and more like that is going to be next weekends project.
Posted By: GOAT Duster

Re: A904 Line Pressure Issues - 08/03/19 07:17 PM

In the middle of valve body rebuild. Adding a Transgo shift kit while I'm in here. Found a broken spring and a stuck plunger so far. Thinking I found the priblem. I'll update once everything is back together.
Posted By: GOAT Duster

Re: A904 Line Pressure Issues - 08/05/19 02:01 AM

Well final post I guess. Put everything back together and got 3 gears. Sweet. Thanks to those of you that gave your input. Learned some things I didnt know for sure.
Again thanks Moparts family
Posted By: moparx

Re: A904 Line Pressure Issues - 08/05/19 02:34 PM

it's ALWAYS happy time when things get fixed ! boogie glad you got it figured out.
beer
© 2024 Moparts Forums