The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > General Truck Forums > Engine & Drivetrain

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 05-29-2005, 07:00 PM   #1
ZmOz
Account Suspended
 
Join Date: Apr 2005
Location: OR
Posts: 235
TH400 won't shift out of first

Took my '79 C20 with a 454/TH400 for a drive yesterday. The trans would not shift out of first unless I manually shifted into first and then back to drive. When I got the truck a couple months and about 50 miles ago, it shifted OK, but seemed to shift at a pretty high RPM. (don't know if anything was wrong or not, I don't have a tach and have never driven anything else with a TH400)

What might be wrong? The fluid level is ok, it could stand to be changed, but it's not that dirty either.
ZmOz is offline   Reply With Quote
Old 05-29-2005, 07:04 PM   #2
1972C10
Account Suspended
 
1972C10's Avatar
 
Join Date: Dec 2003
Location: Texas
Posts: 2,686
Check the vaccum line going to the modulator Located on the passenger side of the transmission Sounds like the line may have come unatttached . Has this truck been running long has it worked right in the past? Or is this a trial run on this setup?
1972C10 is offline   Reply With Quote
Old 05-29-2005, 07:36 PM   #3
tmcgrawlookalike
Registered User
 
Join Date: Jun 2004
Location: warr acres,oklahoma
Posts: 650
make sure you have a good strong intake vacuum(off of the intake,not carb)a good line or hose,and a good modulator.sometimes if you pull off the vacuum line and fluid comes out of line or tip of modulator,mod will be bad.go get a filter kit,fluid,k&w trans x,module,and you should be good to go for a while again,especially if you say it`s time to change filter again anyway.
tmcgrawlookalike is offline   Reply With Quote
Old 05-29-2005, 07:45 PM   #4
ZmOz
Account Suspended
 
Join Date: Apr 2005
Location: OR
Posts: 235
Quote:
Originally Posted by 1972C10
Check the vaccum line going to the modulator Located on the passenger side of the transmission Sounds like the line may have come unatttached . Has this truck been running long has it worked right in the past? Or is this a trial run on this setup?

Is this the metal line that hooks up to the manifold near the distributor? That snapped off while I was setting the timing...forgot about it until now.

Don't know anything about the past of this truck, though according to the mileage on the title it has gone 40,000 miles in the last two years. It came with 5 bills of sales from people who never put the title in their name, so apparently it has bounced around alot recently. I'm pretty sure the guy I bought it from just wanted some cash for meth...
ZmOz is offline   Reply With Quote
Old 05-29-2005, 07:52 PM   #5
tmcgrawlookalike
Registered User
 
Join Date: Jun 2004
Location: warr acres,oklahoma
Posts: 650
that`s it!!!!
tmcgrawlookalike is offline   Reply With Quote
Old 05-29-2005, 11:44 PM   #6
Russell
Professional Grade
 
Russell's Avatar
 
Join Date: May 2003
Location: Fort McMurray, Alberta
Posts: 7,915
Yep, thats what happens when the vac modulator isn't hooked up
__________________
1995 Chevrolet 2 Door Tahoe (6.6L LBZ Duramax / ZF6 / NP241 with 1 ton solid axle swap)
Russell is offline   Reply With Quote
Old 05-29-2005, 11:51 PM   #7
ZmOz
Account Suspended
 
Join Date: Apr 2005
Location: OR
Posts: 235
Great...easy fix instead of a tranny rebuild.

It's alot of fun going down the highway in first on 7 cylinders though...
ZmOz is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 09:19 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com