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03-14-2012, 09:50 PM
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#1 |
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Registered User
Join Date: Jun 2011
Location: Downey, ca
Posts: 262
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TH400 wont shift...
Here's the deal guys...I haven't had any problems with my trans do far. Daily driver. 350/400 combo.
Reverse is fine, neutral is fine. 1,2 is fine but when I put it in drive it just throws it back in to 1st gear...what gives? Posted via Mobile Device |
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03-14-2012, 09:55 PM
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#2 |
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Senior Member
Join Date: May 2009
Location: Fort Worth, TX
Posts: 6,370
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Re: TH400 wont shift...
Check the vacuum line going to the vacuum modulator, The modulator is on the passenger side of a TH400. If vacuum line is good...Replace modulator.
Still no shift?....Pull the governor, Inspect for stripped drive gear. |
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03-14-2012, 10:22 PM
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#3 |
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Registered User
Join Date: Jun 2011
Location: Downey, ca
Posts: 262
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Re: TH400 wont shift...
Line is good...modulator is 2 months old. Could she be acting up due to low trans fluid??? Leaking from oil pan. Can't check the fluid level due to the pan being bent/damaged right in the center.
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03-15-2012, 08:31 AM
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#4 |
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Registered User
Join Date: Aug 2009
Location: S.C.
Posts: 1,593
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Re: TH400 wont shift...
Smashed pan is not good, it'll need to be fixed. Right above the pan is the filter.
Dipstick goes in at the right front of the pan. If you can't check the fluid level, the damage may be worse than you thought. From what I've seen the turbo 400 is sensitive to fluid level. I'm FAR from an expert, so take my thoughts with a grain of salt. But it may be something to consider.
__________________
'86 C-30 dually, 454/tbh400 '73 K-20 350/350/205 (sold  )I'm kinda like duct tape- no real purpose, but handy to have around. |
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03-15-2012, 12:17 PM
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#5 |
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Registered User
Join Date: Jun 2011
Location: Downey, ca
Posts: 262
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Re: TH400 wont shift...
Well I can check the level, it comes up on the dipstick but I don't think its accurate.
I added a qt and a half last night and she's been shifting fine. I'll replace the pan, filter, dipstick and modulator. Anything else I should replace while I'm down there? Posted via Mobile Device |
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03-15-2012, 09:31 PM
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#6 |
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Registered User
Join Date: Jan 2012
Location: Petal,Ms.
Posts: 428
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Re: TH400 wont shift...
I have been told and it has worked for me, pull your modulator out once you finished all the rest of your pan work. When the fluid runs out of the modulator hole it is full. Or mark your dipstick level with top of pan.
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03-16-2012, 04:07 PM
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#7 |
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*** That's interesting ***
Join Date: Oct 2008
Location: Pittsburgh, PA
Posts: 2,772
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Re: TH400 wont shift...
If you use a stock dipstick and tube, the engine must be running in park or neutral before the level will read correctly on the dipstick.
__________________
Tom  Chevy by day... 1969 Chevy C30 Rollback Tow Truck -- 383 stroker, 4L80E 2011 Chevy Caprice PPV 9C3 6.0L 1995 Chevy Caprice 9C1 1994 Chevy Caprice 9C1 #3 1995 Chevy Caprice Wagon #2 1995 Chevy Impala SS Mopar by night... 1969 Dodge Charger 1972 Chrysler Newport 2dr Hardtop (27K miles) Plus others... |
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03-16-2012, 05:12 PM
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#8 |
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~Rest In Peace~
Join Date: May 2005
Location: CALIFORNIA NOR CAL
Posts: 9,707
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Re: TH400 wont shift...
also you need to get it to operating temp. trans fluid will expand when hot ,so if you check cold you wont get a true reading
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is it fast ? it has a lighting bolt donut? B___H please, I can remove 90% of your so called "beauty" with a kleenex |
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03-16-2012, 08:53 PM
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#9 |
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Registered User
Join Date: Jun 2011
Location: Downey, ca
Posts: 262
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Re: TH400 wont shift...
Yeah I knew it had to be in park and operating temps but still won't read. How many quarts is it supposed to take when doing a gasket replacement?
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03-16-2012, 10:35 PM
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#10 |
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Registered User
Join Date: Mar 2012
Location: fortvalley ga
Posts: 345
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Re: TH400 wont shift...
the govenor is hung
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03-17-2012, 12:28 AM
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#11 |
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Registered User
Join Date: Mar 2002
Location: woodstock, alabama, usa
Posts: 938
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Re: TH400 wont shift...
"the govenor is hung"
 
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i survived cancer and kidney stones, but my kids are killing me. |
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03-17-2012, 12:59 AM
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#12 |
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Registered User
Join Date: Dec 2008
Location: NW-Ohio
Posts: 2,525
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Re: TH400 wont shift...
If ya got it apart
Get a pan with a drain plug, or buy the $5 bolt thingy that adds a plug drain to the pan. [drill a hole n two parts screw together making a tight seal, with a center drain bolt] I like the adjustable modulators to fine tune my low speed shift points. [I like it to stay in 1st a bit longer]
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Chevy GMC Trucks Find Of The Day https://www.facebook.com/ChevyGmcTrucksFindOfTheDay or http://ChevyGMCTrucks.com |
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03-17-2012, 05:46 PM
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#13 |
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Registered User
Join Date: Jun 2011
Location: Downey, ca
Posts: 262
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Re: TH400 wont shift...
To stay in first a little longer hehe turn the modulator adjustment screw clockwise or counter...and by the way how many quarts do I put back in...4?
Working on it now. Posted via Mobile Device |
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