TH350 hanging onto 2nd - The 1947 - Present Chevrolet & GMC Truck Message Board Network

OrangeCrush1970 · 02-02-2009, 12:01 AM

The truck is shifting well from 1st to 2nd, but hanging onto 2nd before shifting into 3rd. Sometimes shifts right into 3rd, sometimes hangs in 2nd. Fluid levels are fine, shifter is fine...is my transmission taking a dump on me or could it be a vacuum leak or bad solenoid?
This just started today-

I'll add that the transmission was rebuilt about 30-40k miles ago

72BLUZ · 02-02-2009, 12:13 AM

sounds like maybe the modulator valve, or maybe a hole in the vacuum line going to it.

sandking · 02-02-2009, 12:34 AM

I would say either something with the modulator or maybe some debris somwhere in the valve body. Might be a good idea to do a really good fluid flush.

72freak · 02-02-2009, 05:52 AM

Quote:

Originally Posted by 72BLUZ

sounds like maybe the modulator valve, or maybe a hole in the vacuum line going to it.

That would be my guess?!?!?

OrangeCrush1970 · 02-02-2009, 05:44 PM

Modulator valves are $13. I think i'll get some new hose and throw one on there...after doing a little gooogling i read some and it sounds spot on for a bad mod valve or vac leak.

jay6891 · 02-02-2009, 06:07 PM

x2 vacuum line or modulater were my first guess.

**thelonerife** · 02-02-2009, 06:29 PM

Mine started doing that on my truck. At first I could get it into 3rd by giving it a little more gas but that eventually quit doing it though. I changed my modulator and checked my hoses and fluid first too. I had to get it rebuilt. The clutches were gone. The bad thing was I had two trucks at the time and both started this within two weeks of each other.

72BLUZ · 02-03-2009, 12:08 AM

Quote:

Originally Posted by thelonerife

Mine started doing that on my truck. At first I could get it into 3rd by giving it a little more gas but that eventually quit doing it though. I changed my modulator and checked my hoses and fluid first too. I had to get it rebuilt. The clutches were gone. The bad thing was I had two trucks at the time and both started this within two weeks of each other.

when it rains it pours, or at least around my house it does!

70clone · 02-03-2009, 02:32 AM

if all else fails put some trans x in it the stuff in the silver and blue jug.Works everytime ive ever used it.

OrangeCrush1970 · 02-03-2009, 03:31 PM

I just replaced the modulator and rubber on both ends of the vacuum tube. When I pulled the old modulator off, there was a little fluid inside. Not too much which makes me think that it just started going bad.

It's shifting good now, i'll keep an eye on it and see if there are anymore issues, but I think I have the problem solved. It was a very simple operation (w/ the help of David's lift, etc.) and I figured yall would like some pics. Yes, it is very wet...

Thanks for the help fellas

02-02-2009, 12:01 AM	#1
OrangeCrush1970 Registered User Join Date: Jun 2007 Location: Smyrna, GA Posts: 709	TH350 hanging onto 2nd The truck is shifting well from 1st to 2nd, but hanging onto 2nd before shifting into 3rd. Sometimes shifts right into 3rd, sometimes hangs in 2nd. Fluid levels are fine, shifter is fine...is my transmission taking a dump on me or could it be a vacuum leak or bad solenoid? This just started today- I'll add that the transmission was rebuilt about 30-40k miles ago __________________ *Rottenwood Garage* 1970...71...72 C1500 aka Orange aka Sideshow Bob 540 BB Straub Roller Cam, AFR Magnums, XP 950, TKO 600 2 Tons of Fun Last edited by OrangeCrush1970; 02-02-2009 at 12:03 AM.

02-02-2009, 12:13 AM	#2
72BLUZ Registered User Join Date: Nov 2006 Location: lafayette, ga. Posts: 832	Re: TH350 hanging onto 2nd sounds like maybe the modulator valve, or maybe a hole in the vacuum line going to it. __________________ Freedom is never more than one generation away from extinction. We didn't pass it to our children in the bloodstream. It must be fought for, protected, and handed on for them to do the same.... Ronald Reagan

02-02-2009, 12:34 AM	#3
sandking .....I am working on it..... Join Date: Jul 2007 Location: Anaheim Hills, Ca Posts: 960	Re: TH350 hanging onto 2nd I would say either something with the modulator or maybe some debris somwhere in the valve body. Might be a good idea to do a really good fluid flush. __________________ . . . . . View my build thread HERE

02-02-2009, 05:44 PM	#5
OrangeCrush1970 Registered User Join Date: Jun 2007 Location: Smyrna, GA Posts: 709	Re: TH350 hanging onto 2nd Modulator valves are $13. I think i'll get some new hose and throw one on there...after doing a little gooogling i read some and it sounds spot on for a bad mod valve or vac leak. __________________ *Rottenwood Garage* 1970...71...72 C1500 aka Orange aka Sideshow Bob 540 BB Straub Roller Cam, AFR Magnums, XP 950, TKO 600 2 Tons of Fun

02-02-2009, 06:07 PM	#6
jay6891 Car Knocker Join Date: May 2001 Location: jefferson,arkansas Posts: 664	Re: TH350 hanging onto 2nd x2 vacuum line or modulater were my first guess. __________________ 68 c-10,91 sportside bed,350 .030 over,4 bolt,10-1 comp,2.05 intake/1.94 exhaust,1.6 Harland Sharp roller rockers,edelbrock rpm cam and intake w/750 carb, 700r4, 3.73 gears,Jacabbs Electronic Igntion w/Accel HEI distributer and super coil. ZR-1 roll pan, filled tailights. Blazer tank. Hidden hitch. 2 1/2" Flowmaster 40's. Parts bought but not installed>> ford 9" posi with disc. CCP front and rear lowering kit 4/5. Cab corners,foor boards,rockers, cab braces, Phatom grill, Painless wiring kit. Last edited by jay6891; 02-02-2009 at 06:37 PM.

02-02-2009, 06:29 PM	#7
thelonerife Senior Member Join Date: Jul 2007 Location: Clarksville TN 37043 Posts: 8,702	Re: TH350 hanging onto 2nd Mine started doing that on my truck. At first I could get it into 3rd by giving it a little more gas but that eventually quit doing it though. I changed my modulator and checked my hoses and fluid first too. I had to get it rebuilt. The clutches were gone. The bad thing was I had two trucks at the time and both started this within two weeks of each other. __________________ Chuck 68swb Fleetside build ''Choncho'' http://67-72chevytrucks.com/vboard/s...d.php?t=374892 My trailer redo http://67-72chevytrucks.com/vboard/s...69#post5893869 Chuy my 59 bug http://67-72chevytrucks.com/vboard/s...d.php?t=653798 Putnam 87 GMC Shop truck http://67-72chevytrucks.com/vboard/s...d.php?t=707687

02-03-2009, 02:32 AM	#9
70clone Registered User Join Date: Oct 2006 Location: JACKSONVILLE FL Posts: 200	Re: TH350 hanging onto 2nd if all else fails put some trans x in it the stuff in the silver and blue jug.Works everytime ive ever used it.

02-03-2009, 03:31 PM	#10
OrangeCrush1970 Registered User Join Date: Jun 2007 Location: Smyrna, GA Posts: 709	Re: TH350 hanging onto 2nd I just replaced the modulator and rubber on both ends of the vacuum tube. When I pulled the old modulator off, there was a little fluid inside. Not too much which makes me think that it just started going bad. It's shifting good now, i'll keep an eye on it and see if there are anymore issues, but I think I have the problem solved. It was a very simple operation (w/ the help of David's lift, etc.) and I figured yall would like some pics. Yes, it is very wet... Thanks for the help fellas Attached Images __________________ *Rottenwood Garage* 1970...71...72 C1500 aka Orange aka Sideshow Bob 540 BB Straub Roller Cam, AFR Magnums, XP 950, TKO 600 2 Tons of Fun Last edited by OrangeCrush1970; 02-03-2009 at 03:34 PM.



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.