| Transmission not shifting properly [message #188126] |
Wed, 24 October 2012 18:22  |
Glenn
Messages: 92
Registered: February 2004
Location: Northwestern Ontario
Karma: 2
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Hi All
Leaving Nashville this morning trans did not want to shift to 3rd. Tried manually goiny to 2nd then 3rd and no good. Got it to shift but had to hit 50mph at 3000rpm then let up on throttle. Everything OK once in 3rd not hot temps. This happened 2 maybe 3 times. Stopped at rest area checked all vacuum lines and like new condition, fluid level OK, changed modulator as had spare and then everything ok. Pulling of interstate into Memphis same thing one time then ok. Parked till friday morning and was wondering if anything else i could check? Thanks
HTH.........
Glenn
76 Glensbroke
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| Re: Transmission not shifting properly [message #188137 is a reply to message #188126] |
Wed, 24 October 2012 20:07  |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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Two things come to mind other that a bad modulator.
1. No or low vacuum at the modulator.
1a. Check the hose on the top of the manifold to the steel line on the right side of the manifold.
1b. Check the hose on the other end of the steel line near the modulator.
1c. Check that the steel line is not restricted. I had this one time and could not clear it. I finally removed the line and attached 100 PSI air pressure to the modulator end. Then I heated the line with an acetylene torch near manifold end until the obstruction cleared. A little gray paint on the line and it was as good as new. Note: There is a crimped portion of the line about 2 inches in from the manifold end that sometimes gets obstructed with carbon or rust.
2. Stuck shift down switch on the gas pedal. (I have never heard of this happening)
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: Transmission not shifting properly [message #188146 is a reply to message #188126] |
Wed, 24 October 2012 20:33 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Double check that vac hose--- though it looks good be sure is not the soft type that can kink and suck flat. Ask me how I know.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: [GMCnet] Transmission not shifting properly [message #188212 is a reply to message #188139] |
Thu, 25 October 2012 11:59 |
Glenn
Messages: 92
Registered: February 2004
Location: Northwestern Ontario
Karma: 2
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OK checked vacuum at both ends of steel line and same at each end (15 at low idle). Yesterday installed a brand new modulator. Thats all I can do for now as need to run from Memphis to Thunder Bay. Hope to make home early Monday, winterize the coach, pack the truck then head 8hrs north for work on wedensday.
Thanks for everyones help
HTH.........
Glenn
76 Glensbroke
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| Re: [GMCnet] Transmission not shifting properly [message #188612 is a reply to message #188212] |
Mon, 29 October 2012 04:32 |
Glenn
Messages: 92
Registered: February 2004
Location: Northwestern Ontario
Karma: 2
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Member |
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On Saturday found another vacuum modulator to try hoping my spare was bad, NOT. It would shift to third at around 55mph and 3500rpm. This while not doing the transmission or engine any good was working so we stuck to the interstates. Thinking that the drive up Hwy 61 from Duluth doing this would either kill one or both the motor and tranny it hit me. The only other thing I could change out was the govenor itself.That was it and we made it home around 5pm Sunday thus bring to a close our almost 12000 mile road trip (report to follow later).
HTH.........
Glenn
76 Glensbroke
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| Re: [GMCnet] Transmission not shifting properly [message #188615 is a reply to message #188612] |
Mon, 29 October 2012 08:10 |
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WD0AFQ
Messages: 7111
Registered: November 2004
Location: Dexter, Mo.
Karma: 207
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Senior Member |
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Good, glad you had the spare. After having similar issues I too carry a spare. That is the quickest thing to check and swap out. These governors are getting old and have spun around many times. It is about time they start wearing out, I guess. Jim K has complete governors, new or rebuilt.
Dan
3 In Stainless Exhaust Headers
One Ton All Discs/Reaction Arm
355 FD/Quad Bag/Alum Radiator Manny Tran/New eng.
Holley EFI/10 Tire Air Monitoring System
Solarized Coach/Upgraded Windows
Satelite TV/On Demand Hot Water/3Way Refer
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