| Transmission Hints [message #263095] |
Wed, 01 October 2014 00:07  |
George Beckman
Messages: 1085
Registered: October 2008
Location: Colfax, CA
Karma: 11
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Senior Member |
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From time to time, there are questions here about transmission oddities. This is about my transmission not shifting into 3rd as it had a few days before.
During a the trip to Southern California the transmission began only shifting into 3rd at about 55 MPH (3.21 FD), when the governor forced the shift. I added a bit of fluid as I had lost about a bit full when putting in the transmission temperature sensor.
I also checked the vacuum tubing at the throttle body. I thought about checking the tubing at the modulator but it rained in the night,so we just drove home. The central valley is flat and it only had to shift up a few times. I thought the shift out of low was at a higher RPM than normal, as well.
Yesterday I jacked up the front and found that the curved hose to the modulator was badly cracked; almost separated at the modulator.
So, if you coach won't shift into 3rd, check the vacuum circuit. It can make you happy.
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
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| Re: [GMCnet] Transmission Hints [message #263099 is a reply to message #263095] |
Wed, 01 October 2014 08:13  |
Kingsley Coach
Messages: 2691
Registered: March 2009
Location: Nova Scotia Canada
Karma: -34
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Senior Member |
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George
Vacuum is the last thing I would check.
I'd be so worked up about the cost and effort to remove the transmission,
I might never check it until I was in the process of re-installation. When
the occasion occurs, I hope I can remember the KISS principal.
Tks
Mike in NS
On Wed, Oct 1, 2014 at 2:07 AM, George Beckman wrote:
> From time to time, there are questions here about transmission oddities.
> This is about my transmission not shifting into 3rd as it had a few days
> before.
>
> During a the trip to Southern California the transmission began only
> shifting into 3rd at about 55 MPH (3.21 FD), when the governor forced the
> shift.
> I added a bit of fluid as I had lost about a bit full when putting in the
> transmission temperature sensor.
>
> I also checked the vacuum tubing at the throttle body. I thought about
> checking the tubing at the modulator but it rained in the night,so we just
> drove home. The central valley is flat and it only had to shift up a few
> times. I thought the shift out of low was at a higher RPM than normal, as
> well.
>
> Yesterday I jacked up the front and found that the curved hose to the
> modulator was badly cracked; almost separated at the modulator.
>
> So, if you coach won't shift into 3rd, check the vacuum circuit. It can
> make you happy.
> --
> '74 Eleganza, SE, Howell + EBL
> Best Wishes,
> George
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Michael Beaton
1977 Kingsley 26-11
1977 Eleganza II 26-3
Antigonish, NS
I am not an alcoholic; alcoholics go to meetings.
I am a drunk; I go to parties !
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| Re: Transmission Hints [message #263115 is a reply to message #263095] |
Wed, 01 October 2014 16:10 |
winter
Messages: 247
Registered: September 2007
Location: MPLS MN
Karma: 0
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Senior Member |
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For the first 8 years I owned my rig the transmission would tend to un couple and freewheel when I let off the throttle. When reapplying the throttle, it would spin up and then slam into gear. It didn't seem right but it was the only gmc I had driven so I ran with it. When I replaced my cracked intake manifold I found the vacuum line was hooked to the ported line on the carb. I switched it to a manifold port and now the tranny operates like it should.
Jerrod Winter
1977 Palm Beach
Green Jelly Bean
Twin Cities, Minnesota
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| Re: Transmission Hints [message #263153 is a reply to message #263095] |
Thu, 02 October 2014 09:05 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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So many times vac hoses that look ok have 'perished' and have hidden cracks, splits. Or they have gotten rock hard or exposed to fluids and become soft and colapse.
John Lebetski
Woodstock, IL
77 Eleganza II
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