| transmission modulator location? [message #68410] |
Sat, 26 December 2009 16:16  |
hertfordnc
Messages: 1164
Registered: September 2009
Location: East NC
Karma: 0
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The Revcon has a problem getting out of second gear.
Aprently the modulator is the most likely cause, and in the case of this old beast, a cracked vac line is the culpit.
So where is it and what does it look like?
I'm guessing this is not one of the things GM did change from the Toro.
Thanks
Dave & Ellen Silva
Hertford, NC
76 Birchaven, 1-ton and other stuff
Currently planning the Great american Road Trip Summer 2021
It's gonna take a lot of Adderall to get this thing right.
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| Re: [GMCnet] transmission modulator location? [message #68415 is a reply to message #68413] |
Sat, 26 December 2009 17:05  |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Located on passanger side. Vac line goes there.
On Sat, Dec 26, 2009 at 2:33 PM, Steve Southworth <midlf@centurytel.net> wrote:
>
>
> hertfordnc wrote on Sat, 26 December 2009 16:16
>> Aprently the modulator is the most likely cause, and in the case of this old beast, a cracked vac line is the culpit.
>>
>> So where is it and what does it look like?
>>
>> Thanks
>
>
> http://www.gmcmhphotos.com/photos/showphoto.php?photo=3990&cat=3382
>
> http://www.gmcmhphotos.com/photos/showphoto.php?photo=14999&cat=4277
>
>
> --
> Steve Southworth
> 1974 Glacier TZE064V100150
> Palmyra WI
> _______________________________________________
> GMCnet mailing list
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--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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Jim Kanomata
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jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: transmission modulator location? [message #68438 is a reply to message #68410] |
Sun, 27 December 2009 02:44 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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The two previous postings gave you the location on the right side of the trans. It is held in place with one screw. Start the engine and run it for a minute or two to fill the torque converter and check the vacuum levels outlined below. Shut off the engine, remove the one screw and pull the modulator out. Prior to pulling the modulator, I would remove the hose from it and check it for vacuum preferably with a gauge. If it is not the same as the manifold vacuum (around 18" at idle) then you have a vacuum problem and not a bad modulator.
It is also very common for the steel vacuum line that runs across the top of the engine to rust or plug up with carbon. That steel line has a restrictor built in to it on the intake manifold end. You can unplug the hoses on both ends and blow air through it to make sure it is open. Mine was blocked so bad hat I had to remove it and pressurize it with 100 psi of air while heating it with a flame wrench on the restrictor end to get it open again.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] transmission modulator location? [message #68446 is a reply to message #68438] |
Sun, 27 December 2009 07:19 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Ken,
Your note sparked a memory for me. When I was replacing the manifold on
Double Trouble I moved the vacuum line out of the way so I could get the
manifold off and it broke. When I looked at the ends where it broke I
noticed it was rusted badly and probably had pin holes in it too. I repaired
it by filing the jagged edges of the two ends flat and joined them with a
piece of rubber hose.
I never checked the line to see if it was plugged so another item gets added
to the Double Trouble TTD list!
Thanks,
Rob Mueller
Sydney, Australia
AUS '75 Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Ken Burton
Sent: Sunday, 27 December 2009 7:44 PM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] transmission modulator location?
The two previous postings gave you the location on the right side of the
trans. It is held in place with one screw. Start the engine and run it for
a minute or two to fill the torque converter and check the vacuum levels
outlined below. Shut off the engine, remove the one screw and pull the
modulator out. Prior to pulling the modulator, I would remove the hose
from it and check it for vacuum preferably with a gauge. If it is not the
same as the manifold vacuum (around 18" at idle) then you have a vacuum
problem and not a bad modulator.
It is also very common for the steel vacuum line that runs across the top of
the engine to rust or plug up with carbon. That steel line has a restrictor
built in to it on the intake manifold end. You can unplug the hoses on both
ends and blow air through it to make sure it is open. Mine was blocked so
bad hat I had to remove it and pressurize it with 100 psi of air while
heating it with a flame wrench on the restrictor end to get it open again.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] transmission modulator location? [message #68460 is a reply to message #68446] |
Sun, 27 December 2009 10:39 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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Senior Member |
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""I never checked the line to see if it was plugged so another item gets added
to the Double Trouble TTD list!""
If it shifts OK then it's open. When the modulator isn't working correctly, you'll know it !
Bob de Kruyff
78 Eleganza
Chandler, AZ
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