| Transmission modulator [message #319828] |
Sat, 01 July 2017 08:55  |
tgeiger
Messages: 518
Registered: February 2006
Location: kansas city
Karma: -1
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Senior Member |
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Ok, so kinda want to replace the transmission modulator after cleaning the tube and replacing the hoses. What would be the part number and also does taking the old one out cause transmission fluid to drain out?
Thanks,
Tom
76 Eleganza 2
Kansas City, Mo
Tom Geiger
76 Eleganza II
KCMO
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| Re: [GMCnet] Transmission modulator [message #319831 is a reply to message #319828] |
Sat, 01 July 2017 09:34  |
powerjon
Messages: 2446
Registered: January 2004
Karma: 5
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Senior Member |
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Tom,
Why do you want to replace the present installed modulator? Does it still work and transmission shift correctly?
Yes, you will leak fluid out of the modulator port if the transmission has been sitting for a period of time, this is called leak down from the converter and happen quickly or over an undetermined period of time. It is normal! It is also a good way to check if you have the correct level of transmission fluid and to know what the level means on your dip stick. The way to check the level is to remove the modulator IMMEDIATE after SHUTTING DOWN the engine and see if fluid will come out the port or no fluid comes out the port. Fluid coming out means level too high and no fluid means fluid level is OK or actually a little bit low and you could add
As for a part number if you absolutely must put a new modulator in.
AutoZone: Part# MV105
I have used this one and it works just fine
RockAuto list several and you can use these numbers to find a modulator at other parts store. I always use 1975 Oldsmobile Tornado 455 eng as a search string.
Fram FM2331
AC Delco 89057785
Airtex/Wells 7R1003
Standard Motor Products TM15
Most come with an instruction sheet on how to adjust the shift points.
http://www.gmcmhphotos.com/photos/transmission-install/p26806-img-0716.html
JR Wright
GMC Great Laker MHC
GMC Eastern States Charter Member
GMCGL Tech Editor
GMCMI
78 GMC Buskirk 30’ Stretch
1975 GMC Avion (Under Reconstruction)
Michigan
> On Jul 1, 2017, at 9:55 AM, tom geiger wrote:
>
> Ok, so kinda want to replace the transmission modulator after cleaning the tube and replacing the hoses. What would be the part number and also does
> taking the old one out cause transmission fluid to drain out?
>
> Thanks,
> Tom
> 76 Eleganza 2
> Kansas City, Mo
>
> _______________________________________________
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J.R. Wright
GMC GreatLaker
GMC Eastern States
GMCMI
78 30' Buskirk Stretch
75 Avion Under Reconstruction
Michigan
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| Re: Transmission modulator [message #319847 is a reply to message #319828] |
Sat, 01 July 2017 17:00 |
C Boyd
Messages: 2629
Registered: April 2006
Karma: 18
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Senior Member |
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Sir, if your modulator is OEM it is long, big and inlet is on the side. Replacements are short, small and inlet is in the end. I usually eyeball the line and use a small tubing bender and bend the tube 90* to fit straight in the end. The pointy end of the line goes inside the modulator for stability and rubber hose seals it.
tgeiger wrote on Sat, 01 July 2017 09:55Ok, so kinda want to replace the transmission modulator after cleaning the tube and replacing the hoses. What would be the part number and also does taking the old one out cause transmission fluid to drain out?
Thanks,
Tom
76 Eleganza 2
Kansas City, Mo
C. Boyd
76 Crestmont
East Tennessee
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| Re: Transmission modulator [message #319856 is a reply to message #319828] |
Sat, 01 July 2017 18:56 |
tgeiger
Messages: 518
Registered: February 2006
Location: kansas city
Karma: -1
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Senior Member |
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Well, will hope not to have to replace it but am having shifting idsues once it heats up. Will clean everything down and keep my fingers crossed it does the job. But if not, next is the modulator.
Tom Geiger
76 Eleganza II
KCMO
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| Re: [GMCnet] Transmission modulator [message #319860 is a reply to message #319856] |
Sat, 01 July 2017 19:08 |
powerjon
Messages: 2446
Registered: January 2004
Karma: 5
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Senior Member |
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Tom,
Are you still using the original metal line that run down to the modulator? The line has a factory pinch in it to act as a restrictor to smooth the vacuum out. It is common to have the interior cruded up and maybe plugged. Rinse it out with a good carb cleaner and blow out with air to insure that it is clean. Most if not all of the replacement modulators that I have list come with a rubber 90 degree hose to easy the hookup.
JR Wright
GMC Great Laker MHC
GMC Eastern States Charter Member
GMCGL Tech Editor
GMCMI
78 GMC Buskirk 30’ Stretch
1975 GMC Avion (Under Reconstruction)
Michigan
> On Jul 1, 2017, at 7:56 PM, tom geiger wrote:
>
> Well, will hope not to have to replace it but am having shifting idsues once it heats up. Will clean everything down and keep my fingers crossed it
> does the job. But if not, next is the modulator.
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
J.R. Wright
GMC GreatLaker
GMC Eastern States
GMCMI
78 30' Buskirk Stretch
75 Avion Under Reconstruction
Michigan
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| Re: Transmission modulator [message #319895 is a reply to message #319828] |
Sun, 02 July 2017 18:15 |
tgeiger
Messages: 518
Registered: February 2006
Location: kansas city
Karma: -1
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Senior Member |
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Hey JR, I not absolutely sure on if it has the original metal tube, it appears it is. I'll try cleaning it out and air blowing it out to unclog it. Let u guys know how it goes.
Thanks
Tom
Tom Geiger
76 Eleganza II
KCMO
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