Home » Public Forums » GMCnet » TH425 R.I.P.
| TH425 R.I.P. [message #121844] |
Thu, 14 April 2011 19:49  |
Luvn737s
Messages: 1106
Registered: June 2007
Karma: 2
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Senior Member |
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Well, I guess it's time say a few words in memorium of my transmission.
Summary: I had a problem with not going into gear on cold starts and thought it was a disconnected filter. It wasn't, but I replaced the filter. Replaced 2/3 of the fluid with new mixed with reclaimed old.
I have filled it up and it now works worse than ever. After 10 minutes of running it might go into Drive only to slip out of gear. Reverse is no better, really. Stepping on the brake in drive causes it to slip out of gear and you wait for it to re engage. It generally takes longer to slip back into drive than reverse, but that's not a hard and fast law either.
I can't justify throwing $2000+ into a transmission for it, but I sure wish I knew why it crapped out after working so well for so long.
Is there anything I might have missed in the diagnosis?
Randy
1973 26' Painted Desert
Ahwatukee (Phoenix) AZ
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| Re: TH425 R.I.P. [message #121846 is a reply to message #121844] |
Thu, 14 April 2011 20:11  |
Chr$
Messages: 2690
Registered: January 2004
Location: Scottsdale, AZ
Karma: 1
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Senior Member |
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$700-ish plus shipping from manny...
I feel your pain. Mine sorta died the same way...
Let me know if you want to tackle it yourself. I have the hoist frame thingy from Hasbeen still.
-Chr$: Perpetual SmartAss
Scottsdale, AZ
77 Ex-Kingsley 455 SOLD!
2010 Nomad 24 Ft TT 390W PV W/MPPT, EV4010 and custom cargo door.
Photosite: Chrisc GMC:"It has Begun" TT: "The Other Woman"
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| Re: [GMCnet] TH425 R.I.P. [message #121851 is a reply to message #121844] |
Thu, 14 April 2011 20:22 |
Gary Worobec
Messages: 867
Registered: May 2005
Karma: -1
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Senior Member |
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Manny is way less than $2000.00. We need to think of GMC tranny's as
expendables. Changing it out is not a big deal. You might want to opt for a
lower final drive while you are at it either the chain drive that Manny
supplies or the diff gearing from JimK. I'm thinking less stress on
everything. The Olds motor certainly will handle the extra RPMs.
Thanks,
Gary Worobec
Director, Product Development
PAXTON/PATTERSON
(O) 951-763-0518
(C) 773-230-6226
gtw5@earthlink.net
www.paxtonpatterson.com
----- Original Message -----
From: "Randy" <Acrosport2@hotmail.com>
To: <gmclist@temp.gmcnet.org>
Sent: Thursday, April 14, 2011 5:49 PM
Subject: [GMCnet] TH425 R.I.P.
>
>
> Well, I guess it's time say a few words in memorium of my transmission.
>
> Summary: I had a problem with not going into gear on cold starts and
> thought it was a disconnected filter. It wasn't, but I replaced the
> filter. Replaced 2/3 of the fluid with new mixed with reclaimed old.
>
> I have filled it up and it now works worse than ever. After 10 minutes of
> running it mnkight go into Drive only to slip out of gear. Reverse is no
> better, really. Stepping on the brake in drive causes it to slip out of
> gear and you wait for it to re engage. It generally takes longer to slip
> back into drive than reverse, but that's not a hard and fast law either.
>
> I can't justify throwing $2000+ into a transmission for it, but I sure
> wish I knew why it crapped out after working so well for so long.
>
> Is there anything I might have missed in the diagnosis?
> --
> Randy
> 1973 26' Painted Desert
> Ahwatukee (Phoenix) AZ
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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| Re: TH425 R.I.P. [message #121852 is a reply to message #121844] |
Thu, 14 April 2011 20:33 |
C Boyd
Messages: 2629
Registered: April 2006
Karma: 18
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Senior Member |
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Is there anything I might have missed in the diagnosis? [/quote]
Sir: you might see if the modulater valve will hold vacuum. Just a long shot..
C. Boyd
76 Crestmont
East Tennessee
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| Re: [GMCnet] TH425 R.I.P. [message #121864 is a reply to message #121862] |
Thu, 14 April 2011 21:58 |
Kingsley Coach
Messages: 2691
Registered: March 2009
Location: Nova Scotia Canada
Karma: -34
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Senior Member |
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Randy
The procedure for removal is not too complicated.
Jack motorhome with enough clearance to drag out trans on a piece of
plywood...24" inches I think; maybe 30.
Support engine.
Remove every bolt you can see for 3 days
You can try to lower it with a jack, but it will fall off because the thing
is cock-eyed for weight distribution..try not to get hit when this happens!
Drag out from under, using closest mule...
This may be the unrefined version, but it's the basic one..others may be
more merciful and provide some 'techniques' ..<VBG>
It's just dirty and awkward, but requires little skill...I did it !
Mike
On Thu, Apr 14, 2011 at 11:52 PM, Randy <Acrosport2@hotmail.com> wrote:
>
>
> C Boyd wrote on Thu, 14 April 2011 18:33
> > Sir: you might see if the modulater valve will hold vacuum. Just a long
> shot..
>
>
> Is that procedure in the service manual, or do I just hook a vacuum gauge
> up to it?
>
> As we're just getting into the hot weather, I may end up scrubbing this
> summers travel plans and tackle changing it in the fall, or offer somebody a
> tremendous deal on a static motorhome. :cry:
>
> I'll have a better idea which direction I'll go after I gather all the info
> on what's required to change it out.
>
> Thanks for the offer Chris, I may take you up on it.
> --
> Randy
> 1973 26' Painted Desert
> Ahwatukee (Phoenix) AZ
> _______________________________________________
> 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
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| Re: [GMCnet] TH425 R.I.P. [message #121865 is a reply to message #121864] |
Thu, 14 April 2011 22:02 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Be sure to make yourself one of these to minimize the dropping phase:
http://www.gmcmhphotos.com/photos/showgallery.php?cat=5741
<http://www.gmcmhphotos.com/photos/showgallery.php?cat=5741>
Ken H.
On Thu, Apr 14, 2011 at 10:58 PM, Kingsley Coach <kingsleygmc@gmail.com>wrote:
> Randy
>
> The procedure for removal is not too complicated.
>
> Jack motorhome with enough clearance to drag out trans on a piece of
> plywood...24" inches I think; maybe 30.
> Support engine.
> Remove every bolt you can see for 3 days
> You can try to lower it with a jack, but it will fall off because the thing
> is cock-eyed for weight distribution..try not to get hit when this happens!
> Drag out from under, using closest mule...
>
> This may be the unrefined version, but it's the basic one..others may be
> more merciful and provide some 'techniques' ..<VBG>
>
> It's just dirty and awkward, but requires little skill...I did it !
>
>
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Unsubscribe or Change List Options:
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: TH425 R.I.P. [message #121879 is a reply to message #121870] |
Fri, 15 April 2011 03:44 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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After jacking it up and removing the wheel liners and wheels, It took two of us 1.5 hours to remove my tans on a concrete floor with a floor jack. It took two of us (I had a different helper) 2.5 hours to install the replacement.
Removing the wheels and liners makes the job a lot easier.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: TH425 R.I.P. [message #121881 is a reply to message #121844] |
Fri, 15 April 2011 06:30 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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| Luvn737s wrote on Thu, 14 April 2011 20:49 |
Well, I guess it's time say a few words in memorium of my transmission.
Summary: I had a problem with not going into gear on cold starts and thought it was a disconnected filter. It wasn't, but I replaced the filter. Replaced 2/3 of the fluid with new mixed with reclaimed old.
I have filled it up and it now works worse than ever. After 10 minutes of running it might go into Drive only to slip out of gear. Reverse is no better, really. Stepping on the brake in drive causes it to slip out of gear and you wait for it to re engage. It generally takes longer to slip back into drive than reverse, but that's not a hard and fast law either.
I can't justify throwing $2000+ into a transmission for it, but I sure wish I knew why it crapped out after working so well for so long.
Is there anything I might have missed in the diagnosis?
|
Randy,
Before you do anything rash, CALL MANNY!
As to the swap, I got mine down in less than 4 hours working alone with the coach on jacks.
Without Manny's long distance help it would have been a lost cause.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: TH425 R.I.P. [message #121883 is a reply to message #121844] |
Fri, 15 April 2011 07:13 |
Luvn737s
Messages: 1106
Registered: June 2007
Karma: 2
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Senior Member |
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Good idea, I'll call him in the morning.
Does anyone have a link to a photoblog of them removing the transmission?
The crazy thing is that 3 weeks ago I drove it for about an hour at highway speeds and in stop and go traffic and there was no harsh engagement, no slipping, no indication of any trouble. The transmission has never whined. When the pan came down, there was a little residue, but nothing sticking to the magnet in the bottom.
What are the symptoms associated with:
1. Too much fluid
2. Modulator failure
My meager understanding of automatic transmissions is that they are basically a big ported hydraulic pump (or pumps as the case may be). So could the pump be cavitating for some reason?
Randy
1973 26' Painted Desert
Ahwatukee (Phoenix) AZ
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| Re: [GMCnet] TH425 R.I.P. [message #121886 is a reply to message #121862] |
Fri, 15 April 2011 08:18 |
Steven Ferguson
Messages: 3447
Registered: May 2006
Karma: 0
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Senior Member |
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Get underneath, disconnect the existing vacuum line, connect a short section
of vacuum line, suck on it to build upvacuum. Put your tongue over the end
of the hose. If it holds vacuum, it's good. If not, it's bad. If it is
good, make sure you clear any obstructions from the existing vacuum line
before reconnecting.
On Thu, Apr 14, 2011 at 7:52 PM, Randy <Acrosport2@hotmail.com> wrote:
>
>
> C Boyd wrote on Thu, 14 April 2011 18:33
> > Sir: you might see if the modulater valve will hold vacuum. Just a long
> shot..
>
>
> Is that procedure in the service manual, or do I just hook a vacuum gauge
> up to it?
>
> As we're just getting into the hot weather, I may end up scrubbing this
> summers travel plans and tackle changing it in the fall, or offer somebody a
> tremendous deal on a static motorhome. :cry:
>
> I'll have a better idea which direction I'll go after I gather all the info
> on what's required to change it out.
>
> Thanks for the offer Chris, I may take you up on it.
> --
> Randy
> 1973 26' Painted Desert
> Ahwatukee (Phoenix) AZ
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Steve Ferguson
Sierra Vista, AZ
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| Re: TH425 R.I.P. [message #121892 is a reply to message #121844] |
Fri, 15 April 2011 09:46 |
g.winger
Messages: 792
Registered: February 2008
Location: Warrenton,Missouri
Karma: 0
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Senior Member |
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I would do what Steve F. sugests. Also,,,,look at buying a hand operated vacume pump. I've used mine 20 times in 15 years. Usefull for other vehicles but some egr valves "bleed" and won't hold vacume so you have to be carefull when diagnosing parts. I take the pump to the store and test the new parts and do research beforehand. next, its already broke so you can't hurt it right?. Study the manual, chapter on transmissions. Find out what band,acuator or valve makes it go into gear and is common for forward and reverse. Remove the valve body if your reasearch shows it could be a problem and find it. I don't have the manual with me but I remember alot of fluid paths displayed in color. I also have found that my 72 Cadilac factory manual to be a big help. I wish I had more time to research this but we're leaving on th MC saturday if it doesn't SNOW!!!!yes,,,,possable snow in missery,,,opps,,missouri. Misspelled it again.,,,good luck,,,,,PL
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| Re: TH425 R.I.P. [message #121899 is a reply to message #121892] |
Fri, 15 April 2011 11:47 |
LarryInSanDiego
Messages: 336
Registered: September 2006
Karma: 0
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Senior Member |
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The lack of engagement in both forward and reverse gears suggests a lack of main line pressure, for which there is a test port on the case. That's where I'd look first. It's likely a worn pump if the filter has been changed (and the o-ring and "riser" part of the filter are in place).
Larry Engelbrecht
San Diego, CA
'73 26' ex-Glacier
TZE063V100319 03/07/73
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| Re: [GMCnet] TH425 R.I.P. [message #121900 is a reply to message #121879] |
Fri, 15 April 2011 11:44 |
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haha yeah, talk to Manny. He's the guy that carries a spare in the
toad. Pulls over and changes it out in a parking lot and goes on his
way. AWESOME!
bdub
On Fri, Apr 15, 2011 at 3:44 AM, Ken Burton <n9cv@comcast.net> wrote:
>
>
> After jacking it up and removing the wheel liners and wheels, It took two of us 1.5 hours to remove my tans on a concrete floor with a floor jack. It took two of us (I had a different helper) 2.5 hours to install the replacement.
>
> Removing the wheels and liners makes the job a lot easier.
> --
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
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bdub
bdub.net
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| Re: TH425 R.I.P. [message #121914 is a reply to message #121844] |
Fri, 15 April 2011 14:19 |
Wander Inn
Messages: 100
Registered: January 2010
Location: Phoenix Az.
Karma: 0
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Senior Member |
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Randy,
I have a hand held vacuum pump, give me a call and we
can give it a try.
Mike
Mike & Chris Hughes
1977 Kingsley
Phoenix, Az.
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| Re: TH425 R.I.P. [message #121918 is a reply to message #121844] |
Fri, 15 April 2011 14:56 |
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definately check the modulator, I was ready to junk a ford tranny because of issues, turned out it was just the $20 modulator, a 10 minute fix in most cases!
73 Canyon Lands, (a.k.a. The Yellow Submarine) West Los Angeles CA
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| Re: TH425 R.I.P. [message #121928 is a reply to message #121844] |
Fri, 15 April 2011 18:05 |
g.winger
Messages: 792
Registered: February 2008
Location: Warrenton,Missouri
Karma: 0
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Senior Member |
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Got out my 85 chevy van manual. Covers 3 and 4 spd 350 and turbo 400. Same as ours. Under Vacume Modulator Diagnosis. 1.Harsh upshifts and downshifts. 2. Delayed Upshifts. 3. Soft upshifts and down shifts. 4. Slips in drive and reverse. Transmission overheating. 6. Engine burning trans oil. Gota eat,,,gata go,,,,,PL
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