[GMCnet] TH425 R.I.P.
Randy
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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Chris Choffat
$700-ish plus shipping from manny...
I feel your pain. Mine sorta died the same way...
Let me know if you want to tackle it yourself. I have the hoist frame thingy from Hasbeen still.
--
-Chr$: Perpetual SmartAss
77 Ex-Kingsley 455, Power Drive, 3:21 FD, Quadra bag. The Engineer's Motorhome
Scottsdale, AZ
Photosite: Chrisc "It has Begun"
Gary Worobec
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
gt...@earthlink.net
www.paxtonpatterson.com
----- Original Message -----
From: "Randy" <Acros...@hotmail.com>
To: <gmc...@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
Charles Boyd
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 by Midas
East Tennessee
Kingsley Coach
At a time like this, a long shot at least gives some hope! <g>
Mike....currently in Santa Fe and leaving tomorrow
--
Michael Beaton
1977 Kingsley 26-11
1977 Eleganza II 26-3
Antigonish, NS
Randy
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
Kingsley Coach
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
--
Michael Beaton
1977 Kingsley 26-11
1977 Eleganza II 26-3
Antigonish, NS
Ken Henderson
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 <kings...@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 !
>
>
Charles Boyd
Luvn737s wrote on Thu, 14 April 2011 22:52
> 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.
SIr: pull a vacuum on the modulater and see if it holds. I usually use a new piece of vacuum hose about 2' long and unplug the vacuum line to the modulater, plug in the new piece and suck on it. If it pulls a vacuum plug the end with your tongue and see if it holds. If there is any leakage it could mess with the internal pressures. Only other thing would be take it off and apply vacuum and see if the modulater valve on the internal side is actually working.
A transmission is easier to remove if you leave the differential and axle joints in the coach. About 3 hours with practice from the bottom.
--
C. Boyd
76 Crestmont by Midas
East Tennessee
Ken Burton
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
Matt Colie
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
'73 Glacier 23 Chaumiere (say show-me-air)
SE Michigan - Twixt A2 and Detroit
Randy
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?
Steven Ferguson
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.
--
Steve Ferguson
Sierra Vista, AZ
Charles Wood
IIRC, on mine I had to put on 2 gaskets? on filter to get it to pump up all the time.
--
CBWood
77 Kingslay
MWC OK
Paul Leavitt
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
Larry Engelbrecht
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
'73 26' ex-Glacier
TZE063V100319 030773
Billy Massey
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 <n9...@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.
> --
Mike & Chris Hughes
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
Wander Inn
Phoenix, Az.
Shan Rose
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!
Paul Leavitt
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
Paul Leavitt
More; Causes of Improper Vacume at Modulator
1. Engine
a. Tume UP
b. Loose vacume fittings or improperly routed hoses/lines.
c. Vacume operated accesory leak.
d. Engine exhaust system resriction. (probably not at idle,note is mine,PL)
2. Vacume Line to Modulator
a. Leak
b. loose Fitting
c. Restricted orifice or incorect oriface size.
d. Carbon build up at modulator fitting.
e. Pinched Line
f. Grease in pipe(delayed or no upshift-cold)note from manual.
Randy
Well, I checked the vacuum line and the modulator and all looked good so I fired it up and checked the dipstick again (I had checked it frequently during the previous drive and the fluid was at the proper level) and it was DRY! 3 qts later (that should make about 9 that I added since the pan reinstall) the fluid was again at the proper level and it has gotten me around for the past few miles. We'll see on the ride back to the storage lot, but I'm trying to sty ahead of her ATF addiction. The outside is bone dry also, so maybe the TQ Converter is taking longer to refill completely.
Thanks everyone!
Charles Boyd
Luvn737s wrote on Fri, 15 April 2011 20:53
> Well, I checked the vacuum line and the modulator and all looked good so I fired it up and checked the dipstick again (I had checked it frequently during the previous drive and the fluid was at the proper level) and it was DRY! 3 qts later (that should make about 9 that I added since the pan reinstall) the fluid was again at the proper level and it has gotten me around for the past few miles. We'll see on the ride back to the storage lot, but I'm trying to stay ahead of her ATF addiction. The outside is bone dry also, so maybe the TQ Converter is taking longer to refill completely.
>
> Thanks everyone!
Sir: If the diaphram is ruptured in the modulater valve the engine will suck tranny fluid thru the vacuum line and dump it in the intake and burn it. Tranny will loose fluid with no visable leaks.
--
C. Boyd
76 Crestmont by Midas
East Tennessee
Ray Erspamer
would take off from a stop sign and it would shift into 2nd and then 3rd before
I got through the intersection. New vac modulator, WOW, drives like a sports
car now !!
Ray
Ray & Lisa Erspamer
78 Royale Center Kitchen
TZE368V101144
Wauwatosa, Wisconsin 53226
Email: 78GMC-...@att.net
414-745-3188
Web Site: http://ray-lisa.page.tl/
________________________________
From: Paul Leavitt <leavi...@yahoo.com>
To: gmc...@temp.gmcnet.org
Sent: Fri, April 15, 2011 7:31:17 PM
Subject: Re: [GMCnet] TH425 R.I.P.
Bob de Kruyff
There's no way a vacuum modulator will cause this.
--
Bob de Kruyff
78 Eleganza
Chandler, AZ
Bob de Kruyff
C Boyd wrote on Fri, 15 April 2011 19:01
> Luvn737s wrote on Fri, 15 April 2011 20:53
> > Well, I checked the vacuum line and the modulator and all looked good so I fired it up and checked the dipstick again (I had checked it frequently during the previous drive and the fluid was at the proper level) and it was DRY! 3 qts later (that should make about 9 that I added since the pan reinstall) the fluid was again at the proper level and it has gotten me around for the past few miles. We'll see on the ride back to the storage lot, but I'm trying to stay ahead of her ATF addiction. The outside is bone dry also, so maybe the TQ Converter is taking longer to refill completely.
> >
> > Thanks everyone!
>
>
>
>
>
>
> Sir: If the diaphram is ruptured in the modulater valve the engine will suck tranny fluid thru the vacuum line and dump it in the intake and burn it. Tranny will loose fluid with no visable leaks.
That is true. Earlier I mentioned that a modulator would never cause what you are seeing, but forgot that it could suck out fluid.
--
Bob de Kruyff
78 Eleganza
Chandler, AZ
Randy
When I pulled the vac line off at the engine there was no evidence of fluid having been in the line, so that's good.
I drove it to Little League practice and it ran great.
Summer travel is BACK ON!!!!
Thanks again guys! I hope to get to some rallys some time and meet you in person.
--
Randy
1973 26' Painted Desert
Ahwatukee (Phoenix) AZ