Home » Public Forums » GMCnet » Cooked my tranny (Grades and trouble)
| Cooked my tranny [message #356672] |
Sat, 11 July 2020 16:25  |
lqqkatjon
Messages: 2324
Registered: October 2010
Location: St. Cloud, MN
Karma: 5
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Trying to work out a tow in wyoming.
I was driving back from oregon. Went through yellowstone.
And it did not make it to the top of hwy 16 between 10 sleeps and buffalo, wy.
Downshifting at 45-50mph. Trying to hold speed. (Usually 30-40mph).
I have a 2018 fall rebuilt tranny. 455. With ebl efi. Engine seems ok.
Tranny is hooked up to radiator, then to an external tranny cooler. Running mobil 1.
I am towing 3500 pound crv. And have 3.21 gearing.
When heading over passes westbound. Things seemed well. The engine/tranny seemed to pull the grades fine and hold 40-45mph at 2800-2900 rpm. Maybe 2/3 to 3/4 throttle.
Heading back east it seemed to struggle more and more. (Hills seemed longer.). The one the coach quit moving on was really long. 10 miles??
Think i am pushing it or had some issue with rebuild? I dont know how to take it much easier. Not like I want to pull over facing uphill and try yo het going again? And those spots are few and far between???
Just wondering experience and thoughts.
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/
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| Re: Cooked my tranny [message #356677 is a reply to message #356672] |
Sat, 11 July 2020 19:56  |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Jon,
You've got me concerned. I'm driving that same route in September. I have driven up I-17 from Phoenix to Flagstaff several times and there are some long steep grades along that route. In fact I will be heading up that way next weekend. I have never had a problem. No tranny temp gauge, but maybe I should add one quick between now and then.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: [GMCnet] Cooked my tranny [message #356679 is a reply to message #356677] |
Sat, 11 July 2020 20:28 |
Mike Kelley
Messages: 467
Registered: February 2017
Karma: -2
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Carl S.:
I highly recommend a tyranny temp gauge or a Digipanel (reads 4 or 5 important items) and you can set it to alarm if one of them gets excessive (available from Jim K. at Applied GMC).
Trans temp gauge saved my bacon about 5 years ago when I was in steep inclines on way from El Paso w/ a 65 Corvair in tow. Noticed temp gauge getting pretty hot and getting to far edge of gauge. Found a place to pull off hiway, let it cool for 1/2 hr, then proceeded on my way - no damage but came close to being dizzyastris - just sayin!
Still driving same tranny.
Mike/The Corvair a holic
Sent from my iPhone
> On Jul 11, 2020, at 7:56 PM, Carl Stouffer via Gmclist wrote:
>
> Jon,
>
> You've got me concerned. I'm driving that same route in September. I have driven up I-17 from Phoenix to Flagstaff several times and there are some
> long steep grades along that route. In fact I will be heading up that way next weekend. I have never had a problem. No tranny temp gauge, but maybe
> I should add one quick between now and then.
> --
> Carl Stouffer
> '75 ex Palm Beach
> Tucson, AZ.
> Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles,
> Solar battery charging. GMCSJ and GMCMI member
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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| Re: Cooked my tranny [message #356685 is a reply to message #356672] |
Sat, 11 July 2020 22:14 |
lqqkatjon
Messages: 2324
Registered: October 2010
Location: St. Cloud, MN
Karma: 5
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Looks pink.
My nose is not super. I have seen burnt fluid that is obvious. This is not obvious.
Mobil 1 synthetic. I have never had that in a tranny before this one so I am not super familiar with what it looks like when it’s Burnt.
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/
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| Re: Cooked my tranny [message #356692 is a reply to message #356685] |
Sun, 12 July 2020 05:33 |
6cuda6
Messages: 975
Registered: June 2019
Karma: -6
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Hmmmm i know that in my road race bikes synthetic fluid and clutches didnt really like each other...not sure about this case. Its may be to late but you could try dropping the fluid and putting in regular ATF....nothing to loose, all to gain.
lqqkatjon wrote on Sat, 11 July 2020 23:14Looks pink.
My nose is not super. I have seen burnt fluid that is obvious. This is not obvious.
Mobil 1 synthetic. I have never had that in a tranny before this one so I am not super familiar with what it looks like when it’s Burnt.
Rich Mondor,
Brockville, ON
77 Hughes 2600
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| Re: Cooked my tranny [message #356695 is a reply to message #356672] |
Sun, 12 July 2020 08:15 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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I’ve never used synthetic fluid, probably just in my head but I don’t want to use anything that in theory is slipperier than what the trans was designed for. It gives a few added degrees of temp range before cooking, but then that also subjects the trans to those high temps. I try to not go into those temp extremes. Whose rebuild? I know the 3.21 is The Deal, but towing and mountains may point to 3.55-3.73 as a better combo. Hope you get sorted soon.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: Cooked my tranny [message #356696 is a reply to message #356672] |
Sun, 12 July 2020 10:21 |
lqqkatjon
Messages: 2324
Registered: October 2010
Location: St. Cloud, MN
Karma: 5
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The builder I use was out of South Dakota he had done your GMC motor on transmissions that I am aware of and they have not had any issues. I haven’t had a chance to talk to him yet. Space he is the one that recommended that I use the mobile one synthetic I am usually not a synthetic person. I question the torque converter because they’re always was something a little bit on on how it took off from a stop
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/
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| Re: Cooked my tranny [message #356697 is a reply to message #356696] |
Sun, 12 July 2020 11:37 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Synthetic fluid served me well in the mountains I believe Manny suggests Mobil one in his switch pitch rebuilds. You really got to know your trans temperatures on hard mountain climbs . Towing a CRV on long mountain grades would be a lot easier on the engine and tranny with a 3:73 final then the 3:21 in the mountains I’ve done both but my toad was 900 lbs lighter then yours. If you only have your throttle at 3/4 peddle you shouldn’t be over working the unit though in 2nd I presume. When I was running a 3:21 a lot of those grades would have been a hair raising pull in 1st gear at the summit.
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: Cooked my tranny [message #356698 is a reply to message #356672] |
Sun, 12 July 2020 12:53 |
Ernest Dankert
Messages: 133
Registered: May 2007
Location: Ogden, New York
Karma: 1
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I run AMSOIL synthetic ATF and it has served me well. You will cook the seals and soft parts before damaging the synthetic ATF. I have the power drive gearing and towd an HHR over the same route. We had to unhook and drive independently in the summer.
I agree with the previous posters about trans oil temp gauge and the need for taller gearing.
1977 Eleganza II
Ogden NY
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| Re: [GMCnet] Cooked my tranny [message #356699 is a reply to message #356698] |
Sun, 12 July 2020 13:30 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Well, I have a Manny Transmission in my 78 Royale, along with a 3:70 - 1
final drive ratio. He recommended that I use synthetic transmission fluid.
I started out with Valvoline Synthetic, ran it for a couple of thousand
miles, then drained it as much as I could. I replaced the stock oil pan
with a finned aluminum Ragusa pan that I coated with glyptal and cured in
the powder coat oven in my shop. Would not recommend using the oven in your
kitchen. Serious bitching will occur if you are married and she catches you
doing it.
I then refilled with Valvoline Synthetic ATF and added a temperature
sending unit to it and the final drive at the same time. I drove it a
couple of years before I bothered wiring up the gages, fat, dumb, ignorant,
and happy. Then, I hooked up the gages. The transmission gage registers
160° constantly at the oil pan. Only moves off thet number through the
Siskiyou's on Interstate 5, that has several long climb 6% grades, but only
10° or so. The combination of the in-radiator plus the additional liquid to
air B & M multi finned auxiliary cooler plus the finned aluminum pan keeps
it cool. No.concerns. The final drive? Another matter indeed. Only 2 quarts
of gear oil in there. And lots of heavy loading. That computes to 250°
running down the flat n level, Approaches 300° with any hill climbing. I
use Synthetic Gear Oil in it, and those temps concern me a bit. Been that
way for years, though. No failures yet. Before the gages were hooked up,
never thought about it much. Guess all the gages achieved were to give me
something else to worry about driving down the road! Ah, such is life, I
guess.
Jim Hupy
Salem, Oregon
On Sun, Jul 12, 2020, 10:54 AM Ernest Dankert via Gmclist <
gmclist@list.gmcnet.org> wrote:
> I run AMSOIL synthetic ATF and it has served me well. You will cook the
> seals and soft parts before damaging the synthetic ATF. I have the power
> drive gearing and towd an HHR over the same route. We had to unhook and
> drive independently in the summer.
>
> I agree with the previous posters about trans oil temp gauge and the need
> for taller gearing.
> --
> 1977 Eleganza II
> Ogden NY
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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| Re: [GMCnet] Cooked my tranny [message #356700 is a reply to message #356699] |
Sun, 12 July 2020 19:19 |
sgltrac
Messages: 2797
Registered: April 2011
Karma: 1
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I put whatever Manny says I should put in one of HIS trannys.
Sully
Bellevue wa
On Sun, Jul 12, 2020 at 11:23 AM James Hupy via Gmclist <
gmclist@list.gmcnet.org> wrote:
> Well, I have a Manny Transmission in my 78 Royale, along with a 3:70 - 1
> final drive ratio. He recommended that I use synthetic transmission fluid.
> I started out with Valvoline Synthetic, ran it for a couple of thousand
> miles, then drained it as much as I could. I replaced the stock oil pan
> with a finned aluminum Ragusa pan that I coated with glyptal and cured in
> the powder coat oven in my shop. Would not recommend using the oven in your
> kitchen. Serious bitching will occur if you are married and she catches you
> doing it.
> I then refilled with Valvoline Synthetic ATF and added a temperature
> sending unit to it and the final drive at the same time. I drove it a
> couple of years before I bothered wiring up the gages, fat, dumb, ignorant,
> and happy. Then, I hooked up the gages. The transmission gage registers
> 160° constantly at the oil pan. Only moves off thet number through the
> Siskiyou's on Interstate 5, that has several long climb 6% grades, but only
> 10° or so. The combination of the in-radiator plus the additional liquid to
> air B & M multi finned auxiliary cooler plus the finned aluminum pan keeps
> it cool. No.concerns. The final drive? Another matter indeed. Only 2 quarts
> of gear oil in there. And lots of heavy loading. That computes to 250°
> running down the flat n level, Approaches 300° with any hill climbing. I
> use Synthetic Gear Oil in it, and those temps concern me a bit. Been that
> way for years, though. No failures yet. Before the gages were hooked up,
> never thought about it much. Guess all the gages achieved were to give me
> something else to worry about driving down the road! Ah, such is life, I
> guess.
> Jim Hupy
> Salem, Oregon
>
> On Sun, Jul 12, 2020, 10:54 AM Ernest Dankert via Gmclist gmclist@list.gmcnet.org> wrote:
>
>> I run AMSOIL synthetic ATF and it has served me well. You will cook the
>> seals and soft parts before damaging the synthetic ATF. I have the power
>> drive gearing and towd an HHR over the same route. We had to unhook and
>> drive independently in the summer.
>>
>> I agree with the previous posters about trans oil temp gauge and the need
>> for taller gearing.
>> --
>> 1977 Eleganza II
>> Ogden NY
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
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Sully
77 Royale basket case.
Future motorhome land speed record holder(bucket list)
Seattle, Wa.
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| Re: [GMCnet] Cooked my tranny [message #356705 is a reply to message #356699] |
Sun, 12 July 2020 22:36 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Jim Hupy wrote, " Before the gages were hooked up,
never thought about it much. Guess all the gages achieved were to give me
something else to worry about driving down the road!"
I guess I kind of feel the same way as Jim about the issue of additional gauges. It's not that what you don't know can't hurt you, it sometimes can.
I remember back in June of 1973, the day after I graduated from high school, my parents and I moved back to Tucson after living in Lebanon, PA for five years. My dad was driving the family station wagon, a '70(?) Dodge Polara with a 383 and a 727 automatic transmission. We were flat towing my '53 CJ-3B Jeep, plus a full load of luggage etc. across the country.
When we got into New Mexico, on route 70, and started climbing mountains, my dad became concerned with the transmission temperature, even without a temp gauge on the transmission. He said the transmission heat was transferring to the engine and the cooling system was having a hard time shedding the extra heat. He opted to take a break and make the rest of the trip at night.
I've remembered that all these years and I'm thinking the same applies with the GMC. Maybe the configuration of the front wheel drive transmission doesn't transfer the heat the same as a rear wheel drive set-up does, but I think the same principle applies.
I drive in mountainous terrain quite often and always keep a close eye on my stock gauges, and have never seen my temperature gauge raise much at all on long steep climbs, even in near or over 100 degree outside temps.
Still, I think a transmission temperature gauge is definitely in my future.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: Cooked my tranny [message #356708 is a reply to message #356672] |
Mon, 13 July 2020 05:35 |
lqqkatjon
Messages: 2324
Registered: October 2010
Location: St. Cloud, MN
Karma: 5
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In this case my engine temp was never above 203 degrees.
I have seen some hot engines when climbing grades. And have pulled over years ago to let a car of mine cool down. That day it was by bozeman, mt and 90 some degrees outside at noon.
The gmc engine since i have the new motor and aluminum radiator. Sits at 198 most of time. I have seen maybe 205 in the past year. It is always steady temps.
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/
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| Re: Cooked my tranny [message #356709 is a reply to message #356672] |
Mon, 13 July 2020 08:12 |
6cuda6
Messages: 975
Registered: June 2019
Karma: -6
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Senior Member |
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Jon do you have motion now that your trans has cooled off or is it still the same?
Do you have any gears at all? As its strange you dont have something.
Like i said, if your kinda stuck i would put conventional ATF in it and see what happens....from there you could add some "tranny magic" in a bottle to see what happens (what have you got to loose?)....short of getting a presure test done i dont think there is much you can do.
Stupid question for the masses....what if he lost the governer gear, would that have the same symptons? Im still hung on the "no drive" part as you usually have something.
Rich Mondor,
Brockville, ON
77 Hughes 2600
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| Re: [GMCnet] Cooked my tranny [message #356713 is a reply to message #356709] |
Mon, 13 July 2020 09:26 |
Mike Kelley
Messages: 467
Registered: February 2017
Karma: -2
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Senior Member |
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Rich M.:
When I had the trans problem w/ my 23’ GMC, I had pulled in and parked for breakfast. When I came out, it would not move (in any gear). My mechanic (I am not one) said go to Walmart, buy a bottle of “Trans X”, pour 1/2 in, start engine, try all gears, if does not move wait 10 mins and try again, keep doing it, may or may not solve your problem but worth a try.
It worked after 3rd try (1/2 hr) so I drove it carefully to a nearby large empty car lot and then tried it in every gear. Seemed to be working fine so I drove gently (no heavy throttle and not over 55 mph) for 245 miles to get home. Mechanic checked it next day and said it seems to be fine. Drove it for another year w/ no problems.
I carry a bottle of “Trans X” w/ me in all my GMC’s - had 5 now down to 3.
Mike/the Corvair a holic
Sent from my iPhone
> On Jul 13, 2020, at 8:12 AM, 6cuda6--- via Gmclist wrote:
>
> Jon do you have motion now that your trans has cooled off or is it still the same?
>
> Do you have any gears at all? As its strange you dont have something.
>
> Like i said, if your kinda stuck i would put conventional ATF in it and see what happens....from there you could add some "tranny magic" in a bottle
> to see what happens (what have you got to loose?)....short of getting a presure test done i dont think there is much you can do.
>
> Stupid question for the masses....what if he lost the governer gear, would that have the same symptons? Im still hung on the "no drive" part as you
> usually have something.
> --
> Rich Mondor,
>
> Brockville, ON
>
> 77 Hughes 2600
>
> _______________________________________________
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| Re: Cooked my tranny [message #356722 is a reply to message #356714] |
Mon, 13 July 2020 13:16 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Senior Member |
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Larry has a good point there. Except for the perception that Jon had that the performance seemed to be degrading more and more as he traveled east.
One of the planetary units in my son's Chrysler broke once with the same results, except IIRC, it made some grinding noises. But it seems like if the fluid was in order (not low or burned) something internally breaking would be a logical assumption.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: Cooked my tranny [message #356723 is a reply to message #356708] |
Mon, 13 July 2020 13:19 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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I told this story once here before but I think it applies here so:
When I was 16 and an Eagle scout we went on a week long canoe trip along the Canadian border. Our scoutmaster was driving his Pontiac with 5 of us in it and towing a trailer. We stopped at a toll booth and upon leaving the car would not move. The 6 of us pushed the car and trailer out of the booth and to the side of the road. He said let it sit for 1/2 hour or so and we will OK. Our Scoutmaster was a PHD Chemist working for then Standard Oil of Indiana which is now BP Amaco.
About 45 minutes later we drove away and on to a gas station. He bought 6 or 7 quarts of transmission fluid and away we went. We continued on our trip to the Canadian border. After we set up camp and the trans cooled, we drained the trans and replaced the fluid with new stuff. Trans pans had drain plugs in those days. Our scoutmaster explained that there is an anti-foam agent that wears out after so many heat cycles. He explained the hotter the fluid gets the lesser number of cycles it takes. By replacing 1/2 of the fluid we did not have the problem again. He said when he went back to work (he worked in the Standard Oil lab) he would drain the trans again and replace that fluid a second time. He never had that a problem again. He further explained that most of that foam was generated by and accumulated in the torque converter. Once it cooled down, the air dissipated so it was pumping non-irritated fluid again. He said they had been working on the problem for quite a while. Their then current solutions were to change the fluid more often, or for car manufacturers to make lock up torque converters, or make more efficient trans fluid cooling systems.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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