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Yadkin
08-17-2016, 04:42 PM
I rebuilt my Cruise-O-Matic as part of this restoration and it works perfectly- except when cold. It just won't shift into 3rd for, I'd guess, five to ten minutes of driving. I'm assuming that the reason is higher viscosity of the fluid when cold.

I have O'Reilly's Type F in the system and the level is correct. Do I need to change to another brand of fluid? Or is there an additive that I should use to reduce cold viscosity?

simplyconnected
08-17-2016, 05:21 PM
Are you using an 'automatic transmission' radiator, or do you have a separate transmission cooler?

Yadkin
08-17-2016, 10:43 PM
I have a separate cooler mounted in front of the radiator, behind the AC condensor. I also have an electric cooling fan, behind the radiator with a tight shroud that doesn't turn on until the coolant is hot, then modulates the fan speed to keep the coolant at the set point.


The problem is most pronounced when I'm driving from my cabin in the mountains. It's a 3 mile coast downhill until I get anywhere, so the engine doesn't get to operating temperature either.

simplyconnected
08-18-2016, 12:39 AM
I think you solved your own problem by identifying the cause...
OEM radiators integrate a tank in the bottom that serves two functions. In winter, your engine's thermostat quickly warms coolant until it reaches the proscribed temp, then it opens to convey heat to WARM transmission oil in the radiator.

Depending on ambient temp, the engine normally reaches thermostat temp within two miles. By separating the transmission cooler, you have eliminated any chance of warming by the cooling system.

The trans cooling design engineers really hit on a winner by integrating both heating and cooling functions in one radiator because:

The bottom tank of the radiator is below the transmission's fill level,
The trans cooling tank is out of the way of the A/C condenser,
Fan placement is never an issue,
Trans fluid cooling temp is REGULATED for consistent viscosity,
The tank is protected from stones because there are no fragile and vulnerable cores filled with oil.

It makes sense that corporate wide, ALL brands of autos use the same radiator method to warm and cool automatic transmission oil. - Dave

pbf777
08-18-2016, 02:02 PM
I doubt that a different brand of fluid or rerouting cooler lines would solve this problem (but I have been wrong before!), as the transmission should function properly even when cold (reasonable), with the inherently heavier viscosity fluid which accompanies such.

I certainly can't diagnose for certain exactly what's wrong from here, but, "as-a-wild-a**-guess", I'm thinking a control problem within the valve body, such as a miss-positioned and or binding/sicking shuttle/spool valve which "frees-up" with heat, expansion and vibration?

I wouldn't buy any lottery tickets with these comments, but you asked. Scott.

Yadkin
08-19-2016, 10:09 AM
I suspected the separate cooler was the problem. Dave, is there any way to clean the heat exchanger that is part of the radiator? I don't want to hook it up only to run debris into my newly rebuilt transmission.

simplyconnected
08-19-2016, 12:23 PM
Good transmission shops across the nation are equipped to flush your transmission lines and radiator tank. Call around your neighborhood trans shops and ask about their rates, how long it takes, if there is a warranty, etc.

Joe Johnston
08-19-2016, 01:07 PM
Sorry guys, but I'm not buying the external cooler causing his tranny to not shift for 5 - 10 min. He lives in NC and it isn't below zero there. Those of us who have lived in colder climates may have experienced a bit longer than normal shift points on sub zero days, but even at that, its only minimal. A few seconds perhaps, but 5 min or more?? No way - even on the most bitter cold days driving with a cold engine. I am most certainly not a trans expert, but I highly suspect an internal problem like a sluggish or sticky valve body component.

That said, a fluid change and perhaps a flush may help as well as a product like Trans X. Won't hurt, worth a try and if no help, it can still be checked by a good trans shop.

scumdog
08-19-2016, 08:34 PM
I'm with Joe.

So before going through all the rigmarole of hauling out your radiator and getting your trans cooler tube in it replaced/repaired etc how about trying this:

Cut out a piece of cardboard the same surface area as the front of the cooler and tape it over the front of your transmission cooler.

That would stop the airflow from doing any cooling so that way you will see if it is fact any relevance to your shifting issue.

Remember not to leave the cardboard there forever!!!!!, once the motor temperature is up to normal I would remove the cardboard to avoid the risk of overheating the trans fluid.

Yadkin
08-23-2016, 09:40 AM
Sorry guys, but I'm not buying the external cooler causing his tranny to not shift for 5 - 10 min. He lives in NC and it isn't below zero there. Those of us who have lived in colder climates may have experienced a bit longer than normal shift points on sub zero days, but even at that, its only minimal. A few seconds perhaps, but 5 min or more?? No way - even on the most bitter cold days driving with a cold engine. I am most certainly not a trans expert, but I highly suspect an internal problem like a sluggish or sticky valve body component.

That said, a fluid change and perhaps a flush may help as well as a product like Trans X. Won't hurt, worth a try and if no help, it can still be checked by a good trans shop.

The transmission is was rebuilt last year and operates perfectly when warm. Not a lot of miles on the fluid that's in there. The long warmup times that I experienced happen when I start from cold at my mountain cabin down to Banner Elk, a drop of about 1200' in 4 miles. The engine doesn't even get up to operating temperature. Morning air temperatures are in the high 60's. A typical trip to Lowes hardware is about 5 miles and the transmission never shifts into 3rd. But, when I stop the engine and restart ten minutes later to make the trip back up the hill, third gear is immediately available.

Here in Clemmons where it's about 15 degrees warmer and a lot flatter, the engine/ transmission warm-up time is about half of that.

I have a 180 degree thermostat and an electric cooling fan that comes on at 190.

pbf777
08-23-2016, 12:59 PM
You have acquired a fine observation that your transmission is sensitive to temperature for proper operation, but, your belief that the temperature is the problem which requires addressing seems faulty.

As stated by others, as the temperature falls the shifting function will be affected, but not to the "degree" as you depict; especially if only in the 60s' (F). Scott.

Yadkin
11-18-2016, 03:11 PM
I think you solved your own problem by identifying the cause...
OEM radiators integrate a tank in the bottom that serves two functions. In winter, your engine's thermostat quickly warms coolant until it reaches the proscribed temp, then it opens to convey heat to WARM transmission oil in the radiator.

I finally got around to removing my external cooler, cleaning out the radiator and using the OEM setup. The issue isn't gone but it is better. Test drove this morning, temperature around 60F.

Not sure if a name brand of fluid would be better, or trying some kind of viscosity improver would help.

Yadkin
11-18-2016, 04:15 PM
The only thing that I find that remotely addresses the issue is Lucas Automatic Transmission Fluid Conditioner #10441.

http://lucasoil.com/pdf/TDS_ATF-Conditioner.pdf

"maintains cold temperature properties"
"improves shifting performance"

I've never had much faith in these type of products.

pbf777
11-19-2016, 11:55 AM
I normally advise against using these "miracle in a bottle" elixirs, as anything but a last ditch possible solution prior to removal of the transmission for proper repair. One of their functions is to have an adverse effect on the soft sealing elements within the transmission. The intent is to cause worn and/or collapsed o-rings to swell in order to recover improved sealing performance. This may provide a fine but perhaps only temporary "fix" (popular with used car lots), later, often the effect causes hardening of these sealing elements and inevitable failure requiring a complete replacement. Scott.

Yadkin
11-19-2016, 12:23 PM
There's literally a dozen bottles of stop leak and other junk like that on the shelf at O's, A's and others, including offerings by Lucas. I rebuilt my transmission recently so that is not the issue. The product I listed was not advertised for that.

Yadkin
03-27-2017, 10:49 PM
This is an update. The transmission problem got progressively worse, so I dropped the pan and drained the fluid out of the convertor. A noticeable burned smell and slight brown color to the otherwise red. Gunk in the pan, and the filter coated with it. Although the gunk had a grey color to it I think it was more fiber from the new clutch friction disks than metal. At least I hope so. So the transmission had to get real hot for viscosity to drop in order to pump fluid through the shifter circuit.

I bought a new filter from Oreilly's. China again, it took a lot of tweaking for it to fit properly. However the gasket it came with looked better (neoprene?) than the Felpro one that I had ordered separately. I worked the pan flange carefully to flatten it out as best as I could, then used Permatex RTX black on both sides of the gasket. Hand tightened in several stages in a radial pattern then let sit for an hour, then torqued to 5 #-ft. New stainless steel pre-bent cooling lines and using the OEM cooling circuit (in the radiator). The refill took 11 quarts of Valvoline.

I just test drove it- problem solved.

simplyconnected
03-28-2017, 02:16 AM
Just a couple points...
On all pan bolts, I always use Loctite blue. Valve covers and oil pans distort when tightening their bolts past the recommended torque. If that happens, the cork gasket gets destroyed, then it leaks. Y-Block valve covers only use two nuts on top the 'dome' and NO bolts around the perimeter. It works, too. This is an engine with solid lifters so a major tune-up includes valve adjustments. That means frequent valve cover openings.

Five pounds is less than 'hand tight,' to me. That means the perimeter bolts can come out on their own, without thread locker.

Your transmission uses eleven quarts of hydraulic oil, mainly to carry heat away from all the hot parts, NOT for lubrication. The fastest way to burn any automatic trans is to run it with low oil. The dip stick 'sniff test' reveals a lot.

Keep up the good work. - Dave

Yadkin
03-29-2017, 11:06 AM
Thanks Dave. I didn't use thread lock on this. The Shop Manual specifies 10-13 #-ft for the pan bolts; that would distort the pan a lot.

So far, my garage floor is dry. :)

Yadkin
04-30-2017, 08:39 PM
The slow warm up issue seems to be slowly coming back. With the warm weather we've been having it takes a good 4 miles or so to finally upshift to 3rd.

I was hoping that the fiber plates were going to stop losing material, but if it keeps happening frequent cleanings and oil changes are going to keep me under the car more than I'd prefer. And I hate to have to rebuild this transmission a second time. If I'm going to do that I ought to just go ahead and install an AOD.

I'm wondering if I should just remove the OEM filter and install a cartridge filter in-line with the cooling circuit.

https://www.summitracing.com/parts/der-13090/overview/

simplyconnected
04-30-2017, 09:26 PM
Bring it back to your transmission guy. Transmissions don't take that long to shift and you should NEVER find debris in your trans fluid.

What kind of 'fibers' did he use??? You would have been better off re-using your original steels and fibers. That's what I did with my COM. I didn't like the way new fibers looked and my originals were very decent. OEM parts are frequently better than aftermarket offerings because they went through many years of testing and proof. - Dave

Yadkin
05-01-2017, 09:22 AM
I'm the transmission guy. I ordered a kit from O's and that's what I got. When warm it shifts much better than before. I may still have the old plates, which are worn, around here somewhere but it's a big job that I would like to avoid. And if I do replace the plates it will be new ones that are not worn.