I wasn't aware that you had changed radiators just prior to this transmission issue. Did some research and found this:
Here is what I plan on doing:
-"New" radiator
-New* water pump (AC Delco 251-590) with "6.5 backing plate" (GM 12562659)
-New vacuum pump (AC Delco 215-479)
-"New" alternator (140 amp)
-A/C bypass bracket/pulley (GM 12555023/14102597)
-New* power steering pump (current one started making squealing sounds) (AC Delco 36-517137)
-New fan and fan clutch (AC Delco 15010202/Hayden 2839)
-New belt tensioner (AC Delco 38118)
-Add "serpentine brackets" with new GM bolts
-New radiator mounts. (P/N 6264100 from summit)
According to the key below, the radiator is an unknown quantity:
" '' = part from a pull and pay or a used part
* = a remanufactured part
While the performance of the engine coolant section of the radiator is easily observed, the condition of the transmission cooler section is not so apparent. Proper operation (and normal life expectancy) of the transmission depends on the cooler allowing for the full designed flow rate through the tubes.
If a vehicle suffers a catastrophic failure of the transmission, it is imperative that the ATF coolant section of the radiator be thoroughly flushed as part of the transmission replacement procedure. The tubes that are used in the ATF cooler are tiny. Any debris that results from a transmission breakdown will migrate to - and plug up - the cooler tubes. The result is that the new transmission will fail soon after being replaced.
I am not implying that the radiator you picked up at the J/Y has an obstructed ATF cooler section but it might be worth checking.
A/T - Cooler Replacement/Flushing
BULLETIN NO: 93-7A-97
SECTION: 7A Automatic Transmission
NUMBER: 14
CORPORATE REFERENCE NO: 367102R
DATE: July, 1993
SUBJECT:
Information on Automatic Transmission Cooler Replacement
MODELS:
1993 and Prior Light Duty Trucks Equipped with Automatic Transmissions
When inspection of an inoperative automatic transmission reveals metal material in the oil pan, the transmission oil cooler (located in the radiator end tank) must be replaced. The cooler lines must also be flushed to prevent any debris from entering the transmission oil cooler or the transmission.
If inspection reveals friction material or fluid contamination (but no metal), the transmission cooler must be flushed and a flow check MUST be performed. It is essential to flush the cooler after SRTA installation, major overhaul, in the case of pump or torque converter replacement, or when fluid contamination is suspected. Use Kent-Moore tool J35944 and solvent J35944-20 to flush the cooler. Follow the instructions published in each Service Manual, Section 7A, On Vehicle Service, Transmission Cooler Flushing.
A/T - Fluid Oil Cooler Flow Test
INFORMATION
Bulletin No.: 02-07-30-052H
Date: March 26, 2012
Subject: Automatic Transmission Oil Cooler Flow Test Essential Tool J-45096 TransFlow(R)
Models:
2011 and Prior GM Passenger Cars and Light Duty Trucks
2003-2010 HUMMER H2
2006-2010 HUMMER H3
Equipped with Automatic Transmission/Transaxle including Allison(R) Transmissions
Attention:
For model years 2012 and later, refer to SI for "Transmission Fluid Cooler Flushing and Flow Test" procedures.
Supercede:
This bulletin is being revised to clarify special tool use. Please discard Corporate Bulletin Number 02-07-30-052G (Section 07 - Transmission/Transaxle).
Important
All labor operations that include removal of the transmission from the vehicle include labor time to flow check and flush the transmission oil cooler system.
The J-45096 transmission oil cooling system flow test tool replaces the current tool J-35944-A. J-45096 is a self-contained unit utilizing a 12-volt flow meter, shop air supply and DEXRON(R) VI automatic transmission fluid (ATF). In the flush mode, transmission fluid is cycled through the transmission oil cooling system. High-pressure air is automatically injected into the fluid stream adding agitation to the ATF oil to enhance the removal of contaminated ATF oil and debris. In the flow mode, an electronic flow meter is used to measure the flow capability of the ATF oil cooling system. A digital display indicates the ATF oil flow rate in gallons per minute (GPM) along with the amount of ATF oil in the supply vessel, supply vessel ATF oil temperature, machine cycles and the operating mode. In the flush mode, transmission fluid is cycled through the transmission oil cooling system. High-pressure air is automatically injected into the fluid stream adding agitation to the ATF oil to enhance the removal of contaminated ATF oil and debris. The supply oil vessel has 30 L (32 qt) capacity and the waste oil vessel has 32 L (34 qt) capacity. The waste oil vessel is constructed of a translucent composite material that allows the user to easily identify the oil level. The waste oil vessel can accommodate vacuum evacuation and gravity draining. In the code mode, a random, encrypted code is generated that can be used for verification of flow test results.
Current essential cooler line adapters are used to connect the J-45096 to the automatic transmission oil cooler lines that allows the J-45096 to adapt to General Motors passenger cars and light duty trucks, current and past models (except the Pontiac Vibe, Wave and Chevrolet Aveo).
The tool may be adapted for use on the Pontiac Vibe, Wave and Chevrolet Aveo by dealership personnel with a barbed hose connector and rubber hose obtained locally. The Vibe's/Wave's/Aveo's transmission has a transmission oil requirement that is slightly different from DEXRON(R) VI ATF. However, flow checking and flushing the cooler with DEXRON(R) VI automatic transmission fluid is an acceptable service procedure. Very little fluid remains in the cooler after the flow check and flush procedure and the residual DEXRON(R) VI ATF in the cooler is compatible with the Vibe's/Wave's/Aveo's transmission fluid.
Notice
Insufficient oil flow through the ATF oil cooling system will cause premature transmission failure. The required minimum ATF oil flow rate reading is directly related to the supply oil temperature. Refer to the flow rate chart in SI for the oil flow rate specification based on the temperature of the ATF in the supply vessel.
Helpful Hints for Maintaining the Temperature at or above 18°C (65°F)
Important - The temperature of the supply vessel oil must be 18°C (65°F) or greater for the J-45096 to operate. It is recommended to store the J-45096 in an area of the dealership where the room temperature remains at or above 18°C (65°F) when not in use.
- Do not attempt to increase the fluid temperature in the Transflow(R) machine with an engine oil dipstick, or any other immersion type heater. The Transflow(R) machine has a check valve in the supply reservoir. Inserting a heater will damage the check valve and the subsequent repair expense would be the dealer's responsibility.
- A heater blanket, P/N J-45096-10, is available for the Transflow(R) transmission cooling system flushing tool. This heater fastens around the Transflow(R) internal supply vessel and runs on 110 volts AC. The heater will warm the ATF in the supply vessel to at least 18°C (65°F) and has a thermostat to hold a constant temperature.
Store the Transmission Cooling System Service Tool, J-45096, Transflow(R) machine in a room where the temperature is maintained at or above 18°C (65°F).
Keep the ATF level in the reservoir low when the Transmission Cooling System Service Tool, J-45096, Transflow(R), is not in use. Store several gallons of oil in an area where the temperature is maintained at or above 18°C (65°F). Fill the reservoir of the J-45096 as needed before using the machine on each repair.
With the ATF in a tightly sealed container, place the container in a tub of hot water for a period of time. Then pour the ATF into the reservoir. This method works best with a low fluid level in the reservoir.
Place the Transflow(R) machine in the direct sunlight with the cabinet door open to expose the reservoir to the rays of the warm sun.
The above is from GM and is probably overkill. But you should disco the coolant lines at the transmssion end and flush through them (and the cooler) with a solvent like acetone. Or at least blow them out with compressed air and note whether any debris comes flying out.
IMPORTANT: Whenever flushing any tube type heat exchanger, the flow of flushing media must be counter to the normal fluid flow.
