Bowtie Overdrives - Pressure Test

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Notice

CAUTION MUST BE EXCERSIZED DURING THE INITIAL TEST DRIVE. IF YOU FEEL SOMETHING IS NOT CORRECT, STOP AND CALL US. WE CAN CORRECT WHATEVER THE PROBLEM IS BEFORE ANY DAMAGE IS DONE.
DURING ALL THE YEARS OF TEST- DRIVING VEHICLES WE HAVE NEVER DAMAGED A TRANSMISSION DURING THIS PROCESS. IF SOMETHING DOESN'T FEEL RIGHT, STOP THE TEST AND CALL US TO HELP YOU DETERMINE WHAT IS WRONG.

Test drive procedures

It has been our experience the first hour after start up of a newly built automatic transmission is critical. Realize what we are doing is very similar to starting a new engine. Get through this phase and you are well on your way to a long happy life with your new transmission.

1. When you are ready to test drive place the selector in the overdrive position. Softly run the transmission through all the forward gears. Come back to a stop and do the same thing at least two more times. This will bring the transmission up to operating temperature. Bring the vehicle back to a full stop.

2. Keep the selector in the overdrive position and perform a minimum throttle first to second shift. This will be the slowest vehicle speed you can get the vehicle to ease into second gear. When the transmission shifts to second you need to aggressively floor the accelerator to make the transmission perform a second gear to first gear downshift. If the transmission fails to downshift. Terminate the test drive. Carefully return to your shop and call us.

3. Next you perform a minimum throttle (Minimum vehicle speed) third gear into fourth gear. If you have a tachometer this is easy to see when this occurs. Without a tachometer you might have to play with the gear selector to determine when you are in fourth gear at minimum vehicle speed. When you are certain that you have the vehicle into forth gear at the slowest vehicle speed, aggressively floor the throttle to force the transmission to downshift to second, bypassing third in the process. If the transmission fails to perform this test, terminate the test drive and call us.

4. Let the transmission go back into fourth and check for converter lock up. Put your vehicle in light acceleration with your throttle pedal. Hold that position with your right foot while you gently apply the brake pedal with your left foot. Not enough to apply the brakes but just enough to turn on the brake lights. If your brake pedal disconnect circuit is working; you will feel the engine rpm jump up as the torque converter disengages. Continue to hold the throttle position with your right foot. When you release the brake pedal with your left foot, the engines' rpm should drop right back down as the converter re-engages. You must have some acceleration going on while you perform this test or you probably won't feel the engagement and disengagement when it occurs. Now bring the vehicle back to a complete stop.

5. Select manual first gear. Accelerate to 3000 rpm and hold that setting for five seconds. When you are sure the transmission will not go into second gear on its own, release the throttle pedal back to idle. You should feel a strong compression braking action happening. Accelerate back to 3000 rpm.

6. Select second gear with the selector. You should get a clean crisp shift into second gear. Accelerate up to 3000 rpm and hold that rpm setting for five seconds. When you are sure the transmission won't shift on it's own into third gear, release the throttle pedal back to the idle position and check for engine compression braking once again. Accelerate back up to 3000 rpm.

7. Select manual third gear with the selector. The transmission should cleanly and quickly shift into third gear. Take the engine rpm up to 3000, hold it there for five seconds, release the throttle pedal and confirm that you have the correct engine compression braking. Bring the vehicle back to a complete stop.

8. Perform a minimum throttle first to second gear up shift, then aggressively floor the accelerator pedal to perform a second gear to first gear downshift. This time hold the throttle pedal to the floor and record the rpm that the transmission automatically up shifts to second gear and then to third gear. If you don't have a tachometer, the shift points should feel reasonably close to appropriate for passing situations.
(Note: You will be asked what your transmission and engine temperatures were at this point)

9. Stop the vehicle and open the hood. Feel the return line from your cooling system. Please use some common sense here. Use extreme caution around any moving or hot engine components. Please don't call us complaining of burnt fingers or shredded clothes. When you touch the return line, do so with caution, use a quick, light tap to determine if the line is scolding hot. You should be able to touch this line without burning your hands. Even the outgoing line shouldn't be hot enough to burn you if you touch it momentarily. If you feel very high temperatures on the return line you should add a cooler. A transmission temperature gauge will help determine what is occurring. If you error on this topic, please do with too much cooling. The temperature gauge is recommended even if you don't plan to tow. 150 degrees F or less should be indicated with a temperature probe (sender) positioned in the pan. The fluid can be seriously overheated if pan temperatures exceed 150 degrees F. This happens because overheating is occurring in the converter, not the pan. What they don't realize is the temperature that we are observing is the fluid temperature after it has returned from the cooling system! People are confused about this because they know that Dextron III can withstand higher operating temperatures than 150 degrees F. What they are failing to realize is the gauge is reading the fluid after it has gone through the cooling system. While it is impractical to probe the inside of the torque converter when it is operating, it's known to be the hottest component in the system. The converter is the heat source and the main reason a cooling system is essential to automatic transmissions. So we have learned though years of observation this transmission is doing fine at 150 degrees F and overheating when over that if you are sensing the fluid temperature in the pan.
Call with your observations concerning this drive test. Install the remaining pan bolts. (See torque specification sheet) Check for any leaks. These transmissions normally are not "Leakers", but the cooling lines can sometimes be pesky especially at the transmission end. The lines can be difficult to get a wrench on correctly. Recheck the fluid level.