The problem is predominantly with the 1-2 shift. Ford called its C4 the Cruise-O-Matic while Mercury called its C4 the Merc-O-Matic. I have been racing a C-6 in circle track car since 1991. When bolting on the plate, be sure its slot lines up with the valvebody hole arrow. It just started working one day, then quit again. According tio Kelly Hot Rod, many Ford Automatic transmissions, especially the C-series, can be identified by the bottom pan shape and the bolt count. To cool the transmission, two brass lines connect the side of the transmission to the bottom of the radiator, where it is then cooled independently of the radiator fluid.
If a press in, make sure you have an o-ring. But, they lack the overdriven gears and lockup torque converters the newer transmissions rely upon to boost fuel economy figures. Transmissions that are overfull tend to foam or aerate causing air bubbles to be drawn into the torque converter and pump, which causes a great disruption in control pressure. Use a hand vacuum pump and guage to check the modulator lines for leakage. Since the trans starts in first in L and D, and starts in second in 2, you will get a shift when putting the trans from D to 2 if the trans is in first or third. Inspect the bottom of the gasket for signs of leaks.
It was designed and manufactured by BorgWarner for new-generation gray-wall-iron straight-6 and small V-8s. This valve body was used from 1967 to 1969. Look for other bad sections of line or replace the modulator. It shifts normally under this condition. The exact configuration of the parts may vary slightly in specific valvebodies.
Therefore, knowing how to identify the C6 is vital. Herman Steve Gerland wrote: C6 automatic transmission in a '77 Ford Ranchero will not shift automatically. I have plugged off the hose to modulator valve. Includes our Torque Max torque converter in stall speeds up to 2400 rpm. With the engine running, listen closely for abnormal noise such as torque converter improperly seated, which can cause squealing, no control pressure, and an inoperative transmission.
The fitting will sometimes be clogged up with carbon. Reuse the original check ball s in their original locations. Things to check: Vacuum modulator, fittings, and tubing, as another poster mentioned. Will trans fluid drain out when the diaphragm is removed? The bell housing in located on the front of the transmission. The C6 operates on hydraulic pressure, necessitating a sufficient amount of fluid.
All is well and good there - nothing binding or loose or worn. Because automatic transmissions encompass dozens of tiny parts—clips, balls, pins, valves, springs, and other items—your workspace must be well-lit, neat, orderly. Placing several small magnets on the underside of the cookie pan temporarily magnetizes it, further keeping those small parts together. The oil pan is located on the bottom of the transmission, and uses a total of 17 bolts to hold the pan to the transmission. At the back of the transmission is the extension housing. This spring is slightly shorter than the converter pressure relief spring.
This photo also shows the manual B and downshift C levers. In early applications, the Ford-O-Matic transferred heat to the atmosphere via the torque converter and cooling vents in the bellhousing, instead of using fluid as coolant and a transmission cooler in the radiator. Use a combination of the two to identify the transmission. Think of a torque converter like a water wheel in an old saw mill: the waterwheel is driven by fluid in motion. For 1966, Ford introduced its own heavy-duty C6 3-speed automatic transmission for high-torque applications behind large-displacement big-block V-8s.
If nothing is wrong there I will try the modulator diaphragm. This is where a step-by-step approach to the problem can help get you steered in the right direction. Have a drain pan ready. If the lines are not leaking, replace and adjust the modulator. Kickdown linkage and proper spring back at the : trans.