automatic or manual transmission ?
Check for a vacuum module on the transmission. If you see a vacuum line between the transmission and engine, disconnect the line and look for transmission fluid inside the line. If you see transmission fluid in the line, replace the vacuum module. It probably has a split or damaged diaphragm inside.
You will need the Ford Hydraulic Clutch Quick Disconnect Tool.
I'm not a mechanic / technician but I read once that the modulator valve for the automatic transmission has a vacuum line connected from the valve to the engine and that transmission fluid can be sucked into the engine if something goes wrong with the valve
where can i find a vacuum line diagram for 1989 ford 2.9 liter engine
Wikipedia has a great history of the ford ranger line.
It is located on the driver's side of the transmission toward the front of the transmission. You can identify it by the plastic hydraulic line that is attached to it.
What size is the steel brake line tubing on a 1994 Ford Ranger
Be sure the vacuum supply line from the engine to the transmission vacuum modulator is not disconnected.
If the line is connected directly, without a banjo, or flare fitting, then you will have to loosen the line, unbolt the slave cylinder, and twist the slave cylinder to unscrew the line.
a 92 Ford Ranger stuck in 4th gear can be caused by several things. Low fluid, stopped filter, broken vacuum line or a stuck transmission valve can all be the cause.
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