4.0 starter stays on

[Stranger ranger]

you cant replace the solenoid on the starter itself, you must replace the entire assembly. It sucks but at least you wont have trouble for awhile, If this is your problem. Mine did this to me once, and all I did was use my life time warranty and got a fresh new one.

 

[AllanD]

Actually you CAN replace the solenoid ON the starter
(though not while it's installed on the engine)

But it is often cheaper to buy a reman starter than to buy parts to fix a starter.

Do understand that the ignition switch turns on the fender mounted solenoid,
the fender mounted solenoid turns on the starter mounted solenoid.

the starter mounted solenoid is a linear motor that works a bellcrank
internal to the starter that forces the bendix gear into engagement
to the flywheel BEFORE it energizes the motor itself.

If the solenoid(linear motor) is jammed outwards completing the switch contacts the starter would run until the battery was disconnected.

torque loading MIGHT cause it to jam in some way, but in any event in my mind the problem lies bolted to the bellhousing.

The failure mode is less than likely to be in the ignition switch
and if it's in the fender mounted solenoid I'd recommend
spending your entire paycheck on powerball tickets.

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[Stranger ranger]

My mistake, I could not find parts to replace the solenoid which is why I didnt think it could be done.

 

[Wicked_Sludge]

If the solenoid(linear motor) is jammed outwards completing the switch contacts the starter would run until the battery was disconnected.

except the juice has to flow through the fender mounted solenoid FIRST, and if that solenoid is functoning properly, it is OPEN with the key in the run/off positions.

 

[shadetree]

except the juice has to flow through the fender mounted solenoid FIRST, and if that solenoid is functoning properly, it is OPEN with the key in the run/off positions.

The starter motor solenoid has a connection directly from the battery to provide current to spin the starter motor. The only thing the fender relay does is energize the coil on the starter solenoid, and act as a current limiter.

The PMGR starters with the coil activated solenoid on the starter began with the 1990 4.0's. Other engines received this arrangement in 1992. Up until that time the fender relay provided power from the battery to the starter. The solenoid was still on the starter, but it was energized by the windings on the starter itself.

I agree with Alan D. If the starter solenoid is sticking keeping the contacts closed, the starter will continue to spin. OP says he only has this problem in cold weather, so I would suspect something sticking somewhere.shady