The engine on my 1986 f-250 6.9L diesel won't turn over. The starter engages but immediatly disengages.It happened as I was driving down the road there was a noise like the fan was hitting then a loud pop, the power steering line blew out and the engine stopped. Does anydody have any ideas where I should start?

Looks like you have a failing overrunning clutch drive inside your starter motor. A visual inspection of your flywheel and pinion gears is imperative. ?

The starter gear engages the flywheel, yes. The flywheel is connected to crankshaft, so the engine--flywheel- starter drive gear spins. When you release key to run position, the starter disengages and hopefully the engine is running.
I'm talking automotive.
If your talking riding lawn mower, It's been a while since I worked on one.

Need more info. What engine ? gas or diesel - size engine . Won't crank ???? When you turn the key to the start position what happens ? Does the starter engage an spin the engine over ? This would be a crank - no - start ! Now if nothing happens when you turn the key to start ,this would be a no crank - no - start .Now , which is your problem ? tbc fault ???? Electronic throttle control fault ??????

I think
its the (solenoid) brushes.. Maybe ur starter needs to be serviced by a pro

Bad ignition switch. I have seen lots of these go bad. Also check starter relay. What happened was for some reason the starter relay was activated and sent a signal to the starter to start the car even though the car was running

Check all connections. Battery cables, switch to starter cables, make sure they are all tight. Make sure the starter is engaging and disengaging. Check the belts for looseness. The fact that you were driving when it happened say`s something is loose!

might be a burned spot on the starter contacts where the brushes power the motor.
tap the starter to see if problem goes away.
sometimes you can clean the contacts but that is a temporary fix.

Define - It attempts to turn over but won't catch and run ???? When you turn the key to start does the starter engage an spin the engine ? This would be a crank no start condition . If the starter doesn't engage an spin the engine this would be a no crank no start condition . Sorry to ask but i have only been an auto tech for thirty years an have heard a lot of different discriptions for these simple actions . crank no start or no crank no start . Very different diagnostic procedures . So when you turn the key to start , does the starter engage an spin the engine ,but won't start an run ?

It can be serious because it will ruin the teeth on the flywheel. The "bendix drive" in your starter is going bad. This is the part that engages and disengages the starter. While it is not overly expensive the starter has to come off and apart to fix it. Easier to change the whole starter. Hope this helps.

I had the same thing happen. The automatic locking hubs are faulty, causing one or both hubs to try to engage or disengage onto the front driveshaft. This makes the clicking noise and loud clunking that you hear. You may notice your steering pulling to one side of the road,because one hub is locked in. Replace the automatic hubs with new ones, do not try to fix the old ones. I liked the
convience of automatic hubs but replaced mine with manual hubs, there just way more reliable.