Yuuup - its the old Park to Reverse issue common on F250's with a Cruise O Matic

When Ole Blue is sitting in Park, it frequently will slip into reverse. Happens when starting, when sitting at a stop light, when idling in the garage during a tune up. When Uncle Ken was having Ole Blue worked on in the 90's the mechanic wasn't aware of the issue and actually tore off the driver side door when he left the door open while working up front and the transmission slipped into reverse, idled across the yard (in reverse) and hit a tree or something bending the drivers door towards the front of the truck -- AAACCCKKK. (They found a replacement door and painted it to match Ole Blue's Marlin/Wimbledon colors - it still doesn't fit very well - maybe was off a '64 or something).

Anyway, I was reading threads on the FTE forum the other day and saw where Bill the retired Ford Parts Manager responded to a reader with the following info:

"What you're referring to...is not a defect, it's caused by human error. It's a somewhat common occurrence that affects all 1961/96 trucks with A/T.

People put the shift lever into Park before setting the hand brake, causing the truck to roll...just enough...that the parking pawl inside the trans locks up tight.

Now the shift lever has to be YANKED out of Park and before too long, the detent aka shift gate that the tab on the shift lever locks into between Park & Reverse...snaps off.

C5TZ-7A216-A ... Detent-bolts to bottom of upper steering column flange ~ 1965/66 F100/250 240/300 C4 & 352 MX C-O-M / Obsolete

No Ford Dealer or obsolete parts vendor has any. "

I will try to find and replace this piece while swapping out the turn signal switch ....

Uh Ohhhhhhh

C5TZ-7A216-A Is not available, however, we found this thread on FTE: 

https://www.ford-trucks.com/forums/1091088-update-on-auto-shift-detent-my-repair-worked-too.html 

(Use a detent off a /73 bronco)  

Another story: 

https://www.ford-trucks.com/forums/1316668-shift-detent.html 

(Make sure the detent is the issue - this guys root cause was his shift lever) 

I took off the steering wheel and immediately saw that the 2 'ears' were broken off the turn signal switch - ordered that up from one of the current replacement parts stores. Following the advice of users at the FTE forums I ordered the complete part with wires, as all recommendations say replace the complete switch NOT just try to replace the white plastic thing as this almost never really fixes the problem of turn signals not working correctly.  

Decided to take a look at the detent while prepping for new turn signal switch, I unscrewed the three retaining screws and pulled back the turn signal switch, then removed the two center shifter retaining nuts and lifted out the shift mechanism. Turning over the shift mechanism, the detent looked great - no cracks or deformities.  

Taking a closer look at the Shift lever, the end looked a little different then what was shared on the FTE forums. 

I saw a little piece of steel laying next to the end of the shift lever (see 1 below) and a rough edged on the end of the shift lever - the tab had broken off !! (see 2 below)  

ROOT CAUSE OF OLE BLUE shifting into reverse was NOT the detent at all - it was a broken lock tab on the shift lever!  

Tune Up Time

It has been a few thousand miles and I have noticed that Ole Blue has been coughing a little when I accelerate out of turns on the country roads heading to the beach. I think I need to take another look at the carburetor. So, this morning 'Choke Boy' and I took a drive down the highway a couple of miles and then, with a warm engine, went to work by hooking up the vacuum gauge and timing light.

My plan was to:

1. Note the idle vacuum reading. Normal vacuum at idle should be 19-21 inches for a six cylinder, or 15-18 inches on a low compression engine. 
2. Check the ignition timing, before making any carb adjustments.
3. Lean out the mixture screws (turn in).  
4. After each adjustment is made, reset the idle speed.

I had also picked up a tachometer / dwell meter at goodwill for $1 and I hooked it up as well. The tachometer was reading 800 rpm, the vacuum was at 19 inches and the timing was a bit advanced of my white mark from last year, so I released the lock down bolt and reset the timing to 10 degrees BTDC.

I checked the idle mixture screws. Turning each screw about 1/2 turn in, I was thinking I needed to lean out the carb a little to reduce the coughing. The vacuum was still reading 19 inches so I turned it 1/4 turn more and rechecked the idle speed, setting it at 700.

I cranked down on the distributor hold down bolt, disconnected the meters and took her for a test drive, Choke Boy riding shotgun. She pulled away smooth from full stops and as we headed out of town on the little two lane road west we easily cruised at 55 out to the turns in the road as it meanders through the low hills. Entering the first turn I let up on the accelerator and when I pushed down to accelerate out of the turn Old Blue jumped without any hesitation, pulling us through the corner, accelerating into the straights. Yeah, Baby let's drive this a while and see how it feels!