sean7457

I've got a '79 F150 with a C6 in it. The truck is about 3 weeks new to me, and since I picked it up the column shifter has always felt a little sloppy. It's sometimes difficult to feel exactly where it drops into gear. Is this common?

I assumed all it needed was some adjustment in the cables, but then I took it to get my out of state inspection. I pulled up to the door and shut it off, lady came out and did the 'inspection,' I fired it back up and no matter what gear I put it in she wouldn't budge. Engine just revved up, but it wouldn't drop into gear. It felt like it came out of park, but I was on a flat surface so I can't be sure.

Either way, I shut it off and crawled up under it, and as much as I could see in a DMV parking lot, everything looked fine. Shift linkage was all intact and the transmission was definitely still there. After about 10-15 minutes of poking around, I started it up and it dropped into gear like a new truck and I drove home.

Today, I drove it into work so I could take it over to my buddies garage and tear into it this evening, and it did the same thing again. Could it be a vacuum leak of some kind? It's only happened twice, and it appears to only happen when the truck is warm. It also appears the only solution is to let it cool down for a bit.

Any thoughts would be greatly appreciated.

Thanks!

351W1085

I seriously doubt that the vacuum module would keep it from going into gear. What could have happened is when you thought you were putting it in drive, you were really in neutral and just couldnt tell because the shifter was so sloppy.

sean7457

Vacuum was just the first thing that popped in my head because when it did it the motor dropped a couple hundred RPMs on the idle.

I was thinking I was just missing Drive and getting stuck in Neutral as well, but I pulled the column shifter all the way over from 1st gear to Park several times and ...nothing. I tightened up the linkage as best as I could figure, and it didn't make any big improvement in the sloppy shifter worth bragging about.

On the other hand, It hasn't gotten stuck again. I plan on changing the fluid and filter within the next couple of weeks, but all the lines and everything running to the tranny look in good shape. I just hate to tear down a transmission for something obvious and easy.

Roger Mabry

My '84 was so worn that I could not tell what gear it was really in even though the pointer was "close".

LMC Truck has a good on line parts catalog/ that I use as a parts manual that shows how it all works and has the needed parts. Mine was a couple of small pieces and now it is tight and works fine.

You have to expect a bit of wear after all these years and the parts are not made out of machined steel!

sean7457

I'm pretty confident the actual shifter is not the issue at this point. I was making a slow left hand turn at a 4 way stop on flat, smooth road yesterday and I lost power to my wheels. No pop, no jerk, no nothing. One second I was slowing accelerating through a turn and the next I was coasting.

Is there anything in the transfer case that's known to cause problems on these trucks? Looks like I'm going learn more about a C6 than I had anticipated.

sean7457

Could this be a band adjustment issue? I'm still slightly confused on what exactly the bands in the C6 are for.

BronCowie

I have a '79 F150 351 C6, been sittin for a few years and now won't shift into the forward gears until fully warmed up... we may share a common problem. I'm looking into it.

sean7457

This is my first venture into diagnosing/fixing an automatic transmission, so this might be common knowledge but from what I've read the top 3 explanations are:

1. Linkage is worn/out of adjustment/broke/etc.
2. Not enough or no fluid.
3. Dirty valve body and/or missing the ***** that ride in the raceways in the valve body.

I've checked my fluid level a half dozen times now and it appears to be good. However, everything I read points to it being low. The fluid looks new, but I'm starting to wonder if I'm just seeing residue on the stick and not a hard fill line. I let her warm up and check it in park, but I'm starting to doubt my eyesight.

That being said, the fluid and dirty valve body are top of my list because if I was missing the ***** it would never shift. The plan is to drop the pan, inspect the valve body, replace the filter and refill so I know what's in it. Probably go ahead and put a shift kit in it while I'm at it. Unfortunately, plans don't always get along with time. Hopefully I'll find some over the next week and let you know what I learn.

BronCowie

I am certainly no expert, but keep in mind that it could be more than one problem contributing to this. Check your vacuum at the modulator just to make sure it's good. Dropping the pan is a good idea just to get a baseline on your fluid and to see what kind of debris might be in there. I'm interested in what you find because I also have a C4 that is acting up when it gets warm.

1977f150

My c6 is same way only once in 20 starts will it not go in gear leave it in park wait a minute and it will go Ik these years had ****ty shifting columns