Truck problem

[Warbird]

Possible problem with the transmission.  Was out plowing snow and after finishing up at one friend's house, on the way the next, I noticed the truck wouldn't shift into 3rd gear.  It's an '86 F250 with a 460 big block and a C6 transmission.  1st, 2nd, revers, no problem.  Just wouldn't shift into 3rd.

I got it home, cleaned out the shop, and pulled it in there.  It hasn't thawed out in quite a few weeks.  I took a look at the undercarriage and it had an amazing amount of snow and ice caked up under there.

Any chance something just got froze up or plugged up?  Not sure what it could be but that's my hope and prayer.  Transmissions ain't cheap.  :-\  If that isn't it, what else could it be?

[Dana]

It dosen't sound good. I would change the transmission filter and fluid. No gaurantee that it may will work.If it does,  it probably won't keep the problem away forever.  My 2000 F250 had transmission trouble and I nursed it along for a few months that way. Then it quite working completely and had to be towed to the dealer.

[submarinesailor]

Take it somewhere and have the transmission flushed.  It helped my F250 SD diesel a lot.

Bruce

[moosehunter]

If you change the fluid yourself, you can see what is laying in the bottom of the pan. A good trans will have a small amount of gray crud in the bottom, that is normal clutch material wear.
Lots of crud or any metal is bad.

My guess is something broke.

Good luck

[flip]

Check to see if the vacuum line fell off the modulator valve on the right side of the trans.  If it's not that could be a stuck governer on the inside of the tail shaft housing.  If it does not even try to shift I would look at one of these two FIRST.

[Rocky_J]

The C6 is a very strong transmission, and it was quite popular back in the day. It's still better than most of the electronic junk on today's trucks. Any honest transmission shop should be able to hook you up for not a lot of money. Rebuilds on those are relatively easy (for a transmission guy) and parts aren't that expensive.

[Warbird]

Thanks everyone.  flip, it wasn't trying to shift at all.  1st & 2nd shifted as normal but when it came time to shift into 3rd, nothing.  I'll check the vacuum line when I get home from work tonight.

If it is the vacuum line, wouldn't that mean it wouldn't shift into 2nd, too?  How do I check the governor in the tail shaft housing?  Pull the drive shaft, then...?

This sure is bad timing.  We just got more snow than we have had at one time, in a very long time.  And they are calling for 2 - 3 more inches today.  Lots of folks who aren't able to afford plowing depend on me and this truck.  :( 

[flip]

To get the governor, pull the shaft, if it has transfer case pull that.  You will have to jack the trans. up off the cross member a few inches to clear the trans. mount.  Pull the 6? bolts that hold the extension on the gov will be on the output shaft.  There is a heavy c clip that holds the gov. on and a ball that locates it to the shaft DON'T LOSE THE BALL.  The gov. is bolted together take apart and if it is stuck you'll probably see the little piston that won't move by shaking the housing.  Take piston out, clean and polish with fine 600 grit of finer sand paper, clean again and lube with trans. fluid reinstall everything. 

Sounds difficult but on a lift and air tools probably a 3 hour job.  Could also have a valve body prob.  So hard to know without putting my paws on it.  The gov. and the modulator valve are usually the 2 biggest culprits on the C6 that and forward clutch seals turning into rock and causing delayed forward engagement.

[Warbird]

Wow.  Thanks a lot flip.  I don't have a lift but do have compressed air.  We'll see where it lands.

[olyman]

no pms war??? i go for the vacuum line came off--as said--r rear of trans---that being said--been loosing any trans fluid?? if so--that vacuum mod could have a internal hole in it--which will affect the shifting also---easy to change--tho not cheap anymore---if still wont shift----could be valve stuck in trans----will it manual upshift??? if so, means the clutches and seals in the direct clutch are ok, which leads back to a stuck valve in the vb--

[flip]

If you get real brave there are some 3/8" plugs on the side of the case that are pressure ports to check line pressure, clutch feeds etc.  If you take 1 plug out at a time you can take an air nozzle and blow in the hole, you should hear a dull thump which means the clutch is applying.  I think there is an abbreviation on the ports- dir. int. fwd. line.  Good luck.

[Slabs]

flip beat me to it.  I've seen snow drag the vacuum line off a c6 IN ALABAMA!!

[Warbird]

I only looked briefly but it appears the vacuum line was still connected and all looked well.  Took it on a test drive and when it shifted into 2nd, it seemed to shift harder than normal.  Still never shifted into 3rd.  :(  I'm wondering if the modulator thing the vacuum line plugs into has gone bad.  If not, looks like I'll have to take the truck in and have a pro look at it.

[mburrow]

if it is the modulator it should go ahead and shift to high when you get the truck around 60 mph.

[Warbird]

60??  I'd prolly blow the engine if I tried to get it that fast before it finally shifted into 3rd.  at 45, the engine was already at 3200 rpm.  It's an old motor and I don't want to rev it much past that.

The shop I'm going to take it to does free appraisals.  I can only hope and pray they are honest and will not tell me it needs a rebuild unless it really does.  :-\

[rebocardo]

Modulator is only $20 and very easy to change, I would do that first before bringing it anywhere.

I second everything flip said.

I would like to add, make sure the gear shift indicator is correct. Put it in N, then shift down 1 click, two clicks, three clicks. Then up again to N, then N down one click and take for a test drive.

Put a vacuum gauge on the modulator valve's hose and see if you get a change at WOT (to zero). Usually you can shove a T or splice in there and run a hose to under the hood or through the pass. vent window to watch it.

1986 should still be carb? and it might be a vacuum problem.

Make sure you have 17 (18 psi is better) at idle, otherwise the transmission might not shift correctly.

Be a shame to bring it in for tranny work when it is a simple carb problem or adjustment.

[Warbird]

I'll check into the vacuum stuff.  Yes, it is carburated.  Don't think I have a vacuum gauge laying around anywhere but might be able to borrow one.

[Warbird]

Just took it down to the shop.  All the vacuum lines were hooked up.  They will troubleshoot it and let me know next week what the damages will be.  They are also going to put a beefier spring in the throttle cable to is stops sticking like it is.

[Warbird]

Needed a rebuild.  The clutch (one of the clutches??) was pretty trashed.  All sorts of other issues that a standard rebuild took care of.  the seals on the transfer case were also all leaking, so I had them go ahead and clean that up, too.

Poor old truck.

[DanG]

Poor old truck.

Sounds more like "Poor old Warbird's wallet" to me. :-\

Glad you got it going, though! 8)

[isawlogs]

 Sounds good to me too , sure is alot cheaper then going to get a new one . Glad to hear ya got her fixed up .  8)

[Warbird]

Thanks guys.  The total damages are just over $1,700.  Had them replace the pinion seal, in addition to the other work.

[John Woodworth]

I go with the modulator, you probably got enough snow underneath to knock th hose off either at the modulator or the stte vacuum line comming down around the bellhousing, they don't just go out and do control your 2-3 shift point.