C6 trans slippage '79 F150 4x4

[Eliteman76]

OK. So, been noticing my '79 F150 seems like it's slipping between shifts. Nothing major, but it's become noticeable tonight.
I thought it was a case of low fluid, but the level was about half way in the "ADD" area, below low level line. I topped off, but did not have chance to dive again tonight. Going to let it sit for a day and drive the GTS tomorrow.

Fluid does have a slight tinge of use, but not black and burnt smelling.

I have been having issues with fluid leakage...the old dude has around 270,000 miles on it now.
I will also shamefully admit, the filter has not been changed in 6 years...mainly because I've basically putzed old blue around to work and back for the most part.

Question is, seeing the fluid spots on the driveway, it's lightly seeping from the pan gasket.
I also have been seeing large spots under the truck, about where the engine / trans meet up.
Did see leakage coming from the block plate.
There is fluid all over the trans, and transfer case.
Wondering if the seal on the pump could be done?
The truck has been in the family since 1991, and the trans and transfer case have never been apart.

Not too wild about this...but I'm more tempted to pull the front clip, and box, and pull the entire engine/trans/transfer case, and reseal everything.

Debating if pulling the pan would be worth while, but there is a cross member that is nearly over the back of the pan and not a direct drop-down deal.

[ford141]

I'd suggest changing the fluid and filter, then add a quart of Lucas No-Slip and run it. When I got my '79 F350 the trans slipped between 1 and 2, and between 2 and 3. When I dropped the pan the fluid was brown sludge and the filter was clogged shut. I changed the fluid and filter and added the Lucas. It didn't make it new by any means but it definitely helped. I ran it for 2 more years like that and it was still working 2 weeks ago when I pulled it in favor of a built C6. The Lucas will also help to seal up the leaks.

IMO it isn't worth tearing into the trans to reseal it unless you rebuilt it. They are pretty easy to rebuild and full rebuild kits are only about $250. If you are just looking to get some more time out of, I'd go the Lucas route. Likely the front seal is going bad because the pump/converter bushings are wearing out.

[Beagle]

The Lucas must be the magic cuz every time I change the fluid and filter on a previously unopened 100k transmission, it wastes it. Instant slip-o-rama. Indyshiftman told me when I asked that I drained all the friction material with the fluid. lol. it made sense...

[SpiderGearsMan]

C6 always had second gear servo and band problems ..probably frying the drum too ..not holding , change the band and servo before it gets real expensive ..really old truck , can't believe it lived that long
don't feel bad the 4l80e does the same thing

[ford141]

Lucas basically is friction material. It's like dumping a quart of Elmer's glue in your tranny. It basically makes all of the clutches stick to each other so they can't slip. Makes cleanup a real pain when it does come time to rebuild it, but it works to get some more life out of an otherwise toasted trans.

For the record, I didn't do a complete fluid change on my trans. The pan had to come off to change the filter, and the filter needed changing because it was clogged shut and not making any pressure. I only replaced the ~3 quarts in the pan, but didn't drain the converter.

[STINEY]

So I have to ask, having used Lucas on a few vehicles, mostly as a preventative measure on unknown vehicles (always with a filter/fluid change too).....

What's the general opinion on Lucas in the trans? Good/Bad/indifferent?

I've always had good luck with it, but I don't rebuild automatics either.

[SpiderGearsMan]

old trans fluid has plenty of clutch material in it

[STINEY]

Spidey for the Mr.Obvious award!

[racingsnake440]

+1 for Lucas - made a definite improvement to the shifting on a '66 Galaxie wagon with a C6 that I had. Didn't totally fix the leak tho.

[Beagle]

old trans fluid has plenty of clutch material in it

learned this one the hard way. lol.

off topic, but since I get to change the solenoids on the 4l60e, I'm going to do them all.

I'll give the Lucas stuff a try. It'd tickle the sh*t out of me if that's all it needed.

I'll report in next week.

[SpiderGearsMan]

check the harness too

[gearhed1971]

Can't remember, does a C6 have a push in dipstick tube? I had to put a lokar on my C4, I drove myself crazy chasing a leak. I thought it was the pan gasket, I went through two of them and even bought a new pan with a drain. Turned out to be the tube leaking down onto the gasket.

[Eliteman76]

Going to dig in on Sunday.
Had a hell of a storm roll into Omaha during the 5pm rush hour. Luckily I made it home with the GTS in time...up north of Omaha, TENNIS BALL sized hail.
I was like WTF??!!
I was out having fun for a bit of a drive on an early afternoon and just black wall of hell rolled in.

Anyways...
I am going to clean out my large drain pan, so I can catch as much fluid as possible.
I've used Lucas additive in my old '84 F150's oil, but never the trans.

Then again, this transmission has put up with soo much usage...one of the reasons why I love my '79 is because point it in the direction, and hit the gas pedal...empty or pulling 10k on a trailer.
This thing has every single option at the time for heavy duty cooling, oil cooler, aux trans cooler, which would mean flushing out the system would be a pain in the ass.

Buddy suggested the same, filter first, then look into adjusting the band.
Because of the age and I want to guess at least 150k miles on this trans, assuming it's just old age setting in.
Will report back.

Thanks again guys. Appreciate the help.

[gearhed1971]

As far as leaks go, you can also check your manual shaft seal. Adjusting the band may help with 1-2 gear change, but not 2-3. Did you check your linkage adjustment? Better to check the simple stuff first.

[Eliteman76]

OK, dropped the pan. What a FKN mess.
After trying to lower one side of the pan, catching as much fluid, the pan shifted and it looked like I was a left over from a horror movie set.
Dropped the pan. No large pieces at all. Only thing was a very fine layer of grey in the pan, assuming this was just clutch material.
Dropped the filter {if you want to call is that-was a stamped metal piece and a layer of mesh, nothing like what I think of when you say "filter".
Fluid had no burn smell to it. I ran my hand through the pan, got a filter, and poured into a clean gallon to see if any chunks would come out, nothing.
I elected to install the filter, dumped in 2 gallons of Type F and the quart of lucas, and let it idle for a bit to bring to temp and allow fluid to circulate. Shifted fine, ran ok down the road.

I serverly wonder now if this was a case of I missread the dip stick and it was low due to leakage?

Regardless, the pan now has a nut welded on for easy draining.

Shifts felt where they needed, not sluggish, and not like it has a shift kit, just a good nudge, like it has always had.