Think I smoked my M50D!?

[ExploreNW]

Well, it finally happened, the shade tree mechanic in me did something improperly better than the engineers again
This time it's transmission related. Last Spring when I got the truck I found a lift & sent 'er up for a peek at what's underneath. Looking into the rubber access grommits revealed I had purchased a truck with a brand new clutch. Pulling the oil fill bolt revealed I bought a truck with no oil in the magic box either so I reached for some trusty ol' 80w90 that I put in every gear box I've ever owned.

Fast-forward to yesterday night. It has always ground when shifting into reverse, at least for the ~20k miles I've owned it. Starting around Tues this week however it was getting tough to put it into 1st & 2nd only when the truck is HOT. Now last night I felt like I was pushing into a wall to get the thing in gear, though it never has and still never grinds the forward gears. It won't creep in neutral or in gear with the clutch depressed which would indicate clutch issues. I came home & read for the first time that this thing is supposed to have regular Dex/Merc ATF in it rather than the 80w90 I pumped in.

Before I drag or try to limp this thing all the way to my buddy's shop in Portland to pull the tranny, do you guys think I cooked it & need a buildable core before I pull this one or are there other diagnostic steps I can use to find a solution that doesn't involve pulling trannies in Portland?

Unrelated - recently carb'd my truck in another thread, head swap & all, 1800ish miles ago. It has 201,800ish on the clock.

 

[adsm08]

I see a couple big mistakes in this story.

1) As you have already figured out you put the wrong lubricant in the trans. 80W90 is much too thick and will cause issues shifting and won't get into all the little places it needs to be in. Add to that the viscosity modifiers in it make it get thicker as it warms up.

2) You probably did not check to see if the gear oil you put in was GL-4 or GL-5. Most gear oils made in the last 20 years are GL-5. GL-5 oils have an additive that eats brass. Your synchronizer rings are brass.

3) You ditched a good EFI system for a carb. That was not what I would call a "good choice" no matter your reasons for doing it.

I would start by buying a gallon or two of cheap ATF, drain the gear oil, refill the trans with the right fluid, drive it 10 miles and see if it shapes up any, come back, change the fluid again, and drive it a few hundred miles (maybe one tank of gas worth) before doing a third fluid change.

If it still isn't getting better at that point I'd look at rebuilding it. If you buddy has a well equipped shop with a press and a good selection of bearing pullers the two of you can probably rebuild it yourselves in a weekend. I did synchros and bearings in my own transmission over the summer. Took me about a week, but I was only able to work on it for an hour or two a day, and had to custom fabricate some of the tools I needed because I didn't have the money to go buy the right one, and those were mostly bearing pullers.

 

[RonD]

Yes, +1 ^^^

Drive the truck as best you can to warm up trans gear oil
Then drain it
Refill with Mercon V ATF(or equivalent), it holds 2.8quarts BONE DRY, so will probably take less that 2 quarts

The repeat, but after warming it up again
And if you can park it, or lift it, with passenger side higher even better for draining

Only time will tell if you "smoked it"

 

[ExploreNW]

Thanks for the good feedback! I have several half-bottles of dex/merc ATF that I'll flush it with today & report back. As for the brass synchros, well, that's probably it. Definitely how it feels. Maybe pig lipstick but I'll try this fix first before I bite it & get a core to build. Why a JY core - its a time thing, I'd rather not take up bay space in a working shop for a few days if I can do a one-day pull/reinstall with a rebuilt box.

The gear oil was Parts Master brand GL-5. Still have some left over too. It's been in there for 20k.

As for the carb, that idea hatched out of multiple smoked EECs. I have my own personal enjoyment reasons for doing the conversion and I am extremely happy with the way my motor turned out. It's a $1500 1994 truck, not a Bugatti, and not my work truck.

 

[Dirtman]

Don't forget to put your tools away!

 

[sheep herder]

I prefer smoking pot. Transmissions are too oily.

 

[ExploreNW]

Thanks again, everyone - she's flushed and refilled. The problem was solved, she shifted like an absolute dream... For about 15 mins or so. It seems the synchros are still somehow alive so I don't have to tear it apart.

But perhaps I should. I pulled a lot more metal out of this thing than I like to see. The "fluid" inside was a dull gray, smelled like used axle grease & very thick like what you pull out of a polisher after you run bearing balls through it. The magnet was so coated it didn't want to pull through the hole. New one will get built this summer, maybe I should get a 2.8 for it and p*** off everyone that wasn't offended by my carb swap

The dreaded clutch-in creep started happening once she warmed up. I noticed the level of fluid in the master has decreased handily since my build but there is still fluid within safe range which could indicate a bad slave cylinder or leak. Looks like I'm at least pulling the tranny anyways. I do love how cheap these are to work on: master & slave kit, clutch, release & pilot bearings all on order now; $192 before tax.

Today was the Super Duty's last day of life though. She decided randomly she didn't want to get up & take me to get more ATF, she wanted to sputter back to sleep, so she'll get towed back to the mechanic once again (work truck so not my wallet thank God) but it looks like I'm driving this poor thing clutchless.

 

[adsm08]

If you can, disconnect the clutch line from the slave and try, gently, to push the pedal in. It SHOULD be rock hard and not want to move at all. If you force it it is easy to break things.

If that test gives good results you can take a hand held vacuum/pressure pump, hook it up to the little canister in the pump kit, fill it with brake fluid, stick one of the cone ends right in the line from the reservoir, and pressure bleed the clutch by yourself that way. It should buy you a little time.

 

[ExploreNW]

My bad! Got distracted elsewhere on the forums & never posted the fix.

Bleeding worked but Ford's bleed procedure on these things, well, it's a bit awkward. I was able to use a brake vac/pressure brake bleeder to get it done. I am now able to move the car around just fine if I double clutch it (some getting used to, never in many years of stick have I done it) but 2nd gear is a little crunchy still. It'll get a rebuild kit in the spring/summer & maybe tearing back into this thing will give me an excuse to run a different motor or change things up with this one a bit too ?