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Discussion Starter #1 (Edited)
Ford C-6 Updated, new tranny, new problem...

Hey Guys,

I have ran into a problem with my truck. It is a 81 F-150 4x4 w/ 351M/C-6/NP208.

THe tranny has always been slow to engage into gear (any gear), usually taking about a full second or two. But rigt when i was parking it at a friends house today, it seemed to slip, the engage, and slip and engage, then nothing. I tried selecting all the gears, the tranny would not shift (or at least i couldn't feel it) and it would just free rev. My shift linkage is working fine, and there is ATF coming out from where my tranny meets then engine, dripping from in between the dust cover and the tranny bellhousing.


My first guess is that the torque converter is shot, and leaked all its fluid out.

Second is that the seal on the input shaft of the tranny is shot, whick would be a PITA.

What are your guys' thoughts/recommendations?
Is my tranny toast, or fixable.

How exaqctly could a torque converter wear out? Isn't it just fluid getting pumped against fins???

Thanks in advance,

Mike
 

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Yes fluid in a convertor does just pump through fins.
There are 5 areas that can leak from the front.
1/ pump seal.
2/ pump "O" ring.
3/ pump gasket.
4/ cracked convertor hub.
5/ servo shaft seal.
If there is a no go it is likely there is no or low fluid in the transmission because of the leak.
FYI.
The amount of fluid pumped through a convertor at peak stall is equivalent to 45 - 45 gallon barrels of fluid.
That's 2025 gallons per minute.
So yes technically it does pump fluid.
 

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there are many parts in the converters that can wear out. thrust washers and roller clutches on the non lock up converters.

Late model lock up converters would surprise you by the number of parts in them.

Fliud is constantly flowing into and out of the converter during operation.

Your comment about the converter "leaking it's fluid out and now the vehicle does not move" ..... indicates to me you know nothing about how the tranny functions. You need to find a qualified tranny person to avoid spending money on the wrong solutions to your tranny problems.

Is the tranny full of fluid as the vehicle sits on level ground, engine running , tranny in park?
 

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stu said:

There are 5 areas that can leak from the front.
1/ pump seal.
2/ pump "O" ring.
3/ pump gasket.
4/ cracked convertor hub.
5/ servo shaft seal.
Stu,

Is there any way to troubleshoot which of these might be the problem without pulling the trans? I've got a very slow leak on my 6C that is showing up in the same place as Offroadin's leak. I was guessing main seal in the engine - but now I'm leaning towards the trans. Not enough of a leak to be detectable on either dip stick yet (motor or trans) so I can't use THAT as a clue.
 

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Discussion Starter #5
Is the tranny full of fluid as the vehicle sits on level ground, engine running , tranny in park?
I'd assume not since there was a steady drip coming from it. Its parked at a friends house right now but I'll see when i get there.

Thanks for the information. But how can i narrow it down to what problem it was. Looks like mostly all of the possibilities listed above can be isolated to the torque converter right?

THanks,

Mike
 

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If one of those suspect areas are leaking and the vehicle is in my shop they all get repaired.
No if's and's or but's.
The convertor must be removed to tell which one of the items are at fault.
 

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Discussion Starter #7
Okay. The tranny and Tcase came out tonight. Here's my observations.

Before i pulled it, the dipstick read full cold, but when running in park it didn't show anything.

Converter was almost full, now laying down on the table i can see down the shaft into it, and the fluid level is even with the round casing of the converter.

Seal on input shaft of tranny seems to be in not bad, not cracked or missing. Mating surface on converter has slight scarring, nothing major though.

Couldn't really see any washed areas on the inside of the casing, so i'm not totally sure where the fluid came out of.

Is there any way to visually inspect the TC to see if it is whats leaking?

Any other suggestions?

My Plan for tomorrow is to replace the input seal and look closer at the TC with any new info to decide whether to replace it.

Thanks,
Mike
 

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You can't tell how much fluid is in a convertor by just looking.
It has to be charged.
If you are just going to replace the metal seal your efforts will be wasted.
BTW. It isn't called an input shaft seal.
It is a pump seal.
Remove the pump and replace the other items I listed.
The servo pin doesn't leak that often so just an eye ball exam is ok.
You can drain the convertor and pressure check it.
A plug similar to that used in a radiator shop can be placed in the hub and air applied.
While you have the pump out and apart. You are going to do this?
Replace the bushing as well.
When you have this done and are ready to install it I will give you more pointers.
Don't want to overload you.
 

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Discussion Starter #9
Is replacing the pump seal/O ring/ Pump gasket something your average backyard mechanic can do? Any special tools needed? Special knowledge?

So I'm assuming to do the above i'd just take out the bolts that are in a circle around the pump shaft, and it will pull apart? Where does the pump gasket fit into the picture? Is the o ring right behind the flange with those bolts?

Thank again.

Any more info on the install would be more helpful now as i am not working on it here, so i don't have net access to check after i replaced those parts.
 

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This is great offroadin. I've got to pull my C6 and do what you're doing over this winter...so you are sort of the guinea pig on this one. Keep describing how you are doing it step by step (you will make my life much easier come December). Hey, pics would be even better if you've got a digital camera available.

BTW, where are you getting your replacement parts, Ford, or do you have a cheaper after market source?

Dewey
 

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Not knowing your talents it is difficult to say if you can do it or not.
Stand the transmission up right.
Remove the pump bolts.
Tap two opposing holes to 3/8 NC thread.
Install slide hammers into the holes.
Push down on the input shaft while pulling up on the slide hammers.
The gasket is between the pump and case.
The "O" ring is around the outside of the pump.
Take the pump apart to replace the bushing and seal.
Install two 5/16 NC guide studs and install the pump.
Simple. Right?
 

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Discussion Starter #12
Sounds simple enoguh (I do have my 1st year Mech. Eng.)

What are the 5/16 guide studs for and where do they go?

BTW, I will prob get the parts any place i can, probably NAPA or someplace local.
 

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Discussion Starter #14
Well,

I kinda took the easy way out on this one. I found another almost identicle tranny and TC for a good deal so i bought it.

I split the t case from my old tranny, made a new gasket, installed the new tranny and TC and then the T case. Flushed and replaced the fluid in the T-Case, blew out the tranny lines.

Tomorrow i will drop the pan and change the fluid and filter.

Also found out along the way that my flywheel was cracked all the way around the bolt circle except for in between 2 bolts. Replaced that and continued.

The fluid in my old tranny was burnt and pure black. I might pull it apart in some spare time just to familiarize myself with the world of auto trannies.

Thanks for all your help,
Mike
 

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Discussion Starter #16
So much for periodic maintenance.
Well, i just bought th vehicle recently and was planning to do a trany flush and oil change. I already flushed the coolant system and have changed the u joints etc. I can't just predict whats going to happen before it does. :rolleyes:
 

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Discussion Starter #17
Ok. The replacement trany is in. The tranny looked nice and clean inside, filter and pan free of any shavings/crud. SO I installed it, flushed out the lines, put in new fluid/filter/gasket.

Now, it seems to work, except for it skips 2nd gear (whines out in first then hits 3rd). Also, when in Drive, and I come to a stop, then go to accelerate, it is still stuck in 3rd gear. Manual shifted 1-2-D it works fine.

What could be the cause?

I first thought the vaccuum line, but i checked and its got plenty of vaccuum straight from the manifold. I changed the vaccuum diaphram from my old tranny but still no difference.

Now the kickdown was never hooked up in my truck (propane mixer didn't have brackets/linkage) but even without it, if you were travelling at too low of speed in drive, some throttle input would make it downshift. Just no kickdown at 40+ MPH which isn't a big deal to me.

Any ideas?

Thanks,

Mike
 

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offroadin said:
Okay. The tranny and Tcase came out tonight. Here's my observations.

Before i pulled it, the dipstick read full cold, but when running in park it didn't show anything.
(shakes head)

okay... You are supposed to check the fluid when the engine is "on". The fluid will almost always read full when the engine is off. If you start the car and get an empty reading that means you just need some transmission fluid. If it slid out of gear when you parked or came around a corner to park, this is because the trans is sucking up air BECAUSE there is no fluid.

Why were'nt the simple things checked first? So you may have pulled a trans simply because it needed fluid....

I'll just go back to what I was doing now. :rolleyes:
 

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Crosley said:
Is the tranny full of fluid as the vehicle sits on level ground, engine running , tranny in park?

Above is a quote from my first post in this thread
 

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Discussion Starter #20
(shakes head)

okay... You are supposed to check the fluid when the engine is "on". The fluid will almost always read full when the engine is off. If you start the car and get an empty reading that means you just need some transmission fluid. If it slid out of gear when you parked or came around a corner to park, this is because the trans is sucking up air BECAUSE there is no fluid.

Why were'nt the simple things checked first? So you may have pulled a trans simply because it needed fluid....

I'll just go back to what I was doing now.
quote:


Originally posted by Crosley
Is the tranny full of fluid as the vehicle sits on level ground, engine running , tranny in park?
--------------------------------------------------------------------------------




Above is a quote from my first post in this thread

Geez, do you guys not read anything before posting? I appreciate the help but you guys sure don't seem like the people in the know when you make posts like the last two.

You seriosuly insult my intelligence whe you claim that i have replaced a tranny which just needed fluid. I know how to check the damn fluid ok?

Obviously the old tranny was not working properly because of lack of ATF. The reason for that if you would have read more carefully is because the seal around the pump went. The tranny worked fine previously, until the seal went, leaked out enough fluid to cause the tranny to not function properly.

Now instead of attempting to pull the tranny apart and replace seals I opted to go with a used one, which i got for a good deal and if it doesn't work i get my money back. Replacing the seals is not a 5 minute job so i figured it would be easier, and get my truck back on the road faster if i just threw in another tranny.

Now if you have something intelligent to contribute after reading the entire thread so you know what i'm dealing with, then please, by all mean post away.

But if you're just going to sit back, shoot the **** and try and point out my "mistakes" which are just misreading/misunderstandings on your part, then don't post.

Respectfully,

Mike
 
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