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Discussion Starter #1
Hi!

My '81 has all sort of fun mods that I'm still trying to figure out. The biggest is the 460 that came with it, hooked to a C6 (that may or may not have originally been hooked to _it_. The previous owner got it like that 7 years ago, he's no help with this question.)

Wanting to change some really badly done tranny cooler lines (they are lots of alternating 6" lengths of hardline and hose, mostly leaky) I need to be ready to refill the fluid I lose. Actually, I really should do a complete change and filter job. HOWEVER - I talked to the Ford dealer and was told that the type of fluid depends on the year of the tranny. Fine, but where do I find _that_ out? They can help me once I know that much...

Thanks very much for _your_ help!

BTW, I'm going to just replace the line right now, I need to spend my free time replacing brake and fuel lines, this is a just stopgap to remove one source of under-vehicle fluid leak so I can locate all the _other_ leaks. Later I'm going to follow some excellent posts here about using a thermostat, bigger cooler, temp gauge, and filter block. Later.
 

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Satyr of the Midwest
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Not so fast.

I checked out the transmission fluid chart on Steve83's SM page, but it's kind of inconclusive. C6 transmissions were used for LONG time by Ford in their trucks and cars, and his chart contradicts this. AFAIK, Type F was the prevalent fluid up until the early 1980s, at which point the AOD began showing up as the more-common RWD automatic. Of course, that transmission needs Mercon/Dexron ATF.

As for finding the year of your particular C6, it's going to come down to finding an ID tag somewhere on the body, methinks. Personally, I'd pull down the valve body and look for Ford part numbers in the castings there after thoroughly examining the exterior for them. Then I'd use the latest date code I could find as a basis for determining which fluid to use.

The cool thing is that you can change the fluid if you're wrong. Not the cheapest, but it would work. The least amount of damage would occur if you use Type F first and take it on a test run. If it shifts too harshly, dump it and go to Mercon/Dexron fluid. Going the other way around might cause a lot of excess slippage of the clutch packs.
 

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I have always ran type F in any C6 I have had, actually I run it in just about any off road auto. Back in my SBC powered jeep days I ran it in a TH350. IMO type F gives much better performance.

Later,
Jason
 

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green ones make me horny
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Not so fast.

I checked out the transmission fluid chart on Steve83's SM page, but it's kind of inconclusive. C6 transmissions were used for LONG time by Ford in their trucks and cars, and his chart contradicts this. AFAIK, Type F was the prevalent fluid up until the early 1980s, at which point the AOD began showing up as the more-common RWD automatic. Of course, that transmission needs Mercon/Dexron ATF.

As for finding the year of your particular C6, it's going to come down to finding an ID tag somewhere on the body, methinks. Personally, I'd pull down the valve body and look for Ford part numbers in the castings there after thoroughly examining the exterior for them. Then I'd use the latest date code I could find as a basis for determining which fluid to use.

The cool thing is that you can change the fluid if you're wrong. Not the cheapest, but it would work. The least amount of damage would occur if you use Type F first and take it on a test run. If it shifts too harshly, dump it and go to Mercon/Dexron fluid. Going the other way around might cause a lot of excess slippage of the clutch packs.
yeah that is true.

being as how it is a big block 460 im willing to bet it came out of a pre 80s truck or car. but try and find the id tag on it.
 

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USAF C-17 Maintenance
'94, '92, '88, and '84 Broncos
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Well, the C6 could be as new as a '96 or as old as the early '70s. I'm not even familiar with a casting number on the tranny to tell ya. Pre '78s get F and post '78s get Mercon. I'd go with Mercon.

Adrianspeeder
 

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Discussion Starter #10
I talked to two Ford dealers (started in Service dept, both sent me to Parts dept) about this. The first said "it really depends on the year, good luck with that" (basically). The second said "use fluid marked 'Dex/Merc' and you'll be fine, there's very little chance that there is Type F in there".

I didn't even know there was a single fluid called Dex/Merc, but it turns out that there is. Napa (at least) has it. Huh.

But I still don't really know what to do. I guess I should change it all, since I should do that anyway (new-to-me truck, no idea how old fluid and filter are, and need to re-gasket the pan). So - Type F or Dex/Merc? I know that it will be a good bit of work to get all the fluid out:

1. Remove pan & associated fluid
2. Drain torque converter
3. Drain cooler lines and both coolers (I am replumbing them with ATF-rated hose, the other reason I need to know what to refill with).

I rebuilt an A4LD and know that these three steps still leave some fluid in the tranny, at least in an A4LD... is there anything else _easy_ I can do - not interested in dropping another valve body right now, sorry :) - to get the rest out? Not very familiar with C6's.

And how much fluid should I expect, with both factory coolers (one in radiator, and a small separate one in front of rad)?
 

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And how much fluid should I expect, with both factory coolers (one in radiator, and a small separate one in front of rad)?
a lot.....lol.
but seriously, do yourself a favor and bypass the cooler in the radiator....it will cause nothing but problems.
you are really over thinking this....put some type f in it and call it good.
if the fluid that is in there is brown and burnt smelling....i wouldn't bother even changing it.:beer
 

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I have drained a C6 before by pulling the cooler supply line off and putting it in a 5 gallon pail. It worked exceptionally well. I just started the rig in neutral, and let the trans pump all the fluid out. I got about 3 gallons out that way, and called it good, I assume that there was a bit left in the pan, and the converter, so if you really want to get it all, drop the pan, and drain the converter afterward. The pump in the trans is a positive displacement pump, so it should pump everything out until it sucks air.

Empty capacity is somewhere in the neighborhood of 18-22 quarts, make sure you run the vehicle with trans in neutral after you have put a few quarts in. Trust me, if you don't fill it running, you will never get all of the fluid back in...

Later,
Jason
 

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Discussion Starter #15
Good call. I really should check that :doh0715:
Which one is the 'meathead' smiley?

I checked said dipstick, and looked up the letters, and felt like a dipstick myself.

Turns out that if it says "ESP-M2C138-CJ" that you should use Dexron II or better. So Merc/Dex it is.

Man, though, it's looking really hard to get to the cooler fittings on the tranny - I can see why the current setup is such a hack-job. I think an exhaust pipe or two are going to have to some out, oh joy.
 

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FSB's Bastard Child
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a lot.....lol.
but seriously, do yourself a favor and bypass the cooler in the radiator....it will cause nothing but problems.
you are really over thinking this....put some type f in it and call it good.
if the fluid that is in there is brown and burnt smelling....i wouldn't bother even changing it.:beer

This is really bad advice.


While it may be smart to "flush" it, Basically changing the fluid driving a few hundred miles and doing it again, It will never hurt to put fresh fluid in it.

Look up Sixlitres write up (Along with a few dozen) others about putting a secondary remote filter in place, and you may also consider putting in a quart or 2 of lucas stop slip. Seems to be a pretty popular and highly recommended additive.
 

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Look at some other web sites. I have seen people using John deere hydraulic fluid (no joke) with better results than tranny fluid. It has all of the same properties as the trans fluid BUT it runs cooler and has more postivie shifts.

Chris
 

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This is really bad advice.


While it may be smart to "flush" it, Basically changing the fluid driving a few hundred miles and doing it again, It will never hurt to put fresh fluid in it.

Look up Sixlitres write up (Along with a few dozen) others about putting a secondary remote filter in place, and you may also consider putting in a quart or 2 of lucas stop slip. Seems to be a pretty popular and highly recommended additive.
whats bad advice? i agree to run 2 tranny coolers....but i have seen a few of the radiator coolers rupture and ruin a perfectly good tranny.
bad advice is dumping anything in your tranny besides tranny fluid!
my advice is from experience....not from what i've 'heard' or 'read' other people doing.:twak
 

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AND, replacing new fluid when you do not know the milage on the old tranny is a BAD idea. Tranny fluid is a detergant. When your tranny runs, it makes clearances with parts of the clutches and steals as it breaks down. If you flush it and put all new fluid in, you can cause it to start slipping.

Chris
 
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