*sigh*
Thread Starter
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Mountain Pass
Joined: Jun 2012
Posts: 134
Likes: 5
*sigh*
In my quest to bring my newly acquired '78 F-250 to driveable status, I decided to drop the transmission pan, replace the leaky gasket and replace the filter while I was at it. Since the C6 is original with who knows how many actual miles I decided to use Valvoline's Maxlife fluid. It does feel like the transmission surges a little when coming to a stop, so I was hoping a new filter and some new fluid would take care of the issue.
I checked, and the original fluid on a '78 C6 is MERCON and not Type F. So I bought Maxlife DEX/MERC and put it in after changing the filter/gasket. Took it for a test drive and while it seems to have improved the shutter while braking, the transmission sometimes slips a little while accelerating from a stop. FML.
I checked, and the original fluid on a '78 C6 is MERCON and not Type F. So I bought Maxlife DEX/MERC and put it in after changing the filter/gasket. Took it for a test drive and while it seems to have improved the shutter while braking, the transmission sometimes slips a little while accelerating from a stop. FML.
Junior User
Joined: Mar 2013
Posts: 65
Likes: 0
From: Shelburne Ontario
What I'd like to know is why? You'd think fresh fluid and filter would only help. I know that's what I'm thinking and was pondering doing the same thing to my c6. Told my mechanic buddy and he said it might create problems. So I held off on that, now I read this. Is there a scientific answer as to why this happens that can be explained with simple words?....anyone...
Hotshot
Joined: Feb 2004
Posts: 10,839
Likes: 2,612
From: The Shenandoah Valley
C-6 transmissions used type FA hydraulic fluid, which was designed specifically for Ford transmissions, into 1977, and a CJ spec fluid later in the 1977 model year.
If original and you are unsure, the easiest way to tell which is just check the dipstick.
The stick will reference either the FA specified fluid or an M2C138-CJ specification, which is Ford's designation for Dexron/Mercon.
If a later rebuild, it's likely NOT using type F.
If original and you are unsure, the easiest way to tell which is just check the dipstick.
The stick will reference either the FA specified fluid or an M2C138-CJ specification, which is Ford's designation for Dexron/Mercon.
If a later rebuild, it's likely NOT using type F.
Laughing Gas
Joined: Jan 2013
Posts: 1,016
Likes: 4
From: Gulf Coast, MS
What I'd like to know is why? You'd think fresh fluid and filter would only help. I know that's what I'm thinking and was pondering doing the same thing to my c6. Told my mechanic buddy and he said it might create problems. So I held off on that, now I read this. Is there a scientific answer as to why this happens that can be explained with simple words?....anyone...
Good luck!!
Posting Guru
Joined: Nov 2010
Posts: 1,244
Likes: 1
if the trans is acting up shifting funny or not shifting there is nothing left to do but rebuild it. i know it sounds down right crazy but once a trans is having problems there is no cheap fix most of the time.
Thread Starter
|
Mountain Pass
Joined: Jun 2012
Posts: 134
Likes: 5
C-6 transmissions used type FA hydraulic fluid, which was designed specifically for Ford transmissions, into 1977, and a CJ spec fluid later in the 1977 model year.
If original and you are unsure, the easiest way to tell which is just check the dipstick.
The stick will reference either the FA specified fluid or an M2C138-CJ specification, which is Ford's designation for Dexron/Mercon.
If a later rebuild, it's likely NOT using type F.
If original and you are unsure, the easiest way to tell which is just check the dipstick.
The stick will reference either the FA specified fluid or an M2C138-CJ specification, which is Ford's designation for Dexron/Mercon.
If a later rebuild, it's likely NOT using type F.
I did think of something though, the shift linkage is out of adjustment. I'm wondering if adjusting the linkage will solve the issue. I may have not had it properly in gear. I hope so because minus the little slipping in first, it was shifting like a dream with the new fluid.
Junior User
Joined: Mar 2013
Posts: 65
Likes: 0
From: Shelburne Ontario
So if I was to check my dipstick (to be sure of correct type) and not having a Chevy tranny (revitalize the bands) I should be safe to freshen it up then statistically speaking for the most part?
The reason I want to do it is a) looks like slight leak b) my first truck and want it to last forever c) when accelerating it seems to "stick" and "struggle" a bit when shifting into 3rd gear.
The reason I want to do it is a) looks like slight leak b) my first truck and want it to last forever c) when accelerating it seems to "stick" and "struggle" a bit when shifting into 3rd gear.
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Junior User
Joined: Mar 2013
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From: Shelburne Ontario
Dang me.....dang
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Laughing Gas
Joined: Jan 2013
Posts: 1,016
Likes: 4
From: Gulf Coast, MS
So if I was to check my dipstick (to be sure of correct type) and not having a Chevy tranny (revitalize the bands) I should be safe to freshen it up then statistically speaking for the most part?
The reason I want to do it is a) looks like slight leak b) my first truck and want it to last forever c) when accelerating it seems to "stick" and "struggle" a bit when shifting into 3rd gear.
The reason I want to do it is a) looks like slight leak b) my first truck and want it to last forever c) when accelerating it seems to "stick" and "struggle" a bit when shifting into 3rd gear.
Cargo Master
Joined: Oct 2010
Posts: 2,339
Likes: 32
From: Lost In a Pit of Despair
I was just going to mention the vacuum solenoid.
There is a little solenoid on the back of the transmission on the passenger side. It should have a vacuum line going to it. The solenoid reacts to the amount of vacuum being created by the engine, and tells the transmission when to shift. If the solenoid is bad, or is not getting vacuum, your shifts will be rough.
-Jameson
There is a little solenoid on the back of the transmission on the passenger side. It should have a vacuum line going to it. The solenoid reacts to the amount of vacuum being created by the engine, and tells the transmission when to shift. If the solenoid is bad, or is not getting vacuum, your shifts will be rough.
-Jameson
Junior User
Joined: Mar 2013
Posts: 65
Likes: 0
From: Shelburne Ontario
"When you say stick and struggle....does it shift hard when going in to gear or do the rpms get pretty high before it shifts?"
Into second gear is quick and smooth (good rpms), then into third it starts (at good rpms) but takes a second to finish. For all I know it could be normal. I'll check for the vacuum this weekend in hopes I learn and correct something...worth a shot.
45fmjoe, didn't mean to highjack the thread buddy
Into second gear is quick and smooth (good rpms), then into third it starts (at good rpms) but takes a second to finish. For all I know it could be normal. I'll check for the vacuum this weekend in hopes I learn and correct something...worth a shot.
45fmjoe, didn't mean to highjack the thread buddy
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