I just started noticing a burning tranny smell on my 81' F150 4x2 AOD. Is it time for a fluid flush? I've read to flush it, leave it alone, to only drain the pan, drain lines as well. I can't find much information about draining the TC, something about turning the engine by hand (don't know how to do that either) to access the drain plug on the TC. I was planning on doing a full flush with new filter and gaskets. Any help/advice would be greatly appreciated.

 

If you already smell burnt transmission fluid it might be too late. Check the color of your transmission fluid. If it's dark brown or black then your transmission is probably toast.

If you have your heart set on changing the transmission fluid you can easily do it with the transmission cooler lines. Check it out!

 

After a long drive and with engine running, I unhooked the return line and fed it quart by quart trough the dip stick tube until fluid coming out was clean. I drove it for a few days to let the detergent to its work before dropping the pan and replacing the screen. Would be a good time to add an inline-filter and adjust vacuum modulator and bands. (if AOD has those).

I used Valvoline maxlife synthetic and she's still happy 2 years later. Mercon V is OK for these trans.

 

Chances are the trans is on it;s way out. You may get more life out if by swapping the fluid out to Type F .When the AOD was designed it was designed around Type F, and some of the reliability issues it suffers from is due to Ford's use of Dexron/ Mercon in them.

 

Thank you, this is very helpful.

 

I think I've got a leak and it was getting on the exhaust perhaps, the color on the dipstick is still pretty normal I'm just low on fluid.

 

Turns out I'm low on fluid, the bottom of the pan is covered with fluid, I've got a leak. I'm going to do this method prior to dropping the pan, thank you.

 

Let us know how it goes! Here's some info on the TC drain: https://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1820207

...And you could put a strong magnet in the pan while your at it, I put in an old ceramic speaker magnet.

 

This is what happened when I tried to access the page, do you have another link or do I need to sign up? Thanks

 

No, thats strange: https://www.bobistheoilguy.com/forum...Number=1820207

 

Thanks, I'll give it a go.

 

That is incorrect.

The AOD pump, clutches, valvebody calibrations, and internals were designed around the Dexron/Mercon fluid.

The owner's manual specifies Dexron for an AOD. Pull out the dipstick on any stock AOD and the word "Dexron" is engraved in it.

The only reason to swap to Type F is if you have nothing to lose, or are planning to rebuild the AOD anyway. Even then, you must flush the transmission completely, because Dexron/Mercon and Type F fluids are *not* compatible.

 

The AOD trans was designed around Type F fluid use , NOT DEXRON the basic design it's self is based off a 1950's era transmission.technology.
The AOD was initially designed in the early 60's around the X transmissions (FX & MX later evolving in to the FMX) and their ravigneaux gear sets (this why it shares the same 1-3 gear ratios as all the X transmissions) and then it was shelved . It's base design predates BOTH the C4 and C6. The design was dusted off during the energy crises of the early 70's updated with an all aluminum case and with design and testing completed it was ready for production, but was never used due to no longer being required.

With the looming increased CAFE requirements and the downsizing of the late 70's, the design was once again dusted off a torque converter damper added to take some of the shock loading off the 3-OD input shaft , with NO OTHER design changes made, and it went to production in late in 78 for installation for the 80 model year..

The transmission was designed around the much grabbier Type F fluid but when put in to production it was spec'd with Dexron... Dexron was a much cheaper fluid as it had a much lighter additive package and provided much smoother shifts than the grabbier Type F .. Dexron and Type F are the same base, the only difference between them is the additive package.

The use of Dexron in the AOD came back to haunt Ford as band/drum width in OD and low reverse, and clutch pressures were all inadequate for use with Dexron. The thought was the initial applications with Type F were much higher HP and in much heavier vehicles with no torque converter dampener. And the use in considerably lower HP lighter vehicles with a dampener would compensate for the use of the more slippery DEXRON. This proved to be a huge error and failure rates initially were through the roof. The AOD seen continued improvement throughout it's life with larger servos larger bands and drums increased line pressures etc etc to accommodate the Dexron. It was most post production modified transmission in Ford's history.
So NO the AOD was NOT designed around Dexron trans fluid but TYPE F the specification of Dexron in them is what caused the reliability issues.

Also The fluids themselves are compatible One liter of Type F will turn several liters of Dexron in to basically Type F , Type F can be used in ANY dexron spec'd transmission the results will be firmer shirts and cooler temps, if you are pushing it hard the harder shifts may potentially fracture drums though . Dexron clutch material and Type F Clutch material is identical.... what is different is line pressure.... That is why the old saying goes when in doubt of Dexron or Type F use Type F. As putting Dexron in a type F trans will destroy it in short order.