343 Transmission Fluid Capacity

[mts]

I've seen a couple different capacity amounts in different publications......6+ quarts and 2+ quarts. Kind of a big difference. Which is correct? Stopping by the store on the way home to change the ATF tonight(first time) and realized I'm not sure how much to purchase.

Thanks,
Mike

 

[ParadiseCruiser]

M -

The difference in the figures you have seen has to do with the difference between how much fluid the 343 actually holds, and how much will actually drain out when you pull the drain plug.

The published figures for total capacity is about 12 qts, but what will come out when you drain it will be closer to 4 qts (the FSM says 2 qts, but experience suggests closer to 4 qts).

The general procedure is drain and refill (approx 4 qts) several times over a period of miles - say upwards to 2K mi between drain/refills - in order to get as much of the old ATF that remains in the journals and upper works of the tranny replaced.

Be very careful to not overfill when replacing the ATF - that can lead to all sorts of miserable problems.

Cheers!

R -

 

[Wrench]

M -

ÊThe difference in the figures you have seen has to do with the difference between how much fluid the 343 actually holds, and how much will actually drain out when you pull the drain plug.

ÊThe published figures for total capacity is about 12 qts, but what will come out when you drain it will be closer to 4 qts (the FSM says 2 qts, but experience suggests closer to 4 qts).

ÊThe general procedure is drain and refill (approx 4 qts) several times over a period of miles - say upwards to 2K mi between drain/refills - in order to get as much of the old ATF that remains in the journals and upper works of the tranny replaced.

ÊBe very careful to not overfill when replacing the ATF - that can lead to all sorts of miserable problems.

ÊCheers!

ÊR -

That seems rather excessive don't you think? Can't you just drain it and measure how much comes out and replace it with the same amount?

 

[ParadiseCruiser]

W -

>> Can't you just drain it and measure how much comes out and replace it with the same amount?

Absolutely. That is the proper way to do it.

>> That seems rather excessive don't you think?

Not sure if you mean the interval, or the amount that actually drains out. If the latter, there has been quite a range among various posts from DIY guys who drain/replace.

I'm sure some of the difference has to do with which tranny (not always stated), but 3 1/2 qts + comes out of mine regardless, or my memory and that jug on the shop floor are very forgetful. Ok, so my memory ain't was it was, but as to the jug... what can I say?

R -

 

[Wrench]

But doing it this way you can only use conventional ATF fluid right? Because for synthetic you need to do a power flush right?

 

[ParadiseCruiser]

W -

The debate on the best way to replace tranny fluid is even more contentious than for coolant. It would seem that it has been done any number of ways, though it is very difficult to accurately document the exact effect in each case because there are too many variables.

1. Flushing (with a machine) in trucks that have not had routine fluid replacement is said to dislodge all of the built up gunk, only to cause more problems.

2. Draining and refilling is wasteful, because at each refilling, you are draining a fraction of the new fluid you just put in, though this decreases with each refilling.

3. If you are replacing with synthetic, you can go either way - I'm told they are quite compatible, as far as mixing goes - but each has the drawbacks mentioned.

4. In the final analysis, the way you go about it depends a lot on your specific situation, maintenance history, pocketbook, and perceived advanges of synthetics.

If this (and the coolant debate) were simple, we would all have a great deal less to talk about. I suppose that means more #6s though...

R -

 

[cruiserdan]

Ron,

&nbspon't forget "fluid exchange" when all of the old fluid is pumped out as new is pumped in under normal operational fluid pressure.
Dan,

 

[mts]

Ron,

 Don't forget "fluid exchange"  when all of the old fluid is pumped out as new is pumped in under normal operational fluid pressure.
Dan,

This is the methodology I used. Took 13 qtrs (course I spilled a little).

Mike

 

[Photoman]

If you don't want to practice "safe" fluid exchange you can disconnect your hose at the rad, shove it in a jar, start your engine for several seconds, pump away, replace fluid, and do it again.
Bill