Hello,

Doing a 1100 mile trip over the holidays and want to know if it's worth flushing the transmission fluid before. Now, I've had this car for three years and it always had a somewhat steady tranny fluid leak at the overdrive solenoid that required regular topping off, heh, I probably topped it off with a whole tranny's worth in the time between buying it and fixing the leak. I finally fixed that problem about a year ago, so the fluid is probably only about 14 months old or so. I read that you can use this tool to flush it. Worth doing?

 

I am all for regular trans flushes... If you need it. If your fluid is still reddish, you are good. The IPD hose is nice but not a must.

 

my general rule of thumb is to flush/replace it when its dark and smells burnt. if its just light brown and doesn't smell too fried, and still feels like oil between your fingers, its probably OK. note that if you change it without thoroughly flushing, it will be light brown as soon as it finishes mixing with whatever didn't change.

BTW, I've settled on using Castrol Transmax 'multi-import', its good stuff in these AW7x's.

 

If you change it every 40k or so, these trannies will last forever.
If you follow the right procedure, you can call it 'no pressure" flush, all the fluid gets replaced...

 

I do our 740 every 50,000 after the belt change. Use the book method of disconnecting the line at the transmission and start it up which pumps the fluid into the bucket. Keep refilling and draining. Use maybe 10-15 quarts and then change the filter. 338,000 miles on it now and engine and transmission never opened up.

 

I don't think you need to change the filter every time--it's just a screen fluid strainer; and it's messy job done best on a lift. May be every other time...

 

I don't think you ever need to change that filter unless its broken. just inspect it and clean it and reuse it.

 

I think ALL cars w/ automatics benefit from regular changes; not necessarily complete flushes every time. Volvo recommended fluid changes every 20K, but with a simple change using the conveniently provided drain plug (All transmissions should have this, but most don't) you're only getting about 3 quarts out at a time. I've been slowly converting to synthetic trans fluid this way; each time I change it the percentage of synthetic goes up and eventually it will be completely synthetic.

I bought the IPD hose when the tranny cooler inside the radiator on my 740T developed a leak, which filled my tranny with coolant and my radiator with tranny fluid. Worked like a charm.