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Discussion Starter · #1 ·
I would like to flush my automatic transmission today, via the cooler line on the driver's side of the transmission. However, how does one go about removing what appears to be a flat head type screw from the pan. Also could this screw like drain plug, be replaced with a regular looking 1/2 or 13mm plug? I have thought it out to some degree, but again it appears to be ackward, especially when the plug resembles that of a large flathead screw? I will be using 12-14 qts of decent dino type F fluid. I usually flush my transmission every 10,000 miles or so. What say you? Thanks in advance! Happy New Year 2008!!!!:)

1991 900 turbo 16 valve 2.0 A.T. 177,000 plus original miles, in excellent condition.
 

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I had to use a long piece of steel the thickness of which match the slot in the drain plug top. Fortunately, it was on there so I had no problem getting at it and getting leverage.

Second time was much easier.
 

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As I re-read your message, why would you want to do anything with the cooler line?
Easiest way is to dump what is in the pan, refill with same amount. Drive a few minutes to mix it, and repeat the process. Repeat the process again.
That should about take car of a case of fluid, and give you over 75% new fluid.

And, you haven't disconnected anything that wasn't intended to be disconnected.
 

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91900turbo said:
I would like to flush my automatic transmission today, via the cooler line on the driver's side of the transmission. However, how does one go about removing what appears to be a flat head type screw from the pan. Also could this screw like drain plug, be replaced with a regular looking 1/2 or 13mm plug? I have thought it out to some degree, but again it appears to be ackward, especially when the plug resembles that of a large flathead screw? I will be using 12-14 qts of decent dino type F fluid. I usually flush my transmission every 10,000 miles or so. What say you? Thanks in advance! Happy New Year 2008!!!!:)

1991 900 turbo 16 valve 2.0 A.T. 177,000 plus original miles, in excellent condition.
AFAIK (as far as I know) the reason the drain plug is a completely different style to the engine oil drain plug is that the two don't get confused. They're fairly close together and it would be easy for someone not concentrating to undo the wrong one of they where both the same style. :cool:

I don't know if the thread and depth of the ATF drain plug is the same as the engine oil plugs but if it was you could possibly get away with doing it, providing the outside part of the drain plug doesn't project down past the bottom of the hole in the skidplate.

Up to now I've used Dexron-III in my auto transmissions but I'd be interested to try this type-F fluid in the auto of my 81 turbo to test a few theories. I'm sort of thinking part of the cooling system overheating issue could be that the Dexron-III is giving problems at sustained high-speed or heavy-load driving. Given that the engine has the in-line style (with the lower-radiator hose) of ATF cooler, if the ATF is getting extraordinarily hot, that could translate to the engine coolant system absorbing all that heat via the heat-exchanger inside the inline ATF cooler and hence creating potential for cooling system overheating problems.

Still just a theory until I can actually try it out. Then I might become a convert away from the 'Dexron-III for ATF as well as power steering' school of thought. :cool:

Anyway, if you have a spare engine oil drain plug, just try it out when you remove the ATF drain plug and see if it fits once all the old ATF is out of the transmission. If it fits, and there's enough clearance, etc. it'll probably be ok.

Craig.
 

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DickinFallsChurch said:
As I re-read your message, why would you want to do anything with the cooler line?
Easiest way is to dump what is in the pan, refill with same amount. Drive a few minutes to mix it, and repeat the process. Repeat the process again.
That should about take car of a case of fluid, and give you over 75% new fluid.

And, you haven't disconnected anything that wasn't intended to be disconnected.
And a good thing to do during this process is to replace the transmission pan gaskets if they're the older type, and if the transmission pans don't have the metal bracing pieces which were a later retrofit to help the seals stay sealed and counter fluid leakage problems, get those installed too.

I don't know if the ATF filter can be replaced at the same time - never taken covers off any of the auto's on my 900's yet. :cool:

Craig.
 

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Discussion Starter · #6 · (Edited)
DickinFallsChurch said:
As I re-read your message, why would you want to do anything with the cooler line?
Easiest way is to dump what is in the pan, refill with same amount. Drive a few minutes to mix it, and repeat the process. Repeat the process again.
That should about take car of a case of fluid, and give you over 75% new fluid.

And, you haven't disconnected anything that wasn't intended to be disconnected.
:suprised; I have been doing this for many years on my Volvos, Nissan Maximas, Lincolns, etc... Now my Saab. I simply disconnect the return line, after I apply generous amounts of PB Blaster to the connection. I looked underneath the car and it appears that this line is connected into the side of the tranny on the driver's side. All would simply do is place a funnel in the refill line, and prepare the fluid open bottles etc. Then I would connect a clear pvc line to the disconnected return line(configure) and place the extended end of this line out to a 12 qt bucket that is marked via one qt increments. I would then crank the motor and let the engine self idle, and watch the old fluid pump out. I usually pump out 3 qts at a time, then shut off the engine. I would then immediately add 3 qts of fresh fluid. I would keep repeating the process until the fluid ran through the clear tubing, a nice clear red, then the line would be closed back up and secured. I would then cycle all of the gears from a parked position, in that the fluid make channel through all of the gears. I would then let it idle for another 5 minutes or so to check for any leakage, and then test drive it immediately thereafter. My primary objective is ridding the converter of old fluid, and in addition to this particular car, the cooler too. It makes a huge difference in the way the tranny functions, and prolongs the life of the tranny. I usually go through 12-14 qts of decent dino fluid. Synthetic fluid would be good, but I rather change it more frequently, in that, I may conduct routine inspections etc. Additionally, I usually conduct this procedure once every 10,000 miles are so, unless of course I made a long trip to Florida and back:cheesy: . My filter is usually replaced no more than once unless it is of the paper element type, in addition to me inspecting for any out of the ordinary. My take is once you add good fluid to old fluid, it just contaminates the good fluid (the band-aid approach. Since we have seperate coolers in addition to a converter, a lot of grit/junk,and old fluid flows right out from these localities. :nono; Never Never rev the engine, just allow it to idle and the fluid will self-extract. My Volvo (740/850 wagons) transmissions have gone well over 500,000 plus original miles by me just doing this simple flush. I am not one for the dealers power flushing either:nono; ! Its too harsh and may loosen up some crud and possibly clog up a line, and destroy the transmission:( !And if you have a vehicle where the cooler line is the top line into your radiator its even faster/easier, such as the case with my 94 lincoln towncar:cool: 260,000 plus original miles, and runs very smooth!
My apologizes for such a long thesis:lol: , be well, and Happy New Year 2008

Best Regards:) !
 

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I'm sure doing all that makes you feel better, but you are not changing all the fluid in the transmission.
The pump uses some output to run the valve body, governor, clutches and bands, and some output to the cooler. Despite what you imagine is happening in the transmission, only a portion of fluid is diverted to the cooler; it's not a full-flow system like your engine oil.
You may as well just drain and refill. If you want to do more, change the filter. Why no mention of the A/T filter? Why do my transmissions last the life of the car with only normal maintainance?
 

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Discussion Starter · #8 ·
Jim Mesthene said:
I'm sure doing all that makes you feel better, but you are not changing all the fluid in the transmission.
The pump uses some output to run the valve body, governor, clutches and bands, and some output to the cooler. Despite what you imagine is happening in the transmission, only a portion of fluid is diverted to the cooler; it's not a full-flow system like your engine oil.
You may as well just drain and refill. If you want to do more, change the filter. Why no mention of the A/T filter? Why do my transmissions last the life of the car with only normal maintainance?
:nono; I certainly did mentioned changing the filter, "line16" just next to the cheesy grin:cheesy: . Correct me if I am wrong, but aren't most of these filters the wire/mesh type, and or screen versions? However, I would still do it at least once, in that I would have the chance to inspect/replace the gasket, and clean the pan.:suprised; line 16:roll: ! And yes, I absolutely feel better about doing the ATF flushes, they are simple and cost me pennies and very little of my time, and I never concluded that 100% of the fluid came out, I did account for some residual fluid, but that becomes irrelevant when 12-14 qts of fresh fluid has been interchanged with old fluid and one can visually see the results as they take place, doesn't it:lol: ? It really isn't a big deal to do this very practical cost effective procedure, really. I have heard that these particular trannys are good, but weaker than most, so extra care may go a long way. Happy New Year!

Best Regards
 
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