Sunday, Mar 01, 2009 at 19:10
Jon is correct, & in addition there is often oil volume inside any transmission cooler and the plumbing theretoo as well.
For a COMPLETE trans oil change - there is a method to connect a drum of new trans oil via a CLEAr tube to one of the disconnected trans oil pipe fittings on the transmission, run the engine briefly (a minute or two so that the transmission oil pump sucks NEW oil out of the drum via the oil pump in the transmission, at the same time OLD oil pours out the disconnected pipe - thus exchanging the oil in the cooler and torque converter as well.
When the old darker burnt oil ceases to pour out and the new
bright red oil starts to come thru, you stop the engine, reconnect the pipe to its fitting and THEn measure the amount still required to topp off viw the dipstick and add whatever is still needed.
IMHO after you do this, its a good idea, if your so inclined, to replace the pan filter in your transmission also - often you'll find it hasn't been done since the transmission was built, despite service
places charging for it to be done.
Its not tha hard to do BUT sometimes requires a special small torque wrench in inch pounds (not foot pounds) to re tighten the pan bolts correctly, and the bolt/s holding the pan filter.
Not a LOT of mechanics have an inch pound torque wrench so they get "twitchy" about doing trans pans and the internal filter.
When you do replace the pan filter you'll inevitably find it full of the wear metals from the transmission cylinder body aquired during run in period as well as heaps of wear metals from the torque converter and the wet clucthes of the transmission.
It's also a good time to clean the drain plug magnet as well while there.
The photos below are of my auto trans when I dropped the pan to change the pan filter, I had the trans fluid analysed as well.
I'd just bought the vehicle a few days before hand from a (FORD) dealer, with 104,500 km;s on it and they had just "serviced it" by "changing all the oils" according to the dealer when I picked it up and as they recorded in the service manual.
As you can see the trans oil wasn't changed at all, the used oil analysis shows high wear metals levels:-
(109ppm Fe iron/steel)
(31ppm Pb Lead)
(84ppm Cu Copper)
(12 ppm Sn Tin)
(6 ppm Al Aluminium)
You can see the oil returned an "abnormal" reading, showing that it was badly oxidised thru excess heat, and had waay too high wear metals readings.
This trans temp image table below gives a good indication WHY excessive trans temps kill auto trannies very quickly...and the used oil analysis above shows what happens to the oil if you DON'T change it COMPLETELY, including the oil cooler, torque converter and trans pan filter etc
Putting in the new trans pan filter!
The old trans pan with layers of "gunk" (mostly burnt wet clutch pack debrris and torque converter metal) stuck to the pan drain bolt magnet.
The fact that a dealer says in your log book that trans work was done doesn't necessarily mean that it was!
All this work helps to prolong the transmission life IF you can be bothered doing it properly say every 50,000 km's or so..
AND
If you can keep your transmission oil cool.
Its basic mai9ntenance really that few seem to do these days - heck some of the NEW cars being built today do not even have a transmission oil dipstick to CHECK the condition of your transmission oil.
It is expected that the dealer will do it as per the service manual but as I've just shown you can't trust the stealership to do ANYTHING on your vehicle these days - well not properly anyway!
The paperwork in service manuals these days doesn't mean much unfortunately.
When a transmission fails because it hasn't been maintained properly - you can be facing some hefty bills - its over $20K to replace y transmission - hence the reason I make a point of looking after it, with regular COMPLETE fluid changes, and keeping the oil cool.
I've added a second auxiliary trans oil cooler, a in line disposable filter for the trans oil, a deeper transmission pan with cooling fins, a transmission oil temp gauge
I even added a
water tank with 12V pump and switch connected to garden water misters out front of the radiators, to spray water at will if the trans temps while hauling heavy loads get too high for comfort.
An ounce of prevention is worth many pounds of cure with auto transmissions.
Short cuts with auto transmissions, can and will bite you on the butt quickly, and they are inevitably very expensive lessons.
Cheers
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