O/T Ford transmission

For a complete oil change I remove the pan, install new filter, and oil. Then I go to the cooling line at the radiator unhook it on the pressure side, start the motor remove a qt, then add a qt. I do this until the oil comes out clean. That way I get a complete change of oil. I wonder if anyone else does this. Stan

Remove line TO cooler and start engine. Stop it AS SOON as the oil flow stops. Put several quarts in the pan and repeat. This gets MOST of the dirty oil out of the converter and replaces what's left with new.

Then, drop the pan, and change the filter and install new oil.

I don't know WHY you'd want to put the new filter in before the oil oil was gone from the converter.

Stan, thats what we used to do at the shop I worked at.

I have no transmissions with cooler,but if I did I would go the extra steps.I have always removed as much fluid as possiable from the power steering and brakes on my trucks.

We always unhooked the return line at the transmission that way you get the cooler empty too. If you unhook the pressure line at the cooler the cooler will still be full of old oil.

You can buy a self tapping plug for the converter. It will not put the converter out of balance either. You drill a hole in the converter let it drain then screw in the small plug.

I have also used transmission flush that comes in areosol cans to flush the cooler and lines, after flushing it with two cans of flush we would blow them out with compressed air.

I also do this so all the trans oil gets changed.
I break the return line from the cooler to the transmission after I drop the pan, change filter, and refill the pan with new oil. I then run the engine until the oil coming out of the broken line quits or until the oil is the new oil. This way new oil is pumped into the converter and the old oil is pumped out.

I don't know the flow diagraham of the oil, but I think the oil starts at the pan, where the clean oil is, then to the convertor, and back to the pan,from the radiator, or coler line. I'll bet Allan knows. Stan

You're both right.

Generally speaking:

All oil 'starts it's day' thru the filter, however it's not flowing in a "series" fashion (one big loop), but rather thru parallel circuits (by-pass).

In addition, that returning low-pressure/low volume "cold" oil from the cooler doesn't just "dump" back into the sump. It's routed thru the lube circuit first and then bleeds off to the sump.

Long story short, this means that the good guys are continually being mixed in with the bad guys ahead of the filter. Good news is that due to the routing and pressure differences, the new oil will eventually win.

Ever notice that it takes a good 20 quarts to flush out a 12 quart system this way? :>)

Allan

Most of the new oil goes back into the pan as main regulator discharge. The converter discharge oil is normally routed through the cooler and then to the rear half of the box as lube oil. The heat exchanger in the radiator is very difficult to clean under the best of conditions as it tends to trap the contaminates. Even rapid back and forth flushing doesn't really clean them that well. However rebuilding the box will always tend to coax those little bugger contaminates out of hiding and into the new box.

Most new converters are the locking style so be careful if you plan on drilling and tapping a drain plug in the converter as you could run interference with the clutch plate / piston which is in the front half of the converter. The back half of the converter is the impeller so you don't want to drill there either. Not good. the plugs were eliminated to stop the inevitable oil leaks at that location. Ford went through a big program to eliminate oil leaks from all systems. They actually spent a lot of money on new gasket and seal design and materials to accomplish that goal. Nothing sends a customer through the roof more than an oil leak on their new car or truck.

Up til about 01-02 most ford rear wheel drives still had a drain plug on the torque converter.

Your system works well, but you could save some effort if you drop the pan and filter, and pull the plug on the converter. Let it stand for a good while. Put everything back and refill it. You will save on the amount of fluid used and still get close to the same amount of fluid changed out. That is assuming yours has a drain plug...

The oil strainer is 25 micron, plus or minus 10 micron, and dosen't tend to trap anything more than big chunks of debris. Most (66%) of the contaminates are iron and are down in the 5 to 10 micron size and are all different shapes so they tend to go right through the strainer. ( Oaklahoma State, Fluid Engineering Services, analyzed the trans oil contaminate sizes and elemental break down)

A magnet in the pan will trap those iron particles and Ford already put one of those in to do just that. You could remove the pan to clean the magnet or add more magnets if you want. The magnets become ineffective after they plate over with metal fines.

If you were to pump out the approximate 4 quarts out of the pan and replace that amount of oil then drive the vehicle for 10 miles and do that repeatedly it would take about 5 drains and refills to get the new oil content to approximately 10 quarts of the 12 quart system or about 85% and you wouldn't have to open the system to do it. Make sure you use a good grade of the specified oil for your transmission.

Lubrizol makes most of the additive packages for the name brand oils but there have been instances of the base oil not being compatible with the factory fill and that can cause gelling of the oil.

Judging by the mess on my shop floor a couple years back, the torque converter on a C-6 holds approximately 75 gallons...

Something I have that keeps me from having to drop the pan so much, is an inline filter on the cooler lines. Just takes a regular spin on filter, and I change it at every oil change. When I do drop the pan it is clean as can be. 236,000 miles Jim

Unless it is a bypass filter it can stop oil flow and rear case lubrication in cold weather.

A bypass oil filter would be a good option however the Lubrizol oil additive package still needs to be refurbished every so often or the clutches will stick and slip.

On my Ford and GM cars, I drop the pan put in a new filter and install a magnetic drain plug in the pan. Then at each engine oil change, the transmission is drained and refilled with new oil. Please tell me what is wrong with this approach.

Judging by the mess on my shop floor a couple years back, the torque converter on a C-6 holds approximately 75 gallons...


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I don't care who ya are, thats funny...

You're changing half your transmission oil every 3 to 5 thousand miles?

(quoted from post at 12:14:53 04/07/09) You're changing half your transmission oil every 3 to 5 thousand miles?

Click to expand...

Just dropping the pan will only get a couple quarts... which is still excessive.

I drop the pan, and clean the magnet in my 4R70W every 30k and it still works fine.

I only run flushes through mine anymore and never drop the pan. I've never had a "filter" (actually a screen) come with anything on them yet - much less with enough debris to make you fear that it might clog.

I used to drop the pan and drain the converter on my older stuff (C6, C5, C4, AOD, AODE) but never found anything in them except once in the while on a car I just bought that hadn't been serviced like it should. Local transmission repair shop said that the "wear" particles on "modern" transmissions are so small they pass though the screen - unless you're abusing the transmission causing large wear chunks. They felt that a flush - especially one that started with a solvent to clean the gunk - was better than simply draining the fluid. I started doing that in the 1990s and have only had one transmission fail since - a 2004 Dodge Stratus with only 18K on it. The 5 Star Dodge "Service" Center put 6 quarts of the reclaimed oil back in it after they installed a new pump. I got rid of that car.