My Diff Cooler Build

[GTP]

Actually it's the other end. Use the bent tip of the zip tie to check for oil while the zip tie is pushed in level.

This was handy because I glued in the 1/2NPT-6AN adapters with pipe sealer. So I didn't plan to remove them again. The upper one doesn't leave enough space for the spout. And I no longer could stick my pinky in there to check for oil. So the zip tie method had to do.

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[Bossdog]

I too intend not to add a 3rd opening in the diff cover.
So what do you think of this idea?
when I go to install my diff cooler, I;
1) Put car on lift (4-post for storage)
2)Open top fill port
3) install 90 degree 1/2" NPT to 8AN fitting
4) use slider jack to lift front of car until diff fluid starts to trickle out
5) Use iphone to measure the angle of the body of the car

I can now use that angle when I change and refill the diff fluid. I can use a flexible hose to run up through the 90 degree fitting, pump new/clean diff fluid into the diff housing until it runs out ( like most diffs).
My understanding is the S550 is to be filled to slightly less than flowing out but that will be difficult to determine with the 90 degree fitting installed. I too, like you, don't want to remove the 90 degree fitting each time I service the diff fluid.
My assertion is that this method will allow me to use the simple "pump fluid in till it comes out" method with the 90 degree fitting in place and still achieve the desired "not quite full" (when car is level) fluid level.

Please feel free to poke holes in my proposed diff fluid change method for 2-hole, diff cooler installed fluid service method.

Do you intend to try and get the diff fluid out of the cooling radiator during a service? Seems we should if the cooler is doubling the fluid capacity, otherwise a change is just 50 or 60% of the fluid, leaving 40 or 50% of the old fluid in the system, relegating you to never really having fresh fluid.

 

[GTP]

While I applaud in depth analysis, I think you are overthinking this.

IIRC the spec is to fill within 1cm of the hole. To me this is the minimum level. Obviously you can't overfill because the oil will run out of the open port. To me, this also means it is acceptable to fill right up to the bottom edge of the hole.

In my implementation I used a straight adapter at the port and a AN hose fitting on that. So when I remove the upper hose I have a straight hole and not a 90degree. So it is easy to use a zip tie as a dipstick there.

As for draining, I disconnect the lower port hose, which obviously will drain the diff. The check valve prevents the cooler from draining. But I can run the pump which will force flow out of the cooler and lines.

To refill, I provide fresh fluid to the disconnected lower hose via (temporary) AN-to-barb adapter and clear vinyl tubing to a vessel of oil. The upper hose is temporarily connected to the lower port. I stop the pump when oil starts to come out of the open upper port. Then I quickly reconnect the upper and lower hoses to their (un swapped) ports.

This is confusing at first and will require a couple of readings.

 

[Bossdog]

"Tomster" from this forum says:

"The key here is replace the exact amount of fluid that you took out (assuming it was filled from the factory). Just like JAJ said, it always (and should be) 56 oz. If you fill it to the fill hole, a high G turn will spew fluid out of the vent all over your strut. If the diff has been serviced before, most likely the tech just filled it to the fill hole, and that is overfilled."

The other reason I thinking to be a bit more precise on the fill is that when I add the 1/2"NPT fitting, I am actually making the fill hole smaller by a small bit, increasing the level further till it spills out on its own as you pump it in. Of course with an after market cooling system the quantity will be different but measuring what you took out is always a good idea.
Its easy enough process form me as I am already on a lift with a slider jack. For now its all theory, I wont be changing the diff fluid till next spring. It may be a bit of "overkill" but I don't want to be spitting Diff fluid on the track.

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