Should I flush my MD8 700r4?

Dennis Wilkie · Jul 18, 2019

I removed the pan on my 4x4 92 K1500 last night and there were what seemed to me like an abnormal amount of metal shavings in the pan. But my biggest concern was that the geniuses that rebuilt it in the 1st place used a rubber magnet in the pan and the fluid looked like tomato juice. Should I flush the whole system or just change the filter and refill it?

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df2x4 · Jul 18, 2019

I would just replace the filter and re-fill it with fresh Dexron 6, personally. That and start saving money for a rebuild/replace/swap. I'm no expert but the metal shavings and the color of the fluid definitely don't look promising.

skylark · Jul 18, 2019

Just fill with hopes and dreams - I mean fresh fluid. That is a stock magnet.

Dennis Wilkie · Jul 18, 2019

Ok. After doing a little research, i've come to the conclusion that the coolant has gotten into the transmission cooler lines. I actually just got those yesterday, and now I get to look into a new radiator...fun fun fun

df2x4 · Jul 19, 2019

If that is the case, I probably would flush it instead of just a drain and fill.

Dennis Wilkie · Jul 21, 2019

Just as I suspected. As soon as I disconnected the bottom line, both transmission fluid and antifreeze came pouring out

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Schurkey · Jul 22, 2019

That can't be good.

Fresh fluid (and flush) might save the trans. Might not. Worth a try.

"I" would use Dex/Merc (Dexron III equivalent) rather than expensive Dex VI. Drop the upper cooler tube, replace with a temporary tube that leads to a drain pan. When the pan is clean and reinstalled, add ~5 qts fresh fluid, start the engine, and dump additional fluid down the dipstick tube as fast as you can.

When the fluid coming out of the temporary tube into the drain pan looks clean, shut off the engine, reinstall the regular cooler tube, and top off fluid as needed.

Pray you got it in time.

You'll want to flush the coolant as well--if coolant got into the transmission, ATF got into the coolant. I've used flush-and-fill kits with good success. It may be you'll need some plain water and laundry detergent in the cooling system to scrub the oil out of the engine and heater core, then flush again a couple of times to remove the detergent before adding anti-freeze. Don't do that if you aren't willing to drop the block drain plugs to get all the contaminated water out of the engine.

Ken K · Jul 22, 2019

For years in a shop I worked in, what "Schurkey" described was the only way we serviced functioning transmissions, but with twist. We disconnected the cooling line first, other in pan, then poured 5qts. tranny fluid into the funnel to dipstick tube. Then we pulled the pan with little fluid left and replaced the filter. But, since you've already had the pan off, go for it.
The ATF I have seen is only DEX/MERC full synthetic but label shows DEX-III & DEX-VI both. But I don't get out much either.

Should I flush my MD8 700r4?

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