How To Flush the transmission on a 98 Chevy Venture?

Answer 1

You can either undo the drain cock of the radiator or just pull the bottom hose of the radiator. I usually do the latter. After it is emptied, either fill it with water or water and flushing agent and restart vehicle. Let it run up to operating temperature to get the thermostat to open and recirculate the coolant. Shut off and empty the system again. Repeat until the water runs clear. When it runs clear, refill the radiator or overflow with 50/50 mixture of coolant/water. Run up to temperature and recheck the level, add as needed.

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it asked how to flush the transmission, not the radiator!

With your great instructions, now some half-wit clown is going to try putting water in his transmission. I guess anyone can give "advice" on this site.

Even if you were trying to tell them how to flush the RADIATOR, you missed a key part ---- on the GM 3400 engines in the venture and Montana, etc, YOU HAVE TO OPEN THE AIR-BLEED VALVE WHILE FILLING THE RADIATOR. If you don't, you get an air pocket in the engine and a cracked engine block/head when it heats up! moron

Anyway, to flush the TRANSMISSION, you would need to disconnect the transmission cooling lines at the radiator (passenger side) and "pump out" the bad fluid into a bucket with the engine running while using a small electric pump to "push in" the new fluid through the opposite transmission line. It helps to have a couple of feet of rubber hose to extend to the bucket, etc. It will take approx 19 quarts of fluid to get the old stuff out. An alternate (amateur) method is to disconnect just one transmission line from the radiator and pump it out with the engine running while pouring fluid down in the dipstick filler tube. Warning, if you run the fluid completely out it can cause transmission pump damage.

It can be a messy job, so be prepared.