General Automatic transmission question

[Michael]

If you really want to flush the trans, the safest way is do what I did. Just drain and refill 3 or 4 times over a 500 to 1,000 mile window. Seriously you can do this without even jacking the car up.

I did this during the testing phase of my filters, and ended up putting over 1,000 miles on the prototype filter and during this I dropped the pan for the prototype replacement, and inspection a few hundred miles later, as well as dumping and inspecting the fluid even later on. I figure 3 fluid changes with some mileage in between should effectively "flush" all the old out.

I recently spoke to someone about changing the fluid myself and they said to take the cooling lines off the radiator and run the car until fluid stops coming out and that removes about 98% of everything in the transmission. But screw that up and you'll burn up the pump.

I would fall into that catergory that is against power flushes and I sure as hell wouldn't run the trans dry EVER! Even at idle, the transmission needs fluid. The 4141 is quite possibly the worst transmission ever made. It just wants to break so you have to be gentle with it, that means a complete stop and rpm drop before going to park, drive, reverse, etc. They are very unforgiving so blasting high pressure fluid through the lines and running them dry is something that you shouldn't risk. My way is a bit extensive and possibly excessive, but it's safe.

PS: if you follow Dave Swingle's service method (and one that I like) just dump and fill the fluid at every oil change. You are right there so what is it to remove one more drain plug and pop in 4.5 qts of ATF?

At every 15k, drop the pan and change the filter.

[PJ Grady Inc.]

My understanding of a flush was that they run fresh transmission fund through the collateral lines into the unit until all the old stuff was out. Not any sort of detergent or other materials.

I recently spoke to someone about changing the fluid myself and they said to take the cooling lines off the radiator and run the car until fluid stops coming out and that removes about 98% of everything in the transmission. But screw that up and you'll burn up the pump.

It seemed reasonable to let my local Chevrolet dealer due it and not a third party shop. But since I still have a little while to think about it. I'll just run it for a little bit first.

Yes a flush pumps in new fluid to replace the old which is the only way to replace all the fluid. Solvents are not typically involved. There is no other way to drain the converter other than drilling a hole in the housing (after R&Ring the trans. to access it) and that typically traps a quart or more of dirty fluid. You're doing the right thing...now lets just hope I didn't jinx you by saying so!
Rob

[DMC3165]

Yes please don't jinx it!

[David T]

On newer cars it is recommended that fluids be flushed. This means the power steering, coolant, and transmission. Each one is separate and requires a different machine. Because of the longer service intervals it makes flushing necessary. If you stick to the recommended service intervals for the older cars, flushing is not generally required. Flushing can become necessary especially if you are "resurrecting" a sleeper. The drain and refill method is wasteful and inefficient but it can work. Better to have it flushed in a shop but there can be problems. If the transmission is REALLY dirty and the fluid is all dark and smelly you run the big risk of breaking loose an avalanche of debris which will plug things up inside. In some cases it is better to leave well enough alone. It is a judgement call. The pros and cons should be decided on an individual case basis with the shop. In some cases the drain and refill may be a better way to slowly clean the transmission. Stay away from additives, sealers, and cleaners, they will only aggravate the problems. The filter must be either replaced or disassembled, cleaned, and reassembled. Don't forget the gear oil in the final drive, it is separate on the automatic. Whenever servicing the auto trans you should inspect the wiring harness for damage and security away from the exhaust and all of the external On-Car adjustments. As a general rule on older cars if you don't know what kind of fluid in in there or when it was last changed, it is time to replace it. Fuel is no good after 6 months, brake (and clutch) fluid after 2 years, anti-freeze after 5. Motor oil should be changed annually. Transmission fluid based on condition.

[DMCVegas]

Yes a flush pumps in new fluid to replace the old which is the only way to replace all the fluid. Solvents are not typically involved. There is no other way to drain the converter other than drilling a hole in the housing (after R&Ring the trans. to access it) and that typically traps a quart or more of dirty fluid. You're doing the right thing...now lets just hope I didn't jinx you by saying so!
Rob

That was precisely my understanding as well. The flush pumps out all of the fluid, but it's just regular ATF (or whatever specification you use) and has absolutely no additives. If simply replacing fluid were to cause problems on old transmissions, that would mean that when draining a pan in order to replace a filter, you'd have to catch all of the old dirty fluid and put it back in to avoid a problem. 80% versus 100% doesn't make a difference at all.

I've done the transmission flush before with a vehicle, then waited 2 weeks and replaced the old filter. Even after just the initial flush the truck shifted better.

Flushing an automatic transmission doesn't cause any problems in itself. Mechanic in a Bottle additives are what will cause problems. Existing damage not withstanding of course. Because if you've got a transmission that's already on it's way out, flushing isn't going to help at all. The irreversible damage is already done.

[DMCVegas]

...anti-freeze after 5.

That however depends upon the anti-freeze and the design of the cooling system. DEX-COOL comes to mind. DEX-COOL is *supposed* to be good for 150,000 miles. BUT that is only if it remains clean and uncontaminated. GM has had lawsuits over this in the past. If you have a vehicle that has an overflow bottle attached to the radiator where it is vented to the atmosphere, dirt and grime gets in, contaiminates the coolant, and will subsequently cause premature failure of the coolant and the cooling system when the dirty fluid gets sucked back in.

However, if you have a sealed system with an expansion tank like the DMC-12 uses (which Ford also seems to have adopted for their vehicles) the coolant remains sealed and is protected from external dirt. So you can reach the 150,000 limit on extended life antifreeze with no problems. But still, keep an eye on that fluid.

[Michael]

Only DeLorean owners will put 200 bucks down an AutoArt DMC-12 scale model without batting an eyelash or throw 100 bucks away on a raffle ticket for just a chance to win a car, but when it comes to spending an extra 25 bucks on 5 qts of ATF or 20 bucks on a few gallons of coolant...then we start splitting hairs.

Just an FYI, A new Auto transmission is almost 6 grand plus labor.

[DMC3165]

The only problem I've seen with the transmission I was posting about originally is problems that arise from power flushing at a shop. If there is any metal in the Trans power flushing from the coolant lines has a tendency to jam those particles into areas where the internal pump wouldn't and this can cause damage. I think I might just drop the pan change whatever comes out and due it again in another 10K miles.

[DMCVegas]

Only DeLorean owners will put 200 bucks down an AutoArt DMC-12 scale model without batting an eyelash or throw 100 bucks away on a raffle ticket for just a chance to win a car, but when it comes to spending an extra 25 bucks on 5 qts of ATF or 20 bucks on a few gallons of coolant...then we start splitting hairs.

Just an FYI, A new Auto transmission is almost 6 grand plus labor.

Actually...that IS a very valid point. Not accounting for the fluid drain that goes along with every time you replace the filter, just dumping out the fluid at least every-other oil change would be much cheaper than the flushes, and would keep fresher fluid in place to where they wouldn't be needed at all. And that would be speaking for any vehicle out there.

[DMCMW Dave]

Only DeLorean owners will put 200 bucks down an AutoArt DMC-12 scale model without batting an eyelash or throw 100 bucks away on a raffle ticket for just a chance to win a car, but when it comes to spending an extra 25 bucks on 5 qts of ATF or 20 bucks on a few gallons of coolant...then we start splitting hairs.
.

I don't think it's the same people.