Bob tells me: Hi, I bought a 2000 Mazda 626 with 78,000 miles, 4 cylinder. When I bought it, it ran fine & only needed some minor brake repair. I didn’t know the maintenance history, so I wanted to do some preventative maintenance. I had the coolant changed. I also wanted to have the transmission fluid changed. The auto shop recommended it changed every 30,000 miles. I asked if they changed the filter when they did the service & they said no, they use a power flush to change the fluid & that cleans everything. I had that done for about $150.
About 3 days & 150 miles later, the check engine light came on & the transmission was bucking & doing all kinds of weird stuff. I took it back to the shop & they said I need a new transmission & I have to pay for it. When I called different transmission shops around town for quotes, they told me that they never flush a high mileage transmission because flushing will ruin it. They said flushing only works if you do it every 30,000 miles starting when the car is new. They said they drain the fluid & change the filter only. One of the mechanics even asked me if I had it flushed just before it broke down, without knowing that I had done it.
Is it true that flushing a high mileage transmission can damage it? How can flushing hurt a transmission? The transmission ran fine with no symptoms. Thanks for your help, Bob
Bob, it would all depend on the condition of the fluid to begin with, prior to the flushing. Your transmission is at the point where some problems can begin, yet should not really fail yet, depending on any prior maintenance.
If your fluid was smelling burned, then you were already in a bad situation. Opinions vary on whether or not to flush a tranny when it has a few miles on it, but definitely not if the fluid smells burned. This can break cracked O-rings, loosen sludge deposits and move around other debris which may plug small orifices in the transmission ports. Some people believe if the fluid is in good condition then its OK to flush a tranny with 100k miles on it.
In your case I would replace the filter since that was not done, for starters. I would also have the proper fluid put in. You should also have the trouble codes checked to be sure the tranny is the real problem, there will be a code logged in since your “check engine” light is on.
Take it to a different place to do this because I would not trust the first place that you had it flushed because they apparently didn’t notice something prior to the flushing or could have done faulty workmanship.
Best of luck - Dave
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