Transmission Flushing
Car Repair Advice on When and How to Flush Your Transmission
Auto repair advice from expert Vincent Ciulla. Your questions answered about transmission flushing.
This weekly Q&A session answers your questions about cars and trucks. This week explores transmission services and flushing.
Question: Transmission Flushing
I noticed you didn't advise on flushing the transmission. We flush 8 hours a day and have never had a problem. Snap-On only puts in the same amount of pressure that the transmission puts out. Drop the pan, clean it and add a new filter. Snap-On guarantees its pump not to damage or they will pay for repairs.
Had Ford Explorers going 250,000 miles without a problem and are still going right now.
Love your website.
Answer:
The Snap-On machine is not a flush machine; it is a fluid exchanger. All it does is push out the old fluid. A flush machine uses high pressure and cleaning agents and forces it in the reverse direction of the normal fluid flow.
This is something Ford Motor Company specifically advises against. In big letters in the Ford transmission service manuals it says "Warning: Use only clean automatic transmission fluid. Do not use any supplemental transmission fluid additives, treatments or cleaning agents. The use of these materials affects the operation of the transmission, resulting in internal component failure."
It is not necessary to use a special machine to do the job correctly. Just drop the pan and pull the drain plug on the torque converter. While it's draining, drop the transmission filter, put in a new one and clean the pan. Put a new gasket on the transmission pan and button it back up. Put the drain plug back into the torque converter and fill up the transmission.
This method will get 95% of the transmission fluid out with wasting time hooking up a machine you don't need. Then you can use the money for that machine on equipment you do need.
The facts are this:
- The only ones who recommend a transmission, or engine, flush as a maintenance service are the people who make the machines and the people who sell the service.
- No automotive manufacturer in the world recommends a flush as regular service. If a shop tells you they do; they are outright lying to you.
- All automotive manufacturers specifically recommend against flushing services. Doing so will void new vehicle warranties.
- A transmission, or engine, that has been regularly serviced does not need a flush.
- Flush machine manufacturers specifically advise against flushing "high mileage" vehicles. This loosely phrased warning puts the complete burden of the cost of repairs to components damaged by a flushing service on the shop and leaves them libel free.
So whenever a shop says you need a transmission, or engine, flush; just say no.
That's all for this week. Feel free to browse the archives for past topics and other resources. And, as always, if you are stuck and need an immediate answer you can always call Vince on the phone.
