Leaking J71 AutoPark parking brake actuator cylinder and preventative measures

Leaking J71 AutoPark parking brake actuator cylinder and preventative measures

Lately we’ve seen a huge increase in the reports of J71 AutoPark leaking actuator cylinders.  For years, this malfunction has been almost unheard of, but in the last six or eight months they are popping up with disturbing regularity.

It is nearly impossible to predict which coaches will experience this particular failure, but we are quite convinced that in most cases, the culprit is just plain AGE and in some cases HEAT.

What do we know about this problem?  Several things are pretty sure:

  1. Most of what we’ve seen has occurred on coaches that are ten or more years old.
  2. The majority of dealer outlets don’t want to repair AutoPark actuators.  They strongly lean towards total replacement.  Guessing that the typical charges run $1200 bucks or so, and can be considerably more in todays economy, especially with our suppliers charging exorbitant fees.
  3. Leaking AutoPark actuator cylinders can almost always be repaired at a small fraction of replacement price.
  4. While we’re convinced that age is the primary culprit, we also know there are some cases where brake fluid instead of ATF has been put into the AutoPark reservoir.  Brake fluid is EXTREMELY DISTRUCTIVE to most of the rubber and polymer products that are normally found in systems designed for ATF (automatic transmission fluid).  If you know, or even suspect that brake fluid may have been added to your AutoPark reservoir, you should definitely flush your system, replace the fluid with Dexron III ATF or equivalent, and be on the lookout and prepared for leaks.

Considerations:  If your actuator is already leaking, or you know for sure it has been contaminated with brake fluid, then you will HAVE to take action to avoid AutoPark parking brake system failure and possible lockup of the parking brake.

If your actuator is on a system that is ten years old or more, then you may want to consider some preventative action.  This is purely a matter of opinion and choice.  Many coach owners will prefer to wait until there is a definite actuator cylinder leaking issue before addressing the repair.  Others may choose to take care of this ahead of time.

It should be emphasized that in most cases an actuator cylinder seal leak is something that starts small and grows.  At some point, it HAS to be dealt with, but it is not ordinarily something that happens rapidly and causes immediate road failure or lockup of the parking brake. We are not crying “WOLF” here – – you will almost always get some warning symptoms and have repair options. Watch for leaks and puddles under your coach.

We’ve written a separate data sheet on the various repair options as we see them.  If this is a subject of interest to you, we will be glad to share additional information. There are DIY involved alternatives that will save you a LOT of money.

Questions and comments are always welcome, oldusedbear

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