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Truck continues to roll while parked and in gear

My wife is out of town and while she parked her 1997 Mazda B Series pick up truck this morning she stated that her truck continued to roll while parked on a very slight incline. The vehicle was in gear so she put the emergency brake on. Could the clutch be slipping although she said it seemed to be shifting fine. She has to drive back 3 hours over the rolling hills of Nevada and is very concerned that something else could be wrong. What could I have her check besides the clutch fluid?

Thank you,

This is a Manual Transmission???

Any manual transmission can roll even in gear…UNLESS you put the parking brake on. Do NOT rely on the transmission to HOLD the vehicle.

And yes…the clutch could be slipping…and clutch fluid will have nothing to do with a slipping clutch.

Well, if the wife put the thing in 1st or Reverse, it should not roll on a slight incline. However, if the engine is worn much and the compression low, it might move. A very bad clutch would probably hold on a slight incline. And as was just posted, clutch fluid will have nothing to do with a clutch slipping.

“Any manual transmission can roll even in gear…UNLESS you put the parking brake on. Do NOT rely on the transmission to HOLD the vehicle.” [MikeInNH]

This was worth repeating

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buelluly:

Your manual transmission will allow the force of gravity to rotate the driveline, and torque on the driveline will translate to torque on the engine crankshaft. This will result in the pistons moving and the car rolling forward as pressure bleeds out of the rising piston cylinders.

The best way to go about it is to apply the parking brake and leave the transmission in reverse. The reverse gear has the highest gear ratio in the transmission, and also lacks a synchronizer gear. Leaving your transmission in 1st while parked on a hill will apply constant pressure to this gear, potentially leading to smoothness issues when shifting between 1st and 2nd.

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For sure, reverse is a much more dependable choice for parking but curbing seems the most certain method to keep a vehicle from rolling down a hill. And the parking brake when no curb is available will greatly improve the situation. Does the pickup ever jump out of gear when decelerating in 1st or 2nd?

I have a 2006 GTO with 77,000 miles and a steep driveway. This was surprising to me that the engine cylinders could slowly “leak down” and cause the car to roll. The engine kicks a$$ so doubt I have low compression. Your thoughts? Thanks, Michael

My thought is that, unless you perform a compression test, you really don’t know whether the engine has lost compression over the years.

Additionally, Mr. Meehan–who was one of our valued contributors for many years–is now deceased, and will not see your reply to him.

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All engines leak a bit of compression while cold. Doesn’t mean you don’t have great compression while hot when the pistons and rings expand and close the gaps. Completely normal even for a big V8 to roll back if you haven’t set the parking brake.

All manual trans cars should have the parking brake set on a hill and turn the front tires into the curb.

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Reverse offers more resistance to rolling and high gear the least.