Manual Transmission Slipping?

[Jerry Sanders]

When I park my 91 XL with manual tranny, it tries to roll. Is this a sign that I might need a transmission rebuild or could it be something simpler?

Thanks,
Jerry
91 XL
154,000 mi

 

[KEbert]

I'm not sure I understand. You park it and it rolls. You mean with the e-brake on or in neutral without the brake or what?

 

[Jerry Sanders]

When I shut the truck off in gear on a slight incline, it will not hold at that spot, either with or without the emergency brake. It will move in short segments, like the transmission is trying to hold it but it can't. I'm not concerned about the emergency brake right now, but I am concerned about the transmission. I'm going to replace the engine and the clutch soon and I'm wondering if I should also rebuild the transmission at the same time. It's got 154,000 mi on it.

Thanks again,
Jerry
91 XL 4x4

 

[JJS]

probably just your engine turning over. it has lost compression over the years and easier to roll now.

 

[Jim F]

JJS, my thought exactly. Manual transmissions have a direct connection to the engine (no torque converter). If the engine has lost some compression with age, it will only be able to hold the vehicle until the pressure in the cylinders can leak off then the crank, tranny and wheel will turn until a new pressure buildup can form.

 

[KEbert]

Even if your Explorer has lost compression, I doubt it would be enough that in first gear it would still roll. I don't know how it rolls with the emergency brake on too. That should not happen. How is your clutch? Does it slip at all?

 

[Jerry Sanders]

Yeah, the clutch is on its last legs, too. I plan on getting a new clutch when I replace the engine. I was hoping it wasn't the transmission.

I appreciate your help. This is a great board - very informative!

 

[Jenkins1581]

I had a Toyota with 300000 miles on it. It did the same thing. It was the motor. IT was losing comperssion. But it was noticeable when I was driving. It was tired. Your problem is the cluch. Unless your engine is really weak I doubt it is the engine. Your tranny is fine. With a manual you will know when something is wrong. Definatly change the cluch with the new engine.