I just bought a 2000 F-350 7.2 turbo diesel. I think the previous owner may have put a turbo brake on the truck. What I get is when I let off the throttle (From OD)and coast, I feel some backpressure on the motor but not a whole lot. But if I tap the brake pedal it seems to release some of the back pressure and drops the RPM, almost feels like it shifts into a higher gear. I let off the brake and it goes back to back pressure again (Feels like it shifts back into gear). I don't know if I have a problem or if it is something that is supposed to happen. I have not looked for a black box anywhere as to I would not know where to look. Does this sound like I may have a brake on it? This only happens from Overdrive. Like I tap the brake and it feels like it comes out of gear and when I let off the brake I feel it go back into gear.

 

It sounds like it's got a brake on it, but you won't find a black box. Look around the back of the turbo.

 

I don't see anything around the Turbo but I heard there are electronic brakes available and it may have one of them....I don't know where to look for it.

 

Electronic brakes for a PSD Thats a new one on me.

 

http://www.westerndiesel.com/dsp_ford_brakes.asp

 

>I just bought a 2000 F-350 7.2 turbo diesel. I think the
>previous owner may have put a turbo brake on the truck.
>What I get is when I let off the throttle (From OD)and
>coast, I feel some backpressure on the motor but not a whole
>lot. But if I tap the brake pedal it seems to release some
>of the back pressure and drops the RPM, almost feels like it
>shifts into a higher gear. I let off the brake and it goes
>back to back pressure again (Feels like it shifts back into
>gear). I don't know if I have a problem or if it is
>something that is supposed to happen. I have not looked for
>a black box anywhere as to I would not know where to look.
>Does this sound like I may have a brake on it? This only
>happens from Overdrive. Like I tap the brake and it feels
>like it comes out of gear and when I let off the brake I
>feel it go back into gear.

I believe what your experiencing is the coast clutch. It should only do this while in overdrive, Ford's way of trying to up the fuel milage on them. There are kits availible to keep it from releasing so you would have a little engine braking while towing.

 

>http://www.westerndiesel.com/dsp_ford_brakes.asp

Ineresting. A box that taps into the factory EBV. I would think you could rig something like that up yourself and save the $$

An exhaust brake looks something like this: http://www.bankspower.com/System.cfm?appid=AF01&sysid=SF19

I didn't even think about the coast clutch, but then again, I drive a handshaker.

 

Yes that is a good description of it. Coast Clutch....Hmmm it does only happen in overdrive. Where can I find info about this thing. I have never seen it anywhere but I bet that is what I am feeling.

 

Sounds like the electronic lockup on the torque convertor. If you let it coast down to like 38mph then I think you will feel the same thing.
Aaron.

2001 F250 PSD 6-SPD 4x4 SCMT Banks Monster Exhaust EGT, Boost, Oil Pressure, Oil Temp/Trans Temp Gauges