2000 F-350 7.3 Exhaust back pressure valve problems?

[fizbancor]

Hi Everybody,

I have a 99 F-250 with the 7.3 and just picked up a 2000 F-350 dually with the 7.3, 2wd and 6-spd, also 280k on it.

The F-350 is having an intermittent problem. At partial throttle while driving it feels like the EBP valve is opening and closing. It feels like somebody is putting the brakes on and then taking them off. Sometimes last for a few seconds, other times it varies every second or so. It is accompanied by a realatively loud hissing sound.

It seems to happen more when the vehicle is driven at lows speeds an when it is cold, that has happened at low speeds when warmed up. Goes away during full throttle or when not on the accelerator. Doesn't seem to happen at higher speeds, or I don't notice it. As drove 250 miles on the highway without noticing.

Also, the vehicle seemed to have a fairly bad oil leak (could have been fuel) of about one drip every 3 seconds coming down from the passenger side of the engine. Though it seems to have stopped now.

Just curious if you all think my guess is right, and how to verify this, and what I will likely need to do to fix. I appreciate any help.

Thanks, Ross

[venom_nitrous]

This is normal operation of the EBPV

[shovelrog]

There's how to's on cleaning the exhaust back pressure valve check out Welcome to guzzle's Ford PSD Web Pages
For the oil/ fuel leak I'd look around at the top vally of the motor. maybe degrease it and then check it after driving a bit. anything leaking on top of the motor drains down the passenger side due to gravity. For oil leaks look for a leak at the turbo base or the HPOP. For fuel leaks check out the fuel filter/bowl and its drain valve. These are common spots from what I have learned.