Happy Day!

I recently purchased a 1995 F-350 with the 7.3L Diesel engine. At first when I would start the truck you could hear what I think is the back pressure relief valve rattle a little and then slap shut. I was told originally that it was the waste gate sticking then closing. After reading up on Alldata about the Garrett TP-38 I discovered that it instead had the back pressure relief valve. The truck ran fine and this did not seem to cause a problem.

I recently started the truck and I did not hear that familiar rattle and slap as before. When the truck was idling the exhaust had a loud hissing sound. When I started to drive the truck had no power. Depressing the accelerator would cause what sounded like the pressure relief valve to close for a moment, the loud hissing sound would stop then slowly the hissing sound would return and the truck had no power. depressing and holding the accelerator would make the turbo work for a short time but the hissing sound and lack of power would slowly return.

I was told by a mechanic today that my back pressure relief valve was opening and causing me to lose pressure. I was told by another mechanic that it sounded like the back pressure relief solenoid was not closing the relief valve like it should.

I would add that the truck spent several hours tonight in the shop. When we pulled the truck in it had the same hissing sound and lack of power. When we started up the truck to pull it out of the shop. We instantly heard the rattle and slap of the relief valve and the truck ran fine.

Alldata does not have a pinpoint test that covers this particular symptom. Where should I begin? The truck is undrivable when this problem happens. It doesn't have enough power to get out of its own way.

Thanks

 

You can just unplug the two wire connector under the turbo on the drivers side. It controls the ebpv. If for some reason it sticks closed and you have no power, get it open and wire it open and unplug it. Lots of us have unplugged it, some like me completely removed it.

 

The solenoid could be going bad or the flapper could be obstructed or wearing out where it hinges. I would grab the rod that controls it and see if it is hard to move. I cant see where you live , but , all it really does is help the motor to warm up when its cold. It doesnt regulate turbo pressure while driving.

 

Welcome to the site! 2x for just unplugging the EBPV. In fact I deleted mine as well to free up the exhaust.

First of all, I would be hesitant to take your truck back to either of the garages that looked at your truck since they apparently aren't all that familiar with the 7.3 PSD. These trucks don't have a wastegate, or a back pressure relief valve or anything like that. What they DO have, is an EBPV (Exhaust Back Pressure Valve) that acts to aid in cold warmup. It is essentially a butterfly valve that closes and adds resistance to the exhaust to (supposedly) help the engine warm up faster.

Here is a picture of the EBPV open.



And Closed (with the housing removed from the turbo):



And here is a picture of the turbo after the EBPV delete. You can see how much deleting the EBPV frees up the exhaust.



Here is a picture of the turbo out of the truck where you can see the connector for the EBPV solenoid.

If you're prone to wrenching on your own truck, this site will give you all the help you need to do as much as you want to do on your own. These guys have taught me TONS in the last year.



These things are very notorious for closing when they shouldn't. Just unplug it, wire it open by the linkage on the exhaust side of the turbo and never look back.

 

Great pics DIY!

 

Oh, and make sure the FPR screen is clean while you're in the bowl. It is a small strainer screen located inside about a 1/2" hole on the driver side of the bowl, toward the top. Use a matchstick or the stick from a cotton swab to gently scraper the crud out of that hole.

 

Thanks for all of your replies. So if I understand correctly... When the truck had no power and the exhaust sounded different the EBPV was closed? unplugging the solenoid and holding the EBPV open or removing it entirely should solve this particular problem?

Thanks,
Dave

 

unless there are other symptoms, yes that is correct.

 

BTW... Welcome to FTE!

 

If you have the time and more importantly the patience i would just gut the ebpv that most lf us have done and drop a three inch down pipe. Thats if your going to want to lower egts later on. Its not that hard just have to lnow how to weld and get a plug. I did the dete and love it but i expierenced the same problem as you anx wired it open for the time being.

 

You can do it w/o doing any welding also. A person can use freeze plugs to cap the hinge holes.

 

I used the freeze plug to cap the hole in the exhaust housing, but to do the pedestal delete as well you have to have someone weld the oil passages shut where they go into the piston for the actuator. I had a local shop weld mine for me, I know they guy and he only charged me $10 to do it!



Doing the pedestal delete will make it TONS easier to remove the pedestal in the future, if need be.

 

I am pretty sure I already know the answer to this but...

if the EBPV is deleted there is no way to utilize an exhaust brake right? I would love to have the lower EGT's and better flow, but really love the brake.

 

Nope, it's one or the other. Can't have your cake and eat it too!