I recently installed a Back pressure gauge since I had the EBPV brake mod and wanted to keep an eye on BP. Someone here asked me to post what I found so here it is. I am a little late but I wanted to gather some good info before posting and I just took the 36' 5th wheel for a short camping trip this weekend. I estimate it wieghs around 15,000 lbs.

When going 45-50 mph down a significant grade near here I flipped the switch and the pressure started raising. It topped off at 32 psi. Keep in mind I was not on an interstate, just a country road with a good 1/4 mile descent. The gauge fluctuates pretty bad and bounces between 28-32 psi at the max on this day. I am not sure why it bounces so and it only does it when on a steep decline. I thought I may have a kink in the line somewhere but after this tryout I don't think so. I believe it is just because the reading comes directly from the exhaust manifold and that is the way it is gonna be.

My truck is a '97 and made in September '97. I changed the BP line that goes from the manifold to the sending unit because when I pulled it off for cleaning it had a hole in it. The line comes to the top of the motor in the same location as the SD's (in front of the HPOP reservoir, instead of behind like in most all OBS trucks). I had a time getting the right line. The regular OBS one didn't fit and the SD one didn't either. Apparently Ford changed the location from March '97 to the end of the '97's to this one. So if you have one made between these times this is the one you need to get. For some reason on the package it says "EGR valve to...", not sure why. This is not an EGR valve. Here are some pics, Hope this helps someone.

 

nice job Neal. So it looks like you just used a T where the sensor goes, Right? Did you use nylon or copper guage line? Did you just use another boost gauge or did you find a BP guage?

 

Good info Neal. Tryed to rep ya but need to spead it around first. EGR valve, huh? Works for me

BTW: How much pressure is too much pressure? if there is such a thing.

 

I think over 40 is danger much like boost pressure. I think the exhuast brake manufacturers set theirs to around there between 35-40 before it opens as a fail safe. I can't remeber what the guy form BP said in that thread about EB with Steve a while back.

 

Thanks Tim, that sounds reasonable, 40 psi. I had forgotten about that conversation, must be getting used to it.

 

getting used to it!? LOL Those type "conversation" seem to be getting more frequent don't they!

 

Yah, I hope it goes away soon so we can get back to doing what we do best...helping each other.

 

Agreed!!!!

 

the flutter is probably the pulses from the exhasut pushing against the flapper valve
and i sisnt knwoyour name was neal _________

 

Yup I used a "T" and used nylon line. It hasn't melted yet. Before I did this I would pop the hood after a good drive in the East TN heat and grab the sending unit to see how hot it is. I also noticed that the top of it is made of plastic so in all my infinate wisdom I deduced that nylon would suffice. And if it melted I would just drop back and punt with a copper line.

The gauge I used is from hweitt industries. It is a boost gauge with two needles. 0-50 psi. I used the red needle for boost and the white one for BP. It was cheaper that way. single gauge-> $30.00 dual gauge-> $45.00. not bad for 15 bucks.

 

AAhhhmen brother. It does get old. If I wanna hear that I go somewhere else. This is the nice side of town.

I thought the BP release was between 40-45 in the "real" brakes but I may be wrong. Still I haven't tested it in the real hills of the smoky mountains at interstate speeds. I don't expect to see it get to 40 but then again that is why I installed thge gauge. Thanx Cuda and Tim I knew you were interested so I posted this. Sorry it took so long for the test results. I plan on hauling the camper to Cherokee the last weekend of the month and that will be the real test. I will post back when I get more extreme use #'s. BTW I love the brake. I almost don't have to touch the brake when I use it. It provides more noticable braking with the trailer than without it.

 

I thought that is where the flutter came from but wasn't sure.

And for the last 6 words in your post... DU-HUH? I didn't think you drank. LOL

 

Very good write up Neal, I send you rep points. about the brake, I also noticed that provides more braking with the trailer than without it.

 

Thanx guys for the reps but that isn't what I am here for. just the knowledge. You guys are great

 

good lord, how much did i drink? thats pretty rough