Community Forums

scenic route · 07-17-2010, 05:45 PM

Has anyone with a Jeep Wrangler with the SMI Duo braking system had the SMI engine check valve go bad (will not allow engine vacuum to the Jeep's brake booster while NOT towing)? This is the second one in about a month. SMI's rep. says he has not ever heard of one of their engine check valves going bad and the first time, they bent over backwards to get the new one to me while we have been traveling.

My system was professionally installed, our Jeep is as it came from the factory with no mods. The engine compartment does get pretty warm though, but the system's check valve seems to be installed per manual instructions(teed just to the right of the Jeep's brake booster...the valve is also partially wrapped in wiring wrap as well.

I've been taking the valve out of the vacuum line to get brakes back on the Jeep while not towing and reinstalling it while I'm towing...works fine.

I'll contact SMI Monday, but in the meantime, inquiring mind wants to know...Anyone else have this problem?? And how does this valve know when it's the weekend to go bad?

Bob

DriVer · 07-17-2010, 05:59 PM

Quote:

Originally Posted by scenic route

And how does this valve know when it's the weekend to go bad?

Bob, Why isn't that the way it's supposed to not-work?

Honestly I have not had a problem with our DUO during its entire stay under our hood.

I'm anxious to see the response you get from SMI.

scenic route · 07-17-2010, 06:18 PM

Quote:

Originally Posted by DriVer

Bob, Why isn't that the way it's supposed to not-work?

Honestly I have not had a problem with our DUO during its entire stay under our hood.

I'm anxious to see the response you get from SMI.

Yeah, I guess we just got lucky...on both counts

!

Anyway, we'll be in Cody, WY. for a week come this Wednesday(I can smell the buffalo already

), so hopefully they can come up with a reason/fix...I'm stumped on this one. My Jeep isn't any different than the next.

Yellowstone, here we come!

Bob

scenic route · 07-19-2010, 05:20 PM

I talked to SMI tech. assist today. They are sending another engine vacuum check valve to us via UPS to Cody, WY. ...rather nice of them considering this is the second failure.

After some discussion (among themselves) they thought maybe I'm getting some small debris in the valve causing it to clog. I dunno...I just separated the two halves of the first one and found nothing. The small rubber diaphragm was coated with a small amount of that looks like engine oil...that was all that was inside...no rocks. I use regular dinosaur 10W30 and the diaphragm doesn't look distorted or swollen (although I do not have a new one for comparison). I thought maybe it was the heat frying the rubber, but it is supple. I can't take the other valve apart until I get the new one (need it installed in the system for toad braking while under tow).

So it goes...when I get the new valve, I'm going to insulate it and route the vacuum line higher in a effort to get it further away from the exhaust heat shield and try to cut down on any oil mist coming into the hose. At this point I'll try anything.

Sooo, no other Wrangler owners with the Duo have this kind of trouble? SMI says they've have no other valve problems. Any ideas, anyone? Bob