Jim Warman Posted September 22, 2012 Share Posted September 22, 2012 Let me begin by stating that the Envacon positive air shutoff valve is a quality piece. It appears to be well built and robust and doesn't seem to have the concern that affects Roda Deaco valves that aren't exercised regularly. However, when mounted in trucks equipped with the 6.7, there is an apparent problem. The flattened metal strip at the top of the valve is supposed to guard the solenoid pintle (the little stubby stem with the hole in the middle of the cover). This strip was originally a hoop and, over time, hits the bottom of the hood and flattens out. Subsequently, the pintle of the solenoid hits the hoop and cannot rise enough to allow the valve to trip when required. I don't know how many of you work on trucks equipped with these sorts of devices. We work on them all the time and I am trying to get our crew to remember to test the operation of these devices when they service a truck so equipped. File this in the "just so ya know" folder.... Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted September 22, 2012 Share Posted September 22, 2012 Jim if you are motivated to do so you might contact the manufacturer of the valve/system and let them know about this issue. I went to their website and read up on the device. Looks like they are in Alberta. Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted September 22, 2012 Author Share Posted September 22, 2012 Our parts monger and I have both tried to contact Envacon regarding this. All of my e-mails bounced and our partsmongers phone call was met with disinterest. I have started informing fleet operators when I find faulty devices during inspections. I think there may be a little disbelief or whatever on the part of Envacon since the concern does take time to manifest itself. I bent the hoop on the valve pictured here back up and the valve worked again - even after opening and closing the hood several times. But it is obvious that it will return to the point where the valve no longer functions eventually. The truck that this valve was installed on failed it's commercial vehicle inspection with the valve cited as one of the reasons. Obviously, I cannot fail a vehicle if this valve still functions, but we are seeing that (and I remind you that I do think the valve itself is a good piece) when installed on 6.7 trucks, space constraints do the valve no favours. Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted September 22, 2012 Share Posted September 22, 2012 This is a case where the valve install has clearance when shutting the hood in the bay but not when the engine is under load and torque pushes the engine toward to hood. It is too bad that your efforts in trying to inform Envacon went they way they did. Perhaps sending the truck back to the installer for a warranty repair might get attention. Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted September 22, 2012 Author Share Posted September 22, 2012 The truck is getting a Roda Deaco valve with implicit instructions that the valve be exercised regularly. As I'd mentioned, I'm trying to get at least our guys to cycle the valves during maintenance and report any failures. I can't babysit these cretins but I can certainly try my best to keep them from killing themselves. Quote Link to comment Share on other sites More sharing options...
Brad Clayton Posted September 23, 2012 Share Posted September 23, 2012 Are runaway engines common in your area? Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted September 23, 2012 Share Posted September 23, 2012 I would think that any place gasses can be released pose a potential hazard for runaway engines... the Alberta oil patch for example. Remember that oil drilling can produce gasses. Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted September 23, 2012 Author Share Posted September 23, 2012 Actually, no. Most oil patch facilities (batteries, satellites, plants, compressor stations et al) require any diesel engine to be fitted with a positive air shut off device. There is no requirement (AFAIK) for automatic devices (self actuating) but manually actuated devices are required for entry to specific areas. We've come close a couple of times in the shop and on road tests due to overfull crankcases but still haven't had to use the CO2 extinguishers. The last runaway that I can recall occurred in the Nipisi area about 7 years or so ago. A tanker truck (not sure if it was fitted with a PAS or not) ran away while loading crude at a battery (caution - memory thing happening). The truck and trailers were a total loss - I saw the pictures - and the facility received significant damage. Thankfully there was no loss of life but the cost did run into a couple or three million bucks plus lost production. When we consider that, when I perform a commercial vehicle safety inspection, I am certifying that a vehicle complies with an expected level of safety. If I fuck up - it isn't going to be about a couple of thousand bucks of truck hardware. It could have my name listed along with Joe Hazelwood and Francesco Schettino in the history books. And that last paragraph could refer to almost any one of us. Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted September 23, 2012 Share Posted September 23, 2012 Absolutely correct Mr Jim. I doubt many technicians ever give thought to being liable for injury, loss of life and property damage. Quote Link to comment Share on other sites More sharing options...
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