c210pa18 Posted March 13, 2023 Share Posted March 13, 2023 I have found two air leaks both are Meritor PPVs on the rear air tank. Both have the number Meritor 9348990040. I called a truck repair here in the Phoenix area and didn't get a lot of help except he said it crossed to a Meritor RKN31000. However, not having worked on these before not sure how they work. There seems to be a high and a low pressure setting maybe by part number? Anyway one is leaking a lot and one is leaking much less both leaking out the hole on top of the spring cover. I assume that means they are bad and need replaced. Am I going down the right path here? I can't find the original part number online but I did find the RKN31000 number online. Some help with this would be wonderful. Link to comment Share on other sites More sharing options...
Tom Cherry Posted March 13, 2023 Share Posted March 13, 2023 37 minutes ago, c210pa18 said: I have found two air leaks both are Meritor PPVs on the rear air tank. Both have the number Meritor 9348990040. I called a truck repair here in the Phoenix area and didn't get a lot of help except he said it crossed to a Meritor RKN31000. However, not having worked on these before not sure how they work. There seems to be a high and a low pressure setting maybe by part number? Anyway one is leaking a lot and one is leaking much less both leaking out the hole on top of the spring cover. I assume that means they are bad and need replaced. Am I going down the right path here? I can't find the original part number online but I did find the RKN31000 number online. Some help with this would be wonderful. What my OTR shop did was pull out my leaking one and took it to a Truck parts house and had them either cross reference of pull one with the rated Pressure and the same thread size and style. That was 8 years ago and no issues. About every 4 years, I get him to do the bubble test on all the brake fittings and the leveling. Link to comment Share on other sites More sharing options...
Bill R Posted March 14, 2023 Share Posted March 14, 2023 @c210pa18 Gerald - I got mine at Advanced Auto Parts. https://shop.advanceautoparts.com/p/world-american-pressure-protection-valve-inlet-port-1-4-n.p.t.-outlet-port-1-4-n.p.t.-accessory-port-b-1-4-accessory-port-c-1-8-replaces-midland-kn31000-wakn31000/11052291-P?searchTerm=WAKN+31000 Link to comment Share on other sites More sharing options...
96 EVO Posted March 14, 2023 Share Posted March 14, 2023 1 hour ago, c210pa18 said: Anyway one is leaking a lot and one is leaking much less both leaking out the hole on top of the spring cover. That right there is what probably caused your problem! Monaco, for some unknown reason made a habit of mounting these valves upside down! The drain hole should point down. Link to comment Share on other sites More sharing options...
Solution jacwjames Posted March 14, 2023 Solution Share Posted March 14, 2023 I got mine at Advanced Auto also, ordered them from the local store and they had them the next day. If I were doing it I'd replace all of them and be done with it. Also, while I was working on my air leaks I posted a picture on IRV2 and one of the more senior members stated that they were upside down. The drawing that I had showed them with the cap pointing up. Did a bunch of searching and found installation instructions>> sure enough the cap should be pointing down. Had to back and rotate the four that I had installed. PPV installation instructions.pdf Link to comment Share on other sites More sharing options...
c210pa18 Posted March 14, 2023 Author Share Posted March 14, 2023 Thanks for the help. Are they basically all the same pressures ? Opening Pressure of 65 PSI - Closing Pressure of 45 PSI Link to comment Share on other sites More sharing options...
96 EVO Posted March 14, 2023 Share Posted March 14, 2023 Nope! here's one with a 55psi closing pressure.... https://www.anythingtruck.com/product/070-KN31000.html Link to comment Share on other sites More sharing options...
Bill R Posted March 14, 2023 Share Posted March 14, 2023 12 hours ago, c210pa18 said: Thanks for the help. Are they basically all the same pressures ? Opening Pressure of 65 PSI - Closing Pressure of 45 PSI Yes - https://mpparts.com/part/world-american-wakn31000-pressure-protection-valve-wakn31000 Link to comment Share on other sites More sharing options...
c210pa18 Posted March 14, 2023 Author Share Posted March 14, 2023 Thanks, guys good information that was very helpful. I found two here not too far away in our corner of the Phoenix area. I tried Advanced Auto they were over a week out. The MP parts were going to be close to $60 just for shipping. Fleet Pride had them so drove about 45 min away to pick them up. So tomorrow I will get them installed and check for more leaks. Hope this is all. It is interesting that they were upside down but still lasted over 20 years and $190,000 miles. You can tell they are original as they have undercoat spray on them which was factory installed on this coach. Link to comment Share on other sites More sharing options...
96 EVO Posted March 14, 2023 Share Posted March 14, 2023 (edited) Mount the new ones upside down if you like. You would likely get 20yrs out of them as well. Edited March 14, 2023 by 96 EVO Link to comment Share on other sites More sharing options...
c210pa18 Posted March 15, 2023 Author Share Posted March 15, 2023 12 hours ago, 96 EVO said: Mount the new ones upside down if you like. You would likely get 20yrs out of them as well. Naw, I think I'll follow the directions. These actually are labeled TOP on the top. I'm not sure that will make them last any longer but might as well do it right. Link to comment Share on other sites More sharing options...
96 EVO Posted March 15, 2023 Share Posted March 15, 2023 I think Jim found the springs corroded under the cap from having the collected moisture no way of draining out. Link to comment Share on other sites More sharing options...
jacwjames Posted March 15, 2023 Share Posted March 15, 2023 1 hour ago, 96 EVO said: I think Jim found the springs corroded under the cap from having the collected moisture no way of draining out. I took them all apart and found all had corrosion, but they were ~20 years old. I did make sure to point the cap with hole it down. Funny how they all started leaking at the same time. In early 2021 I sprayed all the air connections and fittings on the tanks just to make sure there were no leaks. I filled up my air system and monitored the air pressure, stayed up over a week. Then took a trip in Nov and noticed the air was leaking down fast, probably still acceptable for driving but headed home and fixed the problem. Link to comment Share on other sites More sharing options...
c210pa18 Posted March 17, 2023 Author Share Posted March 17, 2023 I took mine apart and did not find any corrosion but the diaphragms were both cracked and leaking. So it was time for a replacement. 1 Link to comment Share on other sites More sharing options...
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