mechohaulic Posted September 8 Share Posted September 8 that wouldn't be a valve NORMALLY associated with parking brake system / should be a regulator valve , question is = what system ?? suggestion would be to trace lines best possible, or what valve / switch do you move to make a difference in valve leak. Quote Link to comment https://www.bigmacktrucks.com/topic/63244-young-guy-old-mack-b61-dump-truck/page/6/#findComment-582429 Share on other sites More sharing options...
mechohaulic Posted September 8 Share Posted September 8 4 minutes ago, Mark T said: Reversing relay for the puff limiter. "stopped leaking when I set the brakes" == why a puff limiter ?? Quote Link to comment https://www.bigmacktrucks.com/topic/63244-young-guy-old-mack-b61-dump-truck/page/6/#findComment-582430 Share on other sites More sharing options...
Mark T Posted September 8 Share Posted September 8 It gets air when you release the parking brakes, then meters air to the puff limiter on the injection pump in relation to manifold pressure. 1 1 Quote Link to comment https://www.bigmacktrucks.com/topic/63244-young-guy-old-mack-b61-dump-truck/page/6/#findComment-582432 Share on other sites More sharing options...
mechohaulic Posted September 8 Share Posted September 8 8 minutes ago, Mark T said: It gets air when you release the parking brakes, then meters air to the puff limiter on the injection pump in relation to manifold pressure. possibly what's throwing me off (besides the long day/ Yukon Jack ) is the picture posted!! I remember the intake manifold having an air cyl 1 in +- dia with line going to injection pump ; not the picture posted . Quote Link to comment https://www.bigmacktrucks.com/topic/63244-young-guy-old-mack-b61-dump-truck/page/6/#findComment-582437 Share on other sites More sharing options...
Mark T Posted September 9 Share Posted September 9 6 minutes ago, mechohaulic said: possibly what's throwing me off (besides the long day/ Yukon Jack ) is the picture posted!! I remember the intake manifold having an air cyl 1 in +- dia with line going to injection pump ; not the picture posted . There's a couple different types 1 Quote Link to comment https://www.bigmacktrucks.com/topic/63244-young-guy-old-mack-b61-dump-truck/page/6/#findComment-582440 Share on other sites More sharing options...
Smoothy Posted September 9 Author Share Posted September 9 2 hours ago, Mark T said: It gets air when you release the parking brakes, then meters air to the puff limiter on the injection pump in relation to manifold pressure. Thanks Mark, that makes perfect sense to me now. I've managed to scrounge up the Mack service manual on puff limiters from another thread on the site. What I don't understand now is that if the reverse relay leaking/ bleeding air off into the atmosphere with the brakes released is normal, surely not right? There's no figure showing the different ports on the reverse relay, but it does mention a test port. Is that what is leaking on my relay and simply needs plugged? The only other thing messing with my head on this one is that the control valve appears to be removed. Quote Link to comment https://www.bigmacktrucks.com/topic/63244-young-guy-old-mack-b61-dump-truck/page/6/#findComment-582445 Share on other sites More sharing options...
Smoothy Posted September 9 Author Share Posted September 9 Well, it took some digging. But this problem was one I invented. Thanks again, BMT forums. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/63244-young-guy-old-mack-b61-dump-truck/page/6/#findComment-582446 Share on other sites More sharing options...
Mark T Posted September 9 Share Posted September 9 Looks like maybe someone tapped into the same fitting on the manifold for a manifold pressure gauge (?) . Try explaining that leak to a DOT guy in 2025 🤔 Quote Link to comment https://www.bigmacktrucks.com/topic/63244-young-guy-old-mack-b61-dump-truck/page/6/#findComment-582487 Share on other sites More sharing options...
Smoothy Posted September 10 Author Share Posted September 10 3 hours ago, Mark T said: Looks like maybe someone tapped into the same fitting on the manifold for a manifold pressure gauge (?) . Try explaining that leak to a DOT guy in 2025 🤔 Yeah I'm not exactly sure what's going on with this thing. The plastic line coming off the fitting in the manifold is just dangling off not attached to anything and the puff limiter line from the injection pump that goes to the reverse relay is also removed. It seems the puff limiter has been disabled, but they didn't clean up their work. Wondering if I should just finish it off and cap the lines to the manifold and maxi brakes. I can't imagine the reverse relay is doing anything at the moment. Quote Link to comment https://www.bigmacktrucks.com/topic/63244-young-guy-old-mack-b61-dump-truck/page/6/#findComment-582505 Share on other sites More sharing options...
Smoothy Posted 2 hours ago Author Share Posted 2 hours ago Well, I have been running the R model off and on when I can find the work, it has steadily been trickling in. I have been doing mostly hauling stone out of the quarry for driveways and such so far this winter. It's been a pretty fun year with the new truck, and good news is I have a pretty big job coming up for it. I've had to replace a few things, like a brake chamber and some lights. Had to fight through the cold and snow just to get her started up after cold soaking for a week while I was in Texas. But, it has beat the 9-5 redundancy I was used to and I'm enjoying the adventure. I hauled a load of rock today at probably 80 miles round trip and when I landed back at home, I noticed a drip from the passenger front wheel seal leaking down the backside of the hub. Yipee for me, shouldn't be too bad to do, just hope nothing is torn up. Anyways, this sent me down a path for finding a parts diagram or part numbers. So I referenced the original build sheet to find my axle. The truck has the FAW537C 12,000lb front axle. It got me thinking about the GVWR on my truck. It's rated for 48,860lbs. Referencing that sheet again, it says that the 10,860lbs listed under "tire and rim" is my gvwr for the front axle, of course because they are lowest rated components. So, my question is, was it the wheels or the tires that were at their limit at 10,860#? I think I have H/16 ply steer tires on at the moment that are rated for 6610 a piece. Am I right in thinking this bumps my GVWR up to 50,000 pounds if the limit was the original tires? And I'm sure there's a chance I might need to get it verified in some way too. I'd sure like to be able to haul a 14t load. It's all new to me, so I'll go back to looking for parts. 02.pdf Quote Link to comment https://www.bigmacktrucks.com/topic/63244-young-guy-old-mack-b61-dump-truck/page/6/#findComment-586669 Share on other sites More sharing options...
terry Posted 2 hours ago Share Posted 2 hours ago 12,000 pound axle is kind of small for a tandem axle dump truck, will wear the kingpins out pretty quick. Also pretty weak springs for alot of weight on the steer axle. terry Quote Link to comment https://www.bigmacktrucks.com/topic/63244-young-guy-old-mack-b61-dump-truck/page/6/#findComment-586675 Share on other sites More sharing options...
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