biffidun Posted September 24, 2011 Share Posted September 24, 2011 Just a basic question. Up here in the great white north (Canada). The feds made everyone raise their pressures in the brakes systems a couple of years ago. Long story short, my "new to me" 1976 DM685S smokes a bit much, well, alot. I yanked the puff limiter valve and cleaned it, but not much change. Here's my question, if the system pressure has been raised, wouldn't the puff limiter be out of spec?I tried adding two washers to the top of the spring inside the valve, thinking that more pressure would be required to overcome the spring - delaying full rod stroke in the pump. Is my thinking correct or is it reversed? Quote Link to comment Share on other sites More sharing options...
theakerstwo Posted September 24, 2011 Share Posted September 24, 2011 Just a basic question. Up here in the great white north (Canada). The feds made everyone raise their pressures in the brakes systems a couple of years ago. Long story short, my "new to me" 1976 DM685S smokes a bit much, well, alot. I yanked the puff limiter valve and cleaned it, but not much change. Here's my question, if the system pressure has been raised, wouldn't the puff limiter be out of spec?I tried adding two washers to the top of the spring inside the valve, thinking that more pressure would be required to overcome the spring - delaying full rod stroke in the pump. Is my thinking correct or is it reversed?The air pressure in the tanks being some more than it was will not change the pressure going to the puff limit cyl on the pump. Quote glenn akers Link to comment Share on other sites More sharing options...
tanbuddy Posted October 3, 2011 Share Posted October 3, 2011 what year did the puff limter start on these trucks? Quote 79 U237 5 sp Link to comment Share on other sites More sharing options...
Lmackattack Posted October 3, 2011 Share Posted October 3, 2011 I want to say the puff limiters came on all the turbocharged engines. all the ones I have seen had the relay valve on the intake manafold. I do recall a early model that may have been located on the pump? Quote Link to comment Share on other sites More sharing options...
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