frantzevan Posted February 6, 2015 Share Posted February 6, 2015 There's a popping noise at idle. Sounds as if there is something metal bouncing around inside the motor. It has been doing this for months now. After you idle it up a few hundred RPMS the clatter goes away. The truck is used as a site truck and rarely sees full temp or full boost. The motor and pump are fresh (less than 3 years). It's an EM6 285 turned up 20%. Runs strong outside of the idling issue. Quote Link to comment Share on other sites More sharing options...
b61mack Posted February 6, 2015 Share Posted February 6, 2015 If it is a 2 valve could be a loose valve seat, does it sound like a thumping noise when you lit off of the accelerator petal don't know weather the 4 valves come loose or not. don't know much about the 4 valve. Quote Link to comment Share on other sites More sharing options...
BGarofalo Posted February 6, 2015 Share Posted February 6, 2015 I have seen sticking valve guides and also pumps do this. Is it an am AMBAC pump? If so take the plate off the side of the pump and see if there is a little pile of brass in the corner. Quote Link to comment Share on other sites More sharing options...
ranchhopper Posted February 6, 2015 Share Posted February 6, 2015 Timing could be off too I had a military blazer with a 6.5 diesel in it that clattered so loud when you had the hood open you couldn't stand close to it or your ears would hurt turned out the timing was a bit off got the timing right and the extra noise went away. Quote Link to comment Share on other sites More sharing options...
frantzevan Posted February 6, 2015 Author Share Posted February 6, 2015 It is an American bosch. To be completely honest, it start shortly after I switched to synthetic. I wanted the cold tempreture advantages more than anything. I leave this truck wherever I can park at and rarely have a place to plug in. Quote Link to comment Share on other sites More sharing options...
BGarofalo Posted February 6, 2015 Share Posted February 6, 2015 American bosch is the AMBAC pump. The bushings in the roller lifters in the injection pump tend to fail on these pumps. You can hear a noise at idle sometimes but once your in the throttle you never notice it. Its pretty simple to take the side cover off the pump and check for debris. Nothing scary in there that's going to fall apart when you pull the cover off so don't worry. Quote Link to comment Share on other sites More sharing options...
thomastractorsvc Posted February 9, 2015 Share Posted February 9, 2015 When was the last time the valves were adjusted? Did they reuse the springs? Quote Robert"I reject your reality and substitute my own." Link to comment Share on other sites More sharing options...
frantzevan Posted February 10, 2015 Author Share Posted February 10, 2015 I probably should have mentioned that this noise started shortly after switching to synthetic motor oil. Amsoil to be exact. I've had the oil in for 9 months now and I was down to the add mark on the fill stick. I didn't have any extra Amsoil and didn't want to pay the shipping on 1 gallon. So I grabbed a jug of rotella T-6 to stay with a synthetic blend. After adding the rotella the truck made the clanking noise upon start up but shortly after the noise disappeared. I heard it briefly at really low RPMS but for the most part has disappeared. Obviously I will be switching oil brands on my next change but I'm still curious as to why the Amsoil created this noise. Quote Link to comment Share on other sites More sharing options...
Maddog13407 Posted February 10, 2015 Share Posted February 10, 2015 does it have a Jake? the 2 valves would wear the valve guides from excessive jake use and would sound like the jake was stuck slightly and make a popping noise when you let off it. Quote Link to comment Share on other sites More sharing options...
frantzevan Posted February 10, 2015 Author Share Posted February 10, 2015 (edited) It is a 2 valve but it has a dynatard for an engine brake. Edited February 10, 2015 by frantzevan Quote Link to comment Share on other sites More sharing options...
frantzevan Posted February 10, 2015 Author Share Posted February 10, 2015 (edited) Thanks for the quick responses! Edited February 10, 2015 by frantzevan Quote Link to comment Share on other sites More sharing options...
frantzevan Posted February 10, 2015 Author Share Posted February 10, 2015 No debris in the injector pump. Does anyone have an explanation for this?? Quote Link to comment Share on other sites More sharing options...
farmer52 Posted February 10, 2015 Share Posted February 10, 2015 Have you tried putting your regular non-synthetic oil in the engine to determine if the noise goes away? Quote Ken PRR Country and Charter member of the "Mack Pack" Link to comment Share on other sites More sharing options...
dog doctor Posted February 10, 2015 Share Posted February 10, 2015 I would try disconnecting wire ti engine brake to see if brake is coming on. I have seen faulty switch and wires rubbing together and causing power to be applied with switch off. Quote Link to comment Share on other sites More sharing options...
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