dieselfuelonly Posted May 26, 2021 Share Posted May 26, 2021 Driver said he noticed a loss of power and engine wasn't running as smooth as usual like it was missing slightly. Changed fuel filters didn't fix anything. Pulled a vacuum on fuel line that feeds injector pump, clean fuel no air seems to flow fine. Hooked up a gauge at the same area I pulled vacuum on, runs around 25ish PSI maybe 20ish under load for a quick moment when on a hard pull. No boost leaks, hooked up gauge to intake manifold only see around 10psi boost max which seems low, but this truck had never had much power and doesn't feel like it's running lower boost than usual. No boost leaks at boots or CAC. I high idled it earlier and started loosening injector lines one at a time at the pump, however the miss that became noticeable when the line was loosened seemed similar across all six. When it was cold this morning I goes it up and put my ir thermometer on the manifold at each cylinder, didn't notice anything to point me towards one specific cylinder. Removed air line to the puff control valve and it seems to be doing it's job just fine. Any other ideas on at least narrowing down the source of the issue? Definitely a slight miss ... But hard to detect. Thanks for suggestions on what else to start looking at before I start pulling injectors. Quote Link to comment https://www.bigmacktrucks.com/topic/66747-em6-300-slight-miss-and-power-loss/ Share on other sites More sharing options...
mrgumby Posted May 26, 2021 Share Posted May 26, 2021 Did you try adj the valves and check the camshaft. Seen quite a few of these eat cams. Just a thought Quote Link to comment https://www.bigmacktrucks.com/topic/66747-em6-300-slight-miss-and-power-loss/#findComment-474302 Share on other sites More sharing options...
dieselfuelonly Posted May 26, 2021 Author Share Posted May 26, 2021 Might have got too far ahead of myself, think I've found some leaks in the CAC. Do these E6 engines vary how hard they fuel depending on boost, kind of like some of the older CATs and Cummins do? Still doesn't explain the slight miss but if it is fueling less because of a lack of boost pressure that explains his loss of power. Quote Link to comment https://www.bigmacktrucks.com/topic/66747-em6-300-slight-miss-and-power-loss/#findComment-474317 Share on other sites More sharing options...
Yoos Brothers Construction Posted May 28, 2021 Share Posted May 28, 2021 Could be injection pump cam shaft. Had that happen a few times Quote Link to comment https://www.bigmacktrucks.com/topic/66747-em6-300-slight-miss-and-power-loss/#findComment-474417 Share on other sites More sharing options...
Rob Posted May 28, 2021 Share Posted May 28, 2021 Send the pump and injectors at the same time to the fuel shop. Best all be calibrated together and balanced. Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/66747-em6-300-slight-miss-and-power-loss/#findComment-474430 Share on other sites More sharing options...
mrsmackpaul Posted May 28, 2021 Share Posted May 28, 2021 To clear a few things up in my peanut sized brain This isnt a tip turbine motor or is it (CAC) I gather is some short abbreviated thing for after cooler or something along those lines Rough idle or hunting as it is called in Australia is very common on old mechanical injector pump motors so nothing maybe a problem there So some real basic tests Does it make lots of smoke and does the smoke clear as the boost climbs ? If it doesn't make smoke your not getting fuel, dont panic it might be really really simple fix If it makes smoke and it doesn't clear up your lacking air, once again dont panic this may also be a really simple fix Before you pull anything apart you need to sort out whats going on or more to the point, what isnt going on Paul 1 Quote Link to comment https://www.bigmacktrucks.com/topic/66747-em6-300-slight-miss-and-power-loss/#findComment-474445 Share on other sites More sharing options...
h67st Posted May 28, 2021 Share Posted May 28, 2021 CAC = charge air cooler (aftercooler). Before you start changing expensive parts, I'd check the transfer pump and check valves real close. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/66747-em6-300-slight-miss-and-power-loss/#findComment-474449 Share on other sites More sharing options...
Joey Mack Posted May 28, 2021 Share Posted May 28, 2021 there is a reversing relay on the the top of the intake manifold. It goes to the bimber valve in the front of the injection pump. Just check to see that the air line and fittings are good, sealed, tight,,, etc.. stay simple for a bit. The E-6 is a great engine... Go bull dog! Quote Link to comment https://www.bigmacktrucks.com/topic/66747-em6-300-slight-miss-and-power-loss/#findComment-474463 Share on other sites More sharing options...
mrsmackpaul Posted May 29, 2021 Share Posted May 29, 2021 4 hours ago, Joey Mack said: there is a reversing relay on the the top of the intake manifold. It goes to the bimber valve in the front of the injection pump. Just check to see that the air line and fittings are good, sealed, tight,,, etc.. stay simple for a bit. The E-6 is a great engine... Go bull dog! I have had the air supply line ware thru on the alternator were the air line comes up from the chassis Paul Quote Link to comment https://www.bigmacktrucks.com/topic/66747-em6-300-slight-miss-and-power-loss/#findComment-474476 Share on other sites More sharing options...
JoeH Posted May 30, 2021 Share Posted May 30, 2021 Before you pull expensive parts, pull the valve covers and see which rocker has too much slop. More often than not, you'll find either one of the engine brake valve plates popped out from a weak valve spring or a bent pushrod, or worn cam lobe. We have had all 3. If it's the engine brake valve plate missing on an exhaust valve then just delete the engine brake. Quote Link to comment https://www.bigmacktrucks.com/topic/66747-em6-300-slight-miss-and-power-loss/#findComment-474527 Share on other sites More sharing options...
JoeH Posted May 30, 2021 Share Posted May 30, 2021 When a cam lobe gets wiped it gets worn to nothing fast. Check for bent pushrod, driver could have over revved the engine and floated the valves a bit. Quote Link to comment https://www.bigmacktrucks.com/topic/66747-em6-300-slight-miss-and-power-loss/#findComment-474528 Share on other sites More sharing options...
JoeH Posted May 30, 2021 Share Posted May 30, 2021 Thinking about it more, I'm going to go out on a limb and say Fuel Filters are possible. My E7 did that, sounded almost like the Jake brake was coming on above 1500 rpm under load, and didn't quite have as much boost as it should as it neared the governor. Took 2 sets of fuel filters to clear it up, hasn't done it since. Quote Link to comment https://www.bigmacktrucks.com/topic/66747-em6-300-slight-miss-and-power-loss/#findComment-474529 Share on other sites More sharing options...
JoeH Posted May 30, 2021 Share Posted May 30, 2021 Also, you should be seeing around 25 psi of boost under full load working hard. If you're trolling around empty on flat you'll never see more than 10 or 15. Need to hit a good hill at low rpm in a taller gear to make this engine work enough to build boost if you don't have any weight on. Quote Link to comment https://www.bigmacktrucks.com/topic/66747-em6-300-slight-miss-and-power-loss/#findComment-474530 Share on other sites More sharing options...
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