Mr.NightHawk79 Posted March 21, 2022 Share Posted March 21, 2022 MACK E7, We are having a wooshing sound from exhaust only on #6 cylinder.. we have compression checked all 6 are 380-390#s with no leakdown, new nozzle, new rack on 4-6, ran overhead, does sound better but still puffing on #6 only, verified cam and rollers are all good, new E up and lines... Cracked one at a time only #6 doesn't change the rest it was obvious stumbling more ? I'm stumped 🤔 Quote Link to comment https://www.bigmacktrucks.com/topic/69416-mrnighthawk/ Share on other sites More sharing options...
terry Posted March 21, 2022 Share Posted March 21, 2022 Exhaust valve seat loose? Quote Link to comment https://www.bigmacktrucks.com/topic/69416-mrnighthawk/#findComment-492879 Share on other sites More sharing options...
Mr.NightHawk79 Posted March 21, 2022 Author Share Posted March 21, 2022 3 minutes ago, terry said: Exhaust valve seat loose? That's what we were thinking but the compression test and leak down were solid 390 we repeated the test several times.. we even did a 5/6 at same time to see if we were swapping compression but no luck there either Quote Link to comment https://www.bigmacktrucks.com/topic/69416-mrnighthawk/#findComment-492880 Share on other sites More sharing options...
terry Posted March 21, 2022 Share Posted March 21, 2022 2 hours ago, Mr.NightHawk79 said: That's what we were thinking but the compression test and leak down were solid 390 we repeated the test several times.. we even did a 5/6 at same time to see if we were swapping compression but no luck there either But with the exhaust valve closed, would that seal up the seat? Quote Link to comment https://www.bigmacktrucks.com/topic/69416-mrnighthawk/#findComment-492891 Share on other sites More sharing options...
Onyx610 Posted March 21, 2022 Share Posted March 21, 2022 Why did you change all those parts? This started after the install? Quote Link to comment https://www.bigmacktrucks.com/topic/69416-mrnighthawk/#findComment-492893 Share on other sites More sharing options...
Mr.NightHawk79 Posted March 21, 2022 Author Share Posted March 21, 2022 33 minutes ago, Onyx610 said: Why did you change all those parts? This started after the install? It came back from a run " concrete truck" running bad, we found two eups that were weak, it ran better but #6 still woofing... So we figured ok maybe#6 is weak too no change, then ok maybe it was the nozzle.. nada, tried another eup just in case we got a bum unit... Nothing... So we did notice alot of oil pumping from #6 rocker and went out on a limb and thought what if the dip/spike that rocker is pumping out is causing a spike and cracking a Jake ... Nothing changed after the rear rack was replaced and properly adjusted... So I think we're gonna be pulling the head tomorrow cause it makes sense 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69416-mrnighthawk/#findComment-492895 Share on other sites More sharing options...
Onyx610 Posted March 22, 2022 Share Posted March 22, 2022 Yea sounds like a plan. Just weird since leakdown was good and compression. Push tubes are good? Quote Link to comment https://www.bigmacktrucks.com/topic/69416-mrnighthawk/#findComment-492897 Share on other sites More sharing options...
Joey Mack Posted March 22, 2022 Share Posted March 22, 2022 I would re-run the rack..... Start on #1, and DO NOT deviate from the way Mack lays it out... Did you set the bridges to .010"? do you have an engine brake? lash on that will be .017" or .021" if it was updated... jojo Quote Link to comment https://www.bigmacktrucks.com/topic/69416-mrnighthawk/#findComment-492901 Share on other sites More sharing options...
Popular Post Mr.NightHawk79 Posted March 22, 2022 Author Popular Post Share Posted March 22, 2022 Update: we found the issue after pulling the cylinder head.. #6 nozzle was not indexed correctly and was driven in, so it wasn't seated correctly and was causing the cylinder to misfire .. so the bore is ruined, new head will be here today. Noobs I tell ya 🤣 3 Quote Link to comment https://www.bigmacktrucks.com/topic/69416-mrnighthawk/#findComment-492939 Share on other sites More sharing options...
Onyx610 Posted March 22, 2022 Share Posted March 22, 2022 (edited) I was gonna say make sure the injector line/nozzle was installed and torqued correctly. But looks like you guys got right to it. Sucks a simple mistake can cost a lot of money and work. Edited March 22, 2022 by Onyx610 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69416-mrnighthawk/#findComment-492941 Share on other sites More sharing options...
Popular Post Mr.NightHawk79 Posted March 22, 2022 Author Popular Post Share Posted March 22, 2022 1 hour ago, Onyx610 said: I was gonna say make sure the injector line/nozzle was installed and torqued correctly. But looks like you found you guys got right to it. Sucks you a simple mistake can cost a lot of money and work. Yeah basically the science of it is... Incorrect fuel angle was causing the fuel to burn out of time and was likely still burning as the exhaust valves were opening up.. causing the woosh/puffing sound... Makes sense now, I think the head is usable but, better safe that sorry later down the road... I super appreciate everyone's input in this situation... Hopefully I can be of help in the future 4 Quote Link to comment https://www.bigmacktrucks.com/topic/69416-mrnighthawk/#findComment-492944 Share on other sites More sharing options...
doubleclutchinweasel Posted March 22, 2022 Share Posted March 22, 2022 You just described exactly what happens when somebody tries to run racing gas or aviation gas in a gas engine that does not have enough compression to cause proper ignition. The mixture is still burning as it goes out the exhaust port. This leads to burnt exhaust valves and other issues. Never thought about it doing something similar in a diesel, but your explanation draws a great picture. Old race car mechanic I knew summed up the too-high octane problem like this: "Make sure you have enough 'squish' to make it go 'pop'". 1 Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment https://www.bigmacktrucks.com/topic/69416-mrnighthawk/#findComment-492946 Share on other sites More sharing options...
Joey Mack Posted March 22, 2022 Share Posted March 22, 2022 Glad you posted the issue.. sorry that its gonna cost so much.. Jojo Quote Link to comment https://www.bigmacktrucks.com/topic/69416-mrnighthawk/#findComment-492950 Share on other sites More sharing options...
theakerstwo Posted March 22, 2022 Share Posted March 22, 2022 You should look at the injector line seat were it seals to the injector and make sure its not damaged 1 Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/69416-mrnighthawk/#findComment-492964 Share on other sites More sharing options...
Onyx610 Posted March 22, 2022 Share Posted March 22, 2022 I would replace the injector line and nozzle. I’m sure he will. Seems to know what’s up. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69416-mrnighthawk/#findComment-492965 Share on other sites More sharing options...
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