Granitecv713 Posted January 5 Share Posted January 5 Sounded like engine skipping through exhaust (appeared to be a dead cylinder). Felt loss of power and as I throttled truck, sounded like spark knock (lightening bolt appeared on dash but before I could count blinks, it cleared). What would I be looking for or checking into that may cause this? Sounds to me like an injector trying to work, but not working. Does not sound like valve train - sounds like an individual tick. Any leads on what to check on next? Quote Link to comment https://www.bigmacktrucks.com/topic/73728-2007-mack-tandem-dump-aset-engine-skip-tapping-under-of-valve-cover/ Share on other sites More sharing options...
Joey Mack Posted January 5 Share Posted January 5 Did you use a stethoscope to locate the sound? Do you have an infrared temp gun to check the exhaust. Manifold per each cylinder? Quote Link to comment https://www.bigmacktrucks.com/topic/73728-2007-mack-tandem-dump-aset-engine-skip-tapping-under-of-valve-cover/#findComment-544651 Share on other sites More sharing options...
mechohaulic Posted January 5 Share Posted January 5 4 hours ago, Joey Mack said: Did you use a stethoscope to locate the sound? Do you have an infrared temp gun to check the exhaust. Manifold per each cylinder? stethoscope/ infrared temp gun??? what are these things you speak of ??? guess you forgot the yellow crayon method. .forgive me Sir , I had a tooo!!!!🤣major long day out in the cold prepping for the north east Blissard which mistakenly I assumed those projects for me were over 40-50 yrs ago, Jack Daniels hasn't kicked in yet, knees let me know == not going to fill gas cans. gotta get back on topic .my john deere fires on all cyl ok== both of them LOL Quote Link to comment https://www.bigmacktrucks.com/topic/73728-2007-mack-tandem-dump-aset-engine-skip-tapping-under-of-valve-cover/#findComment-544658 Share on other sites More sharing options...
Joey Mack Posted January 5 Share Posted January 5 Yes I did forget about the crayons,, I didnt use them much.. as far as a stethoscope goes, Yes I have one, but I actually use a long peice of 3/8'' car brake line to listen to the engine and so-on.. The temp gun is pretty cool, you can stand back and take temperature.. sorry Old Man but there are some neat ways to diagnose,,, i mean trouble shoot, issues.... I always chuckle when you post.. Jojo 1 Quote Link to comment https://www.bigmacktrucks.com/topic/73728-2007-mack-tandem-dump-aset-engine-skip-tapping-under-of-valve-cover/#findComment-544662 Share on other sites More sharing options...
Granitecv713 Posted January 5 Author Share Posted January 5 Thanks. I tried using stethoscope, but was too noisy for me to detect. I used temp gun and attached are the temps at engine idle. It's obvious the front cylinders are significantly lower. I was initially thinking it could be an injector, but wondering if I should lift the front valve cover just for a visual inspection. Just looking for some guidance. Quote Link to comment https://www.bigmacktrucks.com/topic/73728-2007-mack-tandem-dump-aset-engine-skip-tapping-under-of-valve-cover/#findComment-544665 Share on other sites More sharing options...
Joey Mack Posted January 5 Share Posted January 5 when was the last time valve lash was checked? Quote Link to comment https://www.bigmacktrucks.com/topic/73728-2007-mack-tandem-dump-aset-engine-skip-tapping-under-of-valve-cover/#findComment-544666 Share on other sites More sharing options...
Granitecv713 Posted January 6 Author Share Posted January 6 3 years @ NexTran . Truck is driven local around 60 k per year . Quote Link to comment https://www.bigmacktrucks.com/topic/73728-2007-mack-tandem-dump-aset-engine-skip-tapping-under-of-valve-cover/#findComment-544670 Share on other sites More sharing options...
Solution Joey Mack Posted January 6 Solution Share Posted January 6 it wouldnt hurt to check lash again,, have you ever run the rack on an ASET-I or C engine? Just curious.. It is not the same as Earlier Macks, Cat or John Deere, for example.. Jojo Quote Link to comment https://www.bigmacktrucks.com/topic/73728-2007-mack-tandem-dump-aset-engine-skip-tapping-under-of-valve-cover/#findComment-544671 Share on other sites More sharing options...
Granitecv713 Posted January 6 Author Share Posted January 6 No and probably won’t attempt it . I am trying to get a feel for what or how to diagnose the problem . I just hate taking it In with no clue ? Im sure it involves the two front cylinders , thinking it may be odd for 2 injectors to croak at the same time . Just don’t want to start experimenting without some knowledgeable advice . I know these engines are computer controlled , wasn’t sure about loosening injector lines or other manual testing methods ! Thinking I will lift valve cover on front and take a look for loose rockers on the two cylinders that are in the 150 degree range. What’s your thoughts ? Quote Link to comment https://www.bigmacktrucks.com/topic/73728-2007-mack-tandem-dump-aset-engine-skip-tapping-under-of-valve-cover/#findComment-544673 Share on other sites More sharing options...
JoeH Posted January 6 Share Posted January 6 I'd pull valve cover. Never know what you'll see, broken rocker arm shafts, broken valve stem.... I'd also look into condition of the camshaft EUP's and H Clips, you could have broken bits there eating up the camshaft. If so, this would be a prime time to read the "old dog dead dog loggin dog" remediation thread to delete your ASET AI (guessing your truck is a granite) emissions system. Quote Link to comment https://www.bigmacktrucks.com/topic/73728-2007-mack-tandem-dump-aset-engine-skip-tapping-under-of-valve-cover/#findComment-544676 Share on other sites More sharing options...
Joey Mack Posted January 6 Share Posted January 6 yes, pull the valve covers, certainly wouldnt hurt to drop the oil pan. if you have lifter issues there will likely be bits in the pan. you describe the sound as a clicking. so it is not popping back into the intake or ''poof poof poof'' out the exhaust? is the oil level raising up, and /or is the oil diluted with fuel. you can do a simple 'halo' test on a piece of cardboard to see if the oil is diluted. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/73728-2007-mack-tandem-dump-aset-engine-skip-tapping-under-of-valve-cover/#findComment-544677 Share on other sites More sharing options...
terry Posted January 6 Share Posted January 6 10 hours ago, Joey Mack said: yes, pull the valve covers, certainly wouldnt hurt to drop the oil pan. if you have lifter issues there will likely be bits in the pan. you describe the sound as a clicking. so it is not popping back into the intake or ''poof poof poof'' out the exhaust? is the oil level raising up, and /or is the oil diluted with fuel. you can do a simple 'halo' test on a piece of cardboard to see if the oil is diluted. Joey your comment on the poof poof out the exhaust, I once had a DM with a 237, when ever you backed off it or coasted down a hill it would do that, had a loose exhaust seat, ran a long time that way. When I eventually pulled the head you could see where it was moving up and down in the carbon buildup. Terry 1 Quote Link to comment https://www.bigmacktrucks.com/topic/73728-2007-mack-tandem-dump-aset-engine-skip-tapping-under-of-valve-cover/#findComment-544697 Share on other sites More sharing options...
Granitecv713 Posted January 7 Author Share Posted January 7 thanks for all the input ! due to a surgery i had planned i will be down a couple weeks . as soon as i can pull the valve cover i will relay what i find with pictures . i will continue to monitor this topic. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/73728-2007-mack-tandem-dump-aset-engine-skip-tapping-under-of-valve-cover/#findComment-544748 Share on other sites More sharing options...
Joey Mack Posted January 7 Share Posted January 7 Best of luck with the surgery.. Jojo 1 Quote Link to comment https://www.bigmacktrucks.com/topic/73728-2007-mack-tandem-dump-aset-engine-skip-tapping-under-of-valve-cover/#findComment-544751 Share on other sites More sharing options...
Popular Post Granitecv713 Posted March 8 Author Popular Post Share Posted March 8 On 1/5/2024 at 7:07 PM, Joey Mack said: it wouldnt hurt to check lash again,, have you ever run the rack on an ASET-I or C engine? Just curious.. It is not the same as Earlier Macks, Cat or John Deere, for example.. Jojo after recovery from surgery i was able to get on checking on my issue with my skip in my aset engine ! I will not take credit for the repair , but with your comments and my mobile mechanic he set out to go through a valve train adjustment ! that all went well until we rotated the engine back through to double check everything .at this point he said the rear cylinder adj. was out of adj, bad . as he continued inspecting , he found that someone had tighten up the rocker cradle with an impact gun ! Broken and loose bolts had caused my valve adj on rear cylinder to be my issue ! Many thanks to all who contributed input on my issue ! I have had 100% success on every issue i have had using this site (BMT) and its helpful followers 1 1 1 Quote Link to comment https://www.bigmacktrucks.com/topic/73728-2007-mack-tandem-dump-aset-engine-skip-tapping-under-of-valve-cover/#findComment-547787 Share on other sites More sharing options...
Joey Mack Posted March 8 Share Posted March 8 I am Happy On All Accounts... Quote Link to comment https://www.bigmacktrucks.com/topic/73728-2007-mack-tandem-dump-aset-engine-skip-tapping-under-of-valve-cover/#findComment-547789 Share on other sites More sharing options...
fjh Posted March 8 Share Posted March 8 13 hours ago, Granitecv713 said: after recovery from surgery i was able to get on checking on my issue with my skip in my aset engine ! I will not take credit for the repair , but with your comments and my mobile mechanic he set out to go through a valve train adjustment ! that all went well until we rotated the engine back through to double check everything .at this point he said the rear cylinder adj. was out of adj, bad . as he continued inspecting , he found that someone had tighten up the rocker cradle with an impact gun ! Broken and loose bolts had caused my valve adj on rear cylinder to be my issue ! Many thanks to all who contributed input on my issue ! I have had 100% success on every issue i have had using this site (BMT) and its helpful followers Wouldn't hurt to have him replace all the rocker bolts! they are torque sensitive ! 1 Quote Link to comment https://www.bigmacktrucks.com/topic/73728-2007-mack-tandem-dump-aset-engine-skip-tapping-under-of-valve-cover/#findComment-547806 Share on other sites More sharing options...
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