Joey Mack Posted December 2, 2022 Share Posted December 2, 2022 I guess I missed that part... I thought he was waiting for the machine shop answers... Ooop's... Quote Link to comment https://www.bigmacktrucks.com/topic/70801-cylinder-pressure-out-intake-port/page/3/#findComment-516937 Share on other sites More sharing options...
fjh Posted December 2, 2022 Share Posted December 2, 2022 Bro would a Jake spool hang up cause your issue there? I highly doubt it however.... Grasping! Quote Link to comment https://www.bigmacktrucks.com/topic/70801-cylinder-pressure-out-intake-port/page/3/#findComment-516938 Share on other sites More sharing options...
Mark T Posted December 2, 2022 Share Posted December 2, 2022 (edited) This one has me curious now. Edited December 2, 2022 by Mark T spelling Quote Link to comment https://www.bigmacktrucks.com/topic/70801-cylinder-pressure-out-intake-port/page/3/#findComment-516940 Share on other sites More sharing options...
mdixon Posted December 3, 2022 Share Posted December 3, 2022 Have you inspected the valve stems yet? Valve spring pressure test? Sounds like a too tight valve guide or a weak spring. Or a combo. Maybe you'll find witness marks or heat distortion on the valve stem. If it's just hanging up a little after some good heat cycles maybe it's a faulty valve, bad forging or material. Quote Link to comment https://www.bigmacktrucks.com/topic/70801-cylinder-pressure-out-intake-port/page/3/#findComment-516984 Share on other sites More sharing options...
mdixon Posted December 3, 2022 Share Posted December 3, 2022 Parts quality seems to be lacking, especially now that parts supply is non existent. Quote Link to comment https://www.bigmacktrucks.com/topic/70801-cylinder-pressure-out-intake-port/page/3/#findComment-516985 Share on other sites More sharing options...
Joey Mack Posted December 3, 2022 Share Posted December 3, 2022 I was just about to remind this thread of previous posts... I guess you read my mind Onyx.... Quote Link to comment https://www.bigmacktrucks.com/topic/70801-cylinder-pressure-out-intake-port/page/3/#findComment-516990 Share on other sites More sharing options...
Onyx610 Posted December 3, 2022 Share Posted December 3, 2022 11 hours ago, ChallengeDave said: I already pulled the cylinder head off last night. But before I did that I did check the valve set and they were spot on where I reset them after the head retorque after the initial run in. I pulled both valves out of the head and inspected them. Neither intake valves are burnt and the don't seem to bind in the guides at all. I spun them on a drill and they are both true. The seats seam to be intact. I reinstalled the valves and springs, then filled the intake port with break clean and it didn't come rushing out around the seats. Do some people not read all the posts anymore!? (Sorry Joey i had to delete the last post your responding too because I quoted the wrong one.) Quote Link to comment https://www.bigmacktrucks.com/topic/70801-cylinder-pressure-out-intake-port/page/3/#findComment-516991 Share on other sites More sharing options...
mdixon Posted December 3, 2022 Share Posted December 3, 2022 Never mentions checking spring pressure Quote Link to comment https://www.bigmacktrucks.com/topic/70801-cylinder-pressure-out-intake-port/page/3/#findComment-516993 Share on other sites More sharing options...
Joey Mack Posted December 3, 2022 Share Posted December 3, 2022 I get it... no biggie... I try to go back to the beginning if i feel i am off topic.. i have done it tonight on 2 threads.. it goes to show how we will go to any length to help these guys.. Quote Link to comment https://www.bigmacktrucks.com/topic/70801-cylinder-pressure-out-intake-port/page/3/#findComment-516994 Share on other sites More sharing options...
Onyx610 Posted December 3, 2022 Share Posted December 3, 2022 If spring pressure was down a good chance turbo boost could push one open Quote Link to comment https://www.bigmacktrucks.com/topic/70801-cylinder-pressure-out-intake-port/page/3/#findComment-516996 Share on other sites More sharing options...
Joey Mack Posted December 3, 2022 Share Posted December 3, 2022 yeah checking spring pressure in this case is a stretch.. The machine shop probably didnt check them either... the engine is already taken down to a point where the issue may have been passed by, however, he has a large skillset and I expect he will find the issue... I dont see where he test drove the truck to duplicate the issue, so I guess he is going on the driver's story... jojo Quote Link to comment https://www.bigmacktrucks.com/topic/70801-cylinder-pressure-out-intake-port/page/3/#findComment-516997 Share on other sites More sharing options...
Vmac3 Posted December 3, 2022 Share Posted December 3, 2022 Cam timing?? 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70801-cylinder-pressure-out-intake-port/page/3/#findComment-517002 Share on other sites More sharing options...
Onyx610 Posted December 3, 2022 Share Posted December 3, 2022 I don’t know much about this Vmac, but the whole time timing has been screaming at me! Quote Link to comment https://www.bigmacktrucks.com/topic/70801-cylinder-pressure-out-intake-port/page/3/#findComment-517004 Share on other sites More sharing options...
Joey Mack Posted December 3, 2022 Share Posted December 3, 2022 I think he said it ran for 20,000 + miles before this issue came about.. Now I have to go back to the begining to see... Quote Link to comment https://www.bigmacktrucks.com/topic/70801-cylinder-pressure-out-intake-port/page/3/#findComment-517005 Share on other sites More sharing options...
Joey Mack Posted December 3, 2022 Share Posted December 3, 2022 Page 1, now I am back to an overspeed.. Quote Link to comment https://www.bigmacktrucks.com/topic/70801-cylinder-pressure-out-intake-port/page/3/#findComment-517006 Share on other sites More sharing options...
Onyx610 Posted December 3, 2022 Share Posted December 3, 2022 It def seems like a timing issue. But you would see that on all cylinders I believe. Quote Link to comment https://www.bigmacktrucks.com/topic/70801-cylinder-pressure-out-intake-port/page/3/#findComment-517007 Share on other sites More sharing options...
Vmac3 Posted December 3, 2022 Share Posted December 3, 2022 I read and reread the thread. If the cylinder pressure is coming out from the intake then you would think the obvious like a valve hanging open or something pushing down on it such as the engine brake. The only other thing I can think of right now is cam timing. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70801-cylinder-pressure-out-intake-port/page/3/#findComment-517008 Share on other sites More sharing options...
Onyx610 Posted December 3, 2022 Share Posted December 3, 2022 V is online right now so make good use of his time 😁 Quote Link to comment https://www.bigmacktrucks.com/topic/70801-cylinder-pressure-out-intake-port/page/3/#findComment-517009 Share on other sites More sharing options...
Onyx610 Posted December 3, 2022 Share Posted December 3, 2022 Just now, Vmac3 said: I read and reread the thread. If the cylinder pressure is coming out from the intake then you would think the obvious like a valve hanging open or something pushing down on it such as the engine brake. The only other thing I can think of right now is cam timing. 💯 Quote Link to comment https://www.bigmacktrucks.com/topic/70801-cylinder-pressure-out-intake-port/page/3/#findComment-517010 Share on other sites More sharing options...
Vmac3 Posted December 3, 2022 Share Posted December 3, 2022 2 minutes ago, Onyx610 said: It def seems like a timing issue. But you would see that on all cylinders I believe. True. I'm not sure what else. Someone mentioned engine brake possibly. Quote Link to comment https://www.bigmacktrucks.com/topic/70801-cylinder-pressure-out-intake-port/page/3/#findComment-517011 Share on other sites More sharing options...
Joey Mack Posted December 3, 2022 Share Posted December 3, 2022 But how did it run good for 20-25 thousand miles til now??? poor cam timing should be instantly noticed.. Please correct me, for I dont know.. Quote Link to comment https://www.bigmacktrucks.com/topic/70801-cylinder-pressure-out-intake-port/page/3/#findComment-517012 Share on other sites More sharing options...
Onyx610 Posted December 3, 2022 Share Posted December 3, 2022 1 minute ago, Vmac3 said: True. I'm not sure what else. Someone mentioned engine brake possibly. Fjh did and that’s a legit issue Quote Link to comment https://www.bigmacktrucks.com/topic/70801-cylinder-pressure-out-intake-port/page/3/#findComment-517013 Share on other sites More sharing options...
Onyx610 Posted December 3, 2022 Share Posted December 3, 2022 (edited) 3 minutes ago, Joey Mack said: But how did it run good for 20-25 thousand miles til now??? poor cam timing should be instantly noticed.. Please correct me, for I dont know.. maybe some teeth on the cam gear need to be inspected? Maybe they broke or rounded over and jumped time? Edited December 3, 2022 by Onyx610 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70801-cylinder-pressure-out-intake-port/page/3/#findComment-517014 Share on other sites More sharing options...
Onyx610 Posted December 3, 2022 Share Posted December 3, 2022 I feel like anytime you have exhaust/compression going out the wrong valve it’s timing. That’s just what I learned. But I’m green and have learned a lot from a handful of you guys and you know who you are. Quote Link to comment https://www.bigmacktrucks.com/topic/70801-cylinder-pressure-out-intake-port/page/3/#findComment-517015 Share on other sites More sharing options...
Vmac3 Posted December 3, 2022 Share Posted December 3, 2022 I don't think it's a cam because the intake valve would have excessive lash and he would of noticed it. Also the intake would not open all the way because the lobe is worn out. I wonder if the injectors have too much forward leakage (dribbling). 1 Quote Link to comment https://www.bigmacktrucks.com/topic/70801-cylinder-pressure-out-intake-port/page/3/#findComment-517016 Share on other sites More sharing options...
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