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Engine miss


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Was looking at a low mileage e7 full mechanical. Started very easily and idled nice. Oil pressure was about 32 at idle cold and it went up to 80 at full throttle after warmed up. I noticed when the oil pressure hit appx 60 that the engine started to studder and shake a bit then smoothed back out when it hit 70 lbs and was smooth all the way to 80. Any ideas what would cause this ? An injector maybe? Engine has a dynatard on it and it was not working not sure why. Engine had very little blow by out of the top of valve cover and nothing out of draft tube   Any ideas on the miss ?

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oil leak passed an o-ring in the engine brake heads celenoid.. with the higher oil pressure.   FJH, Mech??  what say you? 

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another perspective is :: ok at 32lbs .. rocky at 60 ; better 70+. oil pressure changes with R P M's =correct ? out of balance some where??  32lbs ==idle  :60lbs =RPM's ???. 70lbs + == high  RPM's . dynatard o-ring leak makes a pis- poor engine brake worse , if that's possible .  shouldn't create a shake/ shutter ??  this is fun ,questioning the teacher ,😅

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Mech,, your the teacher...  I'm just trying to be an astute student of your knowledge..  My goal is to impress you..  just sayin'..  :) 

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Was it a stutter or a flutter? Governor springs can cause the engine to flutter at midrange RPMs. My front end loader has been doing it a lot lately, revved up coasting at minimal load the RPMs flutter.  My 95 e7-350 (fully mechanical) will do a similar flutter in that 1300 + or - range coasting minimal load every so often. Truck runs great otherwise.  

Maybe the truck you looked at is doing the same thing mine does or maybe it could use a fuel filter.  

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so would I not be too far off going another avenue to possible RPM's may join the issue ??   once again not being there to see/hear issue adds to challenge. forum is reading of shake/shutter at certain oil pressures, not knowing units "behavior" under operating conditions== good power on road test etc. parked with fuel pedal movement only. ? 

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Truck has been sitting for a couple yrs. Oil filter was last changed in 2018 I see so I can only imagine fuel filters are old. Has really not been used much in last few yrs. I took a video clip on my cell phone maybe my kid can figure out how to down load it   Engine studders or whatever you call it and shakes and then smooths out at higher rpms 

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thanks for update/ more info. oil has 5+ years on it, fuel filters the same (?) on a mechanical = could be big part of issue. might be simple fix. truck meets your approval based on condition / price / mileage ;  go for it.. any answer why it was parked? non working engine brake may be another simple fix = relay: broken wire and so on.

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That sounds like a bit more of a miss than my truck's flutter. Almost sounds like a knock? But I will admit to not having hardly any experience with engine knocks/misses, and my phone has crappy speaker audio.

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So just a comment on this ! If its a ROBERT bosch  manual pump (likely is) identify which cylinder likely number 1 The delivery valve washers are made of copper these have been known to crack and leak by internally ( specially on number one) and cause a miss most noticeable At Idle! Crack fuel lines at the pump till you find one that doesn't change the sound of the engine that will be your culprit !

just something to look for!

 

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On 5/14/2024 at 8:31 AM, fjh said:

So just a comment on this ! If its a ROBERT bosch  manual pump (likely is) identify which cylinder likely number 1 The delivery valve washers are made of copper these have been known to crack and leak by internally ( specially on number one) and cause a miss most noticeable At Idle! Crack fuel lines at the pump till you find one that doesn't change the sound of the engine that will be your culprit !

just something to look for!

 

This is most likely a pump issue you think?

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Not always But a possibility !  is the truck drivable ? do you have a local fuel shop in your area? it requires a special socket to remove the delivery valve!  

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I have heard that sound many times, and im not gonna say its not fuel delivery, but I have a habit of running the valves.  what if a pushrod was off to the side and got put back in the lifter without inspecting it first?  just a few things I have found in the past.. 

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1 minute ago, Joey Mack said:

I have heard that sound many times, and im not gonna say its not fuel delivery, but I have a habit of running the valves.  what if a pushrod was off to the side and got put back in the lifter without inspecting it first?  just a few things I have found in the past.. 

Yup I agree Joey start with the cheap and easy ! It was just an honorable mention at the start there! That said the miss for a push tube would likley be accompanied by a ticking noise  the stumble maybe a clue as well! crack some fuel lines and identify which cylinder it is and start by checking the valve set!

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1 minute ago, Joey Mack said:

yep,, cracking the fuel lines should narrow it down..  this one of those times I wish I/We were there to try and fix it.. 

I'm out sick today, so I will be here bugging people today..  :) 

Get well soon! Bro!

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im ok,  my left knee is in really bad shape,  I had a shot in it yesterday, so today im resting it..  Some of the worst pain ever..  thanks Bud..  

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