bad exaust sound... sometimes - valve?
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bad exaust sound... sometimes - valve?
ive a 1990 F350 7.3L IDI crew cab auto w/200,000 miles. it has a new injector pump and new injectors from diesel injection service. they said the old ones were worn out but not junk, when i start it up it runs great, sounds great, goes great.. but if i really step on it, it might mis-fire some. however.. after it warms up i get a "puffing" sound out the muffler like maybe an exaust valve is hanging open(my guess). this sould will come and go. but it aways sounds good on startup. it always sounds great under the hood. no valve ticking can be heard anywhere. i do have trouble starting it if it has set awhile.. its no longer my primary truck... as for performance of this 1990, my 2001 powerstroke does not impress me, the PS is better, but for all the extra bells, wistles and cost, its not that much better. if my 1990 did not have such a rough body, id keep driving it. thanks in advance for any idea short of a rebuild....or any offers to buy....
thanks joe
thanks joe
Post Fiend
Joined: Nov 2003
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From: Nutter Fort, WV
werpknarly,
Welcome to FTE and the IDI diesel forum.
Does the engine use much oil?
I am thinking you may be getting chunks of carbon holding a valve open just enough to have a compression leak.
I am rebiuilding a 6.9 right now, the amount of carbon built up on the intake valves 1,3,7,and 8 was impressive. Very obvious that the valve stem seals and guides were shot on those cylinders.
The only other thing I could think of would be an air leak or worn IP that was causing your starting issues may be also causing the misfire.
Welcome to FTE and the IDI diesel forum.
Does the engine use much oil?
I am thinking you may be getting chunks of carbon holding a valve open just enough to have a compression leak.
I am rebiuilding a 6.9 right now, the amount of carbon built up on the intake valves 1,3,7,and 8 was impressive. Very obvious that the valve stem seals and guides were shot on those cylinders.
The only other thing I could think of would be an air leak or worn IP that was causing your starting issues may be also causing the misfire.
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carbon buildup
thanks for the reply, would carbon buildup cause the valve to leak sometimes? i have tried to nearly drown the motor in cleaning fluids. thru the fuel and filling the filter several times.
Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 15
From: Nutter Fort, WV
I wish I had taken a picture of the carbon buildup around the intake valves on this engine I am building. That stuff was thick and hard. If a chunk came loose and the valve closed on it, I would bet the valve would not close till it blew through.
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