1979 f250 460 knock
#1
1979 f250 460 knock
Hi guys, i have a 79 f250 with the 7.5 v8 that has been modified. Just today the engine started making a knock sound. Its fairly loud and every time i give it throttle it gets louder and faster and comes close to stalling. The truck has been sitting for about a month or so due to some electrical issues (electrical fires) and a bad starter. I finally got it back up and running good today and when i went to pull out of my shop it started making the noise. It could be the gas from just sitting. It sat almost on empty. I dont think it would be spark plugs because its ran fine up untill now. Within the past few months ive ran 2 or 3 bottles of fuel additive through it. Any ideas or comments are much appreciated. It was my great grandpas truck he bought in 79 and he modified it fairly heavily. Im pretty sure he put a cam, edelbrock 4 barrel carb, intake manifold, lifters, and 429 heads on it. Thanks for the help!
heres a video https://www.youtube.com/watch?v=SzLW...ature=youtu.be
heres a video https://www.youtube.com/watch?v=SzLW...ature=youtu.be
Last edited by Dirtbikehigh; 07-08-2015 at 10:50 PM.
#2
Welcome to the site..
Being 'it just started' knocking with no oiling/pressure issues. Checked?
If the accelerated stall is due to it partially locking up, would be problem. You might install a mechanical oil pressure gauge and confirm pressure, also, take an oil sample and see if there is any suspended metals in the lube. Might confirm a base engine issue if metal is present. The 'coming close to a stall' accelerating in place (?) would seem to indicate a bind of some sort. Knocks, rattles, are hard to ID in script, any chance you can post a vid with sound?
Being 'it just started' knocking with no oiling/pressure issues. Checked?
If the accelerated stall is due to it partially locking up, would be problem. You might install a mechanical oil pressure gauge and confirm pressure, also, take an oil sample and see if there is any suspended metals in the lube. Might confirm a base engine issue if metal is present. The 'coming close to a stall' accelerating in place (?) would seem to indicate a bind of some sort. Knocks, rattles, are hard to ID in script, any chance you can post a vid with sound?
#3
Welcome to the site..
Being 'it just started' knocking with no oiling/pressure issues. Checked?
If the accelerated stall is due to it partially locking up, would be problem. You might install a mechanical oil pressure gauge and confirm pressure, also, take an oil sample and see if there is any suspended metals in the lube. Might confirm a base engine issue if metal is present. The 'coming close to a stall' accelerating in place (?) would seem to indicate a bind of some sort. Knocks, rattles, are hard to ID in script, any chance you can post a vid with sound?
Being 'it just started' knocking with no oiling/pressure issues. Checked?
If the accelerated stall is due to it partially locking up, would be problem. You might install a mechanical oil pressure gauge and confirm pressure, also, take an oil sample and see if there is any suspended metals in the lube. Might confirm a base engine issue if metal is present. The 'coming close to a stall' accelerating in place (?) would seem to indicate a bind of some sort. Knocks, rattles, are hard to ID in script, any chance you can post a vid with sound?
#4
Welcome to the site..
Being 'it just started' knocking with no oiling/pressure issues. Checked?
If the accelerated stall is due to it partially locking up, would be problem. You might install a mechanical oil pressure gauge and confirm pressure, also, take an oil sample and see if there is any suspended metals in the lube. Might confirm a base engine issue if metal is present. The 'coming close to a stall' accelerating in place (?) would seem to indicate a bind of some sort. Knocks, rattles, are hard to ID in script, any chance you can post a vid with sound?
Being 'it just started' knocking with no oiling/pressure issues. Checked?
If the accelerated stall is due to it partially locking up, would be problem. You might install a mechanical oil pressure gauge and confirm pressure, also, take an oil sample and see if there is any suspended metals in the lube. Might confirm a base engine issue if metal is present. The 'coming close to a stall' accelerating in place (?) would seem to indicate a bind of some sort. Knocks, rattles, are hard to ID in script, any chance you can post a vid with sound?
#5
Welcome to the site..
Being 'it just started' knocking with no oiling/pressure issues. Checked?
If the accelerated stall is due to it partially locking up, would be problem. You might install a mechanical oil pressure gauge and confirm pressure, also, take an oil sample and see if there is any suspended metals in the lube. Might confirm a base engine issue if metal is present. The 'coming close to a stall' accelerating in place (?) would seem to indicate a bind of some sort. Knocks, rattles, are hard to ID in script, any chance you can post a vid with sound?
Being 'it just started' knocking with no oiling/pressure issues. Checked?
If the accelerated stall is due to it partially locking up, would be problem. You might install a mechanical oil pressure gauge and confirm pressure, also, take an oil sample and see if there is any suspended metals in the lube. Might confirm a base engine issue if metal is present. The 'coming close to a stall' accelerating in place (?) would seem to indicate a bind of some sort. Knocks, rattles, are hard to ID in script, any chance you can post a vid with sound?
this is where the video is
#6
Nice look'n ol 79..
Header exhaust flange gasket to head leaks, or collector/flange cracks can often mimic a bad lifter/tappet or worse. You can hear the exhaust leaks in the vid. As a start, might be a good move to reseal the exhaust to see how it sounds.
Header exhaust flange gasket to head leaks, or collector/flange cracks can often mimic a bad lifter/tappet or worse. You can hear the exhaust leaks in the vid. As a start, might be a good move to reseal the exhaust to see how it sounds.
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