6.9 knock
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Junior User
Joined: Nov 2006
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From: georgia
6.9 knock
my buddy has an 86 f350 6.9 and just changed the glow plugs and fuel lift pump, but before we moved it into the shop to change the stuff out we either started it about 3 times to get the fuel up cause it looses prime. could the starting fluid have caused to much cylinder pressure and bent a pushrod, only other thing i could think is it is hitting a glow plug but that is not really possible
Post Fiend
Joined: Nov 2003
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From: Nutter Fort, WV
Unless a glow plug tip broke off, it is impossible to hit a glow plug on an IDI with the piston.
The precup is between the glow plug and piston.
Te fuel bleed off was probably the return lines, not the lift pump.
When you replaced the lift pump, did it have an almost straight arm?
If so were there instructions in the lift pump box and did you follow them exactly?
If not, the lift pump arm is probably not where it is supposed to be and that is the knock.
The precup is between the glow plug and piston.
Te fuel bleed off was probably the return lines, not the lift pump.
When you replaced the lift pump, did it have an almost straight arm?
If so were there instructions in the lift pump box and did you follow them exactly?
If not, the lift pump arm is probably not where it is supposed to be and that is the knock.
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Junior User
Joined: Nov 2006
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From: georgia
i changed the glow plugs with autolite plugs and three of them on the passenger side were broke off,also the old ones where autolite, but the engine ran fine before the glow plug and lift pump change. and it seems to be coming from the top end. engine has always smoked a bit. it is a jasper reman but dont know how many miles are on it, another thing is it has never had much oil pressure. if we cant figure it out he has an old 2wd f250 with another 6.9 in it, will just swap them out.
Posting Guru
Joined: Dec 2008
Posts: 2,347
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From: Maysville, Kentucky
Go back to the shop pull every glow plugs and put in motorcrafts. The autolites will quit very quickly.
Could have already broke another tip on the new ones.
Could have already broke another tip on the new ones.
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Junior User
Joined: Nov 2006
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From: georgia
but will this cause a knock they are four days old and only been started on three times,was knocking or what ever so we did not drive it any just been sitting since Friday, and we started it again Sunday. this knock started as soon as we started it up after the glow plug and lift pump install
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Thread Starter
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Junior User
Joined: Nov 2006
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From: georgia
metal knock, a predetonation knock would be hard to hear wouldn't it
Post Fiend
Joined: Oct 2007
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From: Faibanks Ak.
As Dave S. has already said lift pump incorrectly installed will cause a knock but it will not affect timing.
If some of the tips broke off the old gp's and you didn't get them out if it ain't knocking yet it will be. It is the same as dropping a nickel in a carburater it eventually gets on top of a piston and the head has to come off.
When you started it on either did it spin fast or did it almost stop and then take off.
If some of the tips broke off the old gp's and you didn't get them out if it ain't knocking yet it will be. It is the same as dropping a nickel in a carburater it eventually gets on top of a piston and the head has to come off.
When you started it on either did it spin fast or did it almost stop and then take off.
Post Fiend
Joined: Oct 2007
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From: Faibanks Ak.
You said that 3 of the gp's on the passenger side broke off have you removed the broken pieces yet. When you break one off you have to get it all out or it will cause a knock up top as it will be on top of the piston and there is no room for it.
Post Fiend
Joined: Nov 2004
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From: Manitoba
Tips broke off eh!......
http://img.photobucket.com/albums/v7...50/compar3.jpg
http://www.members.shaw.ca/k2pilot/S...lug%20tips.jpg
Any like the above........ If so it is the tips beating on the piston tops...... so do not run it any more. You are now in for a head removal....... the tips will not pass.
http://www.members.shaw.ca/k2pilot/ check out GP tip damage on GP removal.....
http://img.photobucket.com/albums/v7...50/compar3.jpg
http://www.members.shaw.ca/k2pilot/S...lug%20tips.jpg
Any like the above........ If so it is the tips beating on the piston tops...... so do not run it any more. You are now in for a head removal....... the tips will not pass.
http://www.members.shaw.ca/k2pilot/ check out GP tip damage on GP removal.....