dad's truck started knocking...
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Postmaster
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dad's truck started knocking...
dad's truck is an 90 F350 with the 7.3, and driving home from work yesterday it started knocking. i'll be going to look at it tomorrow, but wanted to post here first. so everything in this first post is what he told me its doing...
he was driving along when it suddenly started knocking, sounded like a top end knock not a rod knock, and over the course of the next 30 seconds it faded to a much quieter sound, though still definitely present. some miles later, it again had a sudden event where the knocking got loud, and again it faded to a quiet knock. also, from the time it started knocking he noticed a significant loss of horsepower.
dad's opinion is that he may have had a glow plug tip break off and being pounded between piston and head. the other thoughts i had were a bad injector, or possibly a dropped pre-chamber.
from his description, what do you guys think??
when i get into it tomorrow, i'll listen to it with a stethescope, and pull the glow plugs to see if i can find any issues there to confirm his suspicion.
i'll post back when i have firsthand info.
he was driving along when it suddenly started knocking, sounded like a top end knock not a rod knock, and over the course of the next 30 seconds it faded to a much quieter sound, though still definitely present. some miles later, it again had a sudden event where the knocking got loud, and again it faded to a quiet knock. also, from the time it started knocking he noticed a significant loss of horsepower.
dad's opinion is that he may have had a glow plug tip break off and being pounded between piston and head. the other thoughts i had were a bad injector, or possibly a dropped pre-chamber.
from his description, what do you guys think??
when i get into it tomorrow, i'll listen to it with a stethescope, and pull the glow plugs to see if i can find any issues there to confirm his suspicion.
i'll post back when i have firsthand info.
Elder User
Joined: Feb 2008
Posts: 867
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From: North Bend
Assuming they are proper glow plugs:
I'm no expert but sounds like an injector to me. I'd think if a glow tip fell into the cyl it'd be much more consistent than loud and fading and then loud and fading again.
Plus there would have to be a reason for a glow tip to drop while driving and that seems strange too.
And I have zero understanding on how a prechamber might fall into the cyl so I have no ideas there, sorry. Never been that far into one of these engines!
-Joshua
I'm no expert but sounds like an injector to me. I'd think if a glow tip fell into the cyl it'd be much more consistent than loud and fading and then loud and fading again.
Plus there would have to be a reason for a glow tip to drop while driving and that seems strange too.
And I have zero understanding on how a prechamber might fall into the cyl so I have no ideas there, sorry. Never been that far into one of these engines!
-Joshua
Senior User
Joined: Nov 2003
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From: Saint Maries Idaho
When I had an injector start sticking it was inconsistent also; your problem does sound like an injector.
I don't think it is really possible for a pre-chamber to fall into the cyl as they are held in by the block (the pre-chambers overlap the block when the head is bolted on). The only thing that could cause that to happen is if the pre-chamber fragmented and fell out in pieces.
I don't think it is really possible for a pre-chamber to fall into the cyl as they are held in by the block (the pre-chambers overlap the block when the head is bolted on). The only thing that could cause that to happen is if the pre-chamber fragmented and fell out in pieces.
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Well I took a look at it today and found all 8 glow plugs were Motorcraft and are in good shape. It fired up easy enough and had a noticeable drop for each injector line I loosened (one at a time) but definitely ran rough as seen by the engine shaking and the uneven exhaust sound.
Given all that, I think you guys are right and we have bad injectors. I inspected them and found factory gray paint on them all, I think that says everything about them. A new set of brand new Delphi injectors are on order.
Given all that, I think you guys are right and we have bad injectors. I inspected them and found factory gray paint on them all, I think that says everything about them. A new set of brand new Delphi injectors are on order.
Post Fiend
Joined: Feb 2009
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From: Ottawa, Ontario
When you get the new injectors on, advance the pump a lil, and keep an eye on it for th first 2 weeks observing warm starts.
It happens sometimes new injectors will kill off an old pump. So if it starts having trouble starting warm after a week or 2....pump will be needed as well.
It happens sometimes new injectors will kill off an old pump. So if it starts having trouble starting warm after a week or 2....pump will be needed as well.
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Elder User
Joined: Feb 2008
Posts: 867
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From: North Bend
When you get the new injectors on, advance the pump a lil, and keep an eye on it for th first 2 weeks observing warm starts.
It happens sometimes new injectors will kill off an old pump. So if it starts having trouble starting warm after a week or 2....pump will be needed as well.
It happens sometimes new injectors will kill off an old pump. So if it starts having trouble starting warm after a week or 2....pump will be needed as well.
Finally got a new IP once the old one started leaking consistently.
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Brett Foote
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From: CT, USA
I'd like to thank all the posters who provided the help in this thread.
Especially _Bear_.
My '92 F-250 w 205K starting knocking and I thought it was a rod knock and the truck was finished. But after reading hear I confirmed the knock was intermittent, only under load. And it also started smoking and had a rough idle.
All consistent with an injector problem. I tried Lubri-Molly Diesel Purge in the fuel filter and tank, along with ATF fluid. And letting it sit. But it didn't improve.
I loosened each injector till I found the one that did not knock when I revved the engine. I replaced it,and between the new injector and the other 7 being squeaky clean, the truck runs like NEW!
Very little smoke and a little more power.
Thank you again IDI forum.
You saved the truck last year too with advice on why it wouldn't start when my IP failed.
Especially _Bear_.
My '92 F-250 w 205K starting knocking and I thought it was a rod knock and the truck was finished. But after reading hear I confirmed the knock was intermittent, only under load. And it also started smoking and had a rough idle.
All consistent with an injector problem. I tried Lubri-Molly Diesel Purge in the fuel filter and tank, along with ATF fluid. And letting it sit. But it didn't improve.
I loosened each injector till I found the one that did not knock when I revved the engine. I replaced it,and between the new injector and the other 7 being squeaky clean, the truck runs like NEW!
Very little smoke and a little more power.
Thank you again IDI forum.
You saved the truck last year too with advice on why it wouldn't start when my IP failed.
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Feb 16, 2009 07:19 PM