Locked up 6.9
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5th Gear
Joined: Jan 2025
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Locked up 6.9
I recently picked up a ‘83 F250 4wd 6.9 with a C6. The motor is locked. I have taken the glowplugs out and filled the cylinders with Marvel Mystery Oil and have let it sit for a week or so. I took a breaker bar and tried rocking on the 15/16 bolt on the crank and the bolt broke in half. What am I in for with getting this bolt out and any advice on how to get this thing unstuck would greatly be appreciated. Im a broke teenager with a tight budget.
Logistics Pro
Joined: Sep 2007
Posts: 3,737
Likes: 179
From: Western Mass
I don't have any experience with a locked up engine, but my guess is, you're SOL, sorry bud, start looking for a new engine.
If you have access to a borescope you may be able to snake one in and see what the cylinder walls look like, but I'm not sure if you can get through the injector precups and down into the cylinder itself that way or not. May need to pull an injector as well to get in there.
Just to make sure, glow plugs are still out while you are trying to turn it over?
If you have access to a borescope you may be able to snake one in and see what the cylinder walls look like, but I'm not sure if you can get through the injector precups and down into the cylinder itself that way or not. May need to pull an injector as well to get in there.
Just to make sure, glow plugs are still out while you are trying to turn it over?
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5th Gear
Joined: Jan 2025
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I don't have any experience with a locked up engine, but my guess is, you're SOL, sorry bud, start looking for a new engine.
If you have access to a borescope you may be able to snake one in and see what the cylinder walls look like, but I'm not sure if you can get through the injector precups and down into the cylinder itself that way or not. May need to pull an injector as well to get in there.
Just to make sure, glow plugs are still out while you are trying to turn it over?
If you have access to a borescope you may be able to snake one in and see what the cylinder walls look like, but I'm not sure if you can get through the injector precups and down into the cylinder itself that way or not. May need to pull an injector as well to get in there.
Just to make sure, glow plugs are still out while you are trying to turn it over?
Laughing Gas
Joined: Jun 2007
Posts: 1,106
Likes: 35
From: Virginia
I recently picked up a ‘83 F250 4wd 6.9 with a C6. The motor is locked. I have taken the glowplugs out and filled the cylinders with Marvel Mystery Oil and have let it sit for a week or so. I took a breaker bar and tried rocking on the 15/16 bolt on the crank and the bolt broke in half. What am I in for with getting this bolt out and any advice on how to get this thing unstuck would greatly be appreciated. Im a broke teenager with a tight budget.
You can take the starter off and try to rock the engine with the starter teeth on the flywheel.
Cargo Master
Joined: Aug 2004
Posts: 2,899
Likes: 2
From: Lynnwood, WA
Usually, broken bolts can be removed either by using a bolt extractor, or by welding another head on them. I presume it broke in a way the welding is not option, so you need to use a bolt extractor. Make sure you don't break a bolt extractor because removing broken bolt extractors is a real PITA.
If the engine stuck really badly, you may want to remove the pistons one-by-one until the crankshaft is turning. You preferably want the engine out for that.
If the engine stuck really badly, you may want to remove the pistons one-by-one until the crankshaft is turning. You preferably want the engine out for that.
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Tuned
Joined: Sep 2024
Posts: 487
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From: Ougadougou
It may be too late for much help but whenever I am dealing with a stuck threaded item like a bolt or glow plug I gently work it back and forth once it begins to loosen in the hopes that whatever lube I am using will spread out and cover more surface area-- no idea if that would apply to a seized engine. At least you get the opportunity to tear one down and learn a lot if you can afford some new parts. A part-time job and some patience might result in a nice engine.
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5th Gear
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Logistics Pro
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From: Edmond, OK
You mentioned the truck has a C6. Before you remove the engine separate the engine and transmission. Also, go underneath the truck and remove the torque converter from the flywheel. Then when you pull the engine the transmission and torque converter will stay in the truck.
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5th Gear
Joined: Jan 2025
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You mentioned the truck has a C6. Before you remove the engine separate the engine and transmission. Also, go underneath the truck and remove the torque converter from the flywheel. Then when you pull the engine the transmission and torque converter will stay in the truck.
i ain't rite
Joined: Mar 2005
Posts: 65,514
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From: Marlboro Mental Hospital.
to remove the converter you unbolt it from the flywheel.
and support the front of the trans before pulling the engine. it is mounted to the truck by the transfer case adapter at the back of the trans.
if you leave the trans unsupported when pulling the engine, there is very good chance the adaptor will break.
and support the front of the trans before pulling the engine. it is mounted to the truck by the transfer case adapter at the back of the trans.
if you leave the trans unsupported when pulling the engine, there is very good chance the adaptor will break.
Logistics Pro
Joined: Sep 2007
Posts: 3,737
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From: Western Mass
You mentioned the truck has a C6. Before you remove the engine separate the engine and transmission. Also, go underneath the truck and remove the torque converter from the flywheel. Then when you pull the engine the transmission and torque converter will stay in the truck.
Fleet Owner
Joined: Jul 2006
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From: Mi'kma'ki
I recently picked up a ‘83 F250 4wd 6.9 with a C6. The motor is locked. I have taken the glowplugs out and filled the cylinders with Marvel Mystery Oil and have let it sit for a week or so. I took a breaker bar and tried rocking on the 15/16 bolt on the crank and the bolt broke in half. What am I in for with getting this bolt out and any advice on how to get this thing unstuck would greatly be appreciated. Im a broke teenager with a tight budget.
Even a good used IDI truck all running, is very, very poor choice for a broke teen. These trucks are very expensive to run. Cheap compared to modern diesel trucks, but very expensive compared to what you need; a little Honda civic with a 4 cylinder. This will be pennies on the dollar to run comparatively. Don't mess with the old truck. The more you break, the less you're going to be able to sell it for, and less small car that you need, you're going to be able to buy. As soon as you pull the engine; it's going to get you less, even if it is locked up because then someone needs to tow the truck and lift the engine to haul it off. Easier for them still in the truck.