Ford F834 Posted April 16, 2018 Share Posted April 16, 2018 Welcome to the group! I have a soft spot for the 80/81’s and I am a fan of the 6.9/7.3 IDI’s so naturally I think you have a great pair of trucks 🙂. What kind of noise are you hearing on the 6.9? Link to comment Share on other sites More sharing options...
Kevins750 Posted April 16, 2018 Author Share Posted April 16, 2018 Welcome to the group! I have a soft spot for the 80/81’s and I am a fan of the 6.9/7.3 IDI’s so naturally I think you have a great pair of trucks 🙂. What kind of noise are you hearing on the 6.9? Kinda of a thud, I wouldn't call it a definite knock. And it isn't constant. Little back story, original owner was going down the freeway, said he heard a loud noise and the motor locked up. He had the truck towed to a yard and tried turning over the motor with a wrench, wouldn't turn over. I buy the truck have it towed to me , walk over to the truck and just for giggles I try to start the truck. Well to my surprise it fired right up after setting since August . I turned the truck off right away. I started it again and then I could here the thud in the motor. Oil pressure shows 60lbs. I haven't messed with it since then, I did go buy a "ran good when pulled" 6.9 this morning just in case, Link to comment Share on other sites More sharing options...
Ford F834 Posted April 16, 2018 Share Posted April 16, 2018 Kinda of a thud, I wouldn't call it a definite knock. And it isn't constant. Little back story, original owner was going down the freeway, said he heard a loud noise and the motor locked up. He had the truck towed to a yard and tried turning over the motor with a wrench, wouldn't turn over. I buy the truck have it towed to me , walk over to the truck and just for giggles I try to start the truck. Well to my surprise it fired right up after setting since August . I turned the truck off right away. I started it again and then I could here the thud in the motor. Oil pressure shows 60lbs. I haven't messed with it since then, I did go buy a "ran good when pulled" 6.9 this morning just in case, The 6.9’s have a really crappy aluminum rocker arm retainer that bridges the rockers for intake and exhaust. They like to break. My guess is that one let go and jammed a valve into the cylinder. The piston clearance is only like .045”, so it wouldn’t take much to prevent the engine from turning over. That thud is probably a valve that isn’t opening. I’ve heard that when mine oil starved from a broken oil gauge tube and the lifters collapsed. Pull the valve covers and see if anything is amiss. If you have a broken retainer I would recommend replacing all of the rocker arms with the ‘87+ style (7.3’s). It is a significant upgrade, and all replacement parts are of this type anyway. Might not be your problem but it’s a guess. The fact that it started and ran is a good sign that you didn’t drop a valve, but I wouldn’t run it any more until you check that out. You might get lucky and just need valve train parts. Let’s hope... 🤞 Edit: first read through I missed the point that it locked up while running down the freeway... that’s not so good. ☹️. Still might get lucky but there is greatly increases chance of a cracked piston if it was running... at the very least you will want a compression check... Link to comment Share on other sites More sharing options...
Kevins750 Posted April 19, 2018 Author Share Posted April 19, 2018 The 6.9’s have a really crappy aluminum rocker arm retainer that bridges the rockers for intake and exhaust. They like to break. My guess is that one let go and jammed a valve into the cylinder. The piston clearance is only like .045”, so it wouldn’t take much to prevent the engine from turning over. That thud is probably a valve that isn’t opening. I’ve heard that when mine oil starved from a broken oil gauge tube and the lifters collapsed. Pull the valve covers and see if anything is amiss. If you have a broken retainer I would recommend replacing all of the rocker arms with the ‘87+ style (7.3’s). It is a significant upgrade, and all replacement parts are of this type anyway. Might not be your problem but it’s a guess. The fact that it started and ran is a good sign that you didn’t drop a valve, but I wouldn’t run it any more until you check that out. You might get lucky and just need valve train parts. Let’s hope... 🤞 Edit: first read through I missed the point that it locked up while running down the freeway... that’s not so good. ☹️. Still might get lucky but there is greatly increases chance of a cracked piston if it was running... at the very least you will want a compression check... So I took my 85 F250 to a mechanic to look at the engine issue. He called and left a message for me, telling me there is a large hole in the oil pan and didn't investigate any further. I picked up another motor for this purpose, so the are going over it, resealing it, and going to transfer my parts, water pump, injection pump, injectors,glow plugs and all the tin wear. I hope this motor is good enough to last a while. Picture of the vent in the oil pan. Link to comment Share on other sites More sharing options...
Ford F834 Posted April 19, 2018 Share Posted April 19, 2018 So I took my 85 F250 to a mechanic to look at the engine issue. He called and left a message for me, telling me there is a large hole in the oil pan and didn't investigate any further. I picked up another motor for this purpose, so the are going over it, resealing it, and going to transfer my parts, water pump, injection pump, injectors,glow plugs and all the tin wear. I hope this motor is good enough to last a while. Picture of the vent in the oil pan. Ouch! Sorry to hear that. Hopefully your donor engine is in good shape. Link to comment Share on other sites More sharing options...
Kevins750 Posted April 19, 2018 Author Share Posted April 19, 2018 Ouch! Sorry to hear that. Hopefully your donor engine is in good shape. Fingers crossed Link to comment Share on other sites More sharing options...
Gary Lewis Posted April 19, 2018 Share Posted April 19, 2018 Fingers crossed That pan looks like a bit of a problem. Hope the new engine is in good shape. Link to comment Share on other sites More sharing options...
Ray Cecil Posted April 19, 2018 Share Posted April 19, 2018 That pan looks like a bit of a problem. Hope the new engine is in good shape. JB weld and duct tape oughtta fix that right up... Link to comment Share on other sites More sharing options...
Kevins750 Posted April 26, 2018 Author Share Posted April 26, 2018 JB weld and duct tape oughtta fix that right up... So I got my 85 f250 back from the engine swap. It runs well, seems the swapped motor may hold up. I am having a few issues I need to address, not with the motor though I took it on a decent shake down run out through the country, shows some decent acceleration in 4th gear. Got it up around 70mph at times, mostly just cruising it around in 4th. Link to comment Share on other sites More sharing options...
Gary Lewis Posted April 26, 2018 Share Posted April 26, 2018 So I got my 85 f250 back from the engine swap. It runs well, seems the swapped motor may hold up. I am having a few issues I need to address, not with the motor though I took it on a decent shake down run out through the country, shows some decent acceleration in 4th gear. Got it up around 70mph at times, mostly just cruising it around in 4th. Yippee! Glad that appears to have worked out well. Gotta be a good feeling. I know how I felt the other day when I got Big Blue's fuel leak fixed and can use him again. Link to comment Share on other sites More sharing options...
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