Question for the engine builders among us
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Elder User
Joined: Oct 2004
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Question for the engine builders among us
Ok all you engine techies, here is one for you. I have a 7.3 PSD engine out of a 2000 model truck. The owner stated that he heard a "knocking" noise and then immediately shut the truck down. Rather than troubleshoot things, he pulled the engine and stuck in a whole new motor. The engine is now in my possesion and I have begun the teardown. All in all, things have me scratching my head a bit. <o></o>
I have removed the injectors, heads, oil pan, as well as a few other major components. I noted that during injector removal, the viscosity of the oil in the injector rails seems to be abnormally low. Flipped the motor and removed the oil pan. Immediately noticed debris that resembled piston skirts in the pan after removal. Problem is, the all of the pistons appear to be fully intact with no visible damage of any sort. I will confirm this tomorrow when I bring my ridge reamer home from work so I can fully remove all of the pistons.<o></o><o></o>
Removal of rod bearing caps does show some wear, shown in the picture, but no excessive scarring and there is no visible damage to the journals. The journals are however, slightly blued, indicating an overheated condition. Once I fully remove the pistons and pull the crank I will mic everything to check for out of round and all that good stuff. My questions is, if everything checks out ok, is the crank still salvagable? Overheating changes the temper and can weaken things, but do you guys think this is only slightly overheated, and will be ok?
I have uploaded pictures of the crank and bearing cap into my gallery for you guys to look at.
https://www.ford-trucks.com/user_gal...&albumid=29076
I have removed the injectors, heads, oil pan, as well as a few other major components. I noted that during injector removal, the viscosity of the oil in the injector rails seems to be abnormally low. Flipped the motor and removed the oil pan. Immediately noticed debris that resembled piston skirts in the pan after removal. Problem is, the all of the pistons appear to be fully intact with no visible damage of any sort. I will confirm this tomorrow when I bring my ridge reamer home from work so I can fully remove all of the pistons.<o></o><o></o>
Removal of rod bearing caps does show some wear, shown in the picture, but no excessive scarring and there is no visible damage to the journals. The journals are however, slightly blued, indicating an overheated condition. Once I fully remove the pistons and pull the crank I will mic everything to check for out of round and all that good stuff. My questions is, if everything checks out ok, is the crank still salvagable? Overheating changes the temper and can weaken things, but do you guys think this is only slightly overheated, and will be ok?
I have uploaded pictures of the crank and bearing cap into my gallery for you guys to look at.
https://www.ford-trucks.com/user_gal...&albumid=29076
Fleet Owner
Joined: Jun 2004
Posts: 25,090
Likes: 1,112
From: Rio Rico, AZ.
I don't have any answers for you other than the thought that the blue areas on the shoulders are left over from when they machined the crank. IMO the rods would be just as discolored if they ran that dry.
The debris: Got any pictures of that?
I'm not an engine builder by trade, but am very interested in following this thread.
The debris: Got any pictures of that?
I'm not an engine builder by trade, but am very interested in following this thread.
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Elder User
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Kwik, yes, that is one problem. I think I may have gotten lucky too, because the cylinder bore is as smooth as a baby's butt. It still has crosshatching from the original honing. The biggest question is why did it happen. Low oil viscosity, over-revving, over heating because either the water pump or the oil pump quit? I am going to have to spend a bunch of time going over things with the micrometers. It is wierd, the engine is the cleanest engine inside I have ever seen. No sludge whatsoever. It is like one day something just let loose for no great reason.
Post Fiend
Joined: Jul 2005
Posts: 14,582
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From: 21791
The blueing on the crank is normal. It is from when the crank is machined, and then heat treated. They all look like that. Tonight I was torquing down the main caps (three of the 20 bolts were somewhat loose too!) on the 95 oil pan project engine, and the crank looks just like that, don't worry about that. The one rod bearing picture, it looks like there was a small amount of anti-freeze in the oil. If you can recover any of the oil still in the engine, (probably some still in the heads) then i would send it to blackstone for an analysis. May even help figure out why piston 4 cracked. Once you get that piston out, carefully examine, magnaflux it if you have the kit, and look for cracks. May have just been a bad piston from the start.
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Hotshot
Joined: Jan 2002
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From: La La Land
Are all the cooling oil squirters still intact? They've been known to fall out. Loss of cooling to the piston's underside could cause them to get hot and crack.
Pop
Pop
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Elder User
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Ok fellas, I threw some pictures of the piston from cylinder #4 after it was removed from the engine. It is good to know that the bluing is normal for these particular cranks. SpringerPop, the squirter is still there, but whether or not it is plugged, I don't know yet.
From what I have been told in the past, the biggest cause of skirt failure is excessive clearance between the piston and the cylinder wall, allowing a slapping that will eventually cause cracks and then break. I measured the bore and according to the specs I have, I don't think there is excessive wear. In fact, after 164,000 miles, it looks barely broken in, at least in the cylinder area.
From what I have been told in the past, the biggest cause of skirt failure is excessive clearance between the piston and the cylinder wall, allowing a slapping that will eventually cause cracks and then break. I measured the bore and according to the specs I have, I don't think there is excessive wear. In fact, after 164,000 miles, it looks barely broken in, at least in the cylinder area.
Lead Driver
Joined: Oct 2004
Posts: 7,413
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From: Columbia, MO
Do you have any pics of the cylinder bore? Not that I think there's anything wrong with it, but more that I'm just curious.
Now that I'm thinking about it though, does the bore on #4 match the rest of the cylinders? You measured the bore, but how about the piston? I'm thinking the bore may have been ok, but the piston slightly too small or a problem with the rings. It's tough to imagine how there could still be crosshatching in the bore with that many miles on the engine.
Now that I'm thinking about it though, does the bore on #4 match the rest of the cylinders? You measured the bore, but how about the piston? I'm thinking the bore may have been ok, but the piston slightly too small or a problem with the rings. It's tough to imagine how there could still be crosshatching in the bore with that many miles on the engine.
Hotshot
Joined: Jan 2002
Posts: 17,988
Likes: 207
From: La La Land
Damn shame about that skirt failure, as it's obvious someone kept the lube oil virtually spotless. Even the ring lands look good, from what I can see. That bearing shell isn't cause for concern, either, as there's no evidence of copper wear-through and pitting and streaking isn't apparent.
It's unlikely the lube squirters will be found clogged, either.
I believe you have an absolutely excellent candidate to rebuild. If you do, pay attention to detail, and virtually "blueprint" the new stuff to the block. It's not hard, it just takes longer, but with this engine, you've got time. Given the apparent wear, this could be a very reasonable rebuild, cost-wise.
And yes, cross-hatching remaining is not unheard of, especially in engines where the lube oil isn't abused. Did the previous owner have any bypass system installed?
From what I can see, this is a real tribute to someone's meticulous care, and the skirt was just a fluke that may go back all the way to the guy who miked the pistons and bores at the engine assembly plant. Tolerances on either side just "happened".
Pop
It's unlikely the lube squirters will be found clogged, either.
I believe you have an absolutely excellent candidate to rebuild. If you do, pay attention to detail, and virtually "blueprint" the new stuff to the block. It's not hard, it just takes longer, but with this engine, you've got time. Given the apparent wear, this could be a very reasonable rebuild, cost-wise.
And yes, cross-hatching remaining is not unheard of, especially in engines where the lube oil isn't abused. Did the previous owner have any bypass system installed?
From what I can see, this is a real tribute to someone's meticulous care, and the skirt was just a fluke that may go back all the way to the guy who miked the pistons and bores at the engine assembly plant. Tolerances on either side just "happened".
Pop
Last edited by SpringerPop; Jul 6, 2007 at 01:30 AM.