To tear down or not to tear down

[papastruck]

Just thinking here (bad, very bad) – I have a spare ’85 6.9 that I’m contemplating freshening up and putting in the truck, by simple virtue of the fact that I can leave the truck in service in it’s dysfunctional but serviceable state while I do the work in a somewhat heated garage this winter, rather than fight injectors, exhaust manifold, oil cooler, gaskets out in the cold and in the truck. I’d stud it, rebuild the oil cooler, and maybe try an upgraded cam, but my question is: would it be stupid not to rebuild the bottom end, given that I don’t know the real condition of the engine (claimed 90k on it when I got it, looks pretty clean), before moving up top? To put it another way, is there a way to establish the condition of the rotating assembly without pulling it apart? I know you can make inferences by looking at the sludge buildup and the condition of the cylinder walls, but honestly I just pulled apart a 302 with shot bearings that looked good from those perspectives.

 

[icanfixall]

The only way to know for sure is to remove the caps and look at the bearings. then remove the crank and check it too. Kinda a long way into it by then... The bottom ends are stout and strong. Usually the oil pumps are fine.... Its the pressure regulating valve spring in the rear header that wears out and causes low oil pressure on a rebuild....

 

[papastruck]

That's what I was afraid of, but if the motor's out anyway, it probably doesn't add too much time, and it's probably not worth doing everything else without doing that.

 

[GenLightening]

When I picked up an '86 6.9 from the wreckers, it looked pretty good up top and I flipped it, pulled the caps and mains and the bearings were fantastic front to back. No idea how many miles were on it, but other than being really dirty on the outside, it was sweet inside. So there's no telling what the condition is until you dig deep into it. Not really that bad and you get to make sure the pan is sealed good too! Good luck!

 

[icanfixall]

The actual engine I have in my rig now is the engine I bought off ebay for $87.50. It was on the upper desert... opend up and all dirty. I knew the cylinders were going to be wet because it stayed outside with the injectors out. The guy said he replaced it because it had mucho miles driving back and forth to mexico with his lafamila.... The ******* had thrown a rod that just cut the oil pan and nicked the oil pan rail.... He had rubbed dirt and oil into the cut hiding it from me... that really pissed me off. I found all this out when I pulled the heads and tried to hand crank it thru to clean off some rust on the cylinders... number 5 never moved and it would not turn 360 degrees..... But I was able to save that engine and after rebuilding its running fine... A member here said I should have driven back up there and told this @sshole all I did was paint it and install it... Boy that would have been great but I may have done a little more than that too... Like stomp a mudhole in his butt and then walk it dry.... I don't like to be treated unfairly or lied to... BTW all those mains and rod bearings were copper colored. They guy ran all the babbit off the bearings... You get what you pay for in this world most of the time...

 

[papastruck]

The actual engine I have in my rig now is the engine I bought off ebay for $87.50. It was on the upper desert... opend up and all dirty. I knew the cylinders were going to be wet because it stayed outside with the injectors out. The guy said he replaced it because it had mucho miles driving back and forth to mexico with his lafamila.... The ******* had thrown a rod that just cut the oil pan and nicked the oil pan rail.... He had rubbed dirt and oil into the cut hiding it from me... that really pissed me off. I found all this out when I pulled the heads and tried to hand crank it thru to clean off some rust on the cylinders... number 5 never moved and it would not turn 360 degrees..... But I was able to save that engine and after rebuilding its running fine... A member here said I should have driven back up there and told this @sshole all I did was paint it and install it... Boy that would have been great but I may have done a little more than that too... Like stomp a mudhole in his butt and then walk it dry.... I don't like to be treated unfairly or lied to... BTW all those mains and rod bearings were copper colored. They guy ran all the babbit off the bearings... You get what you pay for in this world most of the time...

Yeah, I decided that any used engine I buy, I'll just assume the worst. I went ahead and bought this because it didn't have anything sticking through the pan. Any serviceability I get on top of that is a bonus!

 

[oldmisterbill]

I agree check the lower end anyway. maybe freshen it with new bearings while ur at it. I have only seen 6 or so of these engines apart ,but every one had little crankshaft wear. The most done was to polish the crank. I'm not saying they never wear but they are sure tough. One of mine bent a rod when it hydro locked -never bent the crank.

 

[papastruck]

Hey there, Mr. Bill. Yeah, you & GL put it that way, it's kind of a no-brainer. Overthought this one.

 

[hesutton]

If you knew the condition of the motor before you bought it, then it would be pretty easy to check a few things before pulling the bottom end. If you could have done a compression test and a used oil analysis, that would give you a good idea of the IDI's condition.

That's what I did with my crew cab's 6.9. I suspected a head gasket leak with 322,000 miles on the originals. I'm adding a turbo and head studs as well as doing a "typ4" ZF5 swap. The compression test showed excellent results with the lowest reading being 410 psi on the #1 cylinder. Used oil analysis show only a trace of coolant (again the head gasket leak) but all of the wear elements where great.

Sure enough, the #1 cylinder was where the head gasket was leaking. The cylinders still have the factory hone marks. I didn't touch the bottom end. I put new gaskets/seals all around, studded the heads, rebuilt the oil cooler, and I hope to have the turbo on the motor before the end of the year.

Heath

 

[papastruck]

Yeah, I just bought the motor because it attached to a decent looking IP core, and the whole shebang was cheaper than an IP core charge. I didn't see anything sticking out of the oil pan and figured it was a good deal.