86 f250 6.9 rebuild/refresh advice and questions

And the last two for now. First is a shot down the cam bearings I thought looked cool. Old bearings were down to copper!


And #8 (or at least what I numbered 8... passenger side rearmost) that has consistently shown more wear than the others. Leaky injector? Its also where the head bolt blew. This is a side shot of some funny wear inside where the first compression ring goes. Maybe it's interesting to someone, or maybe someone knows what would do this? It's kind of pitted slightly in a couple spots, only in the one area.



That's all for now, back to work.

Rest of the main bearings including the thrust bearing. Haven't found Emory cloth in a fine enough grit to polish the camshaft locally so that is slowing down reassembly for now.

Went ahead and put the main bearings in to test clearance with plastiguage. They spec'd out front to back at about .0030, .0025, .0018/.0017, .0025, and .0020. Since spec is .0018-.0036, I would say this is alright. The thrust bearing is right on that inner limit (plastiguage is only so precise), but unless anyone chimes in otherwise I think they are good for assembly.

If anyone can read bearings would love to hear what you've got!

Thanks


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I faced a similar piston/valve clearance dilemma with my rebuild. I had the pistons shaved but decided on 20 thou just to have that little extra head room for turbocharging. 10 thou is plenty though.

As for the #8 cylinder.

The two rear cylinders typically run slightly hotter on the stock non turbo IDIs due to the crank case ventilation system. It allows crank case vapors into the intake manifold. The system works well but doesn't distribute the oil vapors evenly to all 8 cylinders. The rear two tend to get slightly more, which amounts to a tad more heat over the life of the engine. Supposedly this is one of the reasons a head gasket failure happens at one of the rear cylinders. Just a theory though. I'm not sure if it's what caused your problem.

stealth13777 said:

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Rest of the main bearings including the thrust bearing. Haven't found Emory cloth in a fine enough grit to polish the camshaft locally so that is slowing down reassembly for now.

Went ahead and put the main bearings in to test clearance with plastiguage. They spec'd out front to back at about .0030, .0025, .0018/.0017, .0025, and .0020. Since spec is .0018-.0036, I would say this is alright. The thrust bearing is right on that inner limit (plastiguage is only so precise), but unless anyone chimes in otherwise I think they are good for assembly.

If anyone can read bearings would love to hear what you've got!

Thanks

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IMO you cannot make a good judgement using plastigauge. The best way is to measure clearance is to mike the crankshaft journal and them mike the ID of the bearings in their bores, caps torqued. Subtract one from the other and that's your clearance. That's how it's done when engines are blueprinted.

On top of that, I see copper showing on that one lower bearing (2nd from right) which looks like it was a lower shell. That would give me pause over the accuracy of the plastigauge because when you get thru the babbitt, you are near the end of the life of the bearing. If you do reuse them, switch the position of the bearings and put the upper shells in the lower position. The lower shells take most of the heavy wear from downward thrust of the power stroke. I would advise replacing the bearings.

Bearings are being replaced. Every one in the engine, and rings. Thanks for the concern haha, but no way I would do this much work and reuse those old bearings! I was spec'ing the new ones

And that's an interesting theory on the heads. The CDR was just bleeding oil into the intake. But I also had a leaky injector. Probably a combo of a few things that did it.

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stealth13777 said:

Bearings are being replaced. Every one in the engine, and rings. Thanks for the concern haha, but no way I would do this much work and reuse those old bearings! I was spec'ing the new ones

And that's an interesting theory on the heads. The CDR was just bleeding oil into the intake. But I also had a leaky injector. Probably a combo of a few things that did it.

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Good! But you never know, so it pays to speak up when offering advice!

When I overhauled my engine, which had 140K on the lower end at the time, I could have reused the bearings but didn't. Clearances were well within tolerance. The bearings had some cavitation showing, which the Clevite engineer I consulted said was from adding the turbo. He suggested reusing the bearings, swapping the shells as I mentioned above. Since I had free bearings, I didn't reuse the old,but I could have.

If you have a cam degreeing wheel, measure the piston depth at 20 degrees BTDC, and 20 degrees ATDC. If the number is different (and the cam isn't off a tooth) suspect the wrist pin bushings. On the up-stroke it's pushing the piston, then pulling it down. If there's any slop in the wrist pin it'll show up on the BTDC/ATDC measurements.

If you can find a later 7.3 cam gear WITHOUT the puller holes it's a nice balanced unit. The older gears weren't balanced, which I suspect may have contributed to your odd cam bearing wear.

stealth13777 said:

You must be registered for see images attach

Rest of the main bearings including the thrust bearing. Haven't found Emory cloth in a fine enough grit to polish the camshaft locally so that is slowing down reassembly for now.

Went ahead and put the main bearings in to test clearance with plastiguage. They spec'd out front to back at about .0030, .0025, .0018/.0017, .0025, and .0020. Since spec is .0018-.0036, I would say this is alright. The thrust bearing is right on that inner limit (plastiguage is only so precise), but unless anyone chimes in otherwise I think they are good for assembly.

If anyone can read bearings would love to hear what you've got!

Thanks


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Click to expand...

Not sure but I'm guessing these are UPPER halves, and if so an ALIGN boring is in order here actually even if they are lower it should be align bored.

Notice the wear offset to the edge and only in one area...like copper and so forth, that bore is NOT SQUARE TO CRANK and will just do same thing, mind you will take quite some time if it's just a rering of old engine you are doing...

I can see lots but don't have lots of time at this post...later to provide more info when I study bearings more

JM2CW

The cam thing makes sense, as does the bearing wear. If this was something that I was doing a couple years into owning the truck, I would probably be building a second engine and hunting down everything I could do to make it a better build. As it is unplanned, I'm trying to do my best with a limited budget to make a reliable truck for the foreseeable future. Cutting as few corners as possible but it's hard as costs just go up and up. Won't be a daily driver (cept when the car needs work). This started as a head gasket issue and has developed from there into a 'well, since I'm already doing this much might as well do more' situation. Where do I draw the line? (Seriously, that's been the toughest part of the whole process for me, is deciding when to stop. Of course I want it perfect...)

That said, I love this feedback, and thank all of you for it. I'm learning a lot, and it's nice to know what's going on with the engine. Because of the situation, I appreciate you including a tip as to whether or not reassembling as it stands now will kill it. Would hate to waste all this time and money. As much as I would love to do everything, budget is a factor. Crank, pistons, rods, cam, valves, and of course block/heads (heads gone through) are being reused. As is the relatively new oil pump and the unknown age but not original injector pump (for now).

This engine had probably over 240k on it. If it will hold up anywhere near that long after this build, I'll have it for 25 years. So while I'm long winded, when you get the down time (and I've seen how busy you are in your threads!) would love to hear more! And thanks again to everyone.


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Edit: the way that sounds, did it ship from the factory like that?!? Or just wear that way?

It likely wore a little crooked. Given that it has 240K miles, that'd really not terrible at all. The engines were designed with a service life of 300K. It really doesn't seem like you're cutting any corners on the rebuild. You're not blueprinting a drag racing engine. If it costs you $4k to rebuild and you only get 100,000 out of it, that's only 4 cents per mile.

I did see a few unanswered questions that you had earlier:
-Injectors: The cost to test them would be about half the price of a remanufactured set. Conestoga Diesel pop tests their sets
-CDR valves don't really go "bad" unless the diaphragm is ruptured. Clean it up well, especially the pinhole on the back

Random rebuild tips:
Don't forget the assembly lube on the face of every bearing and cam lobe. Clean motor oil works well to stuff the pistons in, but put fuel hose on the rod bolts so you don't scratch the crank. Stuffing the cam in is easier if you put a long bolt in the snout. Red loctite the rod bolts and mains. Clean up hardware before re-installing it... a bath of mineral spirits for oily gunk or apple cider vinegar overnight to remove light rust. Use a good damn torque wrench and a high quality socket for the head bolts. Don't torque down the rockers with the piston at TDC. The pushrods have one hardened end, should have a yellow mark or stamp, which points up at the rocker arm. Do your best to prime the fuel system so it fires ASAP.

Type4 has my injectors and is working on them. Thanks for the tip. I may try to get myself an early 'Christmas gift' of one of Conestoga's pumps, depending on where my budget sits. Would prefer to only time the engine once. The real gift would be a running/ driving truck. Will clean and lube everything, and polishing the cam with 2000grit emery cloth just as a precaution. Thanks for the motor oil tip wasn't sure which to use on that step, assembly lube or oil. Havn't decided for sure and I'll take a look at the CDR, but I may just buy one before the new ones are gone forever.

Ordered head studs with both ARP Ultra Torque assembly lube and ARP thread sealer. Which is best for our studs? I noticed ARP mentioned blue loctite as an option too but would prefer their product. Figured even if the studs don't need the sealer the water pump will, anywhere else??

Thanks again to everyone, and to riotwarrior very interested in your ultimate bearing diagnosis (of course whenever you get downtime haha).

I myself would NOT locktite mains and rods...

JM2CW

riotwarrior said:

I myself would NOT locktite mains and rods...

JM2CW

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That's a method I picked up from the gasser world... I don't see how it could be detrimental. If there is a reason it's not recommended I'd like to correct myself

Studs don't need sealer, they go in blind holes. You should use thread sealant on the flywheel to crank bolts, as well as the 4 water pump bolts that go through the timing cover. Also pipe plugs and sensors in coolant and oil galleys.

Coming along, cam and crank in, pistons in. Everything is meeting clearance specs so far which is nice and comforting. On my rings, my manual gives a different ring end gap spec for the two compression rings. It lists the first at ~.020 and the second at ~.050 (ballpark #s as the manual is in the truck which is at the shop, and I'm at home). I got ~.020 on both gaps when checking them and decided that was just fine, installed with the gaps all offset, etc. what's up with the different specs in the manual?

When I stuffed the cam in, I lubed up the bearings but not the lobes as I didn't want it collecting dirt and dust while it sits (I do 'seal' it in a trash bag, but still). Recommendations for lubricating the cam lobes/ new lifters as the assembly comes along? *edit* went ahead and did it. Should have done it before I put the pistons in. Man that and the piston cooling jets were a pain. Hopefully heads tomorrow, been tediously chasing all the head bolt threads and cleaning them out for the studs.

***I am also now in the market for rocker arms. Autozone has jumped their price from reasonable (~$175 for 8 rocker arm sets) to $50 EACH. Figured I would try posting this here for now and see. For now I can still get lifters and push rods for decent prices, but if someone has more than just the rocker arms let me know.

Will include some pics later this week when I get back into the shop (it's closed sun/mon ugh). *edit* finally decided to see which banks kit I have, wastegated or not. Considering all I had to do was look at the turbo I should have known awhile ago, but anyway, Wastegated!!! Once the motor is broken in I'll have to run it out and see how high it lets the boost go, adjust if necessary. Excited at the potential the truck will have with a good motor, typ4 doing the injectors, and the potential of whatever pump conestoga recommends later on (one thing at a time). I don't need nor am I going for max power, but power is power; especially if it's free (like finding out I have a wastegated turbo)!