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Thread: Diesel Pistons

  1. #21
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    Thanks for the pics Bob and good luck with the "Deer." I was in a similar situation many years back with a VW sand-rail engine I raced. Seized up and no way to get at anything. Can't recall what I did, but it took about a week and I figured out a plan, so go with the head and not with the arm.

    I always get nervous when I hear "breaker bar." Often followed with, "I wish I hadn't done that.!"

  2. #22
    Lead Engineer RWOLFEJR's Avatar
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    Quote Originally Posted by Kelly Bramble View Post
    Leaping forward to the year 2001 - John Deere coaxed me into buying a 790 with the 419 front end loader.

    It is my opinion that John Deere built better tractors in the past. Though my 790 has been reasonable things like the battery installation and front seals could be improved.

    Think I have a little more than 200 hours bought new.

    My ride has the Yanmar Diesel 30 horse.

    Attachment 229
    I looked at the utility size machines when I bought my garden tractor the same year but decided that my yard would be better dealt with with the smaller machine. I went with their X585 4x4 with the gas Kawasaki engine. Think it's about 24 hp? It has served me very well... knock on wood...

    It's still a lot stouter than the lawn versions they sell at the box stores and the center of gravity is nice and low with a pretty wide stance. My yard is very hilly and the utility size seemed a little too top heavy for my yard. The bigger $$ tag also helped convince me to go with the garden version. Used to have to sit on the fender and chains and all that jazz with my old cadet. Now I can just sit there and go anywhere in the yard without any worries.

    Sure could've used that front end loader a couple years ago when I pulled up about ten cubes of old brick from my walkway and patio and replaced them with new pavers. (also wiping drool from chin...) Hand picked about half of them until I got the bright idea to give them away to whoever would come and pick 'em, load 'em, and haul them away. Only wish I had thought of it sooner... Got pretty good at throwing them into my little wagon with the pick end of a brick hammer. If you scooped it just right and centered up pretty good you could pull and load in one swoop...!

    Anywho... nice machine. With only 200 hrs. on it you'll be good for a long time... Eleven years and 200 hrs. you'll probably be good for another 50!!

  3. #23
    Project Engineer CCR5600Design's Avatar
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    [QUOTE=PinkertonD;2627] I was in a similar situation many years back with a VW sand-rail engine I raced. Seized up and no way to get at anything. Can't recall what I did, but it took about a week and I figured out a plan, so go with the head and not with the arm.
    QUOTE]

    Been there and done that with the air-cooled boxer engines. I cut my automotive teeth on one of those little magnesium-cased monsters. I've got to tell you, I learned a lot by hot-rodding that thing at a very young age:

    1. How to stretch a buck
    2. How to convert metric measurements to standard (This goes along with how to stretch a buck. I could afford one set of wrenches at the age of 15... I quickly learned which set to buy.)
    3. Basic electrical (converted 6V system to 12V)
    4. Princpals of leverage (Remember removing/installing the rear axle nuts and the flywheel nut with basic hand tools?)
    5. Teamwork
    6. How to eat a sandwich with greasy hands

    There are many other items I could add to the list...



    Ron

  4. #24
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    Quote Originally Posted by PinkertonD View Post
    Thanks for the pics Bob and good luck with the "Deer." I was in a similar situation many years back with a VW sand-rail engine I raced. Seized up and no way to get at anything. Can't recall what I did, but it took about a week and I figured out a plan, so go with the head and not with the arm.

    I always get nervous when I hear "breaker bar." Often followed with, "I wish I hadn't done that.!"
    Quick "Slug bug" story you reminded me of. Had a 71 ragtop VW beetle when I was about 18-ish. The thing just coasted to a stop one day. Wouldn't move. Ran but no motion. I get the thing towed home and was in big hurry to get my ride back on the road. I didn't look into it at all and just jumped all over it. After all when I was 18 I knew pretty much everything so anything I did made perfect sense to me. (humor)

    It was snowing out and I put on the wool and overalls and went at it. I was running around the car jacking it up over and over again and adding cribbing until I could slide the engine sitting on an old tire out from underneath. Somehow in all of my VW wisdom I had figured the motor had to come out and I had already bought several new parts and was going to break speed records getting it done regardless.

    Turned out there was no need to do any of it. All I needed to do was pull a rear wheel and brake drum. The drums were splined and the splines were wiped out.

  5. #25
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    Quote Originally Posted by CCR5600Design View Post
    [

    .... 6. How to eat a sandwich with greasy hands

    There are many other items I could add to the list...



    Ron
    7. Quickest way to get the dried up grease out of the cracks in your hands and around your fingernails is to make a meatloaf...!

  6. #26
    Project Engineer CCR5600Design's Avatar
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    Quote Originally Posted by RWOLFEJR View Post
    Turned out there was no need to do any of it. All I needed to do was pull a rear wheel and brake drum. The drums were splined and the splines were wiped out.
    VERY common problem with those cars. I encountered it TWICE on my '66.



    Ron

  7. #27
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    Don't get me started with VW engines. Had the rods go and stripped it down and found a cup full of sand. Figured it was sabotage in the pits. Really pissed me off. Second time it happened it had not been near the pits so no one to blame. Hadta look hard and deep.

    Found the motor pulley had some German ingenuity with a reverse spiral to drag oil back into the crankcase. Also dragged sand in when the pulley was covered in it. Problem solved, machined for a lip-seal and all were forgiven in absentia.

    Man, I loved those little engines.
    Last edited by PinkertonD; 04-09-2012 at 08:07 PM.

  8. #28
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    Quote Originally Posted by CCR5600Design View Post
    4. Princpals of leverage (Remember removing/installing the rear axle nuts and the flywheel nut with basic hand tools?)
    Had forgotten about that one. Always fun with a couple of heavy screw drivers in the ring-gear leveraged around an engine mounting bolt. I had the correct socket but no bars to fit it, so I welded it to a flat bar.

  9. #29
    Project Engineer CCR5600Design's Avatar
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    Sorry about the threadjack, but seeing that old tractor has me waxing nostalgic. Ah, the good ol' days.... sigh. Thanks for sharing your Deere.

    I really need to get out to the garage and drop the engine back in my Road Runner...


    Ron

  10. #30
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    Figured I'd update a little on the tractor.

    All the hard part is done... sort of. Got the thing apart and bores and pistons weren't the issue. There was one spot on one piston where it was buffed up a little but it wasn't an issue. The wrist pin bushing in that hole was shot and I'd guess that would've added a little funk to the motion. The other wrist pin is fine and this has me wondering why the one and not the other. The bad bushing wasn't spun so it must not have received oil. It's worn so badly it had to have happened pretty early I'd think to have as much slop in it as it does.

    So I pulled the block with the pistons and the crank is still tight. The only issue with the bores was a condensation thing when I initially assembled the engine. After assembling the engine the first time it was well over a year before I had the sub frame done so I could put the wheels back on and start it up. What it looks like is some condensation formed in the bores and it rusted a little at the bottoms. The one piston was up and the other back and there's a skinny trail of little pits in the one bore for about 5 or 6 inches. The other bore has a quarter sized spot of little pits up at the head end. The pistons weren't showing a lot of burn getting past the first compression rings and none past the second so I'm figuring I'll be O.k. with things as they are there.

    The lock up was at the three main bearings. The center bearing is a split bearing with the steel back and then layers of slippery metals. It scored through the silver looking Babbitt or whatever it is, and was into the copper colored material pretty heavy. The two outer main bearings are solid rings of some sort of aluminum alloy pressed into a cast case that bolts into the main case. They were also pretty ugly looking. None of the three main bearings spun but all looked dry.

    I didn't pull the oiling system components yet because I need to do some house keeping under the tractor before I'm gonna feel like laying under it. Also had a heck of a time getting the bearings off the outer mains of the crank and by the time it was out my back needed a break.

    Right now as it stands priority one is knowing exactly why no oil to mains and why for certain the wrist pin issue with one and not the other. Both are fed from the outer mains through the crank and up the rod. If oil was the issue for one then why not the other? Yes they are fed seperately but both outer mains were bad. Maybe one was just getting even less?

    The wonderful news is this...
    Very expensive pistons, rings, and block will be fine. Took a bunch of measurements on crank journals and it will be fine. Checked the runout of the mains with outer mains on precision rolls (Anderson balancing rolls) and was less than .002 at the center main... And some of that is measured ovality at the journals so call it a fat thousandth. Also the throws and mains were well under the Deere suggested maximum specs for taper, and out of round.

    I put the crank in one of our old lathes and polished it up. My main concern was polishing the center main to remove the copper hue to it. I need to get that material out of the surface of the journal. (see picture 1 and copper colored center main journal) Also had a spot on both outer main bearing journals that was large by about .0012-.0015 depending on where you measured it. It was like a rib in the center of them. (see picture 2 and you might see the 1/2" wide section just a little right of center of the pocket to feed the oil hole in the crank?)

    What appeared to have happened was this. The holes that receive oil from the main bearings into the crank had a very sharp edge to them. It looks like the crank scarfed a groove out of the bearings and then all the load was transferred to either side of that band. Any additional wear to the journals would allow another scarfing and it eventually developed into a high rib about a half inch wide around the journal at the hole locations.

    I rounded the edges of the holes and tore a strip of sand paper and dusted the hump off. Then I hit them with some 240 followed by some 500 grit. Looks dandy now. (see pic 3)

    Attachment 267Attachment 266Attachment 268

    Mother Deere calls out is a Minimum of .0055 up to .0075 clearance on the two outer aluminum main bearings when installing and when clearance exceeds .013 it's time to change them. I suppose at approx. 5" x 1/4" wall and the approx. ten times the growth as steel of the aluminum... some clearance will be lost when it warms up. I'll be shooting for .006. I should take the time to calculate this. Recall steel at .0000063-ish. Easy to remember that because of the five zero's then six. The aluminum I'm thinking was about 10 fold. Either way mother Deere already figured this one and I figure in this type of situation a little extra clearance will be better than too little.

    So all my speculation over the winter prior to opening this thing up was a waste... and not accurate at all. I was aware this was certainly a possibility but would've bet heavy on melted pistons.

    Next step is to find the oiling issue...

  11. #31
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    Well, it is good to hear the news isn't too bad. Did you plastigauge the bearings before assembly?

    The oil to the wrist pins: Are the holes in the rods offset and maybe one rod put in back-to-front and missing the feed from the journal?

    Does it have an oil pressure gauge? Maybe this time spin it up with a guts-buster 3/4" power drill or a gas post hole digger with the cylinders open and make sure you have oil pressure before moving on.

    Anyway, good to hear it is not too serious.

  12. #32
    Lead Engineer RWOLFEJR's Avatar
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    Quote Originally Posted by PinkertonD View Post
    Well, it is good to hear the news isn't too bad. Did you plastigauge the bearings before assembly?

    Yes and no... Checked the rod bearings but... no on the crank. The crank bearings are full circle (except center one) and although its a crappy way to measure play, I did as the book suggested, rather than go through the extra work of pulling the crank. Shop manual tells you to put an indicator on the crank and lift up on it to determine clearance. Not really the ideal way to check fit at each bearing since a good fit at any one of them would reduce the measured clearance at a worn one.

    The oil to the wrist pins: Are the holes in the rods offset and maybe one rod put in back-to-front and missing the feed from the journal?

    The rods and caps are match marked and numbered... and the hole runs through the center. But now you have me wondering if there's any possible way that only one of the two halves of the rod to crank bearing inserts is drilled...? The hole up throught the rod was clean and the wrist pin bearing didn't spin to lose sight of the hole. Surely they would've drilled both halves? I'll have to run home at lunchtime and check. Man will I feel stupid if that's the case...

    Does it have an oil pressure gauge? Maybe this time spin it up with a guts-buster 3/4" power drill or a gas post hole digger with the cylinders open and make sure you have oil pressure before moving on.
    Yep has
    a gage. I watch it come up every time I fire it up but don't really look at it after that. The gage is fed from the same manifold which is fed by the same pump. I'll be pulling the pump, manifold and rest of the lines soon and see what I have. Need to get my rebuilt motor for one of my old Fords put in this weekend. Looking like Sunday is no rain in my garage.

    Yep definitely want to verify oil before assembly. The drive unit that turns the oil pump sticks out the side and is driven off the crank gear. Crank gear, to an idler gear, to the pump drive... looks about 1 to 1 but I'll need to verify and then see what sort of speed I get from the drill to equate running speed. might be able to get away with an air or electric wrench but I'm afraid it'll hammer as it starts to spin and don't need to be smacking at the entrails of the pump and the gears. Might need to make a drive for a drill... for the socket... to drive the nut... that holds the gear... that drives the pump. And the thigh bone is connected to the knee bone is connected to the shin bone...


    Anyway, good to hear it is not too serious.
    You can say that again...

  13. #33
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    Quote Originally Posted by RWOLFEJR View Post
    And the thigh bone is connected to the knee bone is connected to the shin bone..
    ...That wiggled and wiggled and tickled inside her.
    But I dunno why she swallowed that fly

    Using enough assembly lube -- everywhere, might it not be OK to spin the crank? I always do that after a motor rebuild, but I have never worked on small diesels. I say "small" as the smallest diesels I have worked on were Blackstone eights, or Mirrlees sixteens.


  14. #34
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    Quick update on the tractor...
    Sent block and pistons and rods back to the fellow who worked them and had .005 over wrist pins made and had him dust the bores. He said less than .002 hone for full clean-up. Some slight settling in I suppose since the green block has seen some heat cycles. Had him make new compression rings too. got that stuff back a couple weeks ago. Ended up buying a big adjustable ream and rounded out my center bearing bore by hand. At about 5" diameter it was quite a chore. Had new custom center mains made and new outer mains. Center main is two halves and they couldn't put the little tabs in them. I put them in then had to scrape them with a bearing knife. Bearing halves fit nice and tight.

    Got the crank in this morning before a much needed rain came in. Crank didn't fit and measure very good... It fit and measured more like perfect...

    Had cleaned and cleaned... then ran oil through everything and cleaned and cleaned again. Ran pump with a 1/2 drill of rpm comparable to idle speed. looked good. After installing crank and bearings ran pump again... not good. Was by-passing heavy under added load of bearing fit and crank etc.. This was setting that gave me high reading on gage and where it ran last. The gage is fed before the crank and not nearly enough oil to crank and rod throws... Would've still thought that pressure at the gage would be same as pressure at crank since the bypass is at the distribution manifold for everything getting oil... gage included? Going to grab another gage and put on the block where the line comes out and see what it says. Maybe my new dash gage is junk?

    Ran pressure adjustment screw in a couple turns... (huge adjustment) Still by-passing like crazy and weak at crank. Ran in a couple more... still weak. Ran it home and oil was gushing out the throws like a spigot. N i c e ... Probably a little much... but better than not enough.

    Tomorrow AM gonna pull my regulator apart. Suspect it's an issue with the pilot & its bushing Will find out tomorrow. But was really pleased to see the issue and now I'm certain I can get where I need to be on this. Want to know for certain what psi I'm at where it "looks" good.

    The rest is all down hill from here. Just a lot of simple wrenching.

  15. #35
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    Hi Bob,

    I was thinking of asking about the tractor. I gotta say, I cannot image how you could do the center bearing 100% in-line with the other two with a hand reamer. More power to you, (pun intended for the tractor) if it works out good.

    As I suggested earlier, I would like to think you would run it up with a big drill or motor of some sort, before hitting the start button and see if that oil is all getting a fair look at the surfaces it needs to pass by. An oil gauge at the down-stream end sounds like a good plan too. What's the difference between idle RPM and full load? Can you may be fit a higher volume oil pump and then back off the relief pressure some?

    Fingers crossed for you this time around.

  16. #36
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    I'm probably not 100% dead on with the center main but it must be terribly close. Feels good and gaged where it needs to be so I'm calling it macaroni. Predicted clearance vs. measured was off by a couple thousandths at the center main. I shot for .007 at the new aluminum center main. The next model deere (the 830) that was basically same as this had a different main that was also aluminum and with that aluminum center the book calls for .0055 minimum for all three bearings. People I spoke with said best to go for .007. Book says better consider changing them at .011+ So I shot for .007 across the board. My crank was straight to about .0015 and some of that could be attributed to some slight out of round on the journals. Well under Deere's spec. When I pulled the center cap after the crank was in place and center main cap torqued... my plasti-gage read .0065 across 70% of the strip and .006 toward the ends. The outers are full circle and they were turned after I shrunk them in their cases so they were pretty much dead on .007 before installation. With all bearings in place and an indicator on the top of the crank at each main... I lift up on an end and got a small .007 at each side. Call it .0065? Close enough for me. I'm confident it'll be fine with good oil flow. Far as the hand reaming goes like they say... I'd rather be lucky than good...!!

    Ordered a Banks EGT pyrometer kit today from Summit. Also ordered a nice oil pressure gage to add close to a main feed. The factory one is fine but L / M / H doesn't quantify things. Once I get a reading from the numbered gage I can see how it compares to the factory.

    Deere says run the pump at 25 psi. It does seem to be a very high volume pump. With a gage in place where I can see it while I'm running the pump... I will be able to adjust and see what's looking good and at what pressure. The fellow who did the block and head works said he wouldn't go over 35 and that probably isn't necessary. I didn't get the regulator apart this AM cause they were calling for more much needed rain. Haven't seen much more than a spit or two here at work. Gonna pull it apart and see what's up after work.

    Idle on this thing is around 700 rpm. Top is 1125. I do need to double check the ratio of the gears that run the pump driver. At a glance in the book they all looked pretty much equal but I did notice they are a little different. It eyeballed up to look like the three gears will wash out to 1:1 but need to figure it real quick. My 1/2 drill runs 600 rpm. My 3/8 will drive the thing I'm sure but I'd need to put my tach on it to see where I'm at in the variable speed range. I'd like to see at least decent flow down to 400 tractor crank rpm and excellent at 700 plus. The pony motor doesn't run it very quick and that's a danger zone firing it. Watching the oil flow with the drill gives me a better appreciation for what lugging them way down does for lubrication. So far I haven't had the load to pull the motor speed way down but It's easy to see how going for it to the point of a stall would cause damage.

    Supposed to have great weather this weekend. Hoping to resolve regulator and get the thing closed up....!!

  17. #37
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    Any chance of making a make-shift handle on the flywheel so you can spin the entire crank/piston assembly before closing it up? Might take some upper body strength.

  18. #38
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    Yep... I can roll it over with the decompression lever locked back. I turn it over before lighting it up when I'm bleeding and checking the injectors before putting them in.

    Ran out of brake cleaner and needed a big sheet of thin hard cardboard so stopped in the shop. Also had the need to feed... Didn't get my gage in today which is unusual from Summit for me. They pretty much always get things to me the next day with regular UPS. They're couple hours away... Checked out the tracking number and be in Monday... Oh well... still plenty to keep me busy.

    Got a good bit done this morning and gonna go get back at it.

    Oh... and found out with some calculations and my old handy dandy "Jaquet speed indicator" that I'm spinng my pump 1,015 rpm when the motor's running 700. My 3/8 drill in low range is supposeed to be 1,000 but is 950 free wheeling and about 875 loaded. Close enough...

    Attachment 376

    Took my oil pressure regulator apart and it was fine. Anxious to see what I have on a good gage.

    There's a saying I run through my head now and then... "The hurrier I go the behinder I get." Had a close call this AM. almost put a big cover on my tranny side without putting a pair of lip seals on that end of the crank first... That would'a sucked...

    Well gonna go put some new guts in my clutch assembly and see if I can't get it on yet today.

  19. #39
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    Ahhh, the good old days. Jones tachs were about $350 each I think from a long tired old memory. Electronic one was $14 including shipping. With +/- 0.85% accuracy 0 to 30,000.

    Progress?
    Attached Images Attached Images

  20. #40
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    Clutch rebuilt and on. Few other misc on that side hooked up. Block, rods, pistons, gaged - torqued - height checked and rolled over. Looks and feels good. Drained oil again just in case. Only had two gallons in it and oils cheaper than issues. New filter and seals and oil. Rolled pump and once the filter was filled my 3/8 drill in low range got a good work out. Should probably borrow the 1/2 drive one here at work again. Dang gage didn't come in yet. Looks good but I want to know where this "good" is. Was ready to put the head on and had it dangling from the picker and it started to rain. Was hungry anyway... After shower the sun was back out.... Doh!

    The radar on the weather shows some pretty good odds on rain this afternoon. We need it. The outdoor gargae has it's moments but rainy days isn't one of them. Guessing a couple more good days and ought to be ready to light it up. Barring anything doesn't go wrong like last go at it. Had a flashback of last go at it when I dropped a little keeper for my govenor rod down in the side cover and had to pull it and a bunch of other stuff back off to get it back out. Note to self... Self... Don't do that agin.

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