743 Excessive Blowby Pushing Oil Out

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gatorguy

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Dec 19, 2019
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Hello, I have a 743 with v1702 Kubota Diesel. Motor ran like a charm and didnt leak a drop of oil until just recently. Well, it still runs fine but just leaks. Drips a drop of oil out of the valve cover breather tube every second or so when revved right up and is pushing oil out the throttle plate cover and a bunch of seals it seems. Pull the dipstick and oil splashes out pretty good. Compression test showed one cylinder at 400 and the otherd roughly around 300psi. Pulled the engine and head off, head gasket looks good, im no expert but cylinder walls seem not too bad, nothing your finger nail can feel anyway and appears to be a bit of crosshatch visible. Pulled one piston out thinking maybe a broken ring but they were all intact. You could squeeze them in with two fingers though. End gap on the first ring was fine, end gap on the second was out of spec. But the side gap between the ring and the edge of the groove in the piston was out of spec. Piston should be softer metal than the ring so i am worried even new rings alone wont get that gap back to where it is acceptable and dont really want to fork over the dough for new pistons...I guess my question is how critical is that side clearance of that ring in the groove? If I can get away with slapping new rings and a headgasket in to get another year of two out of this motor i would be very happy. I just cant have it losing oil all over the place and dripping everwhere. Was losing liters a day and everything was a mess. Appreciate your input. Thanks
 
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gatorguy

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Here are some pictures. https://ibb.co/phVjV73 https://ibb.co/VtvFvjv https://ibb.co/MRRzFWw
 

foton

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Here are some pictures. https://ibb.co/phVjV73 https://ibb.co/VtvFvjv https://ibb.co/MRRzFWw
the end gap sets your ring tension to the block so it is very important, have you checked on finding a engine rebuilder and try doing a exchange deal? Since you have it out I would not go half way with a rebuild do it right or do a exchange vs having to do it again in a few years, your call.
 
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gatorguy

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the end gap sets your ring tension to the block so it is very important, have you checked on finding a engine rebuilder and try doing a exchange deal? Since you have it out I would not go half way with a rebuild do it right or do a exchange vs having to do it again in a few years, your call.
No i havent checked, not sure who around here would be interested. Atleast one of the other pistons has a broken ring and has .013 side gap clearence in the grooze which seems excessively out of spec from the max .005. Unless new rings are quite a bit thicker lookw like i might be on the hook for new pistons. Getting quotes looks like $1200(CAD) for Rings, pistons and a headgasket. The Kumar bros reviews look pretty bad so maybe best to stay away from them for precision engine parts... Found a guy locally who has a v2203 in a wrecked reefer he may want $800 for so I will probably check that out and see if that makes more sense.
 

foton

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No i havent checked, not sure who around here would be interested. Atleast one of the other pistons has a broken ring and has .013 side gap clearence in the grooze which seems excessively out of spec from the max .005. Unless new rings are quite a bit thicker lookw like i might be on the hook for new pistons. Getting quotes looks like $1200(CAD) for Rings, pistons and a headgasket. The Kumar bros reviews look pretty bad so maybe best to stay away from them for precision engine parts... Found a guy locally who has a v2203 in a wrecked reefer he may want $800 for so I will probably check that out and see if that makes more sense.
I have read that the 1902 is a safe swap you will have to watch out for overpowering the machine if you go the 2203 from what I have read and it seems to be logical thought.
 

Tazza

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I have read that the 1902 is a safe swap you will have to watch out for overpowering the machine if you go the 2203 from what I have read and it seems to be logical thought.
Keep looking for pistons and rings, ebay had them for less than that.
Ideally you should measure the bores to check they are still in spec, but you said that the compression in one cylinder was 400 PSI i'd think they'd have to be close. A set of pistons and rings should make it happy again, not perfect as the bearings haven't been done.
I can't send listings from Ebay, as it's only showing ones that will ship to me in Australis.
I rekon you should be able to get pistons, rings and a head gasket for under $500, there is nothing wrong with non genuine parts.
 
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gatorguy

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Keep looking for pistons and rings, ebay had them for less than that.
Ideally you should measure the bores to check they are still in spec, but you said that the compression in one cylinder was 400 PSI i'd think they'd have to be close. A set of pistons and rings should make it happy again, not perfect as the bearings haven't been done.
I can't send listings from Ebay, as it's only showing ones that will ship to me in Australis.
I rekon you should be able to get pistons, rings and a head gasket for under $500, there is nothing wrong with non genuine parts.
Thanks, i actually ordered rings and a headgasket the other day from a local company for about $550. Should be here in a week or se. Ill get them and measure them in the grooves of my old pistons. Yes there was set from Kumar Bros for cheaper but they have horrible reviews and people comaining about them sending parts for the wrong engine and not standing behind it so i figured that wasnt a good idea. Not feeling and slop on the bottom end, but thats judt by feel????
 

Tazza

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Thanks, i actually ordered rings and a headgasket the other day from a local company for about $550. Should be here in a week or se. Ill get them and measure them in the grooves of my old pistons. Yes there was set from Kumar Bros for cheaper but they have horrible reviews and people comaining about them sending parts for the wrong engine and not standing behind it so i figured that wasnt a good idea. Not feeling and slop on the bottom end, but thats judt by feel????
Feeling for play alone will not tell you 100%, but with that said, years ago, I got 3 partial engines, I made one out of all three. I measured the bores, and gave them a hone. I did nothing else to the bottom end other than a good clean.
It did get new pistons and rings, this engine ran better than any that I built from scratch.
Injector pump wasn't touched, the injectors were pulled apart and cleaned.
People will say do the job right, but it is your call if you feel it's worth spending the extra money on it or not. I have slapped new rings on old pistons from my wife's car, I actually didn't measure side gap on them, but the engine ran flawlessly till the day we didn't bother renewing the registration.
 

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