Kubota V1702 Valve Clearance

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Tazza

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Ok, as the thread name states, i have a 743 with a Kubota V1702 engine that i fiddled with today. It has never started as easily as i believe it should. I checked the head bolt tension and most of them required 1/2 or more of a turn to reach tension. I had a quick look at the valve clearance and they seemed to be out, so i got the feeler gauge out and they were indeed out, not by a little, but ALOT as in so far that you loosen the adjusting screw and you see the valve spring move. Most were close but 2 or 3 you could see the spring move.... After setting them up as per the book, it started up but there is a funny noise at medium RPM and under load it blows a fair bit of black smoke, almost like 1 pot isn't firing, but this would usually be white if that was the case rite? I removed the tube line to no1 injector and turned the engine over till it spurted fuel out when it hit TDC, so i knew the firing sequence after that. The book says .007- .009so i went .008

I haven't put a compression gauge to it yet, i need to borrow one. With how loose the head bolts were, i would guess it may have cut the head gasket between pots. I do have a spare gasket that i can use.

Also, just how much blow-by do these engines usually have? this one seems to blow a fair amount of air out the breather tube.... It starts without problems if you glow it for 30 seconds on a 30 degree C day.

Any comments or ideas? (other than the usual, your an idiot, you should have left it alone....)
 

goodtech

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It has been a while since I have adjusted valves on a 1702. The engine may just have a weak cylinder in #1 which may or may not blow smoke. You say you have alot of blow by, your rings may be worn, or the cyclinder walls are tore up up. This is very common when these 1702 over heat. Most people just throw a new head gasket on them and take back off. but all you blow by is coming from the worn rings or cylinder walls. As for the head gasket bolts I would of left them alone. I have learned on these kubotas if they are running, let them run till they die, otherwise you end up where you are, with a bigger headache then where you started. Run a compression test on it, I bet you find your compression low, if it is, I would run till she dies, you would be amazed on how long some of those low compression engines run. Good luck. Now you see why I said something about your hydrostat. good luck
 

Tazza

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It has been a while since I have adjusted valves on a 1702. The engine may just have a weak cylinder in #1 which may or may not blow smoke. You say you have alot of blow by, your rings may be worn, or the cyclinder walls are tore up up. This is very common when these 1702 over heat. Most people just throw a new head gasket on them and take back off. but all you blow by is coming from the worn rings or cylinder walls. As for the head gasket bolts I would of left them alone. I have learned on these kubotas if they are running, let them run till they die, otherwise you end up where you are, with a bigger headache then where you started. Run a compression test on it, I bet you find your compression low, if it is, I would run till she dies, you would be amazed on how long some of those low compression engines run. Good luck. Now you see why I said something about your hydrostat. good luck
Well, i was told i should check the head bolts after a few hrs of operation to make sure they are still rite, this person wasn't a mechanic though (he was in his own mind).
It always did have a bit of blow by, especially under load it choofs a bit of smoke out of the breether tube. I will hopefully borrow a compression tester this week and check it out. The compression can't be too bad, as it does start with a 15-30 second glow. Wouldn't worn rings or a scored bore cause the oil to go black quickly as carbon will be passing by the rings? the oil is still a nice honey colour, only slightly brown.
Hopefully i can get it running reasonably soon, i don't want to keep this machine, i'm in the process of re-building another one this one is going to be used as a guide of where bits go.
So, what should i do on the engine i re-conditioned (for use in another machine), should i just leave the head bolt torque where it is or check after it has been run in? It too took about 15-30 seconds of glowing to start (i have only run this engine for about 3-5 mins), but i have been told the compression will be lower untill it has had a chance to wear in, then it will be good.
 

Tazza

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Well, i was told i should check the head bolts after a few hrs of operation to make sure they are still rite, this person wasn't a mechanic though (he was in his own mind).
It always did have a bit of blow by, especially under load it choofs a bit of smoke out of the breether tube. I will hopefully borrow a compression tester this week and check it out. The compression can't be too bad, as it does start with a 15-30 second glow. Wouldn't worn rings or a scored bore cause the oil to go black quickly as carbon will be passing by the rings? the oil is still a nice honey colour, only slightly brown.
Hopefully i can get it running reasonably soon, i don't want to keep this machine, i'm in the process of re-building another one this one is going to be used as a guide of where bits go.
So, what should i do on the engine i re-conditioned (for use in another machine), should i just leave the head bolt torque where it is or check after it has been run in? It too took about 15-30 seconds of glowing to start (i have only run this engine for about 3-5 mins), but i have been told the compression will be lower untill it has had a chance to wear in, then it will be good.
FIXED!!!
It seems i set the clearance incorrectly, i worked it by setting no1 on TDC then rotated the crankshaft 360 degrees then set 3, then 4, then 2. This just didn't match with when the injector was squirting, so i rotated the engine to when each injector squirted then set the clearance and it works just fine now. But the engine i built i'm sure i set it the exact same way, it worked just fine so i am totally stuffed......
Compression is:
1 - 350
2 - 320
3 - 300
4 - 290
By those figures, it isn't all too happy but it still works. I'm not sure if it was because the battery was going flat or not. It seems like it is using water so i do think the head gasket has gone or worst case the head has a crack....
 

goodtech

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Nov 22, 2005
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FIXED!!!
It seems i set the clearance incorrectly, i worked it by setting no1 on TDC then rotated the crankshaft 360 degrees then set 3, then 4, then 2. This just didn't match with when the injector was squirting, so i rotated the engine to when each injector squirted then set the clearance and it works just fine now. But the engine i built i'm sure i set it the exact same way, it worked just fine so i am totally stuffed......
Compression is:
1 - 350
2 - 320
3 - 300
4 - 290
By those figures, it isn't all too happy but it still works. I'm not sure if it was because the battery was going flat or not. It seems like it is using water so i do think the head gasket has gone or worst case the head has a crack....
Well tazz that is a common problem. People are usually 180 degrees out on those kubota's, I'm glad that you found the problem. Some engine manufactures require you to retorque the head bolts on a motor after like 10 hrs of running after a rebuild. If you are loosing water fetch yourself a psi tester and see where that water is going, I hope that head isn't cracked for you, they are spendy from bobcat or a kubota dealership. I would leave your compression alone that isn't to bad on kubota engine with alot of hrs. I would find your water leak get that baby running so you can sell her. Good luck
 
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