I have a Kubota v1505 in a mini ex that I’ve been working on. It began blowing smoke out the breather tube then after idling for 30 minutes it started to blow heavy smoke and loose all power, then had zero compression. I replaced the piston rings, head gaskets and glow plugs. I can’t for the life of me get it to fire off, even off a shot of ether. I bled the fuel system, I know kubotas can be a pain but this is the worst. It was hard starting prior to the total loss of compression. Cylinder walls and pistons looked good when I did the rings. I also checked the electric fuel shut off on the pump and it’s working. Any thoughts to get it to run?
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Kubota no start after new piston rings and head gasket
- Thread starter MrFritsch
- Start date
Did you check the spark plugs?
Just kidding.
Have you tested compression after the rebuild?
I was welding on a thumb and had it idling when I was working, I looked back and it was smoking out the driveway. I thought it was on fire but it lose all power then wouldn’t restart. I did not brush it, I just checked the walls for scoring all seemed good. I didnt check ring gap either…
Truck Shop
Senior Member
Truck Shop
Senior Member
air.
Do you remember where the earth clamp was?
The damage current can do is amazing. Always connect clamp directly to the components being welded with paint removed.
The cylinder wall cant be glazed or polished. The rings wont seal.
Ring gap is important to measure. It may of had an oversized pistons put in previously.
The damage current can do is amazing. Always connect clamp directly to the components being welded with paint removed.
The cylinder wall cant be glazed or polished. The rings wont seal.
Ring gap is important to measure. It may of had an oversized pistons put in previously.
I had the ground clamp right on the thumb less than a foot away from the welds. I have a feeling I’m going to be removing the pistons and deglazing the cylinders and checking the ring gap. The piston had STD stamped in them and I ordered std rings so hopefully they were good. I’m a backyard or farm mechanic as we say around here that only works on my own farm machinery and trucks
Truck Shop
Senior Member
If compression is that low bypassing rings--with oil fill cap removed it should be a major
huff of air. Chrome rings need a honed cylinder wall, old cast rings will seat on a glazed
bore. Are the valves set correctly to firing order. Are the valves opening at the correct
valve timing.
huff of air. Chrome rings need a honed cylinder wall, old cast rings will seat on a glazed
bore. Are the valves set correctly to firing order. Are the valves opening at the correct
valve timing.
Maybe its spun a key on the crank or something to put timing out.
Pull glow plugs and rocker cover and check timing.
Wind crank over until no.4 rockers overlap. Timing mark should line up on front pully and piston should be at top of stroke.
Pull glow plugs and rocker cover and check timing.
Wind crank over until no.4 rockers overlap. Timing mark should line up on front pully and piston should be at top of stroke.
clueless2
Well-Known Member
If there is smoke in the crankcase, you have a major problem with the overhaul.
Did you stagger the piston ring gaps when you put the rings on the pistons ?
Even if the timing is off there should not be any smoke in the crankcase.
The new head gasket could be your problem.
Did you have the valves ground and have the head magnafluxed ?
Something bad happened before you overhauled it.
Engines don't go from a running condition to no compression on a restart.
New piston rings aren't going to fix it. IMHO
Kubota engines are famous for wavy liners. New rings on wavy liners will not work. By the time they seat…..if they even can, the ring gap will be too large and cause compression loss. You are dealing with compression loss before it even runs.
So stupid question. If you don’t have an adapter, how did you check compression the first time and know there was none?