Iseki TS1610F - Oil gushing from breather cap

[larso1]

Thanks again for the suggestions guys,

The dipstick does screw down, and has a tight seal. I assume this is because these diesel crankcases do pressurize some (according to my mechanic buddy they all have some blowby), and the dipstick is right down there at top of oil pan level. I did check the dipstick oil level when this first happened. And yes, oil pushed out from the dipstick well too. The oil level sat there high at the opening for about 30 seconds, then you hear a gurgle sound and it falls back to normal level. Definitely pressure in the crankcase that isn't getting out. I suspect oil filling the pushrod tunnels finally drained back down into the sump and the excess gas pressure in the crankcase is then allowed to exit up the same path. I think I will, as you suggest, try cleaning out the pushrod tunnels before I do anything major like pulling the head. But I think I will need to remove the oil pan, and therefore the front drive shaft, first to see what's going on from that end too. Thanks again. Keep 'em coming if you have any more of these good ideas. If this thing has a crankcase vent, I'd sure like to know about it. That would be the problem for sure. I'll let you all know how things go as I get into it.

Bill in CO

 

[skent]

Check your Relief valve specs. Seems to me your oil pressure is running on the high side. most run in the 30's.

Oil pump is designed to provide adaquate flow/pressure at idle speed. At higher speeds, pump delivers more so pressure is higher, so relief valve is there to dump the excess.

I had a Opel GT that had a clogged Relief valve. When I added a Mechanical Oil Pressure gauge under the dash, It was always pegged past 80 until the engine was completly warmed up and idling, then it would drop to high 70's. Ended up busting the gauge line (copper tubing) and spraying oil all over the dash. Replaced the relief valve and would hover at 35 PSI forever and a day.

Could be your problem. Let us know.

 

[larso1]

Steve, thanks for responding. I was wondering about that oil pressure. Seemed kind of high to me too, but no-one else has commented on it, not even my mechanic buddy. This idea makes me feel like you're really on to something....it just makes sense that too much oil is getting to the head. I don't seem to have the problem at lower RPM's, but when I wind it up to 2000 or 2500, it's no time before the oil pukes out the breather cap. I will definitely look into this before tearing the motor apart. Thanks again,
]
Bill in CO

 

[larso1]

Further on the topic of high oil pressure, a friend here at worked asked if it was possible if the wrong oil filter could have been installed, or if it might be plugged up. Well, it could have, since a new one was installed on it by the seller when I got it. I don't know what the distribution circuit of the oil delivery system looks like, but seems to me if oil wasn't getting through the filter easy enough, it would just restrict the oil flow to the head, not increase it. On the other hand, if part of the discharge from the oil pump goes through the filter, and part goes to the bearings and head, then it could conceivably cause these problems. Just thinking out loud.

Bill in CO

 

[Kelvin]

larso1,

I can't tell you what your problem is; I can only tell you what my situation was (which sounds similar to yours).

My 3 cylinder 16hp Kubota diesel engine was blowing a heavy mist out of the valve cover breather tube. Then the mist turned to oil droplets, then progressed to a continuous flow of oil. I suppose if I didn't have a breather tube then it would have come out like you describe. My problem was that 2 of the 3 compression rings had gone weak due to a suspected overheat condition from the previous owner.

Similiarties Between Your Condition and Mine:

(1) Indications of good compression on the cylinder(s) closest to the radiator, and indications of weak compression on the cylinder(s) the fartherest away from the radiator.

(2) The engine always started just fine.

(3) The engine seems to run just fine, with seemingly plenty of power.

(4) The apparent "blow-by" got worse as the engine warmed up.

On a side note, I suspect that my overheat condition was caused by the previous owner using 100% antifreeze in the thermo-siphon cooling system (no water pump; no thermostat; otherwise a normal pressurized water cooling system) that's only supposed to have a 50/50 maximum mix.

On the positive side, when I did take my engine apart, the insides were in excellent condition. The engine was left in the tractor; the oil pan and head was removed so that the pistons could be removed. The pistons and cylinder walls were in excellent condition so all I did was replace the rings. I went ahead and rebuilt the head since I had it off (replaced the valve guides & seals, etc). I replaced the rod bearings, but since the crankshaft was left in place the crank bearings didn't get replaced. Overall it seems like I had a little over $1000 total into the rebuild. I had a local automotive shop that I use a lot perform the labor; I'm guessing that the bill would've been $1300 or more at the Kubota dealership.

Hope this helps,
Kelvin

 

[larso1]

Kelvin, thanks so much for the reply. Your situation does indeed sound nearly identical to mine, with the differences being I mine has only two cylinders and the cooling system has a water pump. I understand from a source that 60-65psi oil pressure is what I should expect with these Isuzu enigines. So I probably won't need to woory about main bearinggs either. I am sure hoping that what I find is the same thing you found, i.e., weak compression rings from an oerheat condition. Your cost for the rebuild sounds high if you did the rebuild yourself, minus the head work. Did you replace the rings and hone the cylinders yourself, or did you leave the whole job to the mechanic? My auto mechanic friend will do the head work, but I plan on doing everything else. I figure new rings maybe $100 tops, rod inserts maybe the same, and head gasket maybe $50.00?? I would expect my friend to charge me around $200 for the head work, assuming I don't need new valves.

Bill in CO