Tecumseh 10 HP oil out breather

jbrow1

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Have a an older craftsman ltv10 varidrive lawn tractor with a 10 horse tecumseh on it. Problem is it blows alot of oil out the breather. Currently running without an air filter or the breather hooked up so I can see what's going on, no mowing or driving just runnign the engine. I got the thing from my Dad, and he said it was saturating the air filter with oil. Oil does not seem to be over filled, so I am curious what other things can cause this problem?
 

chance123

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Sounds like over filled oil. It also could be "blow by". This is where the compresson leaks into the crankcase forcing the oil to esxape its only exit, which is the breather.
 

reynoldston

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If you haven't over filled it you could try heavier weight oil. 30SAE or even 40SAE.
 

jbrow1

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I shall try some heavier weight oil. Guess I will also dig out my compression tester, and check the head gasket. Thanks fellas.
 

jbrow1

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Checked the head gasket, it looked rather new, and no signs of being blown anywhere. The cyclinder did seem to have a couple spots that didn't look to good near the top, as in wear spots from somthing, but haven't done a compression check on it yet. Anybody know what compression should be on these engines?

I put a longer hose on the breather and installed a clear fuel filter on it as well. For awhile it did quite well, but I could see smoke coming from the tube. It then started building oil up in the fuel filter that I had put in the line, and smoking quite alot more, as to where I shut it down so I didn't have to breathe it any more. The oil that had filled the filter and tube then must've drained back down to the breather assembly.

Have some other questions, but think I will start a new thread for them as they are about a different subject. This one seems to have run it's coarse.
 

Rivets

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A simple test for excessive crankcase pressure is to start the engine and with it running at half throttle, remove the dipstick and set it on top of the tube. If it jumps around a lot you have to much pressure. Have you checked to see if the breather is bad? Finally, did you replace the head gasket when you checked it?
 

jbrow1

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A simple test for excessive crankcase pressure is to start the engine and with it running at half throttle, remove the dipstick and set it on top of the tube. If it jumps around a lot you have to much pressure. Have you checked to see if the breather is bad? Finally, did you replace the head gasket when you checked it?
I was mowing a bit yesterday with it and the dipstick wasn't screwed in properly (I think it needs replaced) and it began shooting oil all over the place. I took the assembly off and put a simple plug in it for now.

How exactly do you tell if the breather is bad? I did wonder if that part could go bad and cause oil to come out, but it seemed like such a simple part that... well anyhow, how can I tell if it is bad or do I just replace it?

I did not install a new head gasket when I put the head back on. I have taken mower heads off before and reused the old gasket without a problem and didn't think it would matter on this one either. Maybe so.

Funny thing is the engine seemed to work well for about fifteen minutes, then it must've built up pressure as I could see it start smoking more and more, then the fuel filter I had put on the breather line actually filled with oil which surprised me.
 

chance123

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with the dip stick out, it is normal for oil to shoot out. Crankcase pressure is normal, and normally goes out the breather tube via a check valve and because with the dip stick removed, it is larger than the breather tube and is the path of least resistance
 

Rivets

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I my part of the country it is NOT normal for oil to shoot out of the dipstick tube. If you had oil coming out, you have excess pressure in the crankcase. This pressure was so grat that it was causing oil to bypass the greater valve. You said that it ran fine for about fifteen minutes. I think the old gasket lasted as long as it could. With today's overhead valve engines it is never advised to reuse a head gasket. They are too weak to start with. I know that you said it looked good, but i have seen gaskets that show no sign of failure. If I had the engine in the shop, I would do the following. First, replace the head gasket. You must torque the bolts properly, or you may blow it out during the first use. Second, I would remove the breather and clean it throughly. Mineral spirits work, as you can soak the entire breather in it if you don't have a cleaning tank. Don't try to dry it with compressed air, as you can damage the reed valve inside. Shake it out and let it air dry. Reinstall with a new gasket. When you start the engine you should feel it pulsing when you put your finger over the end.
 

jbrow1

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Thanks for the info rivets. I shall order a new head gasket and try cleaning the breather and a new gasket for it as well. The dang engine runs so good I don't want to scrap it. I have another engine for it, but it's just seems like a waste, although I don't want to waste much $$ after a goose chase if the other one fits. A day or two with no kids would do wonders in getting stuff sorted out and working well
:biggrin:
 
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