Blowing oil out of breather

Forest#2 said:

It appears this would be a good engine to get familiar with your leak down tester. Not likely but A bad breather valve can cause such.
My OTC has saved me lots of time, especially not having to do a take apart inspection, such as worn rings, leaking valves, and quickly determining if a engine needs to be salvaged for possible parts vs repairing.
I think sometimes when first getting familiar with a leakdown tester people try to use too much air pressure during the FIRST TEST.

Since you already know this engine is a smoker, would be interesting to me too see if the leakdown shows leakage past the rings.
Sometimes too much oil on the rings or cylinder wall (from a severe oil burner) will not give a true really bad leakage but will indicate marginal. (because the oily bore raises the compression)
I give the cylinder a flush with carb cleaner or gas to flush the oil and re-test.


On OHV engines I disable the valve train so as the valves never open and do a leakdown of the complete piston travel, instezad of just doeing the leakdown at TDC. (as suggested by StarTech) This also help get the bore less oily for a leakdown.

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So I pulled the head and found a lot of carbon around the exhaust valve. I cleaned up the valve heads and the beveled surfaces of the valve and the valve seats. I suppose I could have tried to remove the springs and lap the valves but I didn’t want to mess with pulling the breather as it always seems like I tear the breather gasket…anyway it seemed like the valves were seating well and there was no scoring of the cylinder walls. I put the head back on and hooked up to my Harbor Freight Leakdown Tester and it would not show any reading on the Leak gauge. I think I bought it 7-8 years ago and never used it. I did have 100 psi on the inlet side and as I moved the flywheel I could hear the air leak from the intake side and when rotated closed the leaking stopped. Same thing with the exhaust side when rotated to close the exhaust valve the leaking seemed to stop. I had to charge the battery overnight so the next day it started right up and I let it run for 20 minutes. I had a little smoke when I first started it and it stopped after a few minutes and ran pretty much smoke free after that? I did not have the oil saturated air filter on the engine would that make a difference? I placed my finger over the outlet of the breather hose where it connects to the base of the air box and I could feel a steady flow iof air but no smoke or oil spitting from the breather like I had a few days earlier. I was not able to put a full load on the engine (mower engaged) since the mower belt is broken. I will get a belt and an air filter installed and check it under load. I really want to learn how to run a Leakdown test and I have a new tester on order. The one I have is a US General stock number 94190. I think I paid less than $25 HF no longer carries the US General branded items and now sells a Maddox branded version for $84.95. I have noticed that HF has developed a dozen or more brands trying to do a Good Better Best and charging a whole lot more than their Pittsburgh brand and often the items are virtually identical! I suspect that Sears closing created a lot of opportunity to raise prices.

Anyway I am wondering if there could have been a lot of oil gas mix in the breather and muffler that would explain the smoking and oil spraying out of the breather hose
Spit

The things you were inspecting is one good reason to do a LEAK DOWN TEST FIRST.
You will reach for your new leak down tester quite often when you start playing with engines.

Like I mentioned most people at first inject to much air pressure when getting familiar with a leak down tester.
Do tests in increments of like 40, then 60, 80, etc. Also use your ears as well as watching the leak gauge.

Make sure your oil is not thinned out from gas contamination.
This will produce smoke for awhile until the rod turns loose.

Forest#2 said:

The things you were inspecting is one good reason to do a LEAK DOWN TEST FIRST.
You will reach for your new leak down tester quite often when you start playing with engines.

Like I mentioned most people at first inject to much air pressure when getting familiar with a leak down tester.
Do tests in increments of like 40, then 60, 80, etc. Also use your ears as well as watching the leak gauge.

Make sure your oil is not thinned out from gas contamination.
This will produce smoke for awhile until the rod turns loose.

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Thanks for the reply. I am looking forward to mastering the Leakdown tester. One question I have… how do you recommend positioning the piston to TDC on a L head engine…and then anchoring it onto TDC.
I saw a video that advised using vise grips on the engine output pulley. There was definitely too much pressure with 100 psi on the piston to hold the flywheel by hand. I am a novice and would benefit from your experience on this.

This engine is a vertical 12.5 HP Briggs and it has the common double stacked pulley… top for transmission and lower for mower deck. I’m just asking what methods to prevent the engine from rotating you recommend

Spit

Cfs said:

I am helping a neighbor with a 12.5 hp Briggs vertical engine 289707 1179E-3 020503ZD. It is a single cylinder L Head design. It does not have a Nikki carb.

The engine had no oil to speak of when I first checked it. The oil sump was full of gas. I drained it out and refilled it with oil. I dropped the bowl off of the carb and cleaned the needle & seat and the float, I installed some new fuel line and a shut off valve. I had to jump it to get it started. Once it started it smoked like mad. I hoped it would stop smoking thinking the muffler had old gas and oil in it I had noticed that the air filter was saturated with oil when I had it off to clean the carb and I blew it out with my aidcompressot. The engine started to run rough so I shut it down. Checked the spark plug and cleaned it put it back in and it would not start. Remembering how the air filter looked I removed it and started and ran it with filter off. Started right up but after a few minutes it was blowing oil mist and oil out of the hose from the breather to the bottom of the air filter box. It was getting worse the longer it ran with no filter in it to catch the oil.. it started to look like Mt St Helen’s bad head gasket? Oil breather? Engine ran strong

Help?

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Leakdown test is a good idea. First thing I'd do is run a compression test. Quick and easy. I'll guess more folks have a comp tester than leakdown. You shouldn't bother working on small engines if you don't have a compression tester. I expect it'll be low, which is in line with other replies of broken rings, bad head gasket or valve guide leakage. I'd expect just about anything inside an engine with the mess you described. Love the comment "good learning experience"! So true especially since the engine is a neighbor's and you're doing them a favor. The worst that can happen is you eventually tell them the engine is not worth repairing and there's no charge for that info ;-)

When I dd my 1st and last leak-down test, I brought the piston to TDC. When pressure was applied, it would rotate the engine either CW or CCW, never knew which. I could not stop it from rotating even with a pipe wrench on the lower pulley\shaft. What's the trick?

Freddie21 said:

When I dd my 1st and last leak-down test, I brought the piston to TDC. When pressure was applied, it would rotate the engine either CW or CCW, never knew which. I could not stop it from rotating even with a pipe wrench on the lower pulley\shaft. What's the trick?

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Is why use a low pressure setup. The HF one only uses 15 psi to get to the full scale set mark. With it I can hold the flywheel with one or rotate it TDC to BDC and back. With it on OHV engine I can use it to check the full stroke but is still limited to TDC on L-heads. I seen several engine to pass the TDC test but fail anywhere from mid stroke to BDC.

Cfs said:

I am helping a neighbor with a 12.5 hp Briggs vertical engine 289707 1179E-3 020503ZD. It is a single cylinder L Head design. It does not have a Nikki carb.

The engine had no oil to speak of when I first checked it. The oil sump was full of gas. I drained it out and refilled it with oil. I dropped the bowl off of the carb and cleaned the needle & seat and the float, I installed some new fuel line and a shut off valve. I had to jump it to get it started. Once it started it smoked like mad. I hoped it would stop smoking thinking the muffler had old gas and oil in it I had noticed that the air filter was saturated with oil when I had it off to clean the carb and I blew it out with my aidcompressot. The engine started to run rough so I shut it down. Checked the spark plug and cleaned it put it back in and it would not start. Remembering how the air filter looked I removed it and started and ran it with filter off. Started right up but after a few minutes it was blowing oil mist and oil out of the hose from the breather to the bottom of the air filter box. It was getting worse the longer it ran with no filter in it to catch the oil.. it started to look like Mt St Helen’s bad head gasket? Oil breather? Engine ran strong

Help?

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Check compression. Low compression could mean bad rings letting oil to piston. If it ran with gas for oil, then it could have ruined the rings and causing them to now smoke permanently.

Freddie21 said:

When I dd my 1st and last leak-down test, I brought the piston to TDC. When pressure was applied, it would rotate the engine either CW or CCW, never knew which. I could not stop it from rotating even with a pipe wrench on the lower pulley\shaft. What's the trick?

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Put a break over bar with socket on flywheel nut.

Vertical shaft tells me a push mower. A new engine will cost more than a new mower. Unless you just want to tinker with it. It is your time and money! That much gas in the crankcase tells me the needle valve in the carburetor is leaking gas right down the intake manifold and into the engine when the engine is shut down.