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Crankcase vent pumping oil into air filter

Posted by rboone7760 none (My Page) on
Wed, Jan 1, 14 at 14:11

I have a 16 HP B&S in a cub cadet 582. I had gas in the oil due to a faulty carb. I changed the oid and rebuilt the carb.The problem now is if the oil level is in the upper reagon on the dip stick, oil is coming out of the crankcase vents. It seams that if the oil level is in the lower range the oil does not come out. This did not happen before the gas in the oil.


Follow-Up Postings:

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RE: Crankcase vent pumping oil into air filter

In addition to "fixing the carb", did you add an inline fuel shut off valve and always cut off your fuel when you are not running the engine?
If you do not have and faithfully use an inline cut off valve, you may still be getting a bit of gas into your oil.
Any amount of gas in the lube oil will cause some flow of oil out through the crankcase vent as the volatile gas boils out of the lube oil when the engine warms to operating temperature.
So, if you ain't using a fuel shut off valve, you ain't in full control of your fuel supply.


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RE: Crankcase vent pumping oil into air filter

I have a fuel cut off at the fuel tank but was difficult to reach, I am using it now. There does not appear to be any gas in thr oil now. The engine is still pumping oil into the air cleaner if the oil level is in the upper range on the dip stick.Any suggestions?


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RE: Crankcase vent pumping oil into air filter

This might be due to some wear to the rings during the time before you actually found that gas was getting into the crankcase.
If a carb suddenly drowns an engine in gasoline where it never did before.......we might attribute that event to a piece of trash getting caught in the needle and seat of the carb.
Those events generally alert the operator of a defective condition and the operator will probably try to get the defective condition taken care of right away (hopefully).
But in cases of a needle valve beginning to leak because of accumulated wear to the needle and/or seat, the presence of SOME gas in the oil may not actually be noticed.
Even small quantities of gasoline diluting the engine lube oil will accelerate wear.
Let me say this about how the presence of a small volume of gas in an engine might go undetected.
A carb has leaked a small volume of gas into the lube oil.
Operator checks the oil lever before using the machine and is happy to see that the oil level is at or slightly above the spec level.
Operator begins using the machine and the engine warms up, vaporizing the gas and this vaporizing makes pressure which is vented out through the crankcase vent, carrying a bit of oil with it. This all happens within a few minutes of starting, and so.........you thought you had enough oil in the engine before you started it, but now a few minutes later......the engine is operating with less than the right oil volume.
After you are done with the machine you park it and head off to other things, leaving the fuel system to its own whims and so whatever left over gas is in the tank begins to leak into the engine, artificially raising the oil level as it does.
Next time you use the machine, you MIGHT notice that the oil is just a bit low (not realizing that a portion of what you are reading on the stick is gasoline). So you add a bit of oil and off to mow again.
Once again, in just a few minutes, the gas is boiled off and the oil is low again.
Repeat this often enough and you have achieved some serious wear to piston rings and that might be why the engine seems to use more oil, and vent more out the crankcase vent.
It is very much a type of vicious circle.
For staying in touch with with the health of an engine the oil should also be checked and noted after a hot shut down as well as before a start up.
People who do not have and use a manual fuel shut off valve with a gravity fed fuel system may never be aware of oil dilution caused by leaked gasoline.
In this specific thread, the subject engine may be showing the results of ring deterioration due to insufficient lube/cooling of the rings by the diluted oil.


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RE: Crankcase vent pumping oil into air filter

Is this an opposed twin? External oil leaks as well? Model and spec numbers may be good.


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RE: Crankcase vent pumping oil into air filter

Yes, it is an apposed twin, 16 hp in a cub cadet model 582.
The engine s# is A-314357. I was told that mfg. date was 1979. there is not any external leaks and no exshust smoke prior to the gas oil issue. It seems to run good, with no oil pumping, if the oil level is near the add mark on the dip stick. I would not like to run at this oil level but I do not want to ruin another air cleaner. Any help or suggestions would be appreciated.


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RE: Crankcase vent pumping oil into air filter

Engine should be a-
"Briggs 401417 or 402437"
per Small Engine Warehouse

http://www.smallenginewarehouse.com/Repower-Old-Equipment/


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RE: Crankcase vent pumping oil into air filter

How much run time do you have on this since the fuel issue was repaired? Bill likely has the correct model, but it does help the supply the correct engine info. Breathers on the horizontal op twins were on top the engine. An older one like yours should have 2. Mownie's thoughts of developing worn rings have merit. One other thing that happens when fuel is introduced in an older engine is the fuel can act as a cleaning solvent. Could it be possible that the problem lies with in a breather that can drain back and doesn't have choice but to pump oil vapor? Older less pliable seals may not seal quite as well after being washed down too. I've also seen on horizontal Vangard engines that even a missing dipstick seal will cause them to start pumping oil from the breather. While yours is a different animal, I would still look it over well for potential new external leaks and check the breathers best you can. I don't recall if these even really came apart, you just cleaned them up best you could and checked for a bad reed I think. Drain back holes in the block? It may get you no where, but start with what is simple. Before you get real far into this, parts on these that are available get less and less as the years go by.


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RE: Crankcase vent pumping oil into air filter

Thanks for all the advice. I saw in an older thread, a problem similiar to mine. The suggested problem was probably caused by a defective or stuck crankcase vent valve. How difficult would this be to check or fix, any suggestions.
Thanks.


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RE: Crankcase vent pumping oil into air filter

.045" is roughly equal to 3/64", which is the wire diameter of a standard size wire paperclip. For those who do not own wire spark plug gauges :^)


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RE: Crankcase vent pumping oil into air filter

Would that be the made in USA paper clips or imports? Constantly amazed by you mownie :)


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RE: Crankcase vent pumping oil into air filter

Can the breather valves be rebuilt or do they have to be changed? I have looked online and cannot find a replacement part.


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RE: Crankcase vent pumping oil into air filter

http://www.jackssmallengines.com/Parts-Lookup/495755/311197/ps

http://www.jackssmallengines.com/Parts-Lookup/393153/2658348/PL


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RE: Crankcase vent pumping oil into air filter

***"USA paper clips or imports"***
LOL...I hope they are all about the same.
I compared my wire type .045 spark plug gapper to a paperclip and I could not tell a difference except with a micrometer, and even then it was more like "tight fit" versus "loose fit".
So then I did a search to see if there was any kind of standard and it seems that 1mm is pretty much the paperclip. The Briggs spec is .045" or 1.14mm.
Anyhow, my spark plug wire gauge is different than the style shown by Briggs. Mine is actually a disc of metal with several wires of different diameters. Each piece of wire is bent into a sort of "3 sided squared loop" and the free ends of each loop are soldered onto the flat surface of the disc edge with the loops sticking off the edge in open space.
I think the idea in this design was so you could carry it in a pocket without getting poked. Of course the Briggs type folds into a shielding case like a pocket knife for the same reason.
Of course you can do things with the Briggs type that you can't do with mine, like check the breather disc clearance and get a rough idea of a jet size or other hole.
But I like my antique wire gauge for sentimental reasons.


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RE: Crankcase vent pumping oil into air filter

"Would that be the made in USA paper clips or imports? Constantly amazed by you mownie :)"

They're probably made in China and assembled in Mexico.

Paper clips DO come in different sizes. I had a couple very large ones laying in my junk drawer.


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RE: Crankcase vent pumping oil into air filter

Well, the paper clips for my PDF files just aren't up for this task.....


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RE: Crankcase vent pumping oil into air filter

I would like to thank everyone for their help. I was convinced that the crankcase vent valves were the problem. It finally warmed up enough today to start the engine. I felt that one side surely had more air venting, however they seemed the same, a steady light air flow.The oil level was in the lower section of the dip stick.If I had added oil up to the upper level it would have pumped the extra oil out.Does it seem likely that both vent valves went bad at the same time. The engine did not run with the oil/gas mixture. Do you think that I should change both vent valves or take it to someone that knows more than me?


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RE: Crankcase vent pumping oil into air filter

Whether or not you pay someone to do this, it may be worth your while to have a look. I don't really recall if there are small oil return holes that may have been able to be plugged or not on a horizontal. If there is a breather defect, it wouldn't necessarily need to be both. Maybe as a test, you could insert additional hose inside the breather tubes, feed each one into a separate remote container and see if one really is putting out much more than the other. Top off the oil and run it good and warm if you feel you can safely do so.


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RE: Crankcase vent pumping oil into air filter

Thanks for the suggestion. I added oil, hooked a line into each vent valve and vented into a clear plastic bottle. Both vent valves discharged oil into the bottle.
I saw somewhere that worn piston rings could cause excessive pressure in the crankcase causing oil to discharge into the air filter. I do not have the eqpt to check the compression. The engine is old but has less than 400 hours. This discharge did not occur until the oil/gas mixture.I could change the vent valves but I could not be able to rebuild the engine myself.
I want to save this mower any suggestions would be appreciated.


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RE: Crankcase vent pumping oil into air filter

If this was brought to a shop, they would confirm the oil integrity- making sure it is staying fuel free. Do a physical inspection for external leaks which may indicate that the crankcase is also drawing air in through a leaking seal etc. plus inspect the breathers. My guess is if they did a manometer test, it would show crankcase pressure. From there it goes inside. Mownie eluded to possible ring issue earier and he could very well be right. If the engine damage isn't fatal, it becomes a game of parts availability and moula. Hope this brings some perspective to you.
On a personal note, I like the Briggs op twin engine. Lots of usable torque that you won't get with an Intek that has a 16 HP sticker slapped on the top. Unfortunately, you really have to know what parts are needed and available to do an out of ordinary repair. I work on many of the vertical shaft engines- to less and less each year. Not so many of the horizontals. Maybe a replacement engine is available in a mower bone yard. A similar engine on a chassis for cheap. Depends on your commitment to this project in the end I guess. Keep us in the loop for sure on this.


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RE: Crankcase vent pumping oil into air filter

Thanks, you have given me someting to think about. What should an engine rebuild cost. I do think that the crankcase is leaking because i keep the mower in the garage and have never seen any oil leaks.If replace the exsiting engine , what would work? Where would I look for one? This is a model 582 built around 1980, the next more expensive models 682 and 782 are the same frame but with a 17 HP Kohler. Should I go for an upgraded engine?My commitment to this project is the mower is right when completed. I am not sure of the best way to get there. I feel like I am rambling because I usually know which way to go but not now. Any guidance would be appreciated. I wish that I could set down with you and make a plan. Price is always a concer but in this case not the primary one.
On another not what would a Cub Cadet model 982 that has not run 5 years be worth. I know without seeing it would be difficult,asking 1000.00
I need to address my current problem first.


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RE: Crankcase vent pumping oil into air filter

The Kohler Magnum Op twin is great engine. My guess is it wouldn't exactly be plug and play , but could be a doable transplant. Old Sears tractors had these as well as the Briggs OT . If you feel that the issue is internal, a good running used engine could be an affordable option. You simply need to start at the beginning and set realistic goals for the steps along the way. A shop that currently is in a less busy time of their year that you could trust would be a great asset to you. You will find that shops do not rebuild engines much anymore due to costs involved. If you find a shop that will have a look and has experience with these- maybe they can give a better idea cost wise. Cleaning her up refreshing the rings, resealing it etc. maybe in budget vs machine shops , oversized pistons, new valve guides and I shudder to think. That is IF parts are available. You may post your engines proper model, type and code from the shroud and I can certainly look up parts limitations in these regards. It would be great thing in my estimation to also prepare for the unexpected. Bolts that break, clutches that don't want to come off etc. I broke 3 mounting bolts off an OT which I carefully extracted as a replacement sump was NLA as an example.


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RE: Crankcase vent pumping oil into air filter

The current engine is 401417 0145 01
The tractor no. 2050592U677127.
I will look for a good shop that I feel that I can trust.
Thanks


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RE: Crankcase vent pumping oil into air filter

Sample availability. Breather numbers are #2 Cyl breather 393153 NLA and #1 cyl breather 393243 - $28 list. 27803s are the gaskets (x4). I'm guessing that the intake manifold may need to come off to access breathers 692219 are the intake gaskets (x2). 495868 is the complete gasket set $47 list. If it comes down to it, standard and .020" oversized pistons and rings are still in the system.
In the world of the internet, you probably can find the NLA breather if you need it. Just know many vendors list parts that they don't actually stock, so a phone call is best. Google is your friend. You can also likely find an online service manual if you find you need to check this out yourself. But yes, finding a shop that will work for you may relieve some of the stresses from this situation!


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RE: : Crankcase vent pumping oil into air filter

Any diagnoses yet on this?


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RE: Crankcase vent pumping oil into air filter

Why not just pull the heads off and look at the piston/cyl. condition?


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RE: Crankcase vent pumping oil into air filter

I finally realized that I had checked everything that I could.
My old Cub Cadet is in the shop. They think that it maybe a crankcase leak , I could hear a whizzing noise from the engine that was not there before. They are also going to check the compression. I will report back to the forum when the problem is fixed. Thank everyone for their suggestions.


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RE: Crankcase vent pumping oil into air filter

I just received a call from the shop. The cylinder is scored.They said that they maybe could find a short block or a good used engine but since the engine is so old and a shaft drive it may be hard to find. Any suggestions from the forum.


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RE: Crankcase vent pumping oil into air filter

There are oversized .020? pistons available yet. Shortys, replacement blocks or engines are NLA new anyways. It would be nice to walk into a used one with lots of life left.


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