22hp Brigg Stratton 407777 burning oil

braeburn040(2B/3 BC)March 9, 2013

I have a craftsman y4500 lawn tractor with a 22hp mod 407777 engine its burning and using oil, approximately 250 hrs. proper maintenance given ie oil changes filters etc.
Compression 120 lbs both cyl. plugs oil fouled, crank case ventilator valve seems to be working although oily inside. I don't have a repair manual, is the compression about right?
I'm basically looking for advise before I start tearing it apart. I checked with a local small engine shop. They have a Husky model with the 22hp B&S and they say that problem hasn't shown up yet. I would appreciate any advice. Thanks.

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bill_kapaun

First thing I'd do is smell the oil for the presence of gasoline.
IF the carb is leaking through, it'll dilute the oil to the point that it easily passes by the piston rings and burns.

2. Possible leaking head gaskets.
Have rag handy. Remove 1 valve cover at a time. Start engine and look for "vapor" blowing out on the push rod side of the gasket.

    Bookmark   March 9, 2013 at 2:00PM
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braeburn040(2B/3 BC)

Thanks Bill for the post, I know there's no gas in the oil, I'll try the head gasket test. do you happen to know the compression specs by chance. I should have mentioned the problem isn't constant, ie it doesn't smoke continuely, but on side hills and rough ground its bad.
Chic

    Bookmark   March 9, 2013 at 3:16PM
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bill_kapaun

I don't think they publish compression specs since the various compression release mechanisms small engines use will have an effect.
Leak down tests are typically what's used.

    Bookmark   March 9, 2013 at 5:37PM
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walt2002

B&S does not post compression specs., I suspect head gasket, I can send you a Service Manual IF you like, address below, put in proper format and remind me, model number and what you want.

Walt Conner
wconner5 at frontier dot com

    Bookmark   March 9, 2013 at 7:05PM
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bluemower

here is one idea. Make sure the engine oil is not overserviced.

Park the equipment on a level surface. Make sure all the tires are serviced properly. Check the oil using the dip stick, but make sure the dip stick is screwed down all the way.

another idea is to change the oil and reservice with the correct grade. Recheck for oil consumption.

Consider changing the oil and rechecking the

    Bookmark   March 10, 2013 at 11:04AM
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rcbe(6)

OP - to bluemower's point, just when did your engine start burning oil? Was it just after an oil change or service?

    Bookmark   March 10, 2013 at 2:04PM
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braeburn040(2B/3 BC)

>Bluemowers post I think you are suggesting that I overfilled with oil, I am very careful about that I use 10-30 which is in my operator manual, and when I change the filter I always check and top up after running for a few minutes, It now uses 1/2 pint to a tank of gas.
> rcbe post No I can't relate the problem to a recent service it sort of crept up on me smoking only at times, now its quite bad on uneven ground when mowing.

    Bookmark   March 10, 2013 at 9:31PM
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mownie(7)

I hope you plan to contact Walt and take him up on his offer.
As has already been stated, due to compression release features, a cranking RPM compression test is pointless.
However, a cylinder leakage test using compressed air and the proper procedure can reveal a leaking head gasket much the same as the "wet test" suggested by Bill.
The cylinder leakage test with compressed air is a lot cleaner for the inspector.

    Bookmark   March 10, 2013 at 10:10PM
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braeburn040(2B/3 BC)

thanks for the reply to the post Mownie, Yes I definitely contacted Walt, am now waiting for a reply I haven't acted on Bills reply yet as far as taking off the valve covers and checking for a bad gasket. I'm not familiar with the wet test or the leakage test maybe when I get a manual all this will be revealed. Right now I have the carb and manifold off to check the blow by valve which seems ok to me although it is oily.
Chic

    Bookmark   March 10, 2013 at 10:54PM
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grass1950

The leakage test will cost some investment in eqipment. as you will be putting compressed air in the cykinder. The wet test is free but messy..
By any chance have you recently switched to or from synthetic oil?
You say it is pronounced on rough terrain. Do you mean unlevel where the tractor tips sharply side to side or level land that is just rough, bumpy?

This post was edited by grass1950 on Mon, Mar 11, 13 at 0:34

    Bookmark   March 11, 2013 at 12:22AM
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mownie(7)

Basically, what I call the wet test is removing one valve cover at a time from the the engine and locate the head gasket seam inside the push rod gallery of the head. Identify this seam as being where the cylinder head meets the engine block with the engine not running and shining a bright light into the head.
After you see the spot between the 2 push rods and know where to look, start the engine and watch the same spot. If the head gasket is leaking, you will notice a puff of "smoke" jet out from the cylinder and into the push rod gallery each time that cylinder fires.
If you don't see this on the first cylinder you check, put that valve cover back in place and repeat the procedure on the other cylinder.
Unless you have a source of compressed air to work with you would not be able to do a cylinder leakage test.
If you do have compressed air then you might want to know how to do that. By the way, a "poor boy" cylinder leakage test does not require a full percent of leakage test kit to confirm a blown head gasket (or other defect). It does however, require compressed air and an adapter fitting to put air into a spark plug hole, and a means of holding the engine crankshaft from moving while doing the test.

This post was edited by mownie on Mon, Mar 11, 13 at 10:40

    Bookmark   March 11, 2013 at 2:19AM
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walt2002

While 10-W30 is one of the options listed for B&S engines, SAE30 is still #1 for temps above something like 40 degrees. B&S puts out a note that using multi-vis oil will likely result in higher oil consumption.

For recommended oil, visit the B&S site OR consult a B&S manual, not the mower's owner's manual.

Walt Conner

This post was edited by walt2002 on Mon, Mar 11, 13 at 21:53

    Bookmark   March 11, 2013 at 9:51PM
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braeburn040(2B/3 BC)

thanks grass 1950 for your reply, no I haven't ever used synthetic oil. When I get this problem fixed I think I will take walts suggestion, and use 30 wt. Sitting with throttle full on and riding on my driveway it doesn't smoke with the mower running doing normal lawn cutting angles and rougher ground its pretty bad.

    Bookmark   March 12, 2013 at 7:17PM
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braeburn040(2B/3 BC)

good explanations of both tests mownie, I do have compressed air, but I think I will try the wet test first, the plugs on my motor are smaller threads it seems, it may be harder to find an adaptor, it probably wouldn't be worth it for the one time. My torque wrench registers in foot lbs, and some where I heard 220 inch lbs to torque heads if it turns out I need to. So I'll probably have to buy a lighter wrench if mine won't adjust down.I'll do the tests this weekend if time prevails, I have 24 in. of snow on my lawns, so I've got some time!

    Bookmark   March 12, 2013 at 7:28PM
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rcbe(6)

does the engine smoke more under sudden loads or under rapid deceleration ? smoke color?

    Bookmark   March 12, 2013 at 7:31PM
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braeburn040(2B/3 BC)

to rcbe I guess you mean when I engage the load and release the load of the mower I can't really give you a positive answer, I last used it in October, and I was bagging fallen leaves on a previous cut lawn, so it wasn't to heavy for the machine, but it smoked like "H" the smoke is white to grey not black like an engine running very rich.

    Bookmark   March 12, 2013 at 9:15PM
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Frogmore77

Walt2002 is right about using multiviscosity oil. For small engines used during summer hot months, 30w will reduce oil consumption. The 10-30 is for use in cold weather like snow blowers.

    Bookmark   March 16, 2013 at 9:02PM
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braeburn040(2B/3 BC)

Thank you all for your posts I think I can safely say the problem is probably fixed. I tried the "Wet" test on both cylinders which seemed good. I also changed the oil filter and switched to 30 wt oil. Also did my usual spring tune up ie. new plugs fuel filter, and cleaned and checked air filters, but the single thing which I think may have fixed my problem was the breather valve, and filter under it I had swished out the filter in solvent, and gently blowed dry with air, they looked good at the time but I replaced each any way. After all that I started up and ran till engine was good and hot and took for a burn (on the snow covered drive) engaged the mower on and off so far no smoke, the oil consumption I'm not totally sure, but I think the 30 wt will help that. I took the crank case filter under the reed valve assembly apart, and there was a wafer of a shellack substance in the centre that didn't allow proper (or any) air flow from the reed valve to the crank case (my theory) any way every thing seems good. From here on in I'll change that part rather than clean it! So thanks again every one.
Chic

    Bookmark   March 18, 2013 at 10:33AM
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