mf65 oil smoke

Notsofastfreddie · Posted: Tue Jan 29, 2013 6:35 am Post subject: mf65 oil smoke

Hello, I have a g176 gas motor that smokes bad. How bad, you ask? The first time I ran it after putting the motor back together, some one called the fire department, reporting my house was on fire! And the tractor was in the driveway. Compression chk is 165 in all cylinders. Checked valve adjustment numerous times. Engine idles nice, but must have full choke. Tar-like oil spraying out of exhaust. Smoked heavily before working on it, but had water in the oil, causing white smoke. This is pretty blue. Anyone have any ideas? Exploded view of head does not show any type of valve stem seals, and the head was in good shape when I took it off. Thanks for any advice, Fred

matt p · Regular Joined: 29 Dec 2012 Posts: 87 Report to Moderator

What do your sparkplugs look like,clean or oil soaked? Did you change your valve guides and replace intake seals when you overhauled the motor?What is your oil pressure at? ,what weight of motor oil do you have in it? You could have a bad head gasket leaking oil into #4 cylinder from oil journel up to head and valve train

Eric in IL · Posted: Tue Jan 29, 2013 9:32 am Post subject: Re: mf65 oil smoke

The valve train would NOT be my first suspect in your problem. I don't think they could leak enough oil to make it "spray tar". My 65 is a moderate oiler to the valve train at best. I don't think there is enough oil supply around the valve stems to make one spray tar. Of course if you are running choke full closed the engine would have a very high vacuum-- so maybe I'm wrong in that thinking ??

Matt asked good questions. I too would like to see the spark plugs.

You say it had water in the oil causing it to smoke white. When you had it apart, what did you find as the path for that mixture entering the cylinders ?

Oh, your carburetor needs a serious cleaning. My 65 takes very little choking at 20 degrees F.

Notsofastfreddie · Posted: Tue Jan 29, 2013 10:09 am Post subject: Re: mf65 oil smoke

Matt and Eric, thanks for the replies. Plugs were oil coated and oil is seeping out around the plugs. Did not replace valve guides. Did replace intake and exhaust gasket. Currently has 10w30 oil.Not sure of oil press., as gauge is broken. Thinking vacuum leak could be causing full choke issue. Water in oil was cracks in block. Leak stop cured that,but rod bearings were ruined, causing teardown. Thanks again, Fred

matt p · Regular Joined: 29 Dec 2012 Posts: 87 Report to Moderator

just a thought pull, oil bath air cleaner hose off see if its full of oil,it might sucked the oil out of the out of cleaner

Notsofastfreddie · Posted: Tue Jan 29, 2013 10:59 am Post subject: Re: mf65 oil smoke

Good thought, Matt, but I have been running it without any airfilter for now. Only temporary. used a new head gasket and rebuilt the oil pump. I don't think lack of oil pressure is my problem. Just can't keep it all inside!

matt p · Regular Joined: 29 Dec 2012 Posts: 87 Report to Moderator

check and make sure your breather tube is clear the one on the valve cover

Masseynut(Australia) · Posted: Tue Jan 29, 2013 11:42 am Post subject: Re: mf65 oil smoke

I have to agree, that's not guide or stem smoke.
Have the sleeves been replaced? Did you check the ring gaps? Should have been around .004" for every inch of bore diameter.
One other possibility is that the clearance on the conrod bearings is excessive. This creates excess oil flow from the journals, that the oil rings cannot cope with. Had a Perkins 3 cylinder this problem not that long ago. Did you measure the crank if it went back in worn, or was it ground?
Were the oil control rings fitted correctly?
Let us know,
Evan.

DavidP, South Wales · Posted: Tue Jan 29, 2013 12:17 pm Post subject: Re: mf65 oil smoke

I had the same thoughts as Evan about ring gaps and whether the oil control, or all rings were correct or fitted incorrectly. What did you do in the way of repairs/replacements? With the degree of smoke that you describe it seems that the oil rings are pushing the oil upwards and not down.
DavidP, South Wales

Notsofastfreddie · Posted: Tue Jan 29, 2013 12:37 pm Post subject: Re: mf65 oil smoke

Thanks Evan and David. Pulled the sleeves to replace the o-rings. Reinstalled original pistons to sleeves. Rod bearings were .020 over. Did not remove crank or piston rings from pistons. Know that is not the right way to do it, but wasn't sure water in oil issue was fixed. Thanks again, Fred

DavidP, South Wales · Posted: Tue Jan 29, 2013 12:56 pm Post subject: Re: mf65 oil smoke

Hi Fred,
If nothing has been changed and the problem was there before it looks like you may have worn or seized oil control rings. Looks like you might have to strip it again. One thing I would add though is to fit genuine rings if they are available.
DavidP

Notsofastfreddie · Posted: Tue Jan 29, 2013 4:04 pm Post subject: Re: mf65 oil smoke

Thank you for your help, David. It seems to be the only answer we can come up with here, also. The only thing I can't understand is the good compression numbers. Oh well, I'm only into this tractor for $300, it's worth a risking a little more. Thanks again to everyone who helped out. Fred

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