Gravely walk behind

[Farmall Bob]

my Gravely walk behind started smoking, and don't
know why as the oil pressure is reading 3/4 to the
good. I will run it and when it get's warm it will
start smoking, and it will foul the plug. The oil is
down almost to the fill line. It seems to have good
compression. Any help much appreciated. Thank you.
Bob

 

[504]

Bad rings

 

[Farmall Bob]

Hi 504,

OK, I will pull her down and just see how much can be done. Would I still have high oil pressure with bad rings? Thank for responding so quick.

Bob

 

[Anonymous-0]

Oil pressure has nothing to do with rings. Low pressure indicates bearing/pump wear. If the smoking started all of a sudden, you might have cracked a ring. Also check valve guides for wear, can't remember if the gravely motor has valve seals, or not. If it does, then seal replacement might help the smoking issue, too.

 

[Bret4207]

Probably worn rings. But if you're using 10-30 or 10-40 often going to a single 30 or 40 weight will help. Also make sure your oil fill/crankcase breather cap is not gunked up. Also check the valve cover gaskets for leaking and the oil line for leaks.

 

[Farmall Bob]

Gentlemen,
I just want to thank you for your help. I can't wait to get into this repair. I will report back when completed.
Bob

 

[Farmall Bob]

Question, can I purchase rings at NAPA? or do I have to go through a Gravely dealer? Thanks!
Bob

 

[johnlobb]

I follow a yahoo Gravely forum that has a lot of very Gravely articulate people.

 

[Anonymous-0]

Before you buy rings you may want to check and see if you have the original or an oversized piston. Machines of that age have often been rebuilt--at least on the top end. The rebuilding often involves reboring the cylinder and installing an oversized piston.

Out of curiosity, where are you located?

 

[Farmall Bob]

Hi Tom,
I am from Maine. Thank you for that valuable piece of information. I will tear it down tomorrow and measure the piston and cylinder.
Bob

 

[Bret4207]

(quoted from post at 10:41:19 11/18/13) Question, can I purchase rings at NAPA? or do I have to go through a Gravely dealer? Thanks!
Bob

Bob, Gravely parts are pretty much a Gravely product. There's a place called Richards Lawn and Garden that is pretty much the L model specialist. They'll have whatever you need. But you may want to check Ebay before you order once you figure out whats going on. Your rings could be fine. Do a compression test first. Take a look at the valves too. Check that oil fill cap like I said too. Also, sometimes if you're on a hill they'll start smoking like crazy when the oil runs back or to one side. Usually has to be a pretty good hill. If the rings are worn and you have low compression, under 65-70 lbs (remember these are not high compression engines in the first place), the you may want to do a good rebuild since you have to pull the jug anyway to have bored- if you want to go that route. Check the crank for any play and the rod too. If the rod has ANY play the bushing is going. It's a 2 piece crank shaft and the bushing has to be reamed for the crank pin you are using. I've sent mine out to Richards for this some years back. Getting the crank re-aligned isn't the easiest thing to do without a set of centers that will take it.

Be a good idea to get a shop manual to start with. That smoke could have been from several things. If she's got some good pull when you go to start it the rings are usually okay. Sudden onset of smoking could be a busted ring or piston though.

 

[johnlobb]

The address is Gravelyclub @ yahoogroups.com

 

[Bret4207]

Richards- http://www.gravelyparts.com/

 

[Farmall Bob]

OK, I took the head off and the cylinder ID measures 3.243" plus or minus .0005". Turned the fan to work piston up and down. Oil is getting in there, but seems like when piston is going down there is too much oil left in cylinder? Valves seem to be working OK.
Bob

 

[Anonymous-0]

Your measurement shows that your cylinder is smaller than the standard bore which should be in the 3.2535 to 3.2545 range per the Gravely shop manuals.

I own several L's of various vintages, but an now currently using newer tractors with Kohler Magnum engines. I've rebuilt the upper ends of L's before, but it's been about a decade ago and my memory isn't as good as it used to be (and never was?)

I vaguely recall that a standard piston had STD stamped on the top, and the oversized pistons had ".005, .010, .015 etc stamped on the top.

I also recall that the factory pistons had a notch on one side of the piston. As I recall, the piston should be installed so that the notch was on the exhaust valve side (or was it the other way around?) You should make a note of which direction it is facing before you remove the piston.

If you don't have the manuals, lots of them are available for free on the internet. The jugs all the L's had the same diameter factory bore and used the same diameter pistons, so any manual should meet your needs.

 

[Farmall Bob]

"Oh" OK, I made the measurement and forgot that there is some carbon build up around the top of the cylinder. There is a notch, but it is facing toward the read. I didn't see anything stamped on the top of the piston, but will look tomorrow when I go to re-assemble it. I have cleaned it up real good, took a bottom tap to the bolt holes, wire brushed the head, wire brushed the bolts, and wire brushed the gasket. The gasket doesn't look all that great, and if I have to end up buying new rings I will purchase a new gasket also. I will be cleaning out the filter to the oil filler also. Thank you for helping out.
Bob

 

[Bret4207]

If there are no makings at all it may be the standard, original piston. There shouldn't be oil in the cylinder, much less a lot of it. How do the rings look? Whats your piston to cylinder wall gap? Ring gap? Someone may have run that old girl for 30 years without an air filter for all you know.

If you're going to do the rings it's would be best to get the jug bored true and go to an oversized piston. They aren't expensive. thankfully!

 

[Farmall Bob]

OK, Gentlemen,
I really appreciate your help. I am going to try a few of the ideas you have mentioned.
* The head gasket looked bad, so changed it.
* The oil is a 5-30 so will change that to just 30
* The oil filler cap is plugged, have that soaking
I am like you, and believe the rings have gone, but don't have the time. Need to finish that garden with the rotary plow. The ground will be freezing soon. If the above can get me by until the new rings come in great! Thank you.
Bob

 

[Bret4207]

Switching the 5-30 out and unplugging the oil cap/crankcase vent may solve the problem! Those 2 combined would likely cause what you describe. The rings may not be like new, but those old girls would do their job when they were about worn out. A bad head gasket just adds to the problems.