briggs 273280s versus 796584

[KE4AVB]

Remember to torque the new head gasket to 250 in-lbs in three steps.

[38racing]

So why wouldn't they make the gasket to cover all the metal at the 3 o'clock position between the cylinder and galley? Given that's exactly where it fails.
http://web.ncf.ca/da229/smallengine/20180714_164603.jpg
http://web.ncf.ca/da229/smallengine/20180714_164611.jpg

[KE4AVB]

Unless they have changed the head design it would not help as the push rod galley is straight in this area that mates with the cylinder block and not curved as the cylinder block is. Now a redesign of the head to match this area would help then they could increase the gasket web in this area to match as well.

[38racing]

Might not be clear in my picture but there is metal to the right of gasket at 2-4 o'clock.

[KE4AVB]

Understood but the 310000 series head I looked before dark is what I am referring to as it is straight in that mating area and not curve as the block is in the push rod gallery. I also got the 310000 cylinder out there too where an idiot ran the engine without oil. I can take a snap shot tomorrow of the 796584 gasket on it when I get back to the shop. I am going on a tool run in the morning about 2.5hr round trip drive. Right now it is too dark for my camera to work.

[KE4AVB]

Well for a better shot I had to leave the gasket off as there is hump that protrude (ie hang over the edge in the valve galley. It is simply the webbing on the head isn't wide enough in this for a good gasket seal. It is more of a design nightmare.

[38racing]

Well for a better shot I had to leave the gasket off as there is hump that protrude (ie hang over the edge in the valve galley. It is simply the webbing on the head isn't wide enough in this for a good gasket seal. It is more of a design nightmare.

Curious what thw date code would be. Mine was 311..... which I assume would be before the 31letter ones. Code is 01.... My daughter's was a 31f with code 04... But I don't recall what her block looked like in that area.

[KE4AVB]

On the 31F707-0112-E1 You referenced there were two different heads depending on the date code. The break is at 080427xx/080428xx. The older head 793991 has been superseded to 796026 now. The head I showed is from the the 31P777-0602-E2 (date code 060106ZA) which is the later head. The only difference I see between the 796025 and the 796026 is that the 31P has a cylinder heat shield included in the head kit and the 31F doesn't. BTW the 796025 has been superseded to the 796026 too.

[38racing]

I never actually looked at the metal on the head, just the block. I assumed that they would match. As an aside on this mower. Neighbour had rolled it in a ditch. Visiting son did something to get drive system working. But then he said it was consuming oil. I suspect the blown head gasket had nothing to do with the roll over. There was oil in the air filter but he had tipped it with air filter elevated. So today I just had a chance to try it after gasket replacement. Fired right up and ran fine but I did notice sparks. The deck front was hitting the engine pulley. Initially I thought it was a case that someone knew that they could move deck forward to make sure deck belt stopped (the one missing deck pulley guard could be an issue). So when I look I see deck belt is way down onto the deck because the engine pulley is down because it has no bolt holding it to the crankshaft. Then I notice I can turn pulley left/right with out shaft moving. I pulled the pulley off and the built-in key is a sliver. Don't know if it's been this way since she bought it used last year or her son did it fixing the drive. I better check the threads in the crankshaft in the morning.

[KE4AVB]

That is one thing I learned in my 40 yrs of working on equipment and that is never assume anything. With lawn care equipment it is even more true as you don't know who or what was done to it.
Yes I have seen one mower where a double stack was missing the bolt and was only held on by the deck.

Wait until you see a double stack that is missing the lower half the PTO pulley. The customer couldn't get the deck belt on the pulley for it to work .

Being repaired after a rollover is like a couple cases here.

One was a Craftsman that was overturned by a storm that the operator just uprighted a week later and started cutting his grass. He stop for a soda and the engine would only spin on restart attempt. Both rods broke were broke. I think it was the total lack of engine oil that did it but I may have been wrong. Anyway I put an used engine from a mower I had acquired mainly for the Dana transaxle as another customer shattered his gear case on a Peerless. Very unusual for me to completely part out a mower but did sell both the transaxle and engine and later the front spindles and wheels.

The other was when another customer drove his JD 345 over a 2 ft concrete retaining wall. Just couldn't get the deck to work afterwards. Maybe it was because he ripped off the deck hangers and bent several pulleys. Kinda Glad I took up welding when I was a kid. Seems like I am always needing to do metal fabrication and welding.