engine has a hard time restarting

[dgjks6 6]

My 312-8 with a magnum 12 has always run almost perfect. Two days ago I shut it off during plowing and it had the LOUDEST backfire I have ever heard. After that the engine had a hard time restarting. Since then, it starts normal when cold, but when restarting after it is warm it had a hard time restarting. Sometimes I even have to use a little choke to get it to go.

Anyone have any ideas.

Greg

[refracman 167]

Well if'ins it was a ol' holley i'd say the power valve blew, but since its most likely a walbro hmmmm.

could of bent the exhaust valve, maybe but not likely.

could also be the float sticking .

but im just guessing , hopefully somebody else will chime in

[linen beige 14]

I'm gonna guess, and only guess, that maybe it's time to de coke the cylinder. Something ignited gas to make it backfire. Probably carbon in the combustion chamber? If there is a build up then when it is hot the carbon can hold enough heat to burn the fuel as it enters the cylinder before it gets compressed so it won't start. Could be that using the choke richens it up just enough to overcome this?

Might also be as simple as being slightly out of time.

[Jim_M 178]

I would do a compression test. It sounds like the head gasket blew. That will cause them to start hard when warm.

[dgjks6 6]

I cleaned the head this summer and replaced the head gasket, so I know there is no build up in the combustion chamber. I may just replace the head gasket then. It costs almost nothing and takes only a few minutes.

Can I replace the head gasket in the cold? Do the bolts get more brittle? Should I use the same torque? I work in an unheated garage.

Greg

[Jim_M 178]

Greg,

The temperature won't matter. Just do it like you did last time and you should be fine.

Jim

[dgjks6 6]

Thanks Jim,

Last question. When I did it last time they said no gasket sealer. Should I use some this time?

Greg

[sorekiwi 761]

No sealer, I just put em on dry. Some people swear by silver aerosol paint, but I'm (very) unconvinced...

[KyBlue 655]

when I put a big motor together, I use the Copper spray.. probably does the same thing as paint, but.. I like the added protection to fill in any surface knicks, or deep scratches..

Should be available @ ur local parts store that carries permatex stuff..

[Jim_M 178]

To be honest I've put them together dry and with Indian Head Copper head gasket paint and couldn't tell a difference.

If you put it together dry it will be easier to clean up if you ever have to tear the engine down for a rebuild.

[HorseFixer 2,012]

when I put a big motor together, I use the Copper spray.. probably does the same thing as paint, but.. I like the added protection to fill in any surface knicks, or deep scratches..

Should be available @ ur local parts store that carries permatex stuff..

I have used the silver paint in the past with good results, I may pick up a can of that copper stuff cause my Toro 8hp has a briggs and It has a blown head gasket that I need to fix, think Ill give that a try :hide: