Think I blew a head gasket on my 312-8. How hard to fix?

[handyrandy 7]

Hello everyone, I started up the old 312-8 kohler magnum and started plowing snow and smelled oil burning. Looked down and saw oil on the side of the head and muffler. Is this as easy as buying a new head gasket and cleaning the surfaces and bolting it back down again? I have torque wrenches but not a lot of small engine experience.  I need to get it fixed pronto and need to get the parts ordered. Any suggestions or tips?  Thanks in advance.

[Ed Kennell 38,248]

Not hard at all if you don't break a head bolt during removal.     There are many threads on here with video describing the techniques used to clean remove the  carbon of the head, block, valves, and piston.

Download the manual for your engine where you will find the head bolt torque specs and tightening sequence.     When I remove a head, I use the torque sequence in reverse and only loosen each bolt 1/8 of a turn until they are all loose.  I never had one break.

[squonk 41,164]

I had one break. But it was already broke before I broke it

[WHX?? 48,834]

Yer a  Mike.... 

Very easy to do. So easy even a Squonk can do it.

Hardest part is taking the tins off and putiing them back on. Like Ed said de-carbon as long as your there and glass the head. 

This might help. 

headgasket.pdf

Edited February 1, 2021 by WHX24

[squonk 41,164]

59 minutes ago, WHX24 said:

Yer a  Mike.... 

Very easy to do. So easy even a Squonk can do it.

Hardest part is taking the tins off and putiing them back on. Like Ed said de-carbon as long as your there and glass the head. 

This might help. 

headgasket.pdf 1.22 MB · 1 download

There were bits of this head bolt missing before I even touched it. Broken piece spun out by hand

 

[midpack 866]

Some good fortune there!

[Handy Don 12,244]

26 minutes ago, midpack said:

Some good fortune there!

Indeed!

[Pullstart 62,922]

Here is a link to the post where I started extracting a broken head bolt near the exhaust pipe on “Rebel” our 953.  It wasn’t terrible with a little patience and I ended up drilling the bolt out and retapping the hole.

 

 

 

[Gregor 4,846]

If I am wrong about this, some please feel free to correct me. If you do have a stubborn head bolt, chances are, it will be the one nearest the exhaust. I had that problem with my K161. I was told to re-torque the others, start the motor and get it good and warm. The bolt came right out.

 

Actually, I think that was a K321, now that I think about it.

Edited February 2, 2021 by Gregor

[WHX?? 48,834]

2 hours ago, pullstart said:

Here is a link to the post where I started extracting a broken head bolt 

Let's not jinx him Kev.... just be aware handy ...it happens, Squonk just got blind outhouse lucky.   

If I got a head bolt  that I think is gonna give me problems, like Squonk who always gives me problems , I'll try working it back and forth with say a 1/4 drive socket that doesn't have the hooph to twist it off and go by feel if it's gonna twist off. Slow goes it and use some rust buster if you can get it in ther. 

Edited February 2, 2021 by WHX24

[RandyLittrell 3,884]

Along with a new gasket, check for flatness. Here is a great video. 

 

 

[The Tuul Crib 7,336]

This will help too

[handyrandy 7]

Thanks everyone for the great help. I took the head off today and first thing I noticed was the head bolts where all loose. I photographed the parts. To me everything looks pretty good. I may just clean it all up and put it back together the way it is and see what happens. What do you guys think? I will take the head down to my brothers and check for warpage on his milling machine table.

 

I was afraid I would see all kind of head and gasket damage. I think I am very fortunate. 

 

Also is there some cleaner I can get to clean all the carbon deposits off easily? 

[Pullstart 62,922]

A wire brush or drill attachment do pretty good to remove the deposits.  I wouldn’t recommend it, but one of my 8 hp machines have red RTV on both sides of the head gasket and it’s holding strong since 2008.  I did it to see how long it would last.

[handyrandy 7]

We ended up cleaning everything up and bolted it back together with original head gasket, torqued it down to 30 ft lb, and went back to plowing snow. Seems fine.  Thanks you all for the help.

[WHX?? 48,834]

Hope that works for ya Handy. Personally I would have done it right. What's that guys saying here ...if you don't have the time time to do it right the first time when will you have the time to do it right the second? Just sayin.... 

Retorqueing after some seat time when still warm is not a bad idea. I go to 35 in lbs with thread lube and knowing I have good threads.

Good luck. 

[953 nut 55,329]

17 hours ago, handyrandy said:

I took the head off today and first thing I noticed was the head bolts where all loose.

The head bolts probably had not been retorqued after the first run. This step in quite often overlooked.

[The Tuul Crib 7,336]

10 hours ago, WHX24 said:

Hope that works for ya Handy. Personally I would have done it right. What's that guys saying here ...if you don't have the time time to do it right the first time when will you have the time to do it right the second? Just sayin.... 

Retorqueing after some seat time when still warm is not a bad idea. I go to 35 in lbs with thread lube and knowing I have good threads.

Good luck. 

[Tuneup 1,433]

The blowby through that gasket likely ruined it. That same blowby focused added heat in the leaky areas through the gasket and likely warped the head. Plan on replacing the gasket and planing the head with some sandpaper on a good surface when you have a chance. It's an easy thing to do as you've found out and the gasket is cheap. For now, she'll be happy to get you through the winter storms.

[handyrandy 7]

On 2/3/2021 at 7:12 AM, The Tuul Crib said:

Well, my first priority is finish plowing out my 80+ year old parents from this big storm we had so I can get them out of the house in case of emergency, which is done now. second is setting up my second wheel horse 312-8 mowing tractor to a back up plowing tractor which will be done today. Third is to think about the right way to do it. Thanks everyone for the help, I learned a lot and can fix it correctly now.