Kohler Courage 21 - Blown Head Gasket ?

**Yellowfin36** · 05-21-2011, 07:06 AM

Good morning Gentlemen,

I have a Toro Z5000 powered with a Kohler SV610 that was built in 2007. It has approximately 250 Hrs of service. I've been using Mobil 1 Synthetic 10W-30 since break in.

Recently it has developed an oil leak dripping onto the muffler. I believe it may just be a blown head gasket. But I'm not 100% sure. The oil is definitely leaking out from where the head meets the engine block. I guess it could also be a warped head too ?

Unfortunately I believe this occurred because I added SeaFoam to the fuel under the advice of a friend as the problem developed immediately afterwards.

I have all the tools necessary to repair this myself. Any advice or help you could lend would be greatly appreciated.

Thanks in advance.

YF36

On Edit: I've already downloaded the manual from the Kohler site.

**LawnWorld**

**ILENGINE** · 05-21-2011, 08:30 AM

its more likely that the valve cover is leaking

**Yellowfin36** · 05-21-2011, 09:33 AM

Thanks. It's definitely leaking between the heat sink fins on the head 2 -3 inches behind the valve cover. I'll try to get a pic of it later today.

YF36

**Yellowfin36** · 05-22-2011, 08:46 AM

I took some pictures yesterday. On the photo below taken of the left side of the engine the red arrow shows where the oil is leaking from the head. However the leak is occurring on the other side of the engine. The air filter hosing is in the way of getting a picture of it. I believe this is where the head meets the engine block.

In the photo below taken on the right side of the engine you will see where the oil is dripping down onto the muffler support bracket and running down the muffler assembly. Smells pretty awful too.

Do you gentlemen think that it's just the head gasket or could the rings be damaged/cracked too. As I've said I've taken good care of the engine. I guess I really won't know until I pull the head.

I only wish I hadn't listened to my friend about the Sea Foam fuel additive.

Thanks in advance for any advice.

YF36

**jteuban** · 05-22-2011, 12:31 PM

Yes that could be it, you said it was recently rebuilt
but it sounds to me like a ring prob or a flywheel key that is broken.

**ILENGINE** · 05-22-2011, 01:31 PM

I would say it is just the head gasket but could be a warped head. max out of flatness is .003 inches.

**Yellowfin36** · 05-23-2011, 09:17 AM

Actually no, the engine has not been rebuilt. It has always been running fine prior to the SeaFoam fuel additive.

I always warm it up at idle before increasing the RPMs and engaging the mower and after mowing I let her run for a few minutes at idle to cool down before I put it away.

I'm hoping the head isn't warped. How can you determine if the head is warped. How does a DIY guy measure .003" ?

I just ordered the head gasket and muffler gasket. I guess I'll know once I get the head off if the rings are cracked by visual inspection. As far as the head being warped I guess if it still blows oil after I get it reassembled that will tell me, right ?

It's my gut feeling that the SeaFoam additive increased the pressure in the cylinder and blew the HG. Someone originally suggested I run it through my Ford Diesel truck. But when I cracked the seal and smelled the alcohol I said no way. Then they said it would be good to clean out the fuel system in my lawn mower. I wish I just dropped it off at the haz-mat day at the recycling center.

I'd rather be fishing then pulling apart my lawnmower engine. Oh well.

Thanks again for you replies.

YF36

**ILENGINE** · 05-23-2011, 02:11 PM

Flatness is found by placing head on a piece of plate glass and sliding a feeler gauge around under the gasket mating surface. If it fits underneath at any location it has to be replaced.

**Yellowfin36** · 05-23-2011, 03:19 PM

That's good to know. Thanks. I believe I have a piece of glass. I also have a big 12" Delta shop table saw with a machined flat surface. I'll check it for sure.

Thanks again.

Best regards.

YF36

**Yellowfin36** · 05-23-2011, 04:14 PM

One more question;

If I need to mow the lawn once or twice more before I can fix what I hope is only a blown head gasket does that increase the chances of warping the head if it is not already warped ?

If so, I need to make arrangements to have my property mowed asap as I generally mow 2x a week.

Thanks again.

YF36

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