Kohler Courage 20HP Single Cylinder (SV470-610) Oil Leaking

I have a Kohler Courage single cylinder (SV470-610) mounted on a Huskee model 13AX615H730 that has developed an oil leak at what appears to be the head gasket. It has 725+ hours on it (it's a workhorse) and is still running strong but the leaking oil is getting all over the frame as well as tires and even onto the belt below. The one spot I can see it leaking is off the cooling fins.

I removed the hood and engine cover/shroud a couple of weeks ago to clean the engine and see if I could determine where the leak was coming from. I found three loose bolts on the top of the engine (see below) and tightened them hoping that was the main problem. The engine still leaked after tightening those bolts. I removed the shroud again a few days ago after I noticed oil spraying forward from beneath the shroud and found the same bolts had come loose again. Re-tightened the bolts but oil still leaking.



Question #1: Aside from keeping these three bolts tight (need some Locktight?), could this be a head gasket going?

Question #2: If this is a bad head gasket, how difficult is that to replace? I first thought I'd have to remove rockers, springs and basically disassemble the head to get it off, but after looking at an online service manual (see below) I'm thinking it can be accomplished by removing the valve cover, rocker arms and push rods and then unbolt the head. Is it that simple?



If anyone has a step-by-step procedure for this (and re-assembling) that would be great.

Thanks for reading and any advice and/or experience you can offer.

This is a problem with this engine, sump bolts coming loose. In fact many times I find them broken. Getting and keeping them tight can be solved but it is not easy. If for some odd reason you are a hoarder and still have the reciept from when you purchased the unit, you might be in luck. Kohler has been supplying short blocks, at no cost to you, if you are the original owner and can prove the date of purchase. You must work through an authorized Kohler servicing shop and pay for the labor cost to do the repairs. Because of the age of the unit "no proof of purchase, no short block for free". Just last year I was able to do this for two customers, both with engines like your's. If you fall into the group of "no reciept" there are two methods that have worked for me in the past. One is to use Loctite, as you suggested and the other is Helicoil the bad threads. When I have to go this route I remove the entire sump cover and inspect all bolts and repair any questionable. This can be questionable and I do not warranty this work. I tell the customer this in advance and I have had some fail. Doing it this way, you still will have to deal with the possibility of a bad head gasket, which complicates the decision. I will warn you, if you decide to do this on your own, please have a second set of hands and eyes around to assist. Attached you will find a service manual for your engine and I'll try to assist you if I can, but at the present time my time is very limited. Good luck in your decision.

http://www.mymowerparts.com/pdf/Koh...urage-SV470-SV480-SV530-SV540-SV590-SV600.pdf

In the picture of the block there is a dark area under the wire clamp. Is that a crack or something else.

When those bolts work loose the blocks tend to crack where the barrel joins onto the crankcase.
When cold it is hard to see but when hot it opens up and looses oil.
We call it the Kohler Krack and down here it seems to be limited to Husvarna's 17 to 19 Hp singles.
Other mowers from the same factory do not seem to suffer the same problem.
I have tried a few different ways to "fix" it and finally have found a way to weld the crack.

As for the bolts I have been replacing them with studs that I make myself with a shallow cut thread which deforms the thread in the hole and a lot of loctite.
like the others I had tried all sorts of things but the studs are the only thing that seems to work all the time
The stud is stainless and I use soft ( standard steel ) nuts with shake proof washers ( the starry looking ones ).

Because I am the mug who will be working on the engine next, no silicon, just the standard Kohler gasket with hylomar on the top plate side & axel grease or copper lip on the bottom so it comes off clean next time.
Down here that gasket is $ 25 Aus.

Thanks for the replies and comments everyone, I appreciate it. My apologies for not getting back here and replying sooner.

Rivets said:

This is a problem with this engine, sump bolts coming loose. In fact many times I find them broken. Getting and keeping them tight can be solved but it is not easy. If for some odd reason you are a hoarder and still have the reciept from when you purchased the unit, you might be in luck. Kohler has been supplying short blocks, at no cost to you, if you are the original owner and can prove the date of purchase. You must work through an authorized Kohler servicing shop and pay for the labor cost to do the repairs. Because of the age of the unit "no proof of purchase, no short block for free". Just last year I was able to do this for two customers, both with engines like your's. If you fall into the group of "no reciept" there are two methods that have worked for me in the past. One is to use Loctite, as you suggested and the other is Helicoil the bad threads. When I have to go this route I remove the entire sump cover and inspect all bolts and repair any questionable. This can be questionable and I do not warranty this work. I tell the customer this in advance and I have had some fail. Doing it this way, you still will have to deal with the possibility of a bad head gasket, which complicates the decision. I will warn you, if you decide to do this on your own, please have a second set of hands and eyes around to assist. Attached you will find a service manual for your engine and I'll try to assist you if I can, but at the present time my time is very limited. Good luck in your decision.

http://www.mymowerparts.com/pdf/Koh...urage-SV470-SV480-SV530-SV540-SV590-SV600.pdf

Click to expand...

Thanks for the reply, Rivets. This is, I think, a 2006 model that was purchased in 2007 so I'm probably on my own in regards to warranty of any kind. I think I'll try the Loctite the next time I'm dealing with that problem, assuming it comes up again. On a side note, this engine has over 725 hours on it and this is the first problem we've had with it -- and it's a workhorse. The starter has jammed up a few times but never an engine problem. Even with the oil leak it's humming along fine.

Major thanks for the service manual link. I've found the leak (in a comment to come) but this would have helped a great geal if it were the head gasket. I'm sure it will come in handy down the road at some point as well, so thanks again.

ILENGINE said:

In the picture of the block there is a dark area under the wire clamp. Is that a crack or something else.

Click to expand...

Thanks, Ilengine. I didn't notice a crack or anything there so that just may be the trick of the light. More on a crack (not under the clamp) in a comment to come. Thanks again.

bertsmobile1 said:

When those bolts work loose the blocks tend to crack where the barrel joins onto the crankcase.
When cold it is hard to see but when hot it opens up and looses oil.
We call it the Kohler Krack and down here it seems to be limited to Husvarna's 17 to 19 Hp singles.
Other mowers from the same factory do not seem to suffer the same problem.
I have tried a few different ways to "fix" it and finally have found a way to weld the crack.

As for the bolts I have been replacing them with studs that I make myself with a shallow cut thread which deforms the thread in the hole and a lot of loctite.
like the others I had tried all sorts of things but the studs are the only thing that seems to work all the time
The stud is stainless and I use soft ( standard steel ) nuts with shake proof washers ( the starry looking ones ).

Because I am the mug who will be working on the engine next, no silicon, just the standard Kohler gasket with hylomar on the top plate side & axel grease or copper lip on the bottom so it comes off clean next time.
Down here that gasket is $ 25 Aus.

Click to expand...

Thanks bertsmobile1, I appreciate it. As it turns out, you nailed the problem with the "Kohler Krack" (more on that in another comment).

If the bolts continue to be a problem I think I'll try Loctite and the star washers you suggest.

PS - greetings from Murfreesboro, Tenn (South of Nashville).

Still not sure of what the actual problem was, I removed the hood and shroud once again and placed some aluminum foil on top of the frame (to prevent oil dripping below to belts, etc.) and starting mowing the lawn in an effort to diagnose the oil leak problem once and for all. It didn't take very long as I soon noticed oil accumulating and dripping from the spark plug wire and then noticed a crack (see below) in the block (block?) that was, for a lack of a better term, misting out oil.



The only reason I thought this might be a head gasket problem is that the valve cover gasket didn't seem to be the problem and this was the only other gasket (that I knew of) in the area that could be failing and causing this problem. Looking back at the set of pictures I took for the initial post, this crack was not there (see below, 3 arrows show the 3 bolts that had come loose).



I'm drawn to the conclusion that the three bolts coming loose was the original cause for the oil leaking. I wasn't really checking for cracks the first time out, but I like to think that had it been there then I would have noticed because I gave it a good cleaning and inspection. The second time out (checking this problem) I don't recall doing much than re-tightening the same bolts that had come loose and the crack may have been there then. Regardless, it's certainly there now. (I also thought I may have seen a small crack where ILENGINE has questioned, but I think that's just a manufacturing seam as it continues on through to the head.)

I picked up a tube of J-b Weld SteelStik today and have attempted to seal the crack with that. I'll keep everyone posted on how that works out.

Feel free to post any thoughts, suggestions or experiences (especially with SteelStik) my way.

Thanks again everyone.

SteelStik seems to be holding, haven't gave it a hot test yet.......