K321 head gasket

[Joeyd 35]

Good afternoon guys,

 

New to me 414-8 with a K321S

 

It was smoking quite a bit when I got it so I decided to replace the head gasket. I've never done one before. 

 

I took the head off, cleaned up everything I could. I installed the new one with copper gasket sealer, torqued in the proper pattern to the proper value. 

 

I ran it yesterday and it was fine. Today I ran it and oil was seeping out of the head gasket. Before I stated the tractor I re-torqued the bolts again to the proper value. 

 

I'm guessing it blew another head gasket so I took the head off again. There's oil on the outside on the third fin down but I can't see and cracks or anything. Does this look okay to you guys? Also attached is a photo of the first gasket I put on. It looks like it came apart somehow. 

 

Again, I've never done one of these until the other day so your input will be appreciated. 

 

Thanks

[Achto 26,550]

5 hours ago, Joeyd said:

I took the head off, cleaned up everything I could. I installed the new one with copper gasket sealer, torqued in the proper pattern to the proper value.

One mistake that you made was using gasket sealer. Head gaskets should always be installed dry. Judging by the piston wash, (clean area on top of the piston) I would guess that your rings are probably worn. This would explain the smoking issue you are having. Not knowing how hard you plan on using this tractor I have two suggestions. If your not going to use it hard, put a new head gasket in then run a 50/50 mix of Lucas oil treatment and 30wt to keep the smoking issue down. If you plan on using the tractor hard then I would look at rebuilding the engine. These are my suggestions but feel free to get other opinions.

[DennisThornton 4,769]

4 minutes ago, achto said:

One mistake that you made was using gasket sealer. Head gaskets should always be installed dry. Judging by the piston wash, (clean area on top of the piston) I would guess that your rings are probably worn. This would explain the smoking issue you are having. Not knowing how hard you plan on using this tractor I have two suggestions. If your not going to use it hard, put a new head gasket in then run a 50/50 mix of Lucas oil treatment and 30wt to keep the smoking issue down. If you plan on using the tractor hard then I would look at rebuilding the engine. These are my suggestions but feel free to get other opinions.

I was just thinking about how to extend worn rings until finally breaking down and doing needs to be done.  First I thought of STP oil additive.  80 weight oil or whatever if is.  I'm found of Lucus products but what makes Lucas oil treatment better than the famous/infamous Oil Treatment?  And while I know exactly what you mean could you explain for the others why you think the "piston wash" is indicative of worn rings?  (Crap!  I hope my chuckles can't be heard and folks don't realize I have no idea myself!)

[Shynon 7,435]

Piston wash is evident by the clean side of the piston, if no oil was coming through the rings the top of the piston would be the black color you see all the way across the piston. I would caution using oil additives or thicker oil as the dipper on the connecting rod will just slice through the thicker oil and not sling it around in the motor causing more problems. If I were to use and additive, I would as @achto says a mixture of 50/50 with 30w. Also I would sand the head flat before reassembly.

 

 

[Achto 26,550]

49 minutes ago, DennisThornton said:

And while I know exactly what you mean could you explain for the others why you think the "piston wash" is indicative of worn rings?

Piston wash on a four stoke engine indicates oil getting past the rings and eventually washing carbon deposits from the top or the piston.

6 hours ago, Joeyd said:

Thanks

Notice the clean area on the surface of the piston.

 The top of this piston is covered with carbon, other than the spot that has been scrubbed clean. From the amount  of carbon on this piston I would say that there is nothing wrong with the rings on this engine.

 

Edited September 23, 2016 by achto

[DennisThornton 4,769]

I need to understand the pattern of the oil wash.  The finer details.  Why the area of no deposits vs the shiny black areas.  Why here and not there?

[Achto 26,550]

Wear starts on the thrust surface first. Thrust surface would the front and rear of the piston. The sides of the pistons do not experience the amount of pressure that the front and rear of the piston do.When the cylinder fires the piston is forced down and forces the rod down and towards the front of the engine causing more wear towards the front of the pistons. Looking at the piston with wash, the front of the piston is cleaner because the rings are worn more in the front.

[DennisThornton 4,769]

5 minutes ago, achto said:

Wear starts on the thrust surface first. Thrust surface would the front and rear of the piston. The sides of the pistons do not experience the amount of pressure that the front and rear of the piston do.When the cylinder fires the piston is forced down and forces the rod down and towards the front of the engine causing more wear towards the front of the pistons. Looking at the piston with wash, the front of the piston is cleaner because the rings are worn more in the front.

More oil means CLEANER piston area?

[Achto 26,550]

2 minutes ago, DennisThornton said:

More oil means CLEANER piston area

Correct, the more oil that leaks past the rings the cleaner the top of the piston will be.

[DennisThornton 4,769]

Just now, achto said:

Correct, the more oil that leaks past the rings the cleaner the top of the piston will be.

Easy for my mind to think the opposite!  Thanks for the correction!

[DennisThornton 4,769]

So the cooler oil laden crankcase atmosphere does not "coke" onto the piston and blacken it?  Hard to keep everything in mind, like the exhaust valve burns clean but the intake "cokes" because it's hot enough to do so but not hot enough to burn clean?

[Achto 26,550]

8 hours ago, DennisThornton said:

So the cooler oil laden crankcase atmosphere does not "coke" onto the piston and blacken it?  Hard to keep everything in mind, like the exhaust valve burns clean but the intake "cokes" because it's hot enough to do so but not hot enough to burn clean?

You are correct Dennis. The oil coming past the rings actually does not burn completely this is why it eventually starts to wash the surface of the piston clean. On a diesel engine with higher compression the engine oil would actually burn, but that's a whole new can of worms I won't go into that. The exhaust passing by the exhaust valve heats the valve enough to keep the top surface relatively clean. Under working conditions an exhaust valve can actually turn cherry red from the heat. The intake valve is cooled by incoming air fuel mixture and the surface area of it does not get as hot.

Any visible exhaust from an engine is an unburned fuel source. Black exhaust is unburned fuel (gasoline, diesel), blue exhaust is oil, white exhaust on a liquid cooled engine is coolant or moister in the pipe on those cold days. Oh and yes engine coolant is a fuel source, it will burn. If you don't believe me, spray some on a red hot exhaust once.  Second thought just take my word for it, don't want some one getting hurt.

Edited September 23, 2016 by achto

[Joeyd 35]

Thanks for the info guys. I think I'm going to purchase a rebuild kit. Any recommendations on which one to purchase and from where? Are any better than others? I've never rebuilt an engine before but I think it'll be a fun project this fall. I plan on using it this winter to plow the driveway. 

 

 

Joe

 

 

[Achto 26,550]

1 hour ago, Joeyd said:

Thanks for the info guys. I think I'm going to purchase a rebuild kit. Any recommendations on which one to purchase and from where? Are any better than others? I've never rebuilt an engine before but I think it'll be a fun project this fall.

 

psep.biz offers both OEM and after market kits for you engine. OEM is usually the best, after market is easier on your wallet. Before you order a kit . You will need to disassemble the engine and get some measurements. If your cylinder wear is out of specs, then you will need to have the cylinder over bored. A machine shop should be able to tell you how far over they will need to go to repair the cylinder. Then you can order your kit to size and return to the machine shop with the new piston so they can fit the bore to it. Not a bad idea to have your crank measured also, if it is out of specs it can be turned down to fit an under sized rod. You may get lucky and have every thing still with in specs, if this is the case you will only need a kit for replacing the rings.

 

Small engines are fun to rebuild. There are Kohler manuals on this forum. Down loading one would be the best first step. If you have any questions we're here to help as best as we can.

Edited September 23, 2016 by achto

[tunahead72 2,341]

This is a great thread guys, I'm glad I started reading along.  I have a couple of K241 engines that are worrying me for different reasons, so I'm going to stand in the corner with Dennis and Joeyd and ask questions if you don't mind.

 

First for Joeyd...  You obviously did some homework before you started tearing into something you'd never done before, I like that.  Can we assume your engine is still smoking after you replaced the head gasket?

 

And for achto...  You mentioned that black exhaust indicates unburned fuel.  Does that necessarily indicate that the fuel mixture is too rich, or is there something else that could explain that?

 

[Achto 26,550]

1 hour ago, tunahead72 said:

And for achto...  You mentioned that black exhaust indicates unburned fuel.  Does that necessarily indicate that the fuel mixture is too rich, or is there something else that could explain that?

Black exhaust is result of a rich condition. Causes of this would be choke not opening all the way, air filter is dirty/obstructed, fuel mixture is set wrong on the carburetor.

 

Another result of too much fuel will be a heavy carbon build up on the spark plug. Bad rings will cause this too, but the build up on the plug will look wet.

 

Note: when you start your engine you will usually see black smoke until you shut the choke off.

 

[Shynon 7,435]

I have had good luck with aftermarket kits from bakt4kids and deb's tractor parts. IMO I would not spend the money on Kohler parts. I have about a dozen or so I have rebuilt with aftermarket kits with no problems.  I my area I can buy a kit and have the valves ground, cylinder bored for about 175. Crank grinding is about 100.00    I also think if you are going to open it up might as well do it right the first time, rings and gaskets will set you back close to 100 so for another 75 you can have all new, rod ,piston, gaskets valves ground, totally worth it IMO. Download or buy a kohler manual you will need it, it will tell you step by step how to disassemble and reassemble your engine. Keys to a good engine rebuild are cleanliness and a good machining job. I would also get it done asap as breaking in a new motor in the winter will not build enough heat to seat everything in. Any more questions please ask.

[Joeyd 35]

I replaced the head gasket and it it was still putting out a puff of smoke every 5 seconds or so. It was running fine except for the smoke and the oil coming out around the head gasket. I'm going to buy a kit and get the head flattened correctly. Thanks for all the help guys