# K341 New Head Gasket leaking after 5 hours



## t-craw

*Hey Fellas,
I've re-built this K341 for my cousin. It was in bad shape, in fact EVERYTHING from fuel to electrical was in plum awful shape. Nonetheless, my question pertains to cylinder head gasket. After running this engine for 5 hours after initial start-up (after re-build) I pulled flywheel off. He had issues with charging system and it had to come off. Anyway, after pulling blower housing I noticed some oil in an area of block on the fins just below the head gasket bolt (see pics - have it outlined). I cleaned off oil before taking the picture but have area outlined where it was located.

Now, I used a NEW OEM Head Gasket upon re-assembly as well as new head bolts. Torqued it to specs @ 30 ft/lbs. in correct sequence. Head was in nasty shape after tearing down but re-surfaced it on plate with sandpaper (see pics as well for before/after). Placed head on block and checked for clearance at mating surfaces after doing this and it was within tolerable limits (< 0.003)

I don't quite know why this is leaking oil here but I just can't leave this as it is. 

Upon removal of blower housing and head baffle, I re-torqued heads. Now I read where head bolts are supposed to be re-torqued after first 15 minutes of run time but I did not do this. Instead, I waited 5 hours to re-torque bolts. In addition, there were only a few bolts that actually needed it but the bolt right above the area in question did not need re-torquing (it was still at 40 ft/lbs.).

I've visited Brian Millers website and spent lots of time just educating myself with some of his helpful tips. Was quite impressed with his knowledge. Regarding head gaskets, he recommends just using a Copper Based type gasket material such as "Permatex Ultra-Copper RTV" for head gaskets. I did purchase some but did not use it for Head Gasket as I had a NEW OEM gasket, which is what I used upon re-assembly.

Question: Should I remove head, remove gasket and replace with JUST the permatex ultra copper (without the OEM gasket)? Just feel weird about doing that. Feel like it will ooze into combustion chamber. Obviously I do not torque it initially to 30 ft/lbs when doing this but should I torque to specified value after gasket material is cured?

Or..., should I remove head and attempt to re-surface it to achieve nearly 0.00 clearance between head and block?

Please give me your best judgement recommendation here.
*


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## t-craw

*I realize I should not be getting oil in the combustion chamber. If I am, I guess it would be due to 2nd ring (oil ring) not controlling oil or installed wrong. I know I did not install it upside down and there is no smoke coming from exhaust while running. 

Could a cracked block be the cause of this? Being so high where oil was seen it seems unlikely that would be the case.

Not sure what I should do at this point. Remove head and inspect further?

???*


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## t-craw

*Just came across a picture of the block surface before I installed head. I don't see anything that should raise some sort of flag here. I know the image size is reduced when posting on here so I tried to crop a few areas (especially around surface where I noticed substance on fins) and included them as well. At full resolution, I think I could actually see a crack if there was one there just from looking at this picture.

?

Just a bit miffed here. Spent too much time on this to have some sort of problem with leaking oil or whatever.*


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## t-craw

*I didn't mention that I re-torqued the head bolts when engine was cold. Should I "hot-torque" these bolts?*


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## jhngardner367

First,check to make sure there are flat washers on the bolts,and that the bolts are not bottoming out when tightened.Flat washers help distribute the torque evenly,on the head.Make sure they are against the head,except where the head bolts go through shrouds,etc.,then they can be on top of the shroud.
Install the head/gasket,and torque to specs.
Start the engine,and run for 2-3 minutes,then re-torque to specs(warm).
Oil in the cylinder on rebuilds is normal,until the rings set in,and the valve guides/seals settle.
Use SAE 30 oil for run-in,and change oil after first 5-10 hrs,and every 25-30 hrs after that. Use SAE 30,in warm(above 40f)temps,and SAE 10W30 in cold weather.


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## t-craw

jhngardner367 said:


> First,check to make sure there are flat washers on the bolts,and that the bolts are not bottoming out when tightened.Flat washers help distribute the torque evenly,on the head.Make sure they are against the head,except where the head bolts go through shrouds,etc.,then they can be on top of the shroud.
> Install the head/gasket,and torque to specs.
> Start the engine,and run for 2-3 minutes,then re-torque to specs(warm).
> Oil in the cylinder on rebuilds is normal,until the rings set in,and the valve guides/seals settle.
> Use SAE 30 oil for run-in,and change oil after first 5-10 hrs,and every 25-30 hrs after that. Use SAE 30,in warm(above 40f)temps,and SAE 10W30 in cold weather.


*Yep, new flat washers are on each new bolt (actual head bolts - not just 3/8 -16 x 1-1/2 heat treated bolts) which were lubricated with oil before initially installing and torquing to value. Used SAE 30 Non-Detergent Oil for first 5 hours. Drained oil, changed and while cool I re-torqued each head bolt for first time (as I said, waited 5 hours, not 2-3 minutes and not each bolt accepted more torque). 

I did NOT replace valve guides nor did I run a tap through threads prior to assembly. 

I'm wondering if I should pull head, clean threads, put some Permatex Ultra Copper on both sides of head gasket (just a little) and follow procedure outlined in your thread or just try torquing head bolts again with engine warm.*


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## jhngardner367

Don't use the ultra copper. There should be no need. Try to re-toque when warm.
Looking at your pics, I don't see any cracks,but the pattern shown in 2nd/3rd pics shows a possible warpage in the block's surface.at the lower left of the pics.
Use a straight edge and feeler gauges to check it. More than 0.005" difference,and you should re-surface the block by 0.005- 0.007,to "true it".


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## t-craw

*Thanks, I'll do that but will have to wait a day or so. Gotta get the old ticker checked via stress test today.*


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## t-craw

*Pulled head off this afternoon and I've got to say I'm surprised to see this much oil. This engine only has 5 hours since re-build. I don't see it smoke ANY when it's running. ??? 

Also put a permanent black marker around suspect hole area and you can see in pics before and after lightly running flat mill file over it about 30 times. This area could be an issue..., I dunno. 

Kind of worried about all the oil though.*


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## Beaner2u

t-craw,

You seem to be doing everything buy the book. The block sanding of the head, was that done on something like a flat piece of marble? Did you check the top of the cylinder with a know true straight edge?

Sometimes even a cylinder requires being 're-decked' or machined flat again on the head sealing surface.

I have a couple of pieces of marble window ledge material, they are pretty true and flat, but nothing like a machinist granite comparison table.

Something just does not fit this picture. 

Roger,


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## t-craw

Beaner2u said:


> t-craw,
> 
> You seem to be doing everything buy the book. The block sanding of the head, was that done on something like a flat piece of marble? Did you check the top of the cylinder with a know true straight edge?
> 
> Sometimes even a cylinder requires being 're-decked' or machined flat again on the head sealing surface.
> 
> I have a couple of pieces of marble window ledge material, they are pretty true and flat, but nothing like a machinist granite comparison table.
> 
> Something just does not fit this picture.
> 
> Roger,


*Hey Roger,

I don't have any marble or machinist table (I don't do this kind of work hardly ever - I mean I've rebuilt some old Mercury 2-stroke outboards before - the old green ones but I certainly don't consider myself experienced in this area and definitely don't consider this a hobby. Just trying to help my cousin out..., and doing this for free mind you). 

All I've got is my dining room table..., which is what I used. Put the sandpaper on table then stroked cylinder head across it numerous times.*


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## t-craw

Beaner2u said:


> t-craw,
> 
> Did you check the top of the cylinder with a know true straight edge?


*Forgot to answer your other question: No, I did not check top of block with true straight edge.*


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## t-craw

*Cleaned things up, took picture and upon viewing pic, I saw this. Look closely at cylinder edge facing valves. Very prominent close to piston.*


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## ftorleans1

Checking the block surface with a known "True" straight edge is always a good idea. However, Looking at your pictures, I'm thinking bad valve guides. That is way too much oil for such little run time. 
As for bolt torque, It is "absolutley" necessary to run a tap through the head bolt threads. Any foreign debris(rust, grime,dust,etc...) will cause a false reading due to additional resistance from the foreign material. Don't RTV your head gasket! As long as matting surfaces are with-in specs, proper torque is all you need. A new set of valve guides will most likely stop your oil problem.


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## Fluid

I see some scoring on wall, may be out of round. To get a true torque on bolts I always chase the threads with a tap and blow with air to get out debris. I make sure there is nothing that can stop the head bolts from getting a true torque, oil, cleaner, water, grease, sand from sandpaper, dirt ect. Look in some of the threaded holes in the block, they look like some crap is in them. Those picture are after 5 hours run time? If it is you need to check your carb settings, after you get the head gasket thing figured out. Looks rich to me.


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## t-craw

Fluid said:


> I see some scoring on wall, may be out of round. To get a true torque on bolts I always chase the threads with a tap and blow with air to get out debris. I make sure there is nothing that can stop the head bolts from getting a true torque, oil, cleaner, water, grease, sand from sandpaper, dirt ect. Look in some of the threaded holes in the block, they look like some crap is in them. Those picture are after 5 hours run time? If it is you need to check your carb settings, after you get the head gasket thing figured out. Looks rich to me.


*Just 5 hours of run time. Took a bit of time to get settings correct on carb due to other issues that were causing misfiring but I think I've got it right. Valve guides do not feel bad by wiggling valves although I don't have the proper caliper to check. Mechanic who did Bore/Hone/valve job stated they felt good as well.

I contacted the mechanic who did this work about scratches, showed him the pics. His reply was:

"Those scratches could be normal where rings travel as the pressure is pushing on wall, or there is trash in oil or trash got through air filter. I don't think it will hurt anything. Also, rings do not push equal all the way around cylinder walls. Put it together and run it. Still breaking in. Stop looking at the forest for the trees".

I don't know anymore. I take my time. I do my best but I just don't know what to think.

*


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## t-craw

Fluid said:


> I make sure there is nothing that can stop the head bolts from getting a true torque, oil, cleaner, water, grease, sand from sandpaper, dirt ect.


*Do you lubricate your bolt threads with oil before installing? Kohler repair manual instructs to do that, which I did.*


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## Fluid

Yes I do oil my bolt threads. I put oil on a clean rag and rap the rag around the bolt then turn the bolt so the bolt threads get a very thin coat of oil on them, thats it. Did you chase all the screw threads in the block? that is did you run a tap into all the screw threads in the block to get all the crud out so the screw can screw in the block without hitting against said crud? The best way to check the valves and valve guides, is to remove them and mic them to see if they are to specs. Just trying to move them by hand is not good enough. The bore was honed? I don't see very much cross hatch pattern on the bore after 5 hour run time. I should see more with just 5 hours run time. I would be concerned with that much scoring on the cylinder walls after just 5 hours run time.


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## t-craw

*Showed these pics to Brian Miller. He states:

"This is very interesting! The dark area is caused by the engine running extremely hot. The piston rings loss their expansion against the cylinder wall due to the overheating. Over-advanced ignition timing will cause this. The excess heat will also cause the motor oil to thin out. It all makes sense now. A lean fuel mixture will cause the rings to fail too. If I were you, just install another set of rings, use Mobil 1 10W30 full synthetic oil, make sure the ignition timing & carburetor settings are right & it should be fine. Because at this point, there's nothing else you can do."

Did not want to hear that. *


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## t-craw

*Pulled piston/rod out today. Took a few pics of both piston w/rings as well as cylinder wall. Can see scuffs on opposite sides of cylinder as well as piston.

Ring wear? I don't see anything that jumps out at me but quite frankly I would not know what to look for anyway. In the meantime, I've ordered new ring set.*


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## PeteNM

Guess since it's torn down anyway, might be a good time to check the cylinder wall for roundness and also the piston and ring gap clearence. Just a thought....


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## t-craw

PeteNM said:


> Guess since it's torn down anyway, might be a good time to check the cylinder wall for roundness and also the piston and ring gap clearence. Just a thought....


*Good thought.

I actually ordered a piston/ring kit. 

I don't have an inside caliper (bore gauge) to check roundness of cylinder. The fella who did this bore job is going through chemo right now and not up to par to do anything even as simple as checking roundness. However, I'll remove piston from rod, rings from piston and at least run down into cylinder and visually try to see some irregularity. 

I agree with others, it appears it got VERY hot as evident from the black carbon buildup so fast. It did not wipe off with solvent as did everything else. But why did it get so hot?

Over advanced timing? I statically set timing before installing engine. Checked it after had it running for a while with light and it was nearly spot on, maybe advanced slightly. Spent 45 minutes to an hour with it fast idling trying to adjust points with light but had to go back and forth with adjusting. I'd adjust to correct timing but when I'd tighten up on screw it would either advance or retard. Sometimes I had it right on but when I just put the cover on points, it would throw it off timing. Figured out that was due to wire not in JUST the right spot through grommet on points cover. When I'd put cover back on, the wire was apparently pushing slightly on points just enough to throw it off.

So who knows what went on between that and adjusting carb. Which is another story in itself. 

Was having charging issues (was not charging) that I was unaware about until running for nearly 5 hours. After running a while it would occasionally misfire. What I believe was happening was the batt voltage was getting low, causing a weaker than normal spark, causing the misfire, causing my coil to work harder putting more current through it and burning out the coil (went through 2 coils while breaking this thing in). Point is, I was attributing the occasional misfire to out of adjust carb so I'd try and get it where it would not misfire, perhaps causing it to run way too lean. Discovered charging issue later and addressed that, which is in another post (two magnets in flywheel were installed incorrectly).

Mind you, this Gravely came to me and I was under assumption that a charging issue was not there. My cousin was not aware of it either, but then again, this thing was hopping on last leg when it last run a year ago (which I've never seen or been around this thing while running nor have I ever worked on it so I really don't know much history about it. I do know nearly everything needed attention or replacement).

Gonna try to get to the root of the problem but at this point it's a lot of what if's until I come to a more definitive conclusion..., and that may be a big if.*


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## t-craw

*Today I removed rings from piston, turned piston upside down and slid into bore. Felt for differences in wobble while rotating piston 360* in cylinder and I did not find anything negligible.

As I said in a previous post, I don't have a bore gauge/inside caliper but... will probably have one Monday evening. Big brother said he could probably get one from work. Once I have that I can either rule in/out any "out of roundness" or clearance issue with cylinder, which I'm so curious to know about now.*


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## PeteNM

t-craw said:


> *Today I removed rings from piston, turned piston upside down and slid into bore. Felt for differences in wobble while rotating piston 360* in cylinder and I did not find anything negligible.
> 
> As I said in a previous post, I don't have a bore gauge/inside caliper but... will probably have one Monday evening. Big brother said he could probably get one from work. Once I have that I can either rule in/out any "out of roundness" or clearance issue with cylinder, which I'm so curious to know about now.*


That's probably a good idea to measure everything as it goes back, since it's clear down anyway. Might as well know all is well. It's kind of hell to start at the start but since you're already there you will at least know for sure. 

Here's good luck going back......


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## t-craw

*Today I checked Piston Ring End Gaps and found some interesting values:

K341 Values should be:
NEW-.010/.020. Used-.010/.030

Here is what I found:

Top Ring: .008
2nd Ring: .010

I also checked the top and bottom rails on Oil Control rings and this is what I found:

Top Rail: .026
Bottom Rail: <.002 (and I use the < sign because that's as small as my feeler gauge goes and even that would not fit between gap)

Regarding values on Top ring (.008), I could get a .010 feeler gauge inserted just a bit but between the gap but would not go through and touch cylinder wall. A .008 would go through narrowest point of gap. I did not try a .009 because I do not have that size on my feeler gauge sets (I have 2 of them).

However, what really raises my concern is the difference between the two rails on the oil control ring. I mean, there seems to be no area for expansion and when ring would heat up it could not expand and scuffed up cylinder wall which allowed a passage for oil to travel?. Is this possible? Could it be that the vendor sent me the wrong rail?

Attached is a picture of both rails lying next to each other. Not sure if you can see the difference in gaps by just viewing pic but here they are.*


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## Fluid

Do you know what the term ( flat rate ) means. Is this your first rebuild? You stated that you rebuilt your cousins engine. But by what you wrote on this thread, you only put some new parts in a engine. A good engine builder knows if the right parts were installed. Everything is miced to be sure before it goes into the engine. PeteNM gave you good advice, start at the start. Get an assemble sheet. A check list for an engine rebuild and follow it. Good Luck


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## t-craw

*Forgive my ignorance. Don't quite know what context you are referring to when you use the term "flat-rate". 

This is my first 4 cycle small engine re-build. No, I am not that confident in my abilities to know what I think I should know and I've never claimed to be a "good engine builder". I do have a repair manual and usually follow every inspection method. After receiving block back after re-bore was complete, I asked if I should check ring gap (he had the piston and rings and I kind of assumed he would have checked such) and his reply was "shouldn't have to but if you want to you can, it should be about this much" (held up his fingers and made a small gap). I did put one ring down into cylinder to check end gap with feeler gauge and it was good. Did not do every ring. Again, my mistake and I realize that. I guess I thought the entire ring set (.020 over) would be the same as far as end gaps are concerned. Now I know! 

I could list a slew of things I replaced in this engine by using a micrometer and determining if it was within tolerable limits but I'm not as it would take up a lot of time and would be useless information but thanks for letting me know what a good engine builder does and should do.*


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## Fluid

I'm not trying insult you man. I hope you didn't offend you t-craw and I'm sorry if I did. That was not my intentions. I guess I'm just not good at getting my thoughts across very well without making people mad. Again I'm sorry I came across hard. Flat rate is a term used in the auto trade and others, it means if the job calls for (and this is just an example) removing and replacing (R&R) both front struts on a car. There is a (flat rate) book that says it should take you lets say one hour to complete, R&R two front struts....you are paid one hour, even if it takes you three hours to do it, because you didn't check to make sure you have the right parts. Now you are done with the job, the customer goes home and the car is not riding right so they bring the car back and you did the job so you have to find out whats wrong, you check and you did something wrong and the new part is now f---ed up, your bose is now not very happy with you because the customer is not happy with him. To make the car right and the customer happy a new part has to be put on the car. Who puts the new part on? Who pays for the new part? Your boss pays for the part and you put the part on, but now you put the part on for free because you got payed and f---ed up the other new part. You get paid to do the job right the first time not the second time. Now you finish the free job and all is well, but the job that you would be doing if you hadn't had to redo the strut job has been sitting there waiting for you with your boss asking when will it be done. 
You get the idea. Get a step by step book that give you a run down on how to rebuild an engine, get the right tools to do the job. You kohler shop manual shows you all the tools you will need to get the job done right. Auto zone and others rent tools for doing rebuilds maybe you could look into something like that.. Check before you install then double check and don't skip steps to save time, 9 times out 10 it will come back to bit you in the butt. I hope you can get you job done and learn from your mistakes. Again my sorry if I made you mad. Good Luck


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## Beaner2u

t-craw, 

I ran across the following information at http://gardentractorpullingtips.com/a1carb.htm

"Throttle Shaft Bushings -
A worn throttle shaft is the #1 cause of most engines wearing out prematurely. If a carburetor has a worn throttle shaft, this will create a vacuum leak and the engine will idle poorly, if at all at times. Not to mention the engine will also draw in dirty air, causing wear on the valve faces/seats and piston rings, and engine will burn oil. More than .010" of play is considered too much for throttle shaft wear. Plus, at operating running speeds (3,600 rpm), the extra air will cause the engine to run lean on fuel, which will overheat the combustion chamber and cause the cylinder head to warp (blow a head gasket) and the piston and rings to wear prematurely, eventually resulting in severe engine wear and excessive oil burning. Along with regular maintenance, repair of a worn throttle shaft is required to help an engine last a long time. The most accurate way to check for amount of wear is with a dial indicator."

Roger,


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