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Blown Head Gasket #2 And Damaged Cylinder Head


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#1 FilledTires OFFLINE  

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Posted May 08, 2014 - 11:29 PM

Hi Everyone,

 

So I have my Kohler K321 that is giving me problems with the head gasket.

 

I blew one. Replaced it, and tested the engine out putting it under load and I blew another gasket.

 

I took the head off  moment ago, and they blew in the same spot, and now my cylinder head is damaged. Luckily I have a donor engine, I can get a new head off of.

 

As you will see in the below pictures my engine block uses stud bolts.

 

I have a few observations that hopefully someone can help me understand:

 

1. When I took the head off the second time, the bolts had come loose already (I torqued them to Manual Specs). Should I be using lock washers here to prevent this?

 

2. Head Gasket Blew in the same spot. Does this mean anything?

 

3. Does this have something to do with the Stud Bolt setup on my Ford LGT tractor?

 

Piston, Rings, and Valves looks great. So I am unsure on why I blew the gaskets in the first place. I haven't checked the valve to tappet clearance, but they open and close tight.

 

I realized I made a few mistakes after reading Brian Miller's websie:

 

1. I didn't clean the threads up on any of the stud bolts, or bolts

2. I didn't lubricate threads with oil

 

Will these have such a big impact and cause me to blow another gasket?

 

Help?

 

 

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#2 Texas Deere and Horse OFFLINE  

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Posted May 09, 2014 - 12:31 AM

Did you happen to check the head and block deck for flatness before you put it back together? I am betting you have a warped head or a low spot in the block.

 

And to answer a question for you, yes not cleaning the bolts or studs will cause you a faulty torque reading.


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#3 JDBrian OFFLINE  

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Posted May 09, 2014 - 05:17 AM

Looks like that damage on the head may have happened over a long period of time. When you started the original repair I gave you a link to a topic where I dealt with a HG problem. In that case I spent a lot of time getting both the block and the head flat. I feel this is critical and no matter how much care you take with the rest of the job it can't seal properly if the head and block don't mate up with very close tolerances. If this is your first time doing a HG job then just chaulk it up to experience and try again. You may need to buy another head if that one is too damaged. You need to determine how much you would need to remove to make the head flat again.


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#4 JDBrian OFFLINE  

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Posted May 09, 2014 - 05:29 AM

Another thing just came to mind when I had a second look at your pictures. While you have studs in the block you also have a bolt near where the leak occurred. You need to test that bolt to make sure it screws in far enough to compress the HG without binding. If the bolt bottoms out before the HG is compressed, the torque wrench will still read the proper torque but the HG will be loose. This could be at the root of your problem. So, screw that bolt in by hand  until you get resistance and measure from the block to the bottom of the bolt head, or washer, as appropriate. This distance needs to be less than the height of the head.  Clean the bolt threads and run a tap through the holes in the block if you need to increase the bolt depth. I ran into this problem on my K321 HG replacement. Be careful using a tap in the cast iron block. Use lubricant and don't use too much force. Taps are brittle and don't give you much warning when they break. If that bolt is a standard length I would consider replacing it with a new Grade 8 bolt.


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#5 LilysDad ONLINE  

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Posted May 09, 2014 - 06:05 AM

I'm unsure what other info has already been posted. Find a perfectly flat surface; a piece of plate glass, the top of a table saw, etc.. then lay a sheet of emery paper on it. Lay the bottom of your head on that. Sliding it back and forth a couple of times will quickly tell you how flat it is. Some folks will tell you to put your head on a belt sander to dress it down, but you need to be really good or you will ruin it.


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#6 FilledTires OFFLINE  

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Posted May 09, 2014 - 07:39 AM

Thank you all for the good suggestions. This was my first time doing a HG, I will check out all those things you suggested.

 

I have another Cylinder Head from a tractor I just picked up, so I will take that one, check it for flatness, check the bolt lengths, check the block for flatness, clean the bolts and threads and try again!


Edited by normanng, May 09, 2014 - 07:40 AM.

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#7 FilledTires OFFLINE  

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Posted May 09, 2014 - 08:23 AM

Just got back from the garage, and Brian you are correct about the Bolt near where the HG blew. The threads in the block had some crud in it preventing it from screwing down all the way, and giving me a false torque reading. I need to pick up a Tap and Die set, and will clean that up.

 

Thanks for the tip, I wouldn't have thought of that anytime soon.


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#8 JDBrian OFFLINE  

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Posted May 09, 2014 - 08:31 AM

Just got back from the garage, and Brian you are correct about the Bolt near where the HG blew. The threads in the block had some crud in it preventing it from screwing down all the way, and giving me a false torque reading. I need to pick up a Tap and Die set, and will clean that up.

 

Thanks for the tip, I wouldn't have thought of that anytime soon.

No problem. I ran into it and thought you might also. Keep us updated. That's a nice tractor and we all want to see it up and running for you. That's a lot of what we are about here. We learn from each other and then pay it forward!


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#9 glgrumpy ONLINE  

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Posted May 09, 2014 - 09:20 AM

Think studs are just on there because of added on items over the top of head on this tractor. I would buy new grade 8 nuts for those. Those head BOLTS are probly odd lengths, might need to use one off your other engine if same. Not all bolts were the same length in all the holes on some models. There should be a washer under each nut and bolt head, don't think they are any lockwashers?? When torqing, should use the tightening pattern from the manual while snugging them. Go lower tork range at first all around in pattern, Then go around at higher final tork. Then go around once more just to check them all. Use the pattern each time. Keep in mind it is fairly low tork value, think 35lbs or so is all, check a manual.  I think clean threads are wanted, but not so sure on the oil on them. I've seen manuals for some engines that say NO oil on bolts. I would check a Kohler manual on that too. As noted don't force the tap into hole at bottom, don't wanna break it off, then have BIG problem. There might not even be threads all the way down to bottom as long as enough to let bolt tork correct.


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#10 FilledTires OFFLINE  

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Posted May 09, 2014 - 10:01 AM

And my Cylinder Head is not usable anymore, right? I pulled another one off of a Cub Cadet I just got, but want to make sure it can't be saved first.



#11 LilysDad ONLINE  

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Posted May 09, 2014 - 11:21 AM

It depends how bad the cutting is. Racers cut up to .030"* off the heads to increase compression. In any case, you will need to find a machinist to mill it off. Possibly it will cost $50 - 100.

 

* Any more than .030 and the valves will hit the head.


Edited by LilysDad, May 09, 2014 - 11:23 AM.

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#12 JD DANNELS OFFLINE  

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Posted May 09, 2014 - 03:51 PM

Others have pretty well covered the options.  Your pictures pretty well show where it is blowing. What I'n not sure about is if there is gas cutting in the blowout?

I would lay a straight edge on that block and be sure it is flat. You can use a feeler guage  under the straight edge to see if any material needs to be taken off. You can do the same on the head. ( the amounts taken from both mating surfaces effect the total valve clearance, for the .030 Lily's Dad Mentions)

 

Another thought is a bolt is like a rubber band and has some stretch designed into it.

If it has been overtightened(beyond Torque Specs ) It could have stretched to the point it's not tight.

The next step beyond stretching per manufactureres specs is breaking.


Edited by JD DANNELS, May 09, 2014 - 03:53 PM.

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#13 FilledTires OFFLINE  

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Posted May 09, 2014 - 04:52 PM

If I were to replace the stud bolts too how do I go about doing that? How do I get them out?

#14 FilledTires OFFLINE  

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Posted May 09, 2014 - 05:00 PM

Never mind. I figured it out. Vice grips.

#15 KennyP OFFLINE  

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Posted May 09, 2014 - 05:11 PM

Never mind. I figured it out. Vice grips.

You can also put a double nut on them Tighten the 2 nuts together and back the studs out!


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