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Head Gasket keeps Blowing


NorthIdaho's Avatar
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01-19-09, 08:49 AM   #1  
Head Gasket keeps Blowing

I am looking for some advice.

I have an older snowblower with a 7 HP Tecumseh (H70-130100)
the problem is that it keeps blowing the head gasket. What am I doing wrong or is there something else that I should be looking at.

Thanks.

Bob

 
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cpgixxer's Avatar
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01-19-09, 10:43 AM   #2  
Is the head cracked or warped? Are you torquing it down to the proper torque and pattern? Have you tried new headbolts, they could be stretched?

 
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01-19-09, 11:41 AM   #3  
No Crack that I can see. No Warpage that I can detect using a steel straight edge and a light.

Yes, proper torque on bolts. They are the old bolts though (except 1)

One of the holes was stripped and I put in a thread insert (I just drew a complete blank on the name). Anyway that one bolt is different.

Thanks

 
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01-19-09, 12:08 PM   #4  
Posted By: NorthIdaho No Crack that I can see. No Warpage that I can detect using a steel straight edge and a light.

Yes, proper torque on bolts. They are the old bolts though (except 1)

One of the holes was stripped and I put in a thread insert (I just drew a complete blank on the name). Anyway that one bolt is different.

Thanks
Helicoil I think is what you are looking for. A pane of glass should do for a quick check but I haven't seen a warped head yet. The helicoil is probably your problem.

 
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01-19-09, 01:03 PM   #5  
Yep -- Helicoil was the term/brand I was looking for.

I am not sure I follow you. The bolt with the Helicoil seems to torque down fine and seems to hold well.

Why do you say that the helicoil may be the problem.

 
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01-19-09, 01:29 PM   #6  
Not to horn in on cpgixxer, but just by chance, did those blown gaskets appear to have blown out in the same place each time. This might give you a clue as to which bolt(s) might be at fault.

 
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01-19-09, 06:33 PM   #7  
Posted By: NorthIdaho Yep -- Helicoil was the term/brand I was looking for.

I am not sure I follow you. The bolt with the Helicoil seems to torque down fine and seems to hold well.

Why do you say that the helicoil may be the problem.
I say that cause it is the weak link, i'm not saying thats the problem but it may be suspect. As chuckret said, same spot everytime?

 
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01-19-09, 06:41 PM   #8  
You are not using a gasket adhesive are you?, when putting on new ones?

 
30yearTech's Avatar
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01-19-09, 07:10 PM   #9  
Posted By: cpgixxer I say that cause it is the weak link, i'm not saying thats the problem but it may be suspect. As chuckret said, same spot everytime?
Heli-Coils if properly installed will hold better then original threads cut into aluminum. If the threaded insert is not installed below the mounting service, it may not allow the head to seat properly.

Be sure that you are using the proper head bolt for your engine, if one or more are not all the same grade they may loose their torque when they are heated.

 
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OK

01-19-09, 07:40 PM   #10  
one other thing, unless all of the bolts are the same length the bolts may be installed in the wrong holes, the torque reading will be correct and still the head will be improperly torqued.

are you going to cowboy up or just lay there and bleed?

 
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01-22-09, 12:29 AM   #11  
Bob, has anyone messed with the governer lately? Ur rpms may be set to high putting alot of strain on your head gaskets. Let me know. Rick

 
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