OMC 3.0 Head Gasket Replacment Failed

banko

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I just replaced me head gasket in my 1989 fourwinns 160 freedom with a 3.0 OMC. I had a very small leak so pulled the head had it resurfaced cleaned and inspected the block really well (no cracks) put the new gasket on torqued to the 90ft lbs spec in three stages of 30,60,90#'s, fired it up now it is leaking worse then before. Is it a possibility that it could have been caused by not having enough thread sealent on the head bolts?? I used the permatex threat sealent but followed there instructions which said there was no need to over use it, I am hearing som people use Ultra Black RTV is that a better choice?
 

Reinell-BRXL-191

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Re: OMC 3.0 Head Gasket Replacment Failed

It's leaking out of the threads on the head bolts? Did you replace the head bolts or are you using the old ones? You need to check to make sure the bolts are not torque to yield, because if they are, they are not really holding the head down properly anymore.. you can tell by looking at the bolts - here is a diagram - I would want to make sure the deck hole threads are not corroded or damaged as well - I always use hi-temp black permatex on head bolts that go in to water jackets

headbolts-1.jpg
 

banko

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Re: OMC 3.0 Head Gasket Replacment Failed

It's leaking out of the threads on the head bolts? Did you replace the head bolts or are you using the old ones? You need to check to make sure the bolts are not torque to yield, because if they are, they are not really holding the head down properly anymore.. you can tell by looking at the bolts - here is a diagram - I would want to make sure the deck hole threads are not corroded or damaged as well - I always use hi-temp black permatex on head bolts that go in to water jackets

headbolts-1.jpg

Is is not coming through the head bolts but reather leaking all the way around the head. no water in the cylinders or oil just leaking aroung the head on the outside. I am kind of suspecting that it is the head bolts because I didnt use enough sealent in my opinion. does that sound correct? I used the white permatex thread sealent just lightlt smeared on the threads.
 

banko

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Re: OMC 3.0 Head Gasket Replacment Failed

I am reusing the old bolts that may be the problem as well. My head bolts have the bolt head of the dicard one in the diagram but has a shorter thread section like the re use one mine also do not have the machined step on the shaft so I am guessing that i have the "discard bolts"? Thanks for your quick response Reinell.
 

Don S

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Re: OMC 3.0 Head Gasket Replacment Failed

Have never heard of a 3.0L GM engine having disposable head bolt.

If your head gasket leaked, you may have a warped head or maybe you didn't get it torqued down properly. Did you clean the threads in the block and the head bolts?
 

banko

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Re: OMC 3.0 Head Gasket Replacment Failed

So the 3.0 doesn't have disposable bolts? The head was resurfaced and the block was cleaned good. The head was warped .008 before it was machined so I know the head is not warped. I did clean the threads. That's why I am wondering if it has to do with the head bolts or not having good sealant on the bolts that go into the water jackets which is almost all of them
 

banko

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Re: OMC 3.0 Head Gasket Replacment Failed

I also did torque in a right hand spiral fashion of 30# 60# then finally 90#
 

Don S

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Re: OMC 3.0 Head Gasket Replacment Failed

There is no reason to overdo the sealer on the head bolts, but too little is worse than too much.

I have always used either Permatex aviation form-a-gasket or Mercruisers similar product Perfect Seal and never had a head bolt leak.

Are you sure your torque wrench is accurate?
 

banko

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Re: OMC 3.0 Head Gasket Replacment Failed

I would hope so it is a brand new craftsman torque wrench
 

Don S

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Re: OMC 3.0 Head Gasket Replacment Failed

I would hope so it is a brand new craftsman torque wrench

Had to mention it, for all I know, you could have used something like this hooked on the end of a wrench, :D



704499TOOL.JPG
 

banko

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Re: OMC 3.0 Head Gasket Replacment Failed

Yea I know what your talking about Don. So do you guys think water can come up the bolt then leak out on the sides of the gasket and not the head of the bolt
 

bruceb58

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Re: OMC 3.0 Head Gasket Replacment Failed

You use the following sequence?

30_head.jpg
 

banko

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Re: OMC 3.0 Head Gasket Replacment Failed

That is exactly the torque sequence I used. But I used Permatex high temp thread sealant P/N PX#59214 but I didnt apply it to all threads just a few
 
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