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Block Heater Cracks

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Old Sep 20, 2006 | 10:29 PM
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Block Heater Cracks

I just recently acquired a 84 6.9 with cracks by the block heater area, Are there any fixes for this issue? JB Weld?
 
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Old Sep 21, 2006 | 05:59 PM
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NO.....many have tried but no success.
 
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Old Sep 21, 2006 | 08:38 PM
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got two old macks with 300 six in them with jbweld holding them togeather some said it wouldn't work but ya never know till you try if it don't then call local machine shop they have ways to fix
 
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Old Sep 21, 2006 | 09:20 PM
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The parameters effecting the Mack crack (no pun inteded) and the 6.9 block heater cracked area are probably totally different. Many members have used JB weld, slow heating/welding with several types of rod and slow cooling to no avail. Master welders and expert machine shops have all tried, just once I heard of a partial success. The cost to try was more than the block was worth in the end.
 
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Old Sep 21, 2006 | 09:27 PM
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You interested in buying another motor chowitworks? I noticed you're a member of the NW chapter, and I live in the Seattle area (Kent), and I just happen to have one that may be for sale after tomorrow.

I bought an 86 F250 three weeks ago and it came with a spare engine. I'm doing a compression check on the motor in my truck tomorrow. If it checks out OK, I plan on selling the spare.
 

Last edited by CheaperJeeper; Sep 21, 2006 at 09:30 PM.
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Old Sep 22, 2006 | 06:43 PM
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I think that I will try a combination of KW block sealer and a coat of JB weld on the outside. Will report on success or failure after the fact.
 
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Old Sep 22, 2006 | 07:21 PM
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When I purchased my 84 6.9 two years ago, I noticed it didn't have a block heater...since I was replacing the stock starter with a "mits" I figured I'd put in a block heater...replaced the starter, put in the block heater and just my luck the block heater didn't work and it's a good thing from what I'm reading!
 
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Old Sep 22, 2006 | 11:43 PM
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I have never had any problems with the one in my 83
 
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Old Sep 23, 2006 | 12:20 AM
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So exactly what's the issue? The heat from the block heater causes cracks in the block - or what?
 
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Old Sep 23, 2006 | 01:06 AM
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in the early 6.9 from 83-84 the casting was weak at the freeze plugs essp at the one for the block heaters ford finally figered this out at the end of 84 and international fix the prob but as i stated earlier in the post sometimes ya never know till ya try had and old macinest however ya spell tell me his secret to success is to find the crack an drill very small holes at all the ends of the cracks this relives the stress points the the fixin begains sometimes ya win some ya don't
 
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Old Sep 23, 2006 | 01:21 AM
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Originally Posted by dwaymar
in the early 6.9 from 83-84 the casting was weak at the freeze plugs essp at the one for the block heaters ford finally figered this out at the end of 84 and international fix the prob but as i stated earlier in the post sometimes ya never know till ya try had and old macinest however ya spell tell me his secret to success is to find the crack an drill very small holes at all the ends of the cracks this relives the stress points the the fixin begains sometimes ya win some ya don't
Interesting - makes sense though. I've seen pretty much the same technique used by windshield repair places to stop a crack.
 
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