fz1p5c Posted January 12, 2022 Share Posted January 12, 2022 89 MJ 4.0L 2WD AUTO 140k - found this delightful surprise while going after the thermostat - lower mounting boss broken off - previous owner busted it and basically RTV'd thermostat housing it in place - any suggestion to repair without pulling head would be appreciated - reman CYL head #2686 is hard to find / expensive. Comments on these ideas appreciated 1) clean thoroughly and JB Weld a helicoil in place and use smaller fastener 2) drill into water jacket / tap and use longer fastener - seal with #2 permatex 3) add 2 smaller adjacent fasteners into the cylinder head face on either side of the busted one Any other approaches would be appreciated Link to comment Share on other sites More sharing options...
watchamakalit Posted January 12, 2022 Share Posted January 12, 2022 Edit: I misread the post and thought the thermostat housing was broke. Not sure there is a good fix for this short of a head replacement. Being cast it will be difficult to repair. Link to comment Share on other sites More sharing options...
cruiser54 Posted January 14, 2022 Share Posted January 14, 2022 I like option 2. Link to comment Share on other sites More sharing options...
75sv1 Posted January 14, 2022 Share Posted January 14, 2022 I might try modifying option #1. I would use a Keensert or such. I could also see making an insert with a flange that would be counter sunk about a washers width. Then epoxy into place. Possibly combining with squaring up the back. Add washer and a nut. Link to comment Share on other sites More sharing options...
AZJeff Posted January 14, 2022 Share Posted January 14, 2022 I am with Cruiser. Drill and tap deeper, and use sealant on the threads when they penetrate the water jacket. Older Ford V8's had threaded holes that penetrated the water jacket, and sealant kept those from leaking. Link to comment Share on other sites More sharing options...
cruiser54 Posted January 14, 2022 Share Posted January 14, 2022 4.os have a head bolt that does that!! Permatex #2 seals the threads. Link to comment Share on other sites More sharing options...
87MJTIM Posted January 14, 2022 Share Posted January 14, 2022 My mom used to say to me "You need that like you need another hole in your head." This reminds me of that. Link to comment Share on other sites More sharing options...
cruiser54 Posted January 15, 2022 Share Posted January 15, 2022 2 hours ago, 87MJTIM said: My mom used to say to me "You need that like you need another hole in your head." This reminds me of that. One of my Mom's favorites also. Link to comment Share on other sites More sharing options...
fz1p5c Posted January 16, 2022 Author Share Posted January 16, 2022 Hey y’all - thanks a bunch for the feedback - I’m gonna do some drilling’ and I’ll let you know how it turns out - M8-1.25 threads - and yes the ‘another hole in my head is spot on !” Link to comment Share on other sites More sharing options...
cruiser54 Posted January 16, 2022 Share Posted January 16, 2022 How come you're going metric? Link to comment Share on other sites More sharing options...
fz1p5c Posted January 16, 2022 Author Share Posted January 16, 2022 My bad - I see that bolt ought to be 5/16-18 - I would be keeping same - the current bolt is chewed up so I got the thread size wrong - I’ll also be making a temp jig to guide the drill once I determine the thermostat housing hole to hole distance - thanks for the feedback on the bolt Link to comment Share on other sites More sharing options...
cruiser54 Posted January 16, 2022 Share Posted January 16, 2022 You bet. The 4.0 didn't use mumblemeter measurements. Link to comment Share on other sites More sharing options...
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