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Author Topic: leaking from head bolt hole  (Read 832 times)


  • Posts: 64
leaking from head bolt hole
« on: October 03, 2010, 08:54:04 PM »
Ok this may be a silly question, I had to remove the right side head bolt second from the rear, lower bolt when I began to loosen the bolt after it got about 5 turns it began leaking coolant. when the bolt was fully removed it gushed out. Is this bolt hole open to the cooling flow and this is normal or is it possible It broke through the wall into the water jacket area? 1947 346 flathead. The flow was too much to just be a leak in the head gasket. When the bolt is fully seated and tight no leaking or sign of trouble. Engine seems to run fine. No water in oil system or manifold so I don't think the system is leaking.

Offline TJ Hopland

  • Posts: 10193
Re: leaking from head bolt hole
« Reply #1 on: October 04, 2010, 09:35:29 AM »
I dont know that engine specifically but its not uncommon to have bolt holes that go into the cooling areas.  Usually the service manual will note that the ones that do that require an additional sealant.    This head bolt must attach some accessory bracket so that is why you were removing it? 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

Offline Bob Schuman

  • Posts: 572
  • CLC Number: 254
  • Name: Robert Schuman
Re: leaking from head bolt hole
« Reply #2 on: October 04, 2010, 03:30:02 PM »
On the 1937-1948 flathead V-8 ALL of the head bolt holes go into the water jacket, so what you experienced is normal. A non-hardening sealer(I like Permatex #2) on the bolt heads will prevent leaks. If yours is not leaking, I suggest you leave it as is, and do not remove it again just to apply thread sealer.
Bob Schuman,CLC#254
Bob Schuman, CLC#254
1951 6137
2017 CT6-unsatisfactory (repurchased by GM)
1948 Olds 98 Custom
2020 XT6


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