I have several leaky studs on my flathead (offy heads). Its a new build that someone else had done years ago. She runs like a top with the exception of the leaky heads. Anyway to seal these studs without removing the heads?
You better take a vernier and measure the stud size. If I remember the offy head is bigger then the bolt size and may require "O" rings to fix. When I did my STOCK heads I used Permatex is "aviation grade sealer" The stuff is thick black goo and it stays plyable. Oh, I also had to re-torque my heads about three hot and cool cycles. Not sure on the offy heads but it worked on my stock heads. Brent
Flatead studs went into extra-tight threads in the block, and the original type studs are shaped to bottom into a slight recess in the block. If a rebuilder ran a tap into the block threads...well, 99.999% of all threads out there are cl*** three fit, and will wallow out the block holes (cl*** 4 or 5) so they fit the way normal cl*** three (again, 99.999% of the fasteners you have ever seen) nuts and bolts fit...not water tight. There are several good sealers out there...if you get a good collet type stud puller that grips the threads you can probably pull the affected studs with heads on, apply goo, and run them back in without damaging them. Tapped out threads will also not reliably support the threads at 90 degrees...applying the nut and washer will set the stud to vertical while your goo dries. The Ford threads and stud base shape also did this if not destroyed by a machinest... Imagine if Ford had to fight 48 crooked studs while installing heads on a million engines per year... At any rate, when sealing studs it is good practice to use the head and fasteners to set them to vertical during ***embly.
I agree, this is pretty common practice on studded engines...I have had to do this on a few small chevy race engines, but same premise on a flathead. Sam
Dave, Bruce has some good advice here. A retorque / recheck of torque might be in order too Every spring I'll have 3-4 studs on the Merc that will weep a little on the first few start ups of the season then they seem to seal themselves.
I did a cool torque today and ran it a bit. Still leaking pretty good. Some studs did seal up on their own. If I remember correctly I sold a pair of Offy heads once because I couldn't get them to seal. Posted from the TJJ App for iPhone & iPad
I went to their website and read the instructions. Worth a try. Posted from the TJJ App for iPhone & iPad
Without pulling the heads, you probably cannot reliably distinguish whether you have leaky stud threads or a bad suface/gasket seal that is coming out around an innocent stud. If it's only a few studs, find or borrow a collet puller, seal'm, and see if leak stops...then go on to the heads if you cannot stop the leak.
I was gonna recommend this^ but waited for a few replies...... Did this several times in the race car,and low and behold....... It REALLY WORKS!
Drain the coolant and use hi temp rtv red silicone on the studs . make sure the threads are clean . re torque nuts and let cure for 24 hours ,refill and enjoy. .
The Moroso block sealer really is commonly used to seal studs on race engines. The first time I built a studded race engine I had a few studs that seeped. At the time, I thought it was a half-***ed fix. Since then, I have learned that this is commonly required. If you don't want to use it, than the only other surefire way to seal studs is to use a good thread sealer on the threads going into the block. Then, most stud washers have a small inside chamfer on one side, put some RTV on that side of the washer & install face down on the head. When you torque the nut,the RTV will fill the chamfer & seal the hole. Sam
About half have sealed on their own so far. Looks like lime build up. Just what a old timer said would happen with good old Indiana tap water. Think I'll try that ceramic sealer you guys been talking about next when I'm ready to drive it. My next post will be asking how to clean aluminum heads? May just cover the nuts with caps and drive the **** out of it and go the patina route... Posted from the TJJ App for iPhone & iPad
I go with brent, I have always used aviation glue for years. its hi heat resistant and never hardens. Plus I hope the head gaskets were sprayed with copper spray on bolth sides.
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