If your gaskets are leaking, there's a problem somewhere. The graphtite gaskets do not require any sealant. Sealant won't hurt them, but they do not require it. I've put them on with copper-kote and dry and never had any issues. I have had issues with thread sealers and now only use the permatex. I'm not saying it can't be your gaskets, but it's unlikely. It is normal for the torque to loosen that much on a re-torque... Again, try some waterglass...likely solve your problem.
Well I wouldn't have believed it if I didn't see it with my own 2 eyes. You are absolutely right about the ARP thread sealer. It is basically worthless !! I took the heads off yesterday and I saw that every stud was totally wet except the 4 that are not threaded into the water jacket. I kind of assumed that, but as I unscrewed the studs I was amazed to see that every one of the studs that leaked showed signs of the ARP sealant being washed up the stud and into the fine threads under the nut. The sealant that was very thick and was originally down in the block was all very thin and watery now and would not have sealed anything. It looked like the antifreeze basically dissolved it. Sorry I was so sure this stuff would work, but after getting several recommendations and reading the information about it, it looked like the ARP stuff was tailor made for this application. I guess in this case it just wasn't going to happen. Anyway, this time around I am not taking any chances. I think I will go the permatex #2 route this time, but I am going to mock up a single stud hole that I can use to test out the sealant and then pressurize it to 15 # or so and make sure it really works. then if I need to tweak my application method a bit it will be easy to do and re-test. Then I can be sure.
Dave, How do you mock up heating, cooling, retorque cycle? It'll probably be a bitch cleaning that arp stuff outa the block threads. Please post your results, so we all learn! GOOD LUCK! Dennis
I will not be able to mock up the heating and cooling cycles, but I figure if I just get somthing that does not leak at 15 lbs of pressure I should be doing ok. So far the 2 things I have tried leak at no pressure. One of them started leaking before the engine was even running. The ARP stuff is already a memory. It was easy since it was half dissolved anyway. I cleaned the stuff off the studs in my parts washing tank and the stuff in the block came out easy with a tap. I got some Permatex 2 today and I have something to use to test it with pressure so I will let you know how it turns out.
You tapped the block threads? Or was it just a clean-out/chaser? The threads are cut kind of tight and a standard tap will open them up and remove metal increasing clearance and possibly making it more prone to leak... Bruce Lancaster has more info on this...
Yes I cleaned them out with a standard tap (although it was a used tap). I know this should not be done normally but when I was prepping the block a while ago I did not know about this detail so I used a standard tap at the time to get all the rust and crap out of the threads. I have no idea if the original threads were still there or not. It didn't seem to do any metal cutting, but I was not paying close attension to that at the time. Too late now, I just have to deal with what I have. That is why I want to make up that test set up so I can figure out the best sealant and method for my loose thread situation. obviously this is adding to my difficulties.
By now, most flatheads have been tapped out...some of them by me before I knew anything. And you'd have to watch the average macinest pretty closely to stop him from doing it. But if you have the full original threads, that is a big help, and with original type studs they set down in straight and firm. Old type Permatex is reliable, I understand there is a newer grey form, also non-hardening, that was specified by GM for SBC bolts at one time. Cannot remember name, but it is specifiaclly for head hardware going into water.
When I applied the gooey Permatex, I spread it on the stud threads, but also took a screwdriver and smeared some in the threads in the block. That way I was sure that some would be inside the block, not wiped off at the top when the stud was screwed inward.
I had same problem with leaks. Contacted Flat Head Jack about it. Was told to get rid of the stainless head bolts and use (ready for this) good old permatex on the threds
Your best bet is to use Bars Stopleak. It doesn't have the precautions that sodium silicate does. Just wipe the leakage off every day, as if you don't it will burn on the heads and you won't get it off. It will stop your problem, may take a day or two but it will. It's cheap and it's very effective.
Stainless bolts: what is in my head is that they are generally evil...not very strong except in super duper aircraft formulations unrelated to streetrod hardware entirely, and that something about their surface makes them agressively nasty to the threads they go into unless heavily lubed. Is that correct outside of my head??
One thing I've heard and done (on a Hudson flathead) that I've not seen mentioned above is to slightly countersink all the headbolt holes, both on the block decks and on the block side of the heads. The theory is the metal deforms slightly (pulls up) around the bolt holes when the studs are tightened because this is where the force is applied. By providing a slight countersink, the force is spread over a wider area around the stud, giving better gasket sealing.
This might seem stupid /but 1 time i surface ground the head on a flat head 6 ply leaked like crazy you can have too smoth a surface finish most manufactures use 250 rms finish on heads and blocks for that reason
So now that we are all educated to not use a regular tap in chasing threads in flathead blocks, how are we supposed to clean out the bolt/stud holes in the block (assuming the block still has the tight factory threads)?
There are classes of thread fit, depending on their application. Most of what we see are class 2. Henry apparently made his head studs a tighter fit. If you want to tap a tighter/looser hole, you have to use a tap for the class you want. Kinda specialized for the general public, and may be hard to find. I suppose you could grind a regular tap if you had the equipment. Surely we have a tool and die man on this board. http://en.wikipedia.org/wiki/Unified_Thread_Standard
You can use a thread cleaner/chaser - they're designed not to cut metal. You can also use a bolt with slots cut in it.
If worse comes to worse you can always turn new studs on the lathe and leave the stuff a little bigger when you cut the threads. that makes up for the short threads in the block. Gee, maybe some smart guy would turn out a bunch of bigger studs just for that usage. Maybe a kit, bigger tap and larger studs. doesn't need to be very much bigger. traderjack
EUREKA !! I found out the best way to seal the stud threads. It involves a lot of comments you guys made and it has been under pressure for 19.5 hrs so far with no leaks Set up: I used a pressure test tube that is about 2.5" x 12" tall that used to be a compressed air oiler (see pictures). I cleaned up everything and then tapped out a hole in the bottom cap to mimic the block threads. I made them as loose as possible so they were similar to the block. I also made a plastic spacer to simulate the head so I could tighten down the nut and seat the threads in the block. The idea here is that I could seal up my threads, then fill the thing up with antifreeze so I could check for leaks. I could also pressurize the antifreeze. Test 1 (failure): I used permatex 2 on the stud threads only. I filled every thread just to make sure, turned the stud into the block till it stopped then backed it off 1/2 turn. I let it set at an angle (like the block) for about 1 hour and then put the spacer on and tightened the nut down finger tight. Then I flipped the thing upright, filled it with antifreeze and let it sit for about 1 hour. There were absolutely no leaks at this time. Then as soon as I pressurized the test tank to 10 psi it started to drip. NO GOOD. Test failed. Test 2 (success): Took everything apart, cleaned and dried everything. This time I remembered what Alchemy said about putting the sealant in the block threads. So I used a small screwdriver and smeared it into the threads in about 4 places. Then I applied it to the stud and turned the stud in same as test 1. This time tho, I DID NOT let the sealant set up before I put the spacer on and tightened the nut. I figured this would hold the stud in its final position while the sealant set up. I let this set up for 2 hrs, added antifreeze and let it set for 1.5 hrs, no leaks. Then I pressurized the system to 14 psi and again no leaks. The stud has now been under pressure for 19.5 hrs with no leakage at all. Not even a drop. I think the key here is that the female threads were coated as well. Since I can look at the inside of the test setup where the stud is. I can see that the permatex was squeezed out of the threads as the stud was turned in and formed sort of a seal ring at the end of the stud. I think it also helped that I let dry for 2 hours before adding antifreeze. I still have to try this method on the engine, but I think it will work fine. Thanks to everyone who kept focusing on the studs and the permatex solution. -Dave
Update: The Permatex 2 lasted about 60 hours under 15psi and then it leaked a few drops. I could see the threads were wet and there was a drip forming on the end of the stud. This is with no heating or cooling cycles. I don't think this is good enough. I would like to try some high temp silicone gasket maker in my test setup. I have some permatex copper stuff I have used for the exhaust. To me this would make sense because it is just as thick as the Permatex 2 initially but it hardens much more firmly. I also plan to heat and cool the block that the stud is in just to simulate the engine heat. If I keep testing different materials and methods, I see no reason why I won't find something that will hold up permanently. I know this is a lot of messing around, I just do not want to see another stud leak on this engine. The next time I put the heads on I want to be the last. -Dave
Update: Now I have changed the setup so I can check 3 studs at the same time. This time I tried Permatex #2 coating the stud and inside the hole. I also tried Permatex Ultra copper hi temp silicone sealant in the 2 other holes. On one I coated the stud and inside the hole, on the other, I just coated the stud. I let the setup cure for about 30 hours, then I filled it with antifreeze. I checked after 9 hours and no leaks. Then I pressurized to 14# for 10 more hours and I noticed the Permatex #2 was dripping. I took the Permatex #2 stud out and plugged it with a bolt with Permatex ultra copper sealant on it. This time I wanted to heat the antifreeze, dump it into the chamber and pressurize it. Then I let it cool down and do it over again. I have done this at 150, 180 and 200F and I am at a total of 76 hours so far with no leaks at all. My next step is to remove the studs and see how hard it is to get them out and clean up the threads again. Not that I really care that much since I will probably never take my studs out, but it will be interested to note for other people trying to do this. Again does anyone know a reason why I do not want to use Permatex Ultra Copper to seal these studs? It seems to work better than anything so far. -Dave
Now just repeat the test in Death Valley in August, Minnesota in February, at 10,000 feet altitude, then it's on to the 50,000 mile durability runs in a fleet of NYC taxis, and then... Interesting test! I need to update my goo... I have also heard good things about a grey stud/bolt sealant from Permatex/Loctite made for just this, supposedly also supplied by GM...cannot remember name, findable on their website with a bit of annoyance.
Personally, I hate the overuse of RTV sealants. I find bits and pieces of RTV in most engines I tear down - lots in places where it shouldn't be; radiators, oil pans, etc. Most folks use way too much. Most folks use it where it shouldn't be used. If used judiciously, I can see no reason not to use it on the studs. Personally, I think you're over-thinking this. I've got some heads to change out in the next month or two - it'll be Permatex #2 and nothing else.
I agree with the overuse of silicone. I have run into that as well. That is why I tried 2 different application methods on the studs with silicone. On one, I put silicone in the block threads as well as on the studs. Both of these methods are working excellent, so I will probably not put any selant in the block so I do not have a bunch breaking off and getting caught in the cooling system As far as overthinking this, I understand that several guys on this list have had no problem at all with this. I also see that I have tried 2 other "recommended" ways that did not work for me. So for me I would much rather "over think" this problem than to be caught with my pants down for a 3rd time. If I can seal the block up well from the start I would much rather do that then to have my studs leak, or have to use stop leak down the road. You are lucky that Permatex 2 works so well for you. For me, Permatex 2 worked much better that the ceramic seal or ARP thread sealant, but it does not hold up like the Permatex ultra copper. I gotta go with what works the best. -Dave
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