I’ve got a fresh built 59a flathead with some vintage Edelbrock heads that after driving 500 miles since it’s been on the road has started to seep coolant from 4 or 5 studs total (some seep on right side, some on left side). This just started as low temps here in NC at night dropped to near or at freezing. No seepage of coolant while driving but does after cool down and sits for a day or two cause I drive it everyday if not raining outside. After the first time it happened, I let it cool down overnight and then checked all nuts with torque wrench at 35 ft lbs, then 40 but the same studs are still seeping a bit. looking for recommendations on what sealant product I can use to seal it up? Moroso ceramic, K-Seal, or something else?
No joke, There's a product called K Line, Blue container, orange lid, It stopped at 1/8 hole in a winter truck beater with in 20 minutes... Advance auto, an i think auto zone as well, about $15.00.. Start there..
I like to use the green Prestone antifreeze in old cars. Sealants can also effect radiator or heater cores. Found this on Fordbarn - There are three types of antifreeze available: Inorganic Acid Technology (IAT), Organic Acid Technology (OAT), and Hybrid Organic Acid Technology (HOAT). IAT is mainly used in older vehicles, is usually bright green, and has to be replaced every 30,000 miles. OAT antifreeze/coolant is usually orange, yellow, red, or purple, and lasts much longer — 150,000 miles — but doesn’t contain any silicates or phosphates for additional engine protection. HOAT antifreeze/coolant is typically orange or yellow and can last for 150,000 miles
I doubt there are many who have tried a half dozen different sealers back to back in the past few years. Most tend to stick with what worked before. So I also doubt there are many who can rate them in order with the current formula, not what worked 20 plus years ago. If you don't get a solid consensus, I'd look for product testers who seem to agree with your own experience. Project Farm has seemed honest on the things I've watched, but make your own conclusions. I looked and it seems that isn't one they have tested. https://www.youtube.com/@ProjectFarm/search?query=coolant sealer I hope you do get an answer, but I'd guess there will be some who will say you should pull the heads, studs, seal properly and redo. You might want to say what radiator you have, too. A fresh aluminum or an old br***/copper.
Some of those just seem prone to leak no matter what you do. When I get one of those, I clean the threads up good and put some RTV on it. The only “stop leak” type product I’ve ever used is the ACDelco tabs. I was always HIGHLY opposed to any such snake oil type mechanic in a can repair. Until I learned that more than one highly respected machine shop I use, jams a couple of them in the back of the block before the heads go on engines they’re building. I’ve used them sparingly here and there with great results and no adverse affects.
rad is an original 34 (pickup) that was cleaned and tested by local shop. I am running 50/50 mix of ShellZone dexcool/distilled water, skip Haney rebuilt water pumps, and NoRosion too. I didn’t install studs. They were installed by the engine builder. I ***ume to put some RTV on clean threads, I would have to drain cooling system, remove heads, clean threads, new gaskets, install heads, then RTV on threads, torque down all the nuts? Or just remove nuts that are seeping, clean them , add RTV, install nuts and torque down?
Only correct way to fix is to pull studs and apply sealant to the threads. Anything else is just a bandaid that best case scenario will just impede cooling a bit
The one that looks leaky in the photo appears to be leaking between nut and stud. In that case, I’d just take the nut off, use some brake clean/acetone/etc to clean nut and stud threads, put a little RTV on the stud and torque it down. I always give that a try first as it’s quick and easy. Just never been a huge fan of sealants in the cooling system.
I'm not sure about vintage Edelbrocks but new one need to be torqued 20,40 then 55ft. lbs. You say you did 20 & 40 ft lbs. Maybe your not tight enough.
The big question that no one asked yet, did your builder run a tap through the block at all of the stud holes? If so then that is a big no no, the thread size is proprietary to Fords of the era and was a bit tighter than a standard 7/16”. You can try yanking the studs and throwing some permatex thread sealant on them but they might still leak. I have a few studs that weep on my flathead and I just live with it.
This really doesn't address the question in the OP, but since it's here let's clear some of this up. And my apologies to those who are offended over the digression from the OP. If you aren't interested just scroll past to the next comment. My company sells antifreeze and I provide technical support to our customers on the products. My training on coolants isn't as extensive as on lubricants, but I've been providing technical support on coolants for a couple of decades and have seen the changes in technology take place, so I have more experience & knowledge on the subject than most. When you talk about the IAT, OAT, HOAT technologies your talking about the additive technology used to prevent corrosion and erosion in the cooling system. First thing to understand is they all use either ethylene glycol (highly toxic and probably 90% of antifreezes on the market) or propylene glycol (less toxic, won't kill your cat if they get into it) as the main component to provide reduced freeze point and extended boiling point. The difference between the coolant types is the additive technology used to protect against corrosion and erosion. Second thing to know is there is no industry standard for color in antifreeze, manufacturers die them whatever color they want for their own identification purpose. So you can't just go by color, however with that said, the old school green antifreeze is what the above poster called IAT. That coolant is intended for p***enger cars and light duty diesel engines without wet sleeve cylinder liners. It is lightly additized to prevent corrosion but the main purpose is just to prevent freezing and extend the boiling point. Heavy duty diesel engines with wet sleeve liners require more protection against cavitation erosion of the cylinder liners, so a few decades ago the industry developed supplemental coolant additives for those engines, and if you didn't use it your engine was likely to suffer pin holes in the cylinder liners caused by cavitation erosion (especially if it was a ***mins). Those additives form a protective and self sacrificing layer on the surfaces of the cylinder liners to protect against erosion, this also protects the water pump impellor, and the rest of the system from corrosion. These additive deplete over time and need to be replenished periodically to maintain protection. The glycol still provides protection against freeze point and boiling point but doesn't do anything to protect against corrosion/erosion. A newer technology was developed that uses an organic acid to provide the same protection as the SCA's, but lasts far longer before depletion. Car OEM's started using these types of coolants in p***enger cars to provide added protection, and they've evolved over the years because the first generation OAT's had some problems (anyone remember the m***ive problems GM had with Dexcool? They had to replace a lot of engines because of that, and even more people got screwed and had to pay for it themselves) Modern OAT coolants, aka Long Life or Extended Life, are excellent coolants and provide fantastic protection for the life of the car if they aren't diluted with straight water or non-OAT coolants. (side note, every complaint I've ever investigated about cooling system corrosion from a customer using our coolants, I've found mixtures of different coolant brands and technologies, which of course we can determine using lab ****ysis). HOAT coolants are Hybrid Organic Technology, meaning they use an organic acid technology combined with some supplemental additive technology, like silicates or boron or something. These are usually less expensive than the top line OAT's. Caterpillar has never really trusted just straight OAT's and likes some additional additives. Note there are also NOAT coolants that are hybrid coolants that add Nitrites to OAT coolants for protection against cavitation erosion. In our experience none of these HOAT or OAT technologies provides better or as good of protection as a straight 2nd gen OAT nitrite and silicate free coolant. But my advice is always to pick one technology and stick with it, don't mix them. The only time we see problems is with customers that have mixed different brands and different types, or they fail to maintain SCA's at the proper level, or they have insufficient ground between the engine and the ch***is/frame and develop electrolysis in the coolant which destroys the additives and leave the engine unprotected. OK, sorry for the digression, back to discussion on leaking head studs on flathead engines....
Some good info on antifreeze. I recalled a problem with Dexcool and always stuck with original Prestone.
gonna try this RTV trick first because I’m hesitant to put of these additives to the cooling system. I doubt seriously he tapped out the threads. He’s built a number of flatheads and is a retired NASCAR engine/car builder. I’m hoping some RTV will slow it down enough I can live with it.
If memory serves me correctly,in the past GM adopted these ac Delco stop leak tabs to remedy intake manifold gaskets leaking coolant. You were lucky if the coolant leaked externally and not down the intake valley and thinned the motor oil. I believe the tablets were made by bars leak and were not supposed to clog the cooling system. The gasket failure problem was either gaskets, electrolisis, aluminum intake mounted on cast iron or type antifreeze (death dex cool) they were using.The v6 suffered most.
@Blues4U thanks for the info! I wonder how the poor end consumer can hope to 'not mix types' when the systems are even more complex and the auto makers can't even figure out how to place drain plugs so they don't spill on things! @tarheelrodr RTV turns into a solid. You may want to check online or with your builder about a non-hardening sealer. When the block and stud expand and contract due to normal heat, you want the threads sealed.
A good friend of mine who did my machine work for years was a GM mechanic until the mid eighties and he said GM used a version of this product on every new vehicle produced. He had built a 360 for my shop truck and it had a small water leak at the end of one of the heads after start up. After he had put one of those tablets in the cooling system I literally watched the leak stop and I didn’t have a problem with it for the twenty five years I had the truck afterwards.
We called those rabbit turds. And IIRC Cadillac said to use those with the POS 4100 engine as those were notorious for leaking coolant. The 3400 V6 we owned was on its second set of head gaskets and at 66k was seeping again. Despite working in a dealership parts department GM refused to warranty even with owner participation aka money out of my pocket so I stuck those in it. Stopped the leak.
@shovelheadrider , if you had to do 4100 warranty work, I pity you. I wasn't in a dealer at the time, but a friend was. It's a good thing the NSA wasn't recording all phones back then. The feds would have visited him for the threats he tossed out after a week of those things.
Well I ordered some of them ACDelco “ horse tabs” but not used them yet. A buddy of mine suggested using some permatex Indian Head gasket shellac. So I removed the nuts and washers, used air hose to blow out any moisture, applied some shellac with tiny paint brush around threads at where they stick out from heads, applied thin coat on bottom of washers before putting the on studs, then more shellac on threads in creavis against washers and then ran nuts down to 40 ft lbs. that was yesterday..been curing until tomorrow when I’m going to crank her up to see if that does the trick…if not in goes a “horse tab”… maybe… stay tuned.
The Jalopy Journal
