The Stovebolt Site Forums The Shop Area Engine Shop Leaking Antifreeze Under Head

After installing a "new to me" cylinder head on my 1951 235, it is weeping antifreeze from between the head and the block on the right side, most noticeably directly under the #1 spark plug. There are also some signs of leakage under #4 & #5 plugs.
It's just a tin bit, not a ton of leakage, as in running down the side of the block, but it caused concern. I had ran the engine for a total of maybe 45 minutes after the head was installed. I left the truck alone for 2 weeks while I was at college, and upon my return, there was some antifreeze seeping out. I figured since I had installed the head, ran it, and it had cooled, maybe that was normal. So, I re-torqued the head, hoping that would solve the problem. It didn't. (I have overhauled 2 1940s era tractors, and had the same issue, but re-torquing fixed them) I re-torqued it yesterday, and there was a bit of seepage there today.
I bought the bare head from Old Car Parts in Oregon, had it checked/rebuilt by a reputable cylinder head shop in Oklahoma City, and was given the go ahead by the machinist. He did check it for being level, and said it was indeed level. The head gasket I used was a Fel-Pro, and I coated both sides of it with Permatex Copper "Spray-A-Gasket", as I have done all my cylinder heads in the past.
I did reuse the old head bolts, but I'm not sure those are the problem. I also cleaned out and chased the threads in the block with a tap, so I'm sure I'm getting a correct torque reading with my click-type wrench.

The engine never blows any white smoke once it's warmed up or on start up, so I don't think it's getting into the cylinders.

Any ideas on what to do?
Thanks!

Did you install the head bolts dry, or with some sort of lubricant? If the bolts aren't lubed, some of the torque is wasted overcoming thread friction. Drain enough coolant to keep from spilling it all over the place, then remove the head bolts one at a time , use a lube like 30 weight motor oil on the threads and under the bolt head, and retorque them. If you use a high film strength lube such as never-seez, reduce the torque specification about 5% or so.
Jerry

Out of couriousity, was the head gasket a copper gasket or one of the newer composite gaskets?

HRL, yes, the bolts were lightly lubed with SAE 30.
Dragsix, it wasn't solid copper. It was composite.

Without really knowing why it is leaking, particularly given that you have retorqued the bolts twice, it’s had to say whether it was a defective head gasket, a block that is not true,a head that may not be just right. You could try some Barr’s head gasket fix if you did not want to redo the work. Me, I would probably pull the head and try a new gasket. You might also ask the machinest whether the head was magnafluxed for cracks. You might also ask him if the head was resurfaced when it was rebuilt. If not, I would do both when you pull the head.

The old head I replaced was cracked between the valve seats on 4 cylinders, but never leaked antifreeze from around the head. I doubt the block isn't true, but I won't rule it out. The place I bought it from (Old Car Parts) guaranteed the head was magnafluxed and crack-free. The cylinder head shop I took it to locally said he checked it for being level, and it checked out good, so he didn't surface it, although I gave him the go ahead to do so if need be.
While I would like very much to do it right, I'm also on a deadline. The truck has to be road ready by mid-May. Seems like quite a while, but I'm in college and usually only able to go home and work on it every other weekend, unfortunately. That adds up to only about 20 actual working days. I'm gone right now, but hopefully I can check it out and see if it's leaked anymore when I'm home again.

Given a little time and another retorque or two, seep leaks have a habit of getting better - - - - -or worse- - - - -sort of a "luck of the draw" situation. If there's not an active drip going on, give it some time. It just might correct itself. If not, antifreeze is cheaper than another gasket set!
Jerry

Are you certain that the leak is coming from the head gasket? I have the same issue, and I finally traced mine to the water outlet at the front of the head. It weeps water, that will follow the front of the head down to the little bit of the block deck that is exposed. From there, it makes its way back to underneath the number one spark plug, making it look like the head gasket is leaking.

Thanks, HRL. As long as it won't hurt the engine, I guess a slight weep is okay until I find out if it will "self seal" or if I need to pull it apart. I was just afraid it would ruin the gasket or get in the cylinders/oil.

Tim, that may very well be a possibility! I'll have to check it out. The antifreeze is sitting on the block deck, and has never ran off and down the side, so as you can picture, it's a tiny leak I almost didn't notice. The majority of the weeping is under #1, but there is also a tiny tiny bit around #4 and 5. Under 4 & 5, you can't really see any green, but it is moist looking and there is a small bit of light rust, making me think it has weeped a tad.

I have had this problem with my 1951, low side cover style 216 motor. I have been through several head installations including a replacement because of a crack in the head. It doesn't leak a great deal, just a very small amount. I have the motor apart right now as I am getting the block bored .I have never figured out why it happens.

Sounds like you covered all the bases. I would put in a can of Bars Leaks. I have used it for many years & have never plugged anything up. Make sure the engine is warmed up & the coolant is circulating & covering the radiator tubes. Pour it in slowly. Car companies have used it for recalls & warranty work.

George

I'd recommend running the engine "as is" for several warm up/cool down cycles before using any sort of stop leak. A seep leak will usually self-seal, particularly on a low pressure cooling system where there's not a great deal of stress on gasketed joints. Bar's Leaks is a great sealer, but it turns the coolant a nasty-looking gray color!
Jerry

I'll do as you say, Jerry. I don't usually like using additives for anything unless I have to. It's only got a 7 lb cap on it, but I've removed it when hot, and there is almost no pressure ever behind it.

If that doesn't work, I already have a can of Bar's Leaks on the shelf, for when my radiator starts leaking. The guy at the radiator shop wouldn't clean it for me, because he said if he did, it would leak like a sieve on the bottom. This radiator doesn't leak yet, and hopefully it won't until I can find a good replacement or at least a core.

If you are going to use the bars, it’s not the radiator leak stop. It’s the head gasket repair product. You have to drain the coolant, flush with clean water. The liquid goes in, heats up, flows into the area of leaking, and seals the leak. Drain it out and replace the coolant.

I've done a temporary repair on a pretty severe compression leak with a product known as "water glass"- - - -chemical name "sodium silicate". When Ed Pruss was trying to drive his big 54 GMC fire truck from Cullman Alabama to Denver Colorado, he had to leave it with me about 100 miles north of Cullman after experiencing a head gasket leak, battery charging problems, and dragging brakes. I was able to stop the head gasket leak temporarily and fix the other problems, and drive the rig to Kansas City for the annual reunion. Then Ed flew in from Denver and drove it the rest of the way home. The engine was a 503 cubic inch big GMC gas engine, and there was only one head gasket we could find- - - -all the way up in Canada at an obsolete parts place. If you use it that product, be aware that it can glue the head down better than super glue- - - -Ed had a terrible time getting the head off about a year later when it started leaking again! You can buy pure sodium silicate on Ebay- - - -it's a fairly inexpensive, colorless thick liquid. There is a pretty simple procedure involved in getting the best seal, involving a flush, refill with clear water, add the sealer, warm the engine up, then let it cool down with a little pressure applied to the radiator. When the engine is restarted, any sealer that has found its way to the leak will harden into glass- - - -with a 500+ degree melting point!
Jerry

The gm dealer also sells a product . They look like little pucks. I was told they work well also but have not used them .

I have an 80 year old friend who retired from the Furd Assembly plant in Norfolk, VA, and he said that every new truck that left that plant received one of those pucks in the radiator.
They called it a donkey turd.

If true it must have done a good job, my 98 is still running the original thermostat....
They knew how to build a truck at that plant. Shame they closed it.

The biggest losers of the plant closing was the truck buying public.
There were folks and businesses all over the country who would only order a truck from the Norfolk Plant and pay the extra shipping expense. They manufactured that good of a truck.
I talk a lot of trash about that particular off-brand ( ), but the ones built in the past 10-15 years (maybe longer) have been as good as any other brand.

No Norfolk truck/engine assembly plant when my 48/54 VA trucks were made?

I found a easy way to test this.
Park the vehicle on a slope with the rear raised enough to tilt the engine foward, if the leak is at the water outlet the water will show there and not along the head gasket.

Well I found out it's not coming from the water outlet. 100% dry there...gonna try a bit of "Aluma Seal" and see where that gets me, if it doesn't seal itself up in the next couple of warm ups.

Get ready to buy a radiator- - - - -Alumaseal has clogged up enough radiators to send a BUNCH of radiator shop owners' kids to college! I replaced a radiator in a Ford van once that weighed about 10 pounds more than it should when I lifted it out. During a post-mortem of the rotten radiator to show my students how it was made inside, I found the bottom tank completely full of atomized aluminum powder. There must have been 30 or 40 tubes of the powdered sealer used to try to stop a chronic leak. There's no telling how much there was in the block!
Jerry

Just courious here, but but if you are going to use a product that goes into the cooling system, why were you thinking of using alumsaseal verses the Barr’s head gasket leak stop?

When I took the radiator to a renowned shop to get cleaned I was told since the radiator had deposits on the bottom, it would leak like a sieve if he cleaned it, so he advised I just run it as it was if it wasn't leaking, to save money, since it isn't going in a street rod or daily driver. He said if anything ever started leaking, use Aluma Seal, as he wouldn't trust Bars Leaks in his own radiator. Had another local mechanic friend say that too.
I was just going by what I was told by the shop. I'm not saying they're right, just what I was told.

Any sort of sealer in a cooling system is a "Band-Aid on a brain tumor" situation- - - -it does nothing to solve the problem- - - -it just hides the symptoms. Bar's Leaks is a vegetable fiber based sealer. Atomized powder sealers plug the leak with finely powdered metallic particles, either copper or aluminum, usually. Both have water-soluble glue as a carrier. Vegetable fiber is much less likely to clog radiator passages than metal, at least in my experience of almost 60 years of seeing the results of both products being used. A radiator repairman who is afraid to take one tank off a radiator and rod it out, then repair whatever leaks the process creates, is either incompetent or lazy, or maybe both. The modern design aluminum/plastic radiators are throwaway items, and most shops refuse to even attempt to repair them, other than maybe replacing a cracked plastic end tank. Even then, they run a risk of breaking off the crimped aluminum tabs that hold the tanks on. Soldering a leak in an aluminum core- - - -forget it!
Jerry

The shop said he could fix it, but it would cost about $600. Sounded pretty pricey to me, so I decided to pass.

That sounds like a rcore job. All they reuse is your tanks and side mounting brackets. The entire middle section is replaced. That's not an outrageous price, if indeed you're getting a new copper core. If you want a non-repairable new radiator, an aluminum core exact fit replacement radiator is probably available for less money.
Jerry

Yes, that's correct. He said these cores are not repairable, since the tubes are sandwiched together, unlike more modern radiators.
Anyways, radiator aside, the head gasket is still weeping. Guess the "right" thing to do, if it doesn't seal up on its own, is just pull the head again and install a new gasket?