Technical Top of heads are weeping antifreeze ?

I had my 53 Mercury engine over hauled and torqued the heads four times to 70 lbs. through four heat and cool cycles. The top of the heads by the intake manifold keeps weeping anti freeze. It's has the original heads that were cut. The engine ran fine before it was overhauled . 30 over new pistons, cleaned the crank, new valve guides, reground the valve seats, adjusted valves, original cam, new oil pump, and new gaskets and bearings. The 255 was never opened before this was done. It had the original head gaskets on it etc.etc.

 

Are ya saying that after milling the heads, they've become porous?

 

I had a problem like that on a couple different engines...turn out the machinist didn't do a good job with surfacing the heads. Once they were properly milled, they didn't leak any more.

 

I use to have trouble with copper head gaskets in my flatmotor days....Ford originally used a composite gasket...Went to composite gaskets and never had anymore issues....

 

I've always heard 13 lbs is too much pressure for a flathead's radiator cap. I have a 7 lb cap on my flathead, with a Walker radiator, and it doesn't overheat. I think you should change that first, retorque again, then report back. Maybe need to look elsewhere to keep it cool.

I also spray coppercoat on the gaskets before I install them, whether steel or composite. I've had weepy studs, but never a leak at the edge of a head.

Hopefully whomever rebuilt your flathead didn't retap the head stud holes. That is a major no-no as they were originally a tight tolerance to help keep coolant from seeping up the threads.

 

There's always Bars leak ! Fixed more seepy , weepy cooling systems than a lot of jacking around does !

 

JV>>>and new gaskets>>>

Oh-oh. Didja forget to slather them with plenty of wheel bearing grease?

 

First off ,70 pounds torque is TOO much torque. 50-55 tops on iron heads,45 on aluminum heads. Since 23 out of 24 headbolts go into water, the threads need to be “coated” with some type of sealant that prevents the water or antifreeze from “climbing” upward and making a mess on top of the heads.Were the headbolts “coated” prior to installation,if not, the bolts will continue to “hemorrhage”coolant until a sufficient amount of “schmegma”or dirt makes them seal and the flow of water stops. Excessive torque will NOT stop the water flow no matter how much torque is applied if the threads were not coated prior to installation.Flatheads Forever!!!!

 

I was thinking the same thing, I goofed on a 218 and didn’t seal the threads, didn’t know any better. Got to redo the hole thing again a few months later.

 

John, he said it's weeping out the top edge, not the studs.

 

I always use a composite gasket sprayed both sides with coppercoat. Its a Permatex product. I use Permatex head gasket shellac on the threads of the head bolts. Like said earlier in this thread 55 ft.lbs on the bolts. Thats my routine and I mercilessly beat the flatheads in my cars, no leaks.

As a side note I dont like pressurized caps on these engines but hey who am I.

 

Changed to a new 7Lbs. cap and it's ok . The 7 Lbs. cap i had was old . Look up the torque specs for a 255 is 65 to 70 Lbs. Thank you all. Go figure !!!