Headbolt
 

Sorry I have so many questions, this is #2 for the day! I started up the truck this morning and noticed 3 head bolts that seem to have leaked, just a little tiny bit. Of the 3 1 of them does not seem to be leaking anymore but the other 2 are. Is there a suggestion that anyone has to fix prior to pulling off a head or removing a head bolt?

Also, I bought a temp gun to shoot the engine temperature and the head is showing 150 and engine block showing about 172 when my engine temp gauge is almost to the top, my gauge has a range of normal and it's the very top of normal What is hot for a flathead?

Details on the engine are 192 miles since rebuild. 8BA with aluminium heads.

Re: Headbolt
 

Not unusual for a few head bolts to leak for a while after rebuild. Most of the time the leaks will stop themselves, without having to pull the heads. A bottle of Bars Leaks might be worth a try. I just fixed the thermostat housing leak in my wife's 2008 Mustang, for which the dealer wanted $850 to replace a $30 part. Okay, it is a b**ch to get to.

Re: Headbolt
 

Run it a while unless something serous comes up. I had the engine in my Corvette rebuilt a few years ago and it would overheat if I let it idle more than a couple of minutes. I was just ready to pull it after 800 miles when it stopped doing it. It must have been built real "tight" and it took that long to fully break in.

I think having only two head bolts leaking "just a little tiny bit" on a fresh engine is a sign of a job well done.

Re: Headbolt
 

With that few miles on it it is probably worth checking the torque on them all. Don't go mad, just tighten to the recommended torque figure. I'm not going to recommend a figure, but I used 45 lb ft on a recent build. Some might prefer higher. What I am not telling you to do is go tighter and tighter to stop a leak. That is not what you want to do.
Time rather than torque will probably stop the leak.
Mart.

Re: Headbolt
 

DO NOT USE BARS LEAKS. I had used it for many years in every engine I had built. We used it on our race engines. About 6-8 years ago we seen our temps were higher for no reason with typical grille opening. Upon research we found our radiators were somewhat blocked with all these minuscule hair looking fibers. We stopped using bars leaks & fibers were gone & temps were good. Our engineers called Bars Leaks engineers & yes they changed formula. Said to use the tablets for same as old formula.

Re: Headbolt
 

When installing studs into thw block, they should be torqued into the block 435/40 ft/lbs. to prevent leaks. When installing bolts, I used a sealant for steam pipes, to seal the block from leaks. These tips have always worked for me. Probably better ways now.

Re: Headbolt
 

What do you torque the bolts when re torquing the heads? Would re torquing potentially stop the leak?

Re: Headbolt
 

run hot let cool retorque the say at least 3 times and see what happens

Re: Headbolt
 

Most likely it'll cure it's self. I usually just use a little anti seize when installing. Changes torque settings but helps seal and helps later removal if ever needed. Dollars to donuts it goes away in a bit.

Re: Headbolt
 

I torque ALL my heads to 45/50Lbs thru 3 or more heat cycles. The block has thick and thin spots and over torquing and deform the block causing leaks and cylinder distortion.

Re: Headbolt
 

When you retorque after each of the three heat cycles.....do you loosen ALL the head bolts...not one at a time ....then retorque in steps....30#-40#-50# ?.....using the right pattern....Thanks....Mark

Re: Headbolt
 

Personally I never loosen anything. Torque up in steps on the initial build, then keep checking and tightening any that move to the desired target figure used on build. On the crusty Flatty I used one new (but old) gasket and one used gasket. The used one torqued up after about three cycles the new one took more cycles until things stopped moving.

Mart.

Re: Headbolt
 

NO. One at a time and you only need to loosen 1/4 turn.

Make sure when you assemble the first time, you lube the threads and flat washers with an extreme pressure oil similar to gear oil or the ARP stuff.

Re: Headbolt
 

Thanks guys!!......Mark

Re: Headbolt
 

Thanks Pete, I forgot to mention the harden washers. Memory loss???
Gramps

Re: Headbolt
 

Alright its time for this 3 heat cycle thing. Yes I know my brain day by day is going south.
But all my rebuilds 'too many' I'm talking about valve in block engines like a Cadillac
V8 346 v/s a 337 Lincoln. no mention of heat cycles just torque to specs all makes: Last
summer we built a massive 275 hp Hercules 6 flathead torque to specs. Thats it. So whats this, a small V8 Ford thing. And then my cobweb brain says if the factory had to
do 3 heat cycles for "i'll throw a number 5,000 vehicles a day" not possible and I have
no doubt the dealer did that, because in my youth worked at uncles bus co. Ford shipped the cowl chassis to the body builder like Superior Ward etc no dealer was involve'd. And I doubt the body co. fooled with torquing heads. Then we had two Ford
city buses 1946 I think looked as a 59AB air brakes and ran an run until the 70's no
body ever re torqued those heads ! so I say this is a myth. The torque wrench is only
a tool, and this tool only tightens nuts and bolts evenly that the key...

oh I gonna get hammed from this one ++++

Re: Headbolt
 

The problem with "wet" head studs is often related to the use of a threading tap to clear the threads in the block, instead of a proper cleaning tap. Old cast iron is very fragile from years of hot/cold cycles, and the threads can be damaged. We use a good clearing tap to clean the block, and put sealer on the block end of the studs. New studs are a "must". As for Barr's Leaks, the "factory rebuilt" engines always included some, and seldom caused problems.

Re: Headbolt
 

You should use a common standard class 3 tap for cleaning block threads. It will put the threads back to original and bare metal if they have been distorted.
You CAN NOT get an accurate torque reading with rust and scale in the threads.
You should test the threads when the block is in the machining stage, NOT when you are installing the heads. If one pulls out, it can be repaired without getting chips inside the engine.

As to Bars Leaks, listen to KIWIinUS. (post #5) The NEW stuff is no good.

Re: Headbolt
 

Why would you loosen a nut to re-torque it? Sounds counterproductive to me. Inquiring minds want to know.

Re: Headbolt
 

We haven't brought up the type of thread cutters used. Rolled vs the new taps.