Head Gasket repair 1936 21 stud

[tgarner317]

The story.. Car overheated and blew the top seam of the radiator last year. BrassWorks built a new radiator that I just got around to installing. After reading lots of threads about coolant being lost but cannot find where it’s going, I decided best to pull the heads to check it out.. Coolant leaking into #2 and #3 and looks like cylinder #4 got a little hot. By that I mean it looks like there is possibly some bluing in that cylinder. The number 2 cylinder has some rust from the top to about an inch down into the cylinder.

1. Can the rust be removed fairly easily without harm?
2. What are your thoughts on cylinder #4?

I’ll try to get some pictures posted..

[Ggmac]

Need a lot more information. Was your old radiator in good condition, what temp did it get to ? Did it run after it cooled down, and did it cool down slowly ( no cold water in hot engine ) , what caused the original overheat ? More questions coming after COFFEE.

[Mac VP]

More questions still.....what pressure cap rating was used? Was there a provision for overflow in the radiator design? Were the cylinder head gaskets new?

[tgarner317]

The Radiator was in good condition before the event. Car ran cool 180-190f, but had to keep an eye onthe coolant level. Seems like each time I drove it, I kept having to add coolant. I didn’t know where it was going. It is stock, unpressurized system. The stock temp gauge and the SW underdash gauge never showed overheating.

At first start up there was always a bit of “condensation” from the single exhaust but it would always burn off. The engine was rebuilt in 2003 by the previous owner. He was more of a model T guy and the 36 sat in his garage most of the time, so not many miles were on the engine when I got the car.

[chap52]

Unless you have an overflow recovery system of some sorts as Mac VP stated you will always be "topping off" your coolant. Fill it, drive it and it will establish it's own level. Just make sure the baffle plate in the top of the radiator is covered with water/coolant. These don't usually run full.
You could hook up a temporary recovery tank to the top of the radiator overflow tube, fill it up, drive it and see just how much is exiting out the top.

Coolant in 2,3, and a hot #4 sounds like a head gasket issue to me.

Please keep us posted, it's overheating season. Enjoy the adventure, Chap

[tgarner317]

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I can’t say for sure, but I’ll bet the heads were not retorqued after running the engine. Had I been more experienced with flatheads, I would’ve at least checked the head bolts when I first began driving it. Learning experience.. Hopefully not an expensive one.

[Ggmac]

Take the gasket off and check the deck . I'd check a few valves , make that all the valves also . How would it have blown the tank off if a no pressure system . Compression , possibly, but would of registered high temp .

[tgarner317]

Originally Posted by Ggmac

Take the gasket off and check the deck . I'd check a few valves , make that all the valves also . How would it have blown the tank off if a no pressure system . Compression , possibly, but would of registered high temp .

This was my question also.. Only thing I could come up with at the time was something must’ve lodged inside the overflow tube. Honestly, I don’t know?

[fordwife]

I don't have much experience with the 21 stud engines, but could the head be warped?

[Ggmac]

Pull the gaskets and inspect both the gasket and deck surface. Pull the intake and check for any moisture trails

[tgarner317]

Originally Posted by fordwife

I don't have much experience with the 21 stud engines, but could the head be warped?

Possible.. haven’t checked that yet.

[tgarner317]

Cast iron heads are fine, not warped. I really feel like the heads should’ve been retorqued at some point and weren’t. I think that’s the cause..

Now for the repair!

[Tinker]

with the head off take a long screw driver or/and coat hanger and clean out the back of the block. between rust and casting sand the rear of the block suffers.



Think about a river flow, the pumps are up front and the coolant intake and exit is up front of the block. Where would be a weak spot for sentiment? ....Center outlets don't help much either.


Now if you had room you can flip the heads and draw fliud out the rear of the engine. But like the L head we have limitations.


cleaning the rear of the block will help wonders.

[tgarner317]

Originally Posted by Tinker

with the head off take a long screw driver or/and coat hanger and clean out the back of the block. between rust and casting sand the rear of the block suffers.



Think about a river flow, the pumps are up front and the coolant intake and exit is up front of the block. Where would be a weak spot for sentiment? ....Center outlets don't help much either.


Now if you had room you can flip the heads and draw fliud out the rear of the engine. But like the L head we have limitations.


cleaning the rear of the block will help wonders.

Awesome, thank you!

[Tinker]

You could try a best fiber gasket with spray coat after cleaning things out. Torque - re-torque three cycles. If it leaks you have a warped deck or heads. ( you can get a laymans idea with a straight edge. sort of) But since it's apart and If heads are stock, have them milled .050 anyway before installing.

[tgarner317]

What tool would be abrasive enough to remove the rust from the cylinder without damaging the cylinder wall?

[Tinker]

A cloth and some oil. If it's pitted you might rethink something.



Post a closeup picture for the area your worried about after cleaning it.

[tgarner317]

Been a while since updating.. @Tiinker, the cloth and oil worked perfectly for cleaning up the rust spots in the cylinders. I did the coat hanger trick to get the casting sand from the rear of he block. What seemed to work best is after breaking up all the hardened sand, I used a wet / dry vac and was able to suck out all the loosened sand and rust. I’m still got to do the driver side, but this works great! I’ll post some pictures in a bit.

In the meantime, I dropped my heads off a few weeks ago at a local machine shop. I had him shave .040” off.

[Tinker]

I know you said this was a rebuilt, but 2/3 intakes look a little burnt. Check them, might be running lean.



With the heads off, you can also lap the valves if you pull the intake and valves separately. Little more involved though. Don't want to start a snowball effect if it's running well and you had good compression prior.

[Talkwrench]

If youve taken that much off without knowing if its ever be done before it would pay to put them on without the head gasket and turn the engine over by hand and check nothing is touching , if all good proceed.
If you've scrapped away to remove crud in your cooling system, you might want to consider using something to catch it moving around now. Not sure of what you guys have in the U.S. but here I run cone filters in the top hoses of the radiator.