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Question for the flathead gurus...
Developed a head gasket leak at the front of the head. Bubbles black goo while running. Smells like oil/gas not coolant. I can see it seep w/ bubbles from on top and below the existing gasket (someone before me must have changed it because it is one of the extra hump gasket). Compression test 1-6 is 90/95/90/95/100/100. I suspect that the valves need adjustment too.
Engine runs good.. so my question is...
At this point ...if I remove the head and don't see any other obvious problems, should I just true the head surface and install a new gasket. Funds are tight at the moment, and a total rebuild is out of the question at this time. I would also do the water distribution tube, thermostat and have the radiator cleaned since most of that stiff would be accessible at the time.

longshot2171 wrote: Bubbles black goo while running.

with no oil passages leading to the head I am surprised that you are leaking black goo from around the head. do you have oil deposits in the rad ? is the rad cap oily ? is there any white milkiness on the oil filler cap ?

is the fording vale closed or plugged ?

think about planing the head (if it needs to be removed) to increase compression ratio and get more power and better economy.

No oil or milk in radiator as of yet. If I didn't physically see it, I wouldn't know it was happening. I only caught it because the key must've gotten switched on at a show, and the coil and pertronix fried..coil leaked oil all over distributor. Put a used coil and pionts back in and it runs fine.

I think your compression numbers are a bit less than spec, but are pretty even. Right now probably no need for a complete rebuild. Mine ran well with much less on two cylinders, with broken rings. Having just completed my own engine complete rebuild, I am a lot more familiar with the water pump and its gaskets. There is a large part of the big back plate that is not held tightly with the small bolts to the cast frame. When I removed the back plate of my new water pump, as suggested I resealed the plate to the cast body, but used some temporary bolts to hold the plate on all around while the special water pump gasket sealant dried.

Like above, there is no oil passages in the water pump, so I wonder if the Black Goo is old sealant/rusty coolant pushing thru a rusted incomplete seal on the back of the plate. A water pump replacement is not a big deal, and if you do, I can suggest how to have a leak-free union. My own new rebuild is dry. I also used studs instead of bolts, so I could more evenly and tightly torque the two water pump connections. While there, might be advisable to also take off the big elbow and cleaning that all up. it is cast iron, and gets rusty inside. I de-rusted my elbow and the small upper pump part, that uses the short hose, and then put all the parts on a diamond stone to make them absolutely perfectly flat, making for less "work" for the gaskets to seal tiny void.

Maybe you can enjoy your truck for some miles with just a water pump replacement. And if you really want to know if there is water or gas contamination in your oil, get a Blackstone oil analysis kit, you will get vital information as to what might really be going on in your motor.

Good luck,

NAM VET

Seeing that a rebuild is out of the question and the engine runs OK I'd start by getting the engine warm and checking the torque of the head bolts. You may get lucky and it will seal up and if it doesn't at least you have only invested a bit of time. If it doesn't seal at least you have the tools out to start pulling the head and replace the gasket . Doing nothing until total failure will only cost you more $ in the long run. If you get antifreeze in the oil you'll kill the bearings and if it's blasting combustion gasses across the deck you run the risk of cutting a trough in the block.

I don't think it is the water pump. The block has a small "ledge" where the head ends and the back plate of the pump. I can physically see it start to leak. It starts like a few really small popping bubbles when cold and then grows to small (less than diameter of a quarter) goo spot. I think I will leave it in the garage and plan for a gasket change in the fall. I will start researching local machine shops...if there are any left.. To get the head checked and maybe shaved. It sucks though ...right in the middle of show season. The local auto museum wanted to use it as part of tips winter's American Truck display.

At least it is home and we never got stranded......

I can do the head gasket in a day, easily. Pull it first thing g and get it to the machine shop. Go home And clean the block surface spotless, clean and chase the threads. Pick up the head and install.

one day I did a HG at a gas station in under 40min

...words of encouragement
When I do it, I want to check/change water disto tube and thermostat & flush the whole system.

RMS wrote:one day I did a HG at a gas station in under 40min

There is a difference between an emergency field repair and doing G the job correctly.
The gas station job will get you home. The spend the day won't need to be done again for a long while.

longshot2171 wrote:I don't think it is the water pump. The block has a small "ledge" where the head ends and the back plate of the pump. I can physically see it start to leak. It starts like a few really small popping bubbles when cold and then grows to small (less than diameter of a quarter) goo spot. I think I will leave it in the garage and plan for a gasket change in the fall. I will start researching local machine shops...if there are any left.. To get the head checked and maybe shaved. It sucks though ...right in the middle of show season. The local auto museum wanted to use it as part of tips winter's American Truck display.

At least it is home and we never got stranded......

Check the head bolt torque. As you yourself said it looks like someone changed the head gasket before and it is entirely possible they never retorqued the head. Just because a head gasket leaks does not automatically mean the head has to be planed, that is seldom the case unless it was badly overheated or run for a long time with the gasket blown. Any mechanic with a straightedge and feeler gauges can tell you if it is warped. You do not need to pay a machine shop for that.

After I replaced the head gasket and had my head milled .020", I found our my water jacket was pretty plugged up. I cannot drain the block using the petcock by the distributor. I kind of wished I'd tried to clean it when the head was off. Just another thing to consider

I used the ARP head stud set from VPW. Chased the threads with an ARP special tap, used Permatex #2 sealant, a non-hardening sealant, so you can re-torque anytime. Plus more accurate torque anyway, not working against the corroded and irregular threads on the block. Minor changes to the several that hold the vent tube holders, the set includes several longer studs. You might get miles and years of driving before you decide how and wen to do any major engine out repairs.

NV

Update...
Head checked and resurfaced, new water distribution tube, engine almost back together. Question about the thermostat...Napa lookup is #155. It is a 2 piece with rubber gasket. How do you set the bypass cup...freeze it or press it in?
Old one is the 1 piece that seems to work fine so if I can't get the Napa one to fit I will reuse it

I've used the NAPA stats in a few engines and just set 'em in. I'm curious what the issue is. Any photos?

Andy