VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1929-1932 Sounds like a bad head gasket??

Hey guys. After finally getting a new battery and the alternator I was really excited to get to drive the '31. I was disappointed when I took it out for a test drive into town and saw that it was blowing coolant (antifreeze/water) from the overflow hose. I can't figure this car out. It seems like this is an intermittent problem, but perhaps it just sometimes gets too low to blow it out of the hose?
When I had my head redone a while back I bought a "NOS" head gasket. There has been a leak coming from somewhere in the back of the engine when it is parked but I have not been able to determine exactly where it is coming from because of the tight clearance between the back of the head and the firewall. I have tried every sort of mirror and feeling for dampness and everything else but I just can't tell for sure. I filled the radiator up enough to cover the core, but not all the way to the top, and after I got home it looked like this.



It looks like it was overfilled, but it was not overfilled when I filled it up when it was cold. Is it possible that the leak in the rear, wherever it is, is sucking air and causing the coolant to blow out of the tube?
Some info: I have a new, bearing style water pump, a new thermostat with small relief hole drilled, 4 blade fan, and the radiator has been tested to not have leaks.

I'll kick it off... I can tell you that with two '31s that the water level always comes up at LEAST an inch after it gets warmed up... Maybe an inch and a half. I don't consider it unusual any more.

One question - Once it cools off, does it drop back all the way? IE. to the top of the core?

I've had a similar problem on my 32 and like you have the new water pump, recored radiator, 4 blade fan, 160 stat with bypass hole, correct timing, 18 deg and .040 plug setting, and it will still overheat when pulling a long hill or sitting in traffic for a few minutes. When on flat land I can run for 40 or more miles at 40 or more MPH and it will not overheat. From my heavy truck experience that's an indication of head gasket problems. The only thing I can think of is perhaps the head bolts are stretched as they are original. I am going to recheck the headbolt torque setting and suggest you do the same. Another thought is that the carb ( 569s #421) may be set too lean.

Hello Vetteman61,
If the head gasket was blown in a cylinder, there would be loss of coolant out the exhaust and constant air working thru the cooling system. Is there any evidence of these things going on at all engine temperatures? If the gasket is blown from the water jacket to the outside, how does that happen? I would think that the water pump's pressure would tend to blow coolant out the leak and not pull in air from that leak area. If there is a leak when parked, there should be a bigger leak when running. Thanks for the photo. What was the engine temperature throughout the drive. Did it ever overheat? Could you make up a temporary expansion tank to catch coolant to gage how much is lost while driving? If it stops venting and your not overheating, that might be the amount not needed in the system based on normal expansion as the engine warms up. Are you able to use a paper towel between head and firewall to check for moisture? Let us know.

i wonder what radiator core is in the 31 as i have not seen one with a threaded cap ?

As for the leak at the rear of the engine. I had one on my 31 that drove me crazy. I finally found it by pulling the floor board off and looking at the rear of the block. And much to my surprise there was a flaw in the block and the water was seeping out of the rear of the block. I dried the area and ground it down and used epoxy over that area. That took care of my leak and has held up for many thousands of miles. Good luck with your project.

I believe the threaded filler neck is standard on the 31.

The cooling system is not pressurized so a leak from the head gasket into the cylinder may not leak when the engine is running. When running there is compression pressure that can leak into the cooling system but because of that pressure the coolant will not leak into the cylinder until there is major damage to the gasket. I also am curious about the temperature variation and whether it's overheating and also the coolant level after running and then cooling down.

My two 31 original rads have the locking ear type rad openings. The original 30 that I have is threaded.

Dave

If you have a leak in the head gasket remove the head again....
Be sure the block and de head are flat if you dont have the chance to cut the hed and the block take sand papier with a plan block.
Clean the head an the block with aceton!!!!!!
Use the seal curil T it is like honey between the new head seal and the head is no more leak
Iam a mechanik......i cut my 1930 chey the head and the block... New seal the right torque but the head was not 100% leakproof i the 3 head seals and the head was leak
Until i use the curil t i dont have problems wit the head also with my others oldtimers


Sorry for my bad english
Switzerland
Stephan

Hello m006840,
You are probably correct about the cylinder leak not using up coolant. I was thinking about the intake stroke bringing in coolant, but forgot about the compression stroke more than adequately blowing air into the coolant system. Until we know more details, it's hard to know if there is air in the coolant system or just temperature expansion. I'll agree with your point though, thank you. Edit: Curil T is a sealant made by Elring Co., Europe gasket and sealant manufacture.

Thanks for the replies. I'll investigate per the suggestions mentioned and post the findings. It may be a several days before I can get back to it but this fight is far from over....

Well Harrys31coach I must admit it is more of a guess than knowledge gained from experience. There is a test that can be done I believe to check for exhaust contamination in the coolant system, however simply removing the rad cap and viewing for air bubbles should be sufficient. I agree more details are needed.

The 1929 and 1930 radiator filler necks were threaded. 1931 was the first year for the "bayonet" type of radiator filler neck.

How about using a "Leak Down Test Gauge" before tearing into the motor...?

Assuming you used new head bolts and burped the cooling system. Do not use anything higher than a 50/50 antifreeze/water ratio.
When cold, only fill the radiator to the top of the core tubes.
Place and electric fan in front of the radiator and run it when the engine is running with the radiator cap off.
As the engine warms up the fluid will expand. Only after the car is warmed up and the fluid is up to its "Happy" level, you can maybe notice any air bubbles, but often times you can't see them.
The auto parts store sells a kit that checks for hydrocarbons in the cooling system. To save time, a small investment in this kit will answer your concerns about a leaking head gasket or crack. Personally, this kit would be the first thing I would try.

A perfectly clean white electrode should identify which cylinder is leaking antifreeze into the cylinder.

Leaving the engine sit overnite after warmed up and running smoothly, remove all plugs, have somebody turn motor over while watching to see if any water is spit out of cylinders.

mike lynch

Well, potentially some good news to report. I let the car blow out all the antifreeze it would and it seemed to sustain itself at a level with the coolant just low enough to see the tops of the cores. With all other non-overflow systems I've filled the radiator just to the top of the cores. Apparently, this system wants the coolant just below the tops of the cores. I'm not sure if this is normal or if the new water pump may have something to do with this.

I have now run the car a number of times into town and it has not overheated, remained at a proper temperature and does not blow out any coolant. Unfortunately, it does still have a leak from the back of the head, but it's not bad at all and doesn't seem to effect driveability.

Good to hear. My '31 had all the same symptoms your's has, and now runs fine with the lower antifreeze level, must be a common trait.

Small trick is to add 4-6 inches of clear plastic tubing to the bottom of the overflow tube. That allows overflow antifreeze to pass through the front cross member and empty out below the frame. This helps to keep the undercarriage clean.

Just some stainless wire wrapped around the top holds it to the tube.

Actually a 2-3 foot section of tubing from the bottom of the overflow tube extending to the bottom of an overflow container hung from the radiator support is even better. Keeps the radiator full, reduces air and allows quick check to assure you still have enough coolant and/or if you are losing coolant over time and miles. Also any bubbles seen in the tube or container would indicate an air or combustion gas leak. Don't even need a special cap as the original cap with good seal to radiator neck is all that is needed for the overflow to work perfectly.

If hung can be removed for judging.

that sounds like an excellent idea chipper. I will be doing that...

I have run overflow tanks on my '28 Chevys for years. Sure makes for less stressful touring.

That's a good idea. I also have future plans to install a homemade mason jar overflow jug. I already have a nifty holder that I made a while back out of left over gas tank straps that were new but not needed. Before I installed it I wanted to get everything running at least semi-decent. After all this time, I think I may be ready to move on to the next steps. Because this project has been, basically, a "toy" for me, money for this project has been scare and I have had to exercise extreme patience to get to this point. Now that I am able to drive it into town without constant coolant issues, I can begin to move on to other projects on the car like the windshield and window regulators, death wobble, slight driver side door sag, overflow jug, aftermarket (period correct) blinkers (drivers today have NO CLUE what I'm doing when I signal for a turn and I've almost been hit).