Head gasket?

[NoelChico]

I took the 23 touring out to check it out before next week's Manhattan, Ks tour. After 15 miles and a long uphill pull it started to smell a little warm so I slowed down. I'd put a straight radiator cap on instead of my usual moto meter. After a few miles it was smelling hot so I pulled into our church to check and perhaps fill with water. The rear freeze plug was missing! I cooled the engine down over several minutes with a hose and plugged the hole with a rag to limp a bit over a mile home. The engine had stopped well but was somewhat hard to restart. The tightly rolled up piece of rag was gone. I quickly plugged the hole with a cork, filled it with water, and started it again, still somewhat slow to catch. The cork blew out. I checked compression and got 65lbs in #1 and #4 and 50 lbs in #2 and #3. Previous checks last year with a Z head had been near 75 in all 4. Why would a freeze plug blow out? Hopefully I didn't wreck anything else. I'll put a buffalo nickel plug in tonight and am contemplating pulling the head unless there are other suggestions for this shade tree mechanic.

[Scott_Conger]

the freeze plug may have fallen out but it didn't blow out...T cooling systems do not build pressure

what exactly do you expect to find by pulling the head?

[Norman Kling]

My head gasket blew out! This was in the right rear corner behind the manifold. It was near the steam vent. Cause: years ago the rear bolt thread in the block stripped. I drilled out and put in a helicoil. the problem is that the bolt bottomed out before it was all the way down and my torque wrench read 50 ft lbs but it was the bolt bottoming out not holding the head all the way down. I put a washer under the head of the bolt and have not had a problem with it since. I also replaced the head gasket.

A number of years ago I had a freeze plug fall out while on a tour. I used a socket just about the size of a nickle and a ball peen hammer and made a freeze plug. It worked. Only took a few minutes and I was back on the road.

These things happen. Aluminum heads will sometimes corrode by electrolysis and they will leak, so many things can happen to a T. Always check the fluid level before driving. It can even leak out overnight, so check immediately before leaving, and when you have been parked for a while such as during lunch on a tour, check before you leave because a little can seep out and sometimes in the back behind the manifold. Not always where you would expect such as radiator, or hoses of if you have one a water pump.
Norm

[NoelChico]

Scott, that's my main reason for asking the experts. I am assuming, likely wrongly, that compression or firing impulses are leaking into the water jacket causing the plug to blow. As an aside, I just put in a concave buffalo nickel with Ultra-black tonight and it blew out on starting.

[Scott_Conger]

Huh!

that's a first for me

not a big deal to pull the head but I'd sure want to do a bit more diagnostic work first...I'm trying to see how/where a compression leak leads to the water jacket where it doesn't impact compression severely. I'd expect any pressure that blows out welch plugs would more likely result in large bubbles showing up in the radiator but perhaps the mass of the water is constraining/containing gasses enough allowing the force to concentrate around the valve chamber. If that was the case, I'd think you could feel it or see it blowing coolant spatters behind the exhaust manifold when the engine is running.

this is a good one...I'm going to be very interested to see how this finally sorts out

FWIW, I doubt that you've done any real damage to anything. You've been around this stuff a long time and have always displayed good sense. I wish you a speedy resolution to this puzzle and am sorry it happened at a critical time like it did.

[Bryant]

I had a farm truck with a blown head gasket. When you started it up with no radiator cap it would blow coolant out like a Geyser. Maybe seal the freeze plug back up and try again with the radiator cap off. Path of least resistance? Just a thought.
Bryant

[Steve Jelf]

I had a plug come loose on a trip and leak out most of the coolant, but fortunately it didn't fall out and get lost. My box of spare fasteners under the seat now includes a little bag of nickel plugs, and my tools include a hammer and a drift long enough to reach the plugs. I found old time Permatex #2 unsuitable in that application, but Ultra Black has been OK.

A couple of years ago, due to a radiator leak, I had overheating that caused the car to die in the road. It doesn't seem to have done any permanent damage. I expect your engine is unhurt.

[kmatt2]

I once had a 1987 Mazda pickup with a 2.0 L OHC engine. On restart of a warm engine, thermostat open, the radiator fill catch and 15 lb cap separated from the top tank, torn off by cylinder pressure on power stroke. When I pulled the head , the head gasket had failed, and there were no cracks in the head or block. A new radiator and head gasket got the truck running again for many thousands of miles. The point to this is that cylinder pressure on the power stroke, if it gets into the water jacket can do strange things. I don’t know why the 15 lb radiator pressure cap didn’t release from the top tank or why the pressure didn’t rupture a radiator tube but instead tore the thin top tank brass.

[Norman Kling]

If you fit the base of an old spark plug. The Champion plugs of yore work well fit the base of the spark plug with a tire valve stem and valve. Then put in valve and turn the crank to top dead center with valves closed. Put about 60 lbs pressure in the cylinder. Check the carburetor and exhaust for air escape. If either is getting air, you have a valve sticking ore burnt. with the other spark plugs out listen to hear whether air comes out adjacent cylinders. If it does, your gasket is blown or leaking between cylinders. Listen to the radiator or check for air bubbles. If so, you have a leak into the water jacket. Listen to the oil filler. opening If you have air coming out there, you are leaking into the crankcase, usually around the rings. Repeat with each cylinder. i none of the above, your rings and valves are good and the gasket is good. Other reason for bubbles in the water could be a crack in the water jacket between the cylinder and the water jacket. Most often if this happens the crack is between the exhaust valve and the cylinder wall. If you pass all the above tests, your head gasket should be OK. Unless water is detected anywhere around the outside of the gasket.
Norm

[Allan]

I'm scratching my head like Scott. The cooling system is open. Even if a head gasket is blown, compression from the cylinders will end up down the overflow pipe if the radiator cap is still on.
I have a 1917 block in my scrap pile bored out .125". They fixed the freeze pug problem on that one by fitting screw-in water pipe plugs just like the early cars. You can add to your car's history by doing the same.

Allan from down under.

[Wayne Sheldon]

Probably not your problem, but made me chase my tail for a day or two.
I had put together a temporary engine for one of the Ts I resurrected. It was a tired old engine, really needed a lot more work than I gave it, but it was a wrong year engine and I had a right one I needed to rework properly.
When I first got it running, it seemed to do okay, but it did get a little hotter than I expected it to. I drove the car short distances locally to begin sorting it out and getting things adjusted properly. Each time it got a little hotter, after a couple days, it reached a full boil after only a mile or two. I already had my suspicion, a head gasket failure which I thought unlikely because "been there done that" I was so very careful putting the head on and torqueing it properly. Either that, or a cracked head.
And it got worse FAST! From a full boil in a mile or two, it was cold to a full boil in a few blocks. So I planned one last test. Since it was getting so bad so fast, and not showing signs of head gasket failure otherwise, I suspected a head crack. I let it sit outdoors overnight. Nice and cold. Started up and ran around the block, pulling in my driveway at full boil! With the engine still hot to the touch, I pulled the head. A quick visual examination of the cylinder head revealed a crack more than three inches long arcing across the middle of the combustion dome in cylinder number three. It had probably been there for years, sitting in various parts piles. Rust had basically closed it up a bit, and no doubt running it pushed the crack to grow.
I like to visualize things. Especially failures. Picturing cylinder number three firing, a sudden burst of 50psi exploding to hundreds of psi! The crack is tight enough it really didn't even leak water! Suddenly, pushed by hot exploding gasses (about 2000 degrees Fahrenheit!), the crack opens up and flaming superheated gasses push into the water above the combustion dome. No wonder it reached full boil so quickly!

But even that bad, it never blew out one of the Welch plugs.

[TWrenn]

No expert here and most replies too long for me to take time to read as I gotta get to an appointment. But since these "freeze plugs" (they're really NOT that) are under the head and in the block, you say the cork "blew out" my guess is you have a cracked block to a cylinder near this plug and the pressure from that is blowing it out. Right? Maybe?

[Jerry VanOoteghem]

No expert here and most replies too long for me to take time to read as I gotta get to an appointment. But since these "freeze plugs" (they're really NOT that) are under the head and in the block, you say the cork "blew out" my guess is you have a cracked block to a cylinder near this plug and the pressure from that is blowing it out. Right? Maybe?

I'm thinking something like that is the case as well. To say that the cooling system is not pressurized is true of course, but if a burst of pressure leaks into the coolant, at some point near the problem plug, it will act against the weight of the coolant above it and potentially create a localized high pressure. Like how a depth charge works on a submarine.

I must say, however, that I am not a fan the buffalo nickel repair scheme. It's a novelty, makeshift repair. I think that a proper Welch plug, properly installed, would be fairly hard to blow out. Before removing the head, I'd try a real Welch plug and see what happens.

[Mark Gregush]

Was the plug seated by installing with the crown out and hit with a hammer at its center to spread out or just glued in?

[NoelChico]

I'll get a real welch plug this morning. I believe it's 13/16 but don't see it sized with the vendors. Thanks for the inputs. So far it kept me from pulling the head.

[NoelChico]

I ran the engine for about 10 seconds with no welch plug this morning. I felt no pulses putting my finger over the hole so there is likely no pressure leak from a cylinder. Thanks.

[Scott_Conger]

Well, that's progress!

[Art Wilson]

Thread the holes and install flush 1/2 in pipe plugs as was done in the 1913-1914 blocks. They don't fall out.

[NoelChico]

!!! Filled it with water after putting in a new Welch plug. I used a buffalo nickel as there weren't any correct sized plugs in town. I let the Ultra Black set up for 24 hours before filling the radiator. Started the engine and immediately had bubbling and water pushing to 6 inches above the radiator neck. The pulsatile fumes from the radiator smelled like exhaust. I was all ready to pull the head until I put a torque wrench on the head bolts, which I hadn't checked in over a year. The center ones were down to about 25 ft/lbs! I torqued them all to 45 ft/lbs and it started easier, the compression is back to 73 across all cylinders, and it's no longer burbling in the radiator. Sometimes it's the simple-stupid things that trip you up!

[Bryant]

Old faithful
Bryant

[John Codman]

I wouldn't have used a hose to cool the hot engine. Shock cooling is a good way to crack a casting. I would grin and bear it and let the engine cool down by itself.

[TXGOAT2]

It's best to let hot iron air-cool until you can touch it. Better yet, don't let an engine overheat.
After a head gasket episode, I'd want to change the oil and watch the cooling system very carefully for any evidence of trouble. You might also want to re-check the head torque after a few runs, but don't overtorque it. If there is any further evidence of a leak, I'd replace the gasket and check very carefully for cracks or poor valve seating or any problems with the head bolts/threads while doing it.

[Jerry VanOoteghem]

I have retorqued leaking head gaskets a few times. It always seems to work, but not for long. Once a head gasket has been breeched, it seems the damage will ultimately show itself again. My experience anyway. Hope you're good-to-go, but I'd carry a spare gasket in the car just in case.

Also, check your oil for coolant contamination.

[NoelChico]

I now have a few spare head gaskets, I'll carry one and a torque wrench.

[Norman Kling]

Before you pull the head you need to do two things. One is to locate which cylinder is loosing the compression into the water jacket. Two is to be sure you have a spare gasket. Last year the good ones were back ordered. When you are sure which cylinder is leaking, examine everything inside for cracks. Sometimes the head will be cracked. This is especially true if you put cold water into an overheated engine. Also check the sides of the cylinder next to the water jacket. This can happen anywhere around the cylinder in the top 3 inches of the block. Repair or replace cracked parts.
I did a dumb thing when I was in my teens. My dad had a Nash. It had a belt driven water pump low on the car similar to the ones some people put on their T's. His pump leaked and he told me to always check the water before I drove the car. Well, one day I got in and didn't check. I got on the freeway in the Los Angeles area and it overheated. I took the first ramp and pulled into a station and immediately filled it up with cold water. The head and block were completely cracked in every cylinder and the engine was ruined.
Norm

[Scott_Conger]

Noel

very glad that you worked methodically through the issue and even happier for you that you discovered the root cause and worked that issue rather than work contributing causes which would have solved nothing.

I am greatly suspicious that you lost the welch plug, overheated and lost some preload on the center bolts...in that order. As others mentioned you may (or may not!) be due for a new gasket, but in reality, 50# compression is still darn good and not indicative of a rupture in the gasket. I'd be curious as to what your compression is, and that will probably give a clue as to the future for your gasket.

[Jerry VanOoteghem]

Noel

very glad that you worked methodically through the issue and even happier for you that you discovered the root cause and worked that issue rather than work contributing causes which would have solved nothing.

I am greatly suspicious that you lost the welch plug, overheated and lost some preload on the center bolts...in that order. As others mentioned you may (or may not!) be due for a new gasket, but in reality, 50# compression is still darn good and not indicative of a rupture in the gasket. I'd be curious as to what your compression is, and that will probably give a clue as to the future for your gasket.

Noel states, "...the compression is back to 73 across all cylinders..."

Looks as if all's well for now.

[Scott_Conger]

oops!!

and so he did!

thanks Jerry

[Norman Kling]

Great! I find that I need to re-torque the head several times after I change the gasket and warm it up and then cool off . I do it after each time I drive it until it stays at the proper torque. The bolts will stretch and shrink a bit with temperature and the gasket will compress a bit until everything settles into place.
Hurrah! Now clean out the radiator and cooling system and change the oil so all the oil in the cooling system is gone and the water in the crankcase is gone and you are ready to go. Have fun driving the car.
Norm

[NoelChico]

So far the car starts easily and runs strong. I drove around town for several errands today. I changed the oil which looked a little "funny". I'll bring a head gasket and metalic paint or copper coat and hope for the best. Teresa and I are looking forward to Manhattan, Kansas.

[Scott_Conger]

the little bit funny oil doesn't surprise me...it takes only a fractional amount of water to make oil look odd...I foolishly started a T at about "0" degrees 2 winters ago and shut it down long before it got warm. I ended up with 2 stuck valves the next summer. After I got it running, I changed the oil and boy did the green/grey oil give me a start! I let it sit in a milk jug for about 2 months and got about 2 teaspoons of water settled out in the bottom...it was simply condensation that spent winter cooking in the crankcase and thoroughly welding 2 valves "open" on a fresh valve job.

Now, had I allowed the engine to get good and hot after freeing up the valves the next summer, then that 20 minute old oil would have undoubtedly returned back to its normal state, but as drained, it sure looked odd. I would not be surprised if a tiny bit of coolant got digested into the crank case on your car, but I believe that there was no harm or foul.

Have fun and don't dwell on it.