Old Faithful Geyser

[rheltzel]

My '35 21 stud engine has a bad habit of erupting like a geyser on a long 6% grade at speed. Overheating, of course, is not exactly a new story for our beloved flatheads, but the symptoms are weird. It's not steam that erupts, only hot water. Just before it erupts, the original thermometer-style gauge drops to low normal range. It never registers anything above normal. When I pull over, the engine doesn't seem to be hot and is running just fine. The temp gauge quickly goes back, i.e. up, to normal temp. I've calibrated the gauge, so I know it's correct when operating normally.

There is no indication of water in the crankcase. There are no obvious cracks in the block or heads. I know (because the first time it happened, I removed the heads to check things out) whoever rebuilt the engine filled fairly severe corrosion around studs and water passages on the block with JB Weld. Being an epoxy-type product, JB Weld no doubt has poor heat transfer properties, leading me to believe that under heavy load, there are hot spots created around the cylinders that cause steam pockets to develop, causing the geyser eruptions.

Any ideas or thoughts?

[ford38v8]

JB Weld inside the water jackets??

[Phil Gillespie]

Had exact same problems with 34 coupe. Blowing out water when loaded up and temp on gauge remained ok.
Eventually removed radiator and had it rodded out. It was 40% blocked. No more problems since.
This could be an area worth considering. Dont be put off by the fact that engine is not overheating.
Hope it gets sorted
Phil
NZ

[rheltzel]

Could be...apparently, they overfilled the corrosion depressions and then slapped the heads on. It's possible there are globs of JB Weld blocking water flow, although I've been unable to find any. Some of the water passages were partially blocked by excess that squirted out when the heads were torqued, but I cleaned them out and it still does its imitation of Old Faithful Geyser.

This is more or less an academic inquiry...I've already located a new 24 stud block to use as a replacement; the question is whether to just junk the original numbers matching engine, or (with full disclosure) sell it to someone who is more interested in "show" than "go". It's a fine running engine, as long as you don't push it too hard. I'm in the "go" category, so I need an engine that can be used under all normal daily operating conditions.

I am nevertheless curious as to the cause of my engine's errant behavior.

[rheltzel]

Thanks, Phil. That's worth pursuing.

[36Bill]

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Mine did the same thing. I thought it was a cracked block but another motor was the same. I had the radiator in the shop and that did nothing. I finally filled it will vinegar for two weeks and then back flushed the whole thing, first the radiator and then the block too. It has been fine so far, it runs cold now. Hope you can work it out.

Bill

[B-O-B]

How is your radiator cap & timing & vacuum brake?

[denson1932]

I had this problem it turned out to be porous aluminum heads (in combustion chamber) passing exhaust gas into coolant.

[BILL WZOREK]

I 2nd the radiator / Long pull pumps at top speed. Pumps water into top of
radiator /slow going down radiator no more room so pushes out top.
Temp guage goes down because a lack of water to read. you pull over and by the time you get out to check some water has gotten through,so all looks normal.

You should be able to do the same thing sitting in your yard.
fill radiator the run engine up to top or neer top speed for a bit of time / most likely same thing will happen.

Keep up posted Good luck.

[Mart]

I had a 57 Buick with a partially blocked radiator. While trying to limp it home I stopped at every service area and hosed the radiator down with water. What i noticed was that certain tubes dried very quickly while others remained wet. Of course, what that meant was the tubes that did not dry quickly were blocked.

I took the bottom tank off, rodded the core through and it was fine after that.

You could try wetting the radiator next time it is hot to see if it behaves in a similar way. I don't think having small areas of JB weld on the head or block face would make any difference, It's the water travelling through the motor and through the radiator that transfers the heat, There's no heat transfer to the water from the head or block face as such. (Sort of just thinking this through here).

Mart.

[B-O-B]

Putting too much water in the radiator will also cause it to push the water out. It will establish it's water level about an 1" or so below the top.

[36Bill]

As Bill said in post #9 I was able to blow a geyser out the radiator with the cap off sitting in the yard cold, just run the revs up and thar she blows. Cleaned the radiator and it doesn't do that at all.

Bill

[Jay in Mass]

Originally Posted by rheltzel

C

This is more or less an academic inquiry...I've already located a new 24 stud block to use as a replacement; the question is whether to just junk the original numbers matching engine, or (with full disclosure) sell it to someone who is more interested in "show" than "go". It's a fine running engine, as long as you don't push it too hard. I'm in the "go" category, so I need an engine that can be used under all normal daily operating conditions.

I am nevertheless curious as to the cause of my engine's errant behavior.

This does not help your Old Faithful problem, but how did you ever find an original "numbers matching engine"?
I have found the numbers on the transmission and always thought that the engines were not numbered. Where are the engine numbers located?

[flatjack9]

Engines were not numbered at the factory.

[rheltzel]

Radiator cap is new and tight; newly rebuilt distributor and coil by John Shelor of Virginia...runs perfectly.

[rheltzel]

I'm afraid I misspoke on the engine. Flatjack9 is right...trannys are numbered, but engines aren't. Prior to my purchase, the car had been in the same family since new and the fellow who sold it to me claimed it was the original engine. The tranny was (until I replaced it with a '39), and I believe the seller's claim on the engine, although I can't prove it.

Thanks to all of you for your thoughts and suggestions. My working theory is that the problem is caused by a combination of a weak radiator and an engine that under heavy load at freeway speeds, develops hot spots on the block that cause steam pockets, which in turn force "up stream" coolant into the radiator tank so fast the radiator can't process it, causing it to barf out wherever it can...the cap and the overflow.

Soon, I will have my new engine and radiator installed and this will no longer be a problem. Of course, something else will pop up. After all, this is a Flathead Ford we're talking about and what fun would it be if it always ran perfectly?

Again, thanks to everyone for your thoughts and suggestions.

[Bruce in southern OH]

Had same problem, water pumped to top out it goes at high speed, changed radiator and it will run as fast as you want. Water flow back to engine restricted.

[rheltzel]

Which makes sense, Bruce...if it's pumping water faster than the radiator can send it back to the engine, there would be cavitation behind the pump, leading to the hot spots, setting up, I should think, a pretty bad vicious cycle.

As of today, I'm looking for a new radiator, since I'm not aware of any trustworthy radiator shops in the area.

Anyone know whether the Brassworks reproductions are worth the money?

Again, thanks to everyone for the thoughts and suggestions.

[G.M.]

This is a problem with all old Fords before a pressure cap was installed with the over flow in the radiator neck. First off the old Fords have a 22 quart cooling capacity on most v/8's. They were made to run with a full 22 quarts of coolant to cool the engine. There is a restriction in the radiator from 144 radiator tubes that are around 24 inches long plus the crud and dirt in them. The water won't fully free flow through these tubes, it has to be forced through. Ford put a 4 lb cap on not to raise the boiling point but to keep water in the system. The pressure cap bottom end, this is the spring loaded end that seals the bottom of the filler neck holding the water in the radiator under normal temperatures below 210 degrees. The under side of the cap seals the upper part of the filler neck. In between is a chamber sealed off top and bottom by the cap with the over flow tube coming out the center. When the pressure which is created by heat or a compression leaks gets to 4 lbs it opens the spring loaded bottom end of the cap allowing water into the center chamber and out the over flow tube. The top part of the cap must be sealed or small portion of water will leak out on the top of the radiator. Skip Haney in Florida has made a 3 lb pressure valve that is put on the bottom of the over flow tube keeping the water from being pushed out the over flow tube for radiators with the over flow coming from the top tank. This valve should be removed once in a while and flushed out with water to make sure it don't become plugged. The pressure valve is also a saftey valve incase of high pressures in the system. With a functioning pressure cap or Skips valve the water can be filled up to the top of the radiator tank. With the radiator filled the engine will run cooler and will stay filled for 6 months or longer. The cap gasket on the older radiators needs to be replaced or the top part of the cap will leak. Attached is a picture of the valve. G.M.

[ford38v8]

With reference to G.M.'s post above, for those who may misunderstand, if your fill cap has the overflow tube integral, and you currently use a pressure cap, Skips valve is not needed. It's the radiators having overflow tubes separate from the fill tube that can benefit from Skip's valve.

GM, I hear you need antifreeze in your Ford now! Maybe California will export oranges to Florida this year!