Flathead Cracks:

[40ford]

Can someone tell me if there any signs that show up of a running,driving flathead that may possibly have a crack in the block?

[rotorwrench]

The first two symptoms are steam at the exhaust pipe after warm up and coolant in the oil. If the oil turns milky like a milk shake and you have more oil in the pan than is supposed to be there, then coolant is leaking from somewhere.

[40ford]

I was just curious on what might be the signs!I have a 1952 F-1 that I have owned for forty years.For the last year or so it seems like it has a small miss fire at idle or I should say it has a little rough idle to it.It runs smooth and pulls good with no miss while driving.It cranks right up when cold even in say 30 degree weather.When it is hot it acts like the starter can barely turn it over like a vehicle with the timing way off.I figured the starter was probably shot because I have never had anything done to it.I took it off and took to shop for rebuilt and the man said there was nothing worn really bad!I have not reinstalled starter yet because I had to pull exhaust manifold off to replace the gaskets(got all the bolts loose without a problem,lucky me)I talked to an old flathead mechnic about my problem and he said right off I had a crack in the block!!!This is why the curious question.Sorry for the long post.

[B-O-B]

What are the plugs looking like? sooty,clean,light brown or tan? How is the water level low ,oily? Pull the fan belt & watch the water for bubbles. Do you notice any water or white smoke out the tail pipe?

[40ford]

I have not looked at the plugs in a while.I am not losing any water and see no evidense of water or oil mixing.I use to drive this truck pretty much all the time.I know for a fact,because the speedometer has always worked I have driven her over 50,000 miles.The truck does still have the original wiring and I am thinking this is where problems are coming from.

[flatjack9]

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I'd say your old flathead mechanic has a crack.

[1931 flamingo]

Try running some MMO in the gas and/or "drizzle: some down the carb while running. FWIW
Paul in CT

[40ford]

Hey,I like that flatjack9.You just might be right on that!

[flatford8]

Check your battery and cables. If you haven’t changed your starter cable in forty years, check for corrosion at either end..... Mark

[40 Deluxe]

Originally Posted by 40ford

I was just curious on what might be the signs!I have a 1952 F-1 that I have owned for forty years.For the last year or so it seems like it has a small miss fire at idle or I should say it has a little rough idle to it.It runs smooth and pulls good with no miss while driving.It cranks right up when cold even in say 30 degree weather.When it is hot it acts like the starter can barely turn it over like a vehicle with the timing way off.I figured the starter was probably shot because I have never had anything done to it.I took it off and took to shop for rebuilt and the man said there was nothing worn really bad!I have not reinstalled starter yet because I had to pull exhaust manifold off to replace the gaskets(got all the bolts loose without a problem,lucky me)I talked to an old flathead mechnic about my problem and he said right off I had a crack in the block!!!This is why the curious question.Sorry for the long post.

Since there's no water loss and no sign of water in the oil, most likely there's no cracks. Do a thorough, methodical checkup. Don't assume anything. Do a compression check; manifold vacuum check; all wiring connections including grounds should be removed and cleaned (just being tight is not good enough-a tight connection can still be corroded); check distributor for worn bushings and lobes; carb and intake gaskets for vacuum leaks at idle; verify timing advance with a timing light (no vacuum gauge nonsense allowed here). The points plate could be hanging up causing over advance on hot starts. A slight exhaust valve leak can lose compression at idle but hold good enough to fire at higher RPM. If you're still running 6 volts, make sure you also have the heavier 6 volt cables. 12 volt cables will NOT carry enough amps. Check for voltage drop and amp draw on those hard hot starts.
A good source for specs and procedures is a MOTOR or Chilton's, etc. Manual from the '50's.

[Ken/Alabama]

I agree with 40 Deluxe, friend had the same symptoms with his 53. Turned out to be leaky valve. Those later blocks weren't blessed with hard valve seats and with today's unleaded gas it put some wear on the valve seats. I'd do a compression check.

[40ford]

Well today I went to pull the plugs out of my truck.I went to drivers side and they came out normai with no problem.I went to the pass. side to remove plugs and I thought I was never going to get these four plugs out!!!!I had to use a cheater bar to break them loose and they were pretty much tight all the way out.The threads looked ok on the plugs except one looked like the threads were a little rough.I have never ran into a problem like this before.Believe me I thought something was going to crack or break before I got these plugs out.Now what do I need to do?Has anyone got an answer to why this problem?I have changed plugs probably several times over the years and never had a problem like this!

[Habusailor]

Are the heads both from the car or was the passenger head replaced at some time? Without knowing the history of the engine that’s my first thought


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[40ford]

The heads are the same (8RT) and never been changed since I had the truck.

[Habusailor]

Originally Posted by 40ford

The heads are the same (8RT) and never been changed since I had the truck.

That blows my theory of a different head with bad threads from laying in the junk pile for awhile. I’m not an expert here so will sit back and read what others come up with


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[JSeery]

There are thread chasers for the plug threads. Think I would use an anti-seize when I reinstalled them.

[40ford]

I ordered a thread cleaner from SpeedWay.Not sure if this will help or not.I took a plug back out of the other head and it went in all of them fairly easy except one that was pretty snug going in and back out.
https://www.speedwaymotors.com/Spark...aner,2641.html

[cmbrucew]

Was there any indication of water presence? Were the plugs clean or sooty?
Bruce

[40ford]

Plugs all looked good. No evidence of water.

[marko39]

carbon on the threads can make them hard to get out.