damaged piston what? why?

I agree with Herm and George. Too hot for the available clearance in the assembly. I have seen it many times and it always looks the same.

Solution: Hone the cylinder wall giving it additional clearance and replace the piston with a weight matched one... from the same supplier/manufacturer if possible.

As a precaution, I would power flush the water jacket of the block and prior to flushing, use a strong product that will attack the possible grease and water deposits inside.
Good Day!



Personal Experience: This same thing happened to me on my Phaeton when first I bought it. I unloaded it off the trailer and drove it to town (first drive) to fill the gas tank. 4 miles down the road, it started to seize and actually locked up. I coasted to a stop, let it cool for 10 minutes and then started it. It ran but smoked. I pulled the engine and before taking it to the machine shop to get the cylinders bored and honed, I alternated filling the water jacket with Drano and full strength CLR , 4 cycles if I recall correctly. I flushed between each change. I removed about 2.5 cups of scale and rust. The area behind #4 cylinder was to the point that little water could get through. This lack of water caused the cylinder temperature to exceed the limits of the clearance and aluminum piston.
 
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One (1) mechanical forensic clue for reasons of piston overheating still not answered:

A. After 6,000 miles of past cooling problems, still absolutely no damage to piston no.3.

B. After a short 15 mile drive, (or maybe approximately 45 minutes of running), piston no. 3 is burnt toast.

C. Again, were pistons originally numbered and reinstalled in their original locations?
 
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H. L. Chauvin said:
One (1) mechanical forensic clue for reasons of piston overheating still not answered:

A. After 6,000 miles of past cooling problems, still absolutely no damage to piston no.3.

B. After a short 15 mile drive, (or maybe approximately 45 minutes of running), piston no. 3 is burnt toast.

C. Again, were pistons originally numbered and reinstalled in their original locations?
Click to expand...

It is incorrect to characterize it as "6,000 miles of past cooling problem". To my knowledge (3800 of the ~6000 miles since I have owned the car), the engine has overheated only twice, once when first obtained and second several years and many hundreds of miles ago.

The noise that was heard and the apparent piston damage showed up after the 15 mile drive home from Ken's to my home. To head off other comments: yes, there was adequate water in the cooling system and proper oil in the engine. Did the damage occur during the 15 mile drive home or has it been there for along time? I don't know, only can say that the "thick-thick-thick" noise was never there before and only started at the end of the drive home.

As was mentioned in a previous answer, the pistons were never removed from the engine and, consequently could not have been reinstalled improperly.
 
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Did you have a trace of coolant in the oil pan when you drained before removing? I've seen this many times on a diesel engine in the past when there was a pinhole at the cylinder where the bottom of water jacket is.
 
Once I seized a motor by lugging it. Driving for miles, I was in a strong head wind in the Mohave desert and I should have shifted down a gear. My engine ended up having the same damage done to it. A hard pull at too low of RPM (lugging) doesn't get enough oil onto the cylinder walls.
 
Remember, ALWAYS check piston clearance with those LOOOONG, wiggley feeler gauges! A set of them is a GOOD investment!
Like they say, the loose ones GO & the tight ones BLOW!!
Bill Dragracer
 
Some things to think about. Model A engine does not have water cooling for the bottom of the cylinder wall like most cars. There for they can run hotter at the bottom than they should. Also piston are made from alum. There are lots of grades of alum. Maybe the pistons for the A should have a higher melting point than modern cars with cylinder walls cooled all the way to the bottom. Plus the modern cars have a push water pump not a pull pump. A pull pump could cause air pockets. Trust me the piston damage is melted metal.

This is not new it has happened many times.
 
Per response #24, piston no. 3 was never removed since original rebuild; hence, piston no. 3 .... may .... or may not ...... have possibly worn somewhat prior to subsequently changing engine gaskets and the 15 mile drive.

Seriously: Whatever ....... the best part of this story is Mr. Bill Lee's and Mr. Ken's superior intelligence to open this noisy Model A engine and further investigate; and at the very least, finding that the no. 3 cylinder was not ruined.

Many car owners today would have allowed this engine to keep running and hope this noise would just go away one day.

Dealership mechanics and other mechanics witness this same type of problem involving car owner procrastination every day.
 
The lack of any piston damage above the oil ring says there was no excessive combustion temp or detonation.

So if the oil ring was the problem, that could only have happened through things like too tight end gap and cyl too hot (lack of water), or deformed ring at installation.

For no more damage than there is I would put a light hone on the cyl wall, get a new piston and ring set, measure it all as previously discussed, and reassemble and run with a good 10w30 and confirm radiator full.
 
I may getting a step ahead if Bill, but here goes anyway.
A set (four) pistons and rings and a new full gasket set have been ordered from Snyder's. It was easier to order set than try to match the one odd one. We will scrape the light carbon from the top of each cylinder and then run hone lightly thru each cylinder. ...and yep I will take my cylinder gages and check the diameter top and bot of each.

jfreddie. The oil ring was not the problem. It was jammed due to the scraping of the aluminum and the Al depositing itself into the oil ring groove on the piston , seizing the ring into its groove. clear as mud? ken
 
Ken & Bill,

I just wish both of you great success.

We can all imagine an 87 year old medical patient in a large waiting room asking a doctor why he has severe loose bowels ever since his left knee quit hurting.

Next, many old knowledgeable farts in the waiting room reply that they witnessed this exact same event.

Then the doctor looks around and scratches his head.

So why should Forum responses to similar questions for our 87 year old rusty Model A engines be any different?

Hope this helps.
 
Be sure to check each ring's end gap in it's respective cylinder before installing them on the pistons.

I've seen similar damage from an engine running with spark too far advance, but as jfreddie points out, there was also damage to the piston crown.
 
I've seen this when the spacers on a 3 part oil ring climb out of position on installation.
Not an uncommon thing if the pistons had been removed/replaced. Was the damage at a point where the oil ring gap sat? That would confirm it.
 
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