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03-19-2017, 09:31 AM | #1 |
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damaged piston what? why?
I am posting these questions for my friend and fellow Model A'er and FB'er? Hope he doesn't get mad at me.
Couple months ago we tore his engine down to find out why there was a major oil leak - front and rear. Turned out to be bad gaskets and seals. While into the engine we check all the clearances and they were sopt on .0015 to .00175. Replaced all gaskets and reinstalled his engine and adjusted the valves while we were into it. good news NO LEAKS. Next chapter. On his way home in his A - about 15 miles, His engine started a loud clikcking noise. Like a loud chirping criket. Noise was coming from the center of the block as in # 2 or 3 cyl. Again, his engine came out of the car yesterday and we started tearing it apart to fine the cause of the chirping. Discovery. Severe scraping on the side of #3 piston. See picture below. Two pictures showing each side of the piston. Also the Oil Ring was stuck - as in it would not rotate in its groove - and had to be puled out with pliers. The scraping had damaged the goove to the point it had wedged the oil ring in its groove. Question to you engine gurus? What would have caused this damage? The engine was making no unessary noises before the first tear down. Inquiring minds need to know. ken |
03-19-2017, 09:47 AM | #2 |
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Re: damaged piston what? why?
I would expect the cylinder walls to have scratches as well. Material / debris broken off of that stuck oil control ring is a likely culprit. I have seen this type of failure in an engine that sat idle for a long time, and was started with dry cylinder walls.
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03-19-2017, 09:49 AM | #3 |
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Re: damaged piston what? why?
My guess is that something sneaked in through a plug hole and did the damage. I bet the head has some witness marks.
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03-19-2017, 10:20 AM | #4 |
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Re: damaged piston what? why?
It could have been many things incld a radiator issue. Take everything to a knowledgable place to determine the cause.
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03-19-2017, 10:51 AM | #5 |
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Re: damaged piston what? why?
I would say to close of a fit in the cylinder or to much slug around bore in the block. It was caused by to much heat. Maybe slow timing.
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03-19-2017, 10:54 AM | #6 |
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Re: damaged piston what? why?
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I can't see anything going down the spark plug hole and getting past the compression rings to do that on both sides of the skirt but who knows?? |
03-19-2017, 10:57 AM | #7 |
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Re: damaged piston what? why?
I agree with George Miller. Ford said .002" max clearance, today's pistons and higher speed driving need more. I bore to .003" and hone another .0005" as minimums, more on performance engines.
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03-19-2017, 10:59 AM | #8 |
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Re: damaged piston what? why?
I bore the same as Jim Says
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03-19-2017, 12:05 PM | #9 |
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Re: damaged piston what? why?
Was it just gasket replacement or did you pop in a fresh set or rings while you were in there?
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03-19-2017, 12:06 PM | #10 |
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Re: damaged piston what? why?
Per part of comment in reply #6:
"Did you ensure the pistons were re-installed in the same hole they came out of?" Whether this was the primary cause or not, in re-installing pistons and connecting rods, we are involved with measurements in thousandths of an inch; former engine cylinder/ring wear; and human beings performing the initial re-bore of the block where all cylinders may not be 100% "exactly" alike. FWIW: Always a good idea to provide small marks on tops of pistons and sides of connecting rods, e.g., from I thru IV on piston tops, and small l, ll, lll, llll, vee marks on sides of connecting rods. Mechanical failures always occur for a definite reason: If you would have had several "shop" spy cameras rigged up in your shop, you could re-play the video and possibly "see" the actual cause of the wear ..... maybe not enough water replaced in radiator or whatever ..... "hint", "hint" .... we might have to wait until next year for Model A parts suppliers to offer "shop" spy cameras for after-the-fact mechanical investigation. |
03-19-2017, 01:39 PM | #11 |
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Re: damaged piston what? why?
As Mitch said, it could be any number of things.
I've seen identical damage from timing too advanced, and causing the engine to ping. Of course the ping caused the piston to overheat and do the damage. |
03-19-2017, 07:23 PM | #12 |
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Re: damaged piston what? why?
Jim and George are right. The only time you get piston galling like that is to tight of fit.
Never go by the instructions that come with the set of pistons ! Never under a .001 per inch. Just like main and rod bearings when new. Herm. |
03-19-2017, 07:52 PM | #13 | |||||||
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Re: damaged piston what? why?
Engine is mine.
Quote:
Quote:
Quote:
Quote:
Quote:
No, it did not get hot. No, the piston was not dry when removed. The first tear-down that Ken mentioned was only to replace gaskets and main bearing seals. The pistons were not removed at any time, hence could not have been put back improperly. As noted above, there is NO damage to the cylinder walls. Quote:
Agreed. Quote:
One suggestion from another of my local knowledgeable friends was a possible stuck wrist pin. We were looking closely at that when we removed the pistons and found no indication that that was the cause. The rod moved easily on the pin as well as the pin moving in the piston, completely equivalent to the other three pistons. There was no excess movement. Regards, Bill Lee Photos show one of the other pistons, and the #3 cylinder. Very hard to get a decent picture of the cylinder, and it does not show well that there is NO damage in that cylinder. |
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03-19-2017, 07:58 PM | #14 |
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Re: damaged piston what? why?
Quote--It has been hot in the past, but that has been solved for the past couple of years I have owned it---quote
A hot running engine is a slow death.... very possibly it was not corrected soon enough |
03-19-2017, 08:13 PM | #15 | |
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Re: damaged piston what? why?
Quote:
What is puzzling Ken and me is the COMPLETE lack of any damage to the cylinder itself. I would think that if this piston damage had been going on for a longer time than the last 15 miles I would have 1) heard it long before now, and 2)had significant evidence in the cylinder. Really strange. |
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03-19-2017, 08:42 PM | #16 |
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Re: damaged piston what? why?
Ken & Bill,
If you try a very accurate bore gauge to measure the top and bottom diameters of each of the four (4) individual cylinders, and accurately measure the external diameters of the four (4) pistons, these measurements may give a clue as to what happened. Aluminum pistons will wear quicker than cylinder walls. Takes a tight fit to cause wear like this whether caused by heat expansion or not. |
03-19-2017, 09:30 PM | #17 |
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Re: damaged piston what? why?
It was caused by heat, but that does not mean it was hot on the temp gauge. It means it was hot on that cylinder wall. I have seen it many times. Number 3 runs hotter than 1,2 any way. It could happen if you were running it faster than normal on a hot day, or pulling a long hill, spark retarded to much, or to lean which will make it run hot inside the engine. Or all of the above.
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03-19-2017, 09:47 PM | #18 | |
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Re: damaged piston what? why?
Quote:
Last edited by George Miller; 03-20-2017 at 01:43 PM. Reason: spelling |
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03-20-2017, 08:07 AM | #19 |
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Re: damaged piston what? why?
I think Miller and Blockhead have it. Just suppose there was no water in it by mistake? The temp gage would not show hot. Just hot air in there if no water. Then it ran for 15 min. Sounds possible.
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03-20-2017, 08:42 AM | #20 |
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Re: damaged piston what? why?
It would be coincidental, but maybe the dipper tray developed a hole. The oil would just run out of the tray as fast as the pump replaced it.
Just a thought... |
03-20-2017, 09:25 AM | #21 |
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Re: 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. Last edited by Dave in MN; 03-20-2017 at 06:39 PM. |
03-20-2017, 10:02 AM | #22 |
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Re: damaged piston what? why?
Take a look at the spark plugs too, they may tell a tale about running lean on that cylinder.....
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03-20-2017, 10:51 AM | #23 |
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Re: damaged piston what? why?
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? Last edited by H. L. Chauvin; 03-20-2017 at 11:05 AM. Reason: typo |
03-20-2017, 12:23 PM | #24 | |
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Re: damaged piston what? why?
Quote:
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. Last edited by BillLee/Chandler, TX; 03-20-2017 at 06:13 PM. |
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03-20-2017, 01:08 PM | #25 |
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Re: damaged piston what? why?
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.
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03-20-2017, 01:22 PM | #26 |
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Re: damaged piston what? why?
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03-20-2017, 01:29 PM | #27 |
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Re: damaged piston what? why?
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
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03-20-2017, 02:31 PM | #28 |
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Re: damaged piston what? why?
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. |
03-20-2017, 02:43 PM | #29 |
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Re: damaged piston what? why?
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. |
03-20-2017, 03:42 PM | #30 |
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Re: damaged piston what? why?
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. |
03-20-2017, 04:54 PM | #31 |
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Re: damaged piston what? why?
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 |
03-20-2017, 05:28 PM | #32 |
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Re: damaged piston what? why?
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. |
03-20-2017, 05:31 PM | #33 |
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Re: damaged piston what? why?
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. |
05-21-2020, 08:09 PM | #34 |
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Re: damaged piston what? why?
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. |
05-21-2020, 10:03 PM | #35 |
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Re: damaged piston what? why?
Glen, do you realize your responding to threads that are 3 years old?
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05-22-2020, 11:30 AM | #36 |
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Re: damaged piston what? why?
This is not detonation.
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