Engine troubles

flatjack9

flatjack9

Well-known member
Well after all these years, I had a problem with the engine in the 39. I was headed to Back to the Fifties, when I developed a heavy knock. Pulled over and shut it off. Got it home, pulled the engine and found a 5/16 lock washer in #6 cylinder. Before I left, I had the carb off to replace the spring in the vacuum secondaries on my 4 barrel and must have dropped the washer in then. Put a dent in the top of the piston in only one spot, didn't scratch the cylinder walls or hurt the head. However, when I removed #5 piston, found heavy scoring on the bottom of the skirt below the pin and scoring 90 deg over along the length of the piston. Question is, why the problem in #5 after all these years? By the way, the cylinders show almost no wear and the bearings look great. The engine probably has 50,000 miles on it. All the other pistons look great.
 

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flatjack9 said:
Before I left, I had the carb off to replace the spring in the vacuum secondaries on my 4 barrel and must have dropped the washer in then.
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I am sorry to hear of your problem. Having an engine develope a problem, especially while you were out on the road, is no fun. I do not have any ideas about the scoring of #6 cylinder. It will be interesting to see what you finally come up with.

The lock washer problem is not uncommon. After I did this the first time, more then 50 years ago, I NEVER put lock washers on carburator mounting nuts. I am not sure but I do not think Ford used lock washers under the nuts that hold the carburators in place, but I do know other manufacturers DID NOT. As I am sure you now know, it is too easy to accedently drop a lock washer down the intake when removing the carburator.

I hope you get your engine problem resolved and back on the road soon.

Chris
 
You have that much scoring on the piston, and the cylinders are fine?

Just curious, but did you originally assemble the engine?
 
Mike B said:
You have that much scoring on the piston, and the cylinders are fine?

Just curious, but did you originally assemble the engine?
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Actually there are a few marks in #5, but not severe. I assembled the engine about 17 years ago. Machine work was done at the local NAPA store by a very competent machinist.
 
What scuffed it, would most likely damage the piston (Al I assume?) more than the iron cylinder...might have been some grit left in the oil galleys...do you recall cleaning the oil galleys out with a rifle bore brush, etc...befor eassembly?

Anyway, reason you didn't notice anything (as I can tell) is it looks like all the damage to the piston is below the oilcontrol ring...is the scoring on the cylinder in a spot where the oil control ring and the other rings would have passed through? If so, Maybe when changing plugs over the years, you noticed just scooch of fouling on the #5?

But if all damage to the cyclinder wall was below the bottom of the ring/stroke travel...you'd have never noticed it.
 
Not easy to diagnose without seeing all pistons.and rings.And knowing history of ignition carbs et all.
Definitely got hot could due to many things.Lost lubricating properties on cyl wall. To make it work there must be a clean thin film of oil between moving pieces. No piston can live without adequate lubrication. Combination of many things. Here are few. Lean ,detonation ,fuel wash on start dry start. overheating. This based on the fact that all the clearances were correct in the beginning.Strange to go 50000 without a hiccup. How long has that 4bbl been on recent or some time. Read this for some ideas. Hope it helps.

http://www.enginebuildermag.com/Article/16073/uncovering_the_cause_of_a_burned_piston.aspx

Ronnie
 
Well. I'm no Flathead guru, but running lean, detonation, etc...isn't gonna show up below the l control rings...all tha will be show on top of the pistons (holes in it, broken lansd, maybe ashatterd land or two and a rind to coincide...), but....I dunno, maybe FH V*'s act totally different than any othe engine built?
 
Does the scoring on the piston look like it has been there a while? If so, it could have happened 50,000 miles ago on start-up.
 
I'll take some more pictures tomorrow. This engine is unchanged in 17 years. The damage on the piston is all below the ring pack. Ring lands show no scuffing. Never have had any detonation or preignition. Temp has always been around 180. Was cruising down the highway at 2300 rpm when it happened. The block was chemically stripped when I built it. I had just changed oil and filter the day before leaving. My oil pressure gauge in the car was not working, but I had one under the hood and after the oil change, had good pressure. I will test the pump in my rig. Won't have time to do much this week as I'm getting ready to go to Iola. The other thing to consider is that all the rod bearings look nearly new. No sign of wear or overheating.
 
I'm also wondering now if the noise was from the washer hitting the head in #6 or the piston sticking in #5.
 
That skirt appears like it was set up too tight and gaulded during break in. These can occur and never be known until tear down at a later date. I am confident that the knocking that you heard was the lockwasher too. Trash on a piston can really make a racket. Since your bearings were not worn I am sure that lubrication was not an issue since the bearings are typically the first to go due to lack of lubrication.
I believe I would inspect the bearings and wristpin bushings while I was at it.
 
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