Flat heads and thrown con rods?

[Dodgy6]

I have seen a total of 3 old flat head motors so far in my search for parts.

1. Mine - thrown conrod. Result - holes in either side of the block.

2. A later flathead 6 cyl out of a dodge truck at the wreckers - block had a welded patch, presume thrown conrod.

3. Picked up a Plymouth U(?) flathead 4 cyl motor and gerabox today, (wrong motor, but it was free so I took it home anyway...), with another welded up block - presume thrown conrod.

So thats 3 from 3 on block damage from thrown conrods. Is this something that these motors suffer from or am I just unlucky :confused:

[35cz8]

I have been playing around with these old MOPAR flatheads for over 40 years and I have only run into one with a welded block from a thrown rod. I still have that block and it is from a 1930 Dodge DC8. Whoever repaired it did a good job and it may just find it's way back into a car and on the road someday. I'm sure there were many blocks that experienced a thrown rod but I think they are in the minority. Just my experiences.

[Guest 1930]

I have seen a total of 3 old flat head motors so far in my search for parts.

1. Mine - thrown conrod. Result - holes in either side of the block.

2. A later flathead 6 cyl out of a dodge truck at the wreckers - block had a welded patch, presume thrown conrod.

3. Picked up a Plymouth U(?) flathead 4 cyl motor and gerabox today, (wrong motor, but it was free so I took it home anyway...), with another welded up block - presume thrown conrod.

So thats 3 from 3 on block damage from thrown conrods. Is this something that these motors suffer from or am I just unlucky :confused:

Bad luck :eek:

[1936 D2]

Or 3 for 3 !

Batting 300!

Your lucky day!

Maybe you should go play the lottery!

(All depends on your point of view!)

[Dodgy6]

Or 3 for 3 !

Batting 300!

Your lucky day!

Maybe you should go play the lottery!

(All depends on your point of view!)

Ahhhh, one of those glass half full types eh?!!

I suppose the odds of me finding a good one are getting better and better then

So I take it from the responses that there is no inherent fault with thrown conrods in these engines - I'm just unlucky so far, (or lucky :confused:). I wonder what sort of responses I would get if I started this one on a Chev or Ford forum?

[Rusty_OToole]

Haven't seen any with thrown rods but have seen more than one with broken pistons. It seems when the engine gets worn a ridge forms at the top of the cylinder. Further wear allows the piston to rise higher in the cylinder, hitting the ridge. This only happens at high revs. So, a motor that has given good service at moderate speeds can suddenly break down if taken out on the hiway and driven at high speed. If not revved so high it might have gone on for years.

For the detail oriented types - I realize that it is the top ring that cuts the cylinder and leaves the ridge and it is the top ring that hits the ridge and breaks the piston, I was trying to keep it simple.

[Guest brian j]

My first vehicle i ever owned was a 1950 Chevrolet pickup truck. I was 17 years old.........and hell bent for election. I hardly ever drove it less than wide open throttle.......and hardly knew where the oil dipstick was.....or even cared. Until one day i was bombing down the Cramer road by my house, a 3 mile grade. I made it to the bottom, and was slowing down to prepare to wheel into my driveway, and suddenly the tires locked up, and plastered my face into the windshield,painfully reminding me of my lack of responsibilty. I got out of the truck, and discovered a connecting rod had pierced the side of the block. I'm not sure if it was caused by my speed, or lack of maintenance. The moral of this story is..........you'll find a lot of cracked, split,damaged, blocks, where you find people who don't check the oil or water, or don't put the required ratio of anti freeze, or treat there engines like they were built for NASCAR. I was one of those people, and so were a few of my friends. I'm happy to say the years(and lessons like this) have taught me well, i'm actually overly kind to my engines nowdays. There are just as many engines out there that have been treated well, and are in excellent condition, so i would not let your recent experiences get you down. That motor you're looking for is out there somewhere.........you just have to keep looking. It's too bad you're so far away.... i have 2 good flathead Dodge sixes here in Minnesota. Regards

[Guest 1930]

Haven't seen any with thrown rods but have seen more than one with broken pistons. It seems when the engine gets worn a ridge forms at the top of the cylinder. Further wear allows the piston to rise higher in the cylinder, hitting the ridge. This only happens at high revs. So, a motor that has given good service at moderate speeds can suddenly break down if taken out on the hiway and driven at high speed. If not revved so high it might have gone on for years.

Hey Rusty, thats the top ring that makes that ridge, not the piston silly

[Dodgy6]

I do live in an area which goes below freezing most nights during the winter. We've just started getting frosts again. Could cold weather be a factor?

[keiser31]

I do live in an area which goes below freezing most nights during the winter. We've just started getting frosts again. Could cold weather be a factor?

Unless you can see through to the cylinder, it was more than likely water expansion from freezing (because of no anti-freeze). VERY common in colder climates.

[R.White]

Unless you can see through to the cylinder, it was more than likely water expansion from freezing (because of no anti-freeze). VERY common in colder climates.

John, you are quite right; it's the water jacket which splits due to freezing. A thrown rod will produce the hole.

Do you agree with me that the most likely damage to be caused by a ring hitting the ridge is a broken ring? I have seen this happen (not to me) when new rings have been fitted to a part worn engine without removing the ridge first. I am not saying that a piston couldn't break in this way but is it likely? I think a thrown rod is more likely to be caused by siezure due to lack of water; lack of oil will run a big end or, at worst, break a crankshaft.

It's mostly conjecture on my part - but if it starts a debate...............

Ray

[keiser31]

John, you are quite right; it's the water jacket which splits due to freezing. A thrown rod will produce the hole.

Do you agree with me that the most likely damage to be caused by a ring hitting the ridge is a broken ring? I have seen this happen (not to me) when new rings have been fitted to a part worn engine without removing the ridge first. I am not saying that a piston couldn't break in this way but is it likely? I think a thrown rod is more likely to be caused by siezure due to lack of water; lack of oil will run a big end or, at worst, break a crankshaft.

It's mostly conjecture on my part - but if it starts a debate...............

Ray

Yes, I believe that anything, even as small as a cylinder ridge, can break a piston or ring. If the ring binds, the piston surface between the ring that hits the ridge and the ring below it can break.

[ply33]

Yes, I believe that anything, even as small as a cylinder ridge, can break a piston or ring. If the ring binds, the piston surface between the ring that hits the ridge and the ring below it can break.

And it is possible for part of the broken ring or broken top land of the piston to then get into the combustion chamber. While it is bouncing around in there looking for the exit, it can get in the squeeze are where there is almost no clearance between the head and the piston top. Which can then lead to the piston being pounded at an angle which can break the skirt with pieces dropping into the pan. At least it was possible enough to happen on my engine.

But it makes enough noise that, if you are lucky like I was, no permanent damage is done to the head, block, rod or crank.

[R.White]

I guess I have just been dead lucky. I have had rings break and got away with it. We used to see it quite frequently years ago when I worked in a garage. Then the worst damage I can remember would be a badly scored bore; which if it was too bad, would need sleeving....

Ray

[Chrycoman]

Chrysler built something like ten million flathead engines. Finding three of ten million with holey blocks is, as they say, statistically insignificant. Cracked blocks, especially before WW II, caused by freezing was quite common in cold areas as antifreeze was not that good. An alcohol-based stuff was usually used that had to be treated with care or would, as my father found out, catch fire. He used to fill the rad with this stuff, leave the rad cap off, start the car (a 1936 Graham Supercharger), go back into the house to keep warm and come out when the engine was getting warm. This one time he got back outside a few moments too late and saw the the alcohol antifreeze burst into flame. Flames reached up about three storeys and burnt every rubber and wire piece under the hood as well as the paint on the front end. Normally if the procedure was successful, you drained the alcohol antifreeze and filled with water. If you were going to be out for a while you had to remember to go a start up the car to heat the water up and prevent it from freezing. If you didn't, well, a patch would be called for if you were lucky and an engine if you weren't. Bill Toronto, ON

[Dodgy6]

Here is a couple of pics.

The first is the welded up cracked block of Plymouth 4 cyl that I picked up and the second is my DA motor which I have posted pics of before:

[keiser31]

Here is a couple of pics.

The first is the welded up cracked block of Plymouth 4 cyl that I picked up and the second is my DA motor which I have posted pics of before:

Yep....those don't look to be water jacket freeze burst holes to me.

[R.White]

Yes, I believe that anything, even as small as a cylinder ridge, can break a piston or ring. If the ring binds, the piston surface between the ring that hits the ridge and the ring below it can break.

We used to avoid this by fitting a stepped top ring when the worn rings needed replacement. I suppose it was a quick fix but seemed effective. I don't know whether these ring sets are available now - I haven't seen any for years.

Ray.

[Guest 1930]

Its not just the cold but also dumping cold water down a hot engine that maybe has overheated at the side of the road will do the very same thing

[Guest Randy7]

I also had a early 50's dodge flathead hot rod as a kid. I had a field car with no body, just the floor, 4 wheels and a steering wheel. We have rock quarries here and I spent hours cutting donuts in them and burning rubber on a long concrete bridge. In the summer I would go through a set of "used" tires a week compliments of the local filling station. I drove that so hard that I went through thirteen rear ends and 2 fluid drive transmissions. That included putting a brick on the acc. pedal and going to eat lunch. 20 minutes later I went out and took the brick off and went back to driving it. The spider gears in the rear end are the only weak link in those old dudes. The motors have my highest respect.

[R.White]

One of My dad's favourite stories used to be how as a young man (before WW2) he bought an M.G. He thought he had hit the jackpot until water was seen seeping from the newly painted engine . What he did to repair the cracked block was to 'stitch' it with threaded brass rod (or studding). Apparently, this somewhat labourious method worked and the finished result looked so good it was left unpainted! God rest him.

Ray.

[ply33]

One of My dad's favourite stories used to be how as a young man (before WW2) he bought an M.G. He thought he had hit the jackpot until water was seen seeping from the newly painted engine . What he did to repair the cracked block was to 'stitch' it with threaded brass rod (or studding). Apparently, this somewhat labourious method worked and the finished result looked so good it was left unpainted! God rest him.

Ray.

Drilling and tapping a series of hole and using threaded pieces to fix casting cracks is just about as old a technique as casting parts. A quick search for "stitching cast iron" turns up this modern product for that old technique:

[JACK M]

When I was a kid we used to get soemthing called waterglass from the pharmacy and put it in the radiator. If I am remembering correctly it worked pretty good on a freeze cracked motor..

[R.White]

The technique may have it's limitations but it obviously works - the MG; a 1929 M Type midget still survives, with it's original engine!

Many thanks for posting that, Ply 33.

Ray