Life Expectancy for Mopar Flathead 6

[55 Fargo]

Hi all, on my way home from work last night, stopped at a small country gas station on my route.

The owner (about 65 to 70 YO), was there we have talked about flathead 6s a lot of times before, he has used them for racing cars back in the 50s and early 60s, for farm and industrial uses, he seems to know these engines well.

I asked him how long these engines might expect to last if they are well maintained. and not abused, Now his answer was this about 500000 miles, is this possible?

I also asked him how the flatties would start in the cold weather we were having last night about -20f, he said they would start fine if the oil pans were warmed up. He also mentioned that they would have metal tubes welded on the oil pans to allow tiger troches to be inserted to heat up oil pans, this was used for northern construction sites and such.

The flat head engines were sure versatile and reliable tough engines, but 500000 miles sounds like a lot.Anybody have any ideas on this?

[Captain Neon]

500,000 mi. seems like a very long time for any engine much less 1930s technology. My own experience from trooping around juncqueyards and observing MoPar L6-powered, as well as similar vintage vehicles, juncqued in the early '60s, tells me that they last about 60,000 miles. I'm sure some one will try to tell me different, but that was what I observed.

[greg g]

These old mopars are like Tim Adam's hammer. It was his grandfathers originally. he reports that he has only changed the head once and the handle twice, and is still as useabel as the day his grandfather bought it those many years ago.

Face it when these cars and engines were built, metalurgy wasn't advanced very far from the blacksmith's forge. Lubrication science was in it's formative years, fuel science was pretty basic, filters were basic and sometimes weren't even there. Plus we lived in a newer is better, keep up with the Jonses mentality. So if your 60K 46 Dodge was sitting in the driveway of your 1948 Cape Cod tract house, and all of a sudden your nieghbors starting pulling into their driveways in 54 studebakers, tri 5 chevies and fords, and virgil exners forward look Mopars, it wouldn't be long before you trundled off to the dealership, and traded in your 150 dollar car for something with fins regardless of the condition of you old ride. That car might have had many miles left in it but who wanted to drive it??? So maybe a kid would buy it from the back lot of the dealership, for as long as it took to run the oil out of it, throw a rod, and relegate it to the junk yard. Still in basically good condition and fairly easy to fix but if you could buy another one for 50 bucks, the fix went by the board,

I'm thinking today, with a fresh rebuild and decent maintanence, and prudent operation, there is no reason why a flatty couldn't run basically forever.

[Young Ed]

500,000 mi. seems like a very long time for any engine much less 1930s technology. My own experience from trooping around juncqueyards and observing MoPar L6-powered, as well as similar vintage vehicles, juncqued in the early '60s, tells me that they last about 60,000 miles. I'm sure some one will try to tell me different, but that was what I observed.

My own coupe went to the junkyard at 76K. After I got it we did get it running but it had no oil pressure once the oil got even slightly warm.

[BobT-47P15]

If a flathead didn't get too reamed out before the first rebuild, and it was

only bored slightly oversize......then bored a bit more the next time, etc...

it could probably take several rebuilds. Maybe some people maintained

these engines carefully....and actually got about that many miles out

of them.

I've seen a lot of odometers in the junkyards with 50 to 70-some thousand

miles showing. And that's probably the correct actual mileage on the car.

People didn't drive as much then as today, so it took more years to

accumulate that many miles. And, as Greg says, the styles were changing,

so one would trade up to the latest thing. The old cars were the "back

row beauties" on the dealers' lots......sold for a couple hundred bucks as

a kid's car or a family's second car.

[Fluid drive]

So many of the old cars from the era we love were subjected to terrible roads, questionable lubrication( most oils until the mid '40s were not fully refined and not detergent). One of the few departures from the original equipment I make on all my restorations is the adaptation of the oil bath filter to a paper cartridge. The original oil bath filters let a lot of dirt into the engine too.

I had a friend who ran his '37 chrysler 130,000 miles even under those conditions. With modern oil and care those old L head motors should last a human lifetime.

[greg g]

Not to mention its a hard thing to find a dirt road these days, back inthe 40's only state and federal highways were paved once you got out of populated areas. Dust was a real engine killer back then.

[Normspeed]

My folks went through a lot of used cars back in the 50s and 60s, mostly Packards, Hudsons, Fords and Plymouths. I recall that reaching 100,000 miles was quite an event. I don't remember ever hearing that one of ours rolled over 200,000.

A couple of times the car we were in would reach all nines. My dad would pull over, everyone would climb out, and we would push it down the shoulder until it rolled over to mile 1. Sort of a "thank you" gesture:)

[aero3113]

I met a guy once at a car show who told me when he was young him and a friend had a 1950 plymouth that they wanted to junk. They drained the oil and water, took the carb off and just had the fuel line dripping into the manifold just for fun to see what would happen.The car still ran and they could not get it to seize up. I think that shows how strong these engines are!!!

[Young Ed]

You pushed it 1.1 miles? Thats dedication

[Normspeed]

Give or take a few tenths...

[greg g]

Up here in the northeast, road salt was a bigger culprit to a vehicle's demiss than mechanical failure, especially mopars. Sheet metal protection is a lot better also.

Check out the Volvo owners club highmilage group. Some fellow on Long Island has 2million 6 hundredthousand miles on his 66 1800.

[Young Ed]

Greg thats still the case. I think my dakota will rust away long before the 3.9 dies. Just hit 178K. Rust has pretty much whiped out the front fender flare and the rockers are starting to go now too. Already replaced the box once.

[Norm's Coupe]

I have to agree with the others. Years ago people simply didn't keep their cars that long so 60,000 miles on one was a lot.

That said, if the engine is good and well maintained to begin with it will probably last a lifetime. Here's a few examples of 70's & up cars that I know of personally. The original V6 that was in my sons 80 Firebird was in great shape after about 150,000 miles. Only reason he rebuilt it was to hot rod it, then afterward still wasn't enough power for him so swapped it for a 350 engine. I know a salesman that bought an 84 Chevy Caviler 4 banger new. He put close to 300,000 miles on it in about 4 or 5 years and never touched the engine except for oil changes and tuneups. Then he sold the car to his younger brother who put at least another 100,000 miles on it without touching the engine, except changing oil and tuneups. When he sold it, it was still running like a new car. My neighbor across the street has a 79 Cadillac with the big V8 in it. Has had it since about 1980 and it has about 250,000 miles on it without going into the engine. Car runs like new and he will take it to visit relatives in Ohio about 450 miles away (one way), without a problem. He also bought a 1999 Cadillac a few years ago. That one had about 200,000 miles on it when he bought it. Again, runs like a top and the engine has never been touched except for oil changes and tuneups.

So........I think today if you start out with a good Flathead 6 it will run forever, providing it's well maintained. At least, it will probably last your lifetime and who cares after that.

Added:

Was typing the above when Greg made his last post. In addition to the car he mentioned, I read an article some years ago about a salesman who drove a Chevy (forgot the year and size engine) but was about late 70's model. He also had over a million miles on the original engine.

[Young Ed]

Norm I think I read that too. It was a pickup. I think he lived in WI somewhere and made trips all over the midwest with it.

[Vazlov1949]

I have a 49 Pilothouse with the original motor still running strong at 93,000 miles. It was a state truck for years so maybe it had it's oil changed alot more than most. The head has never been off and it does not burn any oil. It leaks a little around the oil pan. True the science was not far from a blacksmith's forge but the steel was of a quality that was used in WW2. I don't think environmental standards allow for steel to be forged the same way anymore. But what do I know? I've only driven pre-54 vehicles for about 35 years.

[blueskies]

My '50 Plymouth was running at 86,000 when I bought it. But here's what the pistons looked like when I pulled them out...

I drove the car around for a couple of months before tearing it down for a rebuild. Didn't smoke or burn much oil, ran smooth. But had low compression and all of the top rings were broken or missing altogether.

I doubt my engine would have made it to 100k, let alone 500k...

Pete

[p24-1953]

i had mine rebuilt at 75,000. threw a rod but it limped home. Good Car......

[RobertKB]

My original '53 Plymouth has over 96,000 miles on it. I did rings and lapped the valves about 20,000 miles ago with the engine in the car. Bearings are original and were within factory specs. Still has great oil pressure and does not use oil. I sometimes think about giving a total engne rebuild but then ask myself why? It gets about 1000 miles a year and will likely run for a while yet. Transmission is weak compared to the engine and I might rebuild that next year. The flatties will run a long time if not abused and if well maintained.

[Jerry Roberts]

One other thing that hasen't been mentioned that helped wear out these motors ; The low gearing . High gear was usually direct drive .

[Don Coatney]

His answer was this about 500,000 miles, is this possible?

To cut through the crap and answer your question, YES, it is possible.

[55 Fargo]

Hi all, thanx for the replies to this ??. I always though these engines would be good to about 100 k, this old guy I was talking to must have meant 60 k before maybe a ring/valve job would need to be done.

The low gearing on these vehicles, would also no doubt help determine longevity of these engines.

Along with operating conditions, dusty roads, oil that is of lower quality, etc.

I also have a supervisor where I work, he has about a 10 yo Honda Civic with over 300000 miles on it, this guy is from Beaumont, California , and has made a lot of trips back home in this car, as well he lives about 30 miles from work.

I have no idea how many miles I have on my engine, it has great oil pressure 45 at an idle, and 55 on the highway, compression is 100 to 110 psi, no knocks, does not seem to burn oil, but does leak a lot of oil, still need to fix that sometime in the near future.

Here is a pic of inside the valve chambers on my engine last spring when I repaired the heatriser on the manifolds, it was pretty darn clean in there and no sludge........................Fred

[JIPJOBXX]

My old Dodge had over 250,000 miles on it and was still running. Not great but still ran. It was owned by a farmer and he had to keep it running as money was tight!

[grey beard]

My own experience with MoPar flatheads is that most of them die due to sludge accumulation in the valve chambers. This occurs due to short runs and insufficient warmups. Higher thermostats - 180 degrees - and longer running times to get those heavy blocks completely warmed up all help to keep the sludge factor down. AND it goes without saying that regular oil and filter changes are a must to keep sludge formation controlled.

My own engine had 98 K on it when I pulled it apart. One piston skirt was missing and all the rtop ing lands on the pistons were worn out. The valve chamber was packed with hard dry sludge, which kept oil from the timing chain, so it was worn out completely. Interetingly, cylinder taper was just a few thousandths of an inch, so I have to beleive the old oil bath air cleaner did a credible job of keeping the air clean.

Once one of these engines has been renewed back to acceeptable specs. and is maintained properly using HD oils, I believe they will far outlast me. AND, if you want them to outlast your grandchildren, rig up a PCV system, add a good quality paper air filter and use synthetic oil in a full-flow filtration system. It'll still be running when the national debt is all paid off.

[B-Watson]

Mopar flatheads must have been tough and reliable engines. The number one taxi for standard size cars was the Plymouth while DeSoto dominated the LWB taxi market. Both had flathead sixes and their longevity helped give Chrysler vehicles an excellent reputation. If you wanted a car that lasted a long while before needing an overhaul, you bought a Mopar.

Bill

Vancouver, BC