My ’66 F100—with the 240 six—didn’t have the owner’s manual when I bought it in 1987. When I stumbled into one in a used book store some years later, I bought it. The other day I wanted to look something up in it, and when I opened it up I had totally forgotten about these notes written into it by its original owners(s). They document tire replacements and much more disturbingly, two major engine repairs at 24,332 and 27, 017 miles to replace the pistons, rings and connecting rod bearings. Whoa! What caused that? In an engine that is considered to be as bulletproof as any of its time?
Here’s a crop of that section. It’s a bit faded but here’s what it says:
New pistons, rings, con. rod bearing. 24,332 mi.
New rings, pistons, etc. 27,017 mi! Dec. 6, 1967
I’m struggling to to imagine what would have caused the initial damage and then a repeat less than 3,000 miles later. It would seem most likely to have been caused by a massive lubrication issue? But no other damage, as in the valve train. I’m assuming some of you will chime on with a good or likely explanation.
Here’s the inside cover, with the Warranty Number, which indicates a 2WD F100 with the 240 six, assembled in San Jose. The owners lived in Coos Bay, OR and bought it in nearby Reedsport, Or. I obviously picked this up in Eugene after moving here. The bottom of the text has this line:
We are so proud of this truck that we warranty it to you for a full two years or 24,000 miles.
Which raises the question as to whether these repairs were made under warranty.
The warranty spells out that it’s whichever comes first: the 24 months or the 24,000 miles. Given that the first repair was made at 24,332 miles and was within the 24 months, I think it’s pretty safe to assume that Ford honored the repair with a slight extension.
And given that the redo was so soon, and most likely still within the 24 months, it’s pretty safe to assume that Ford covered that one too.
Is it possible they abused the truck when it was brand new and not “broken in”? The break-in instructions were a bit onerous: no more than 40 mph in the first 1000 miles, and not to hold that speed steady, but varying it, to help seat the rings. I still find it hard to imaging that not sticking to these regime, which I suspect many/most drivers didn’t, would have caused such substantial damage.
The other notations are for tire replacements, with the presumably first set at 29,733.0 miles on March 4, 1968. That was followed by a set or recap tires at 77,985.8 miles on July 8, 1971. And then some recap snow tread tires were bought at 76,650 on Dec. 18, 1973. The next set, in size 15-8.55 were put on at Sears on Oct.19, 1974. That size is larger than any of the original tire sizes, which varied with the trucks GVW (Gross Vehicle Weight).
The base tire size was 7.75 x 15 4 ply. With the optional 1250lbs rated rear springs, 8-ply rated tires the same size upped the GVR from 4200lbs to 4500lbs. Larger 8,15 x 15 tires upped that to 4800lbs. And 6.50 x 16 tires upped that to 5000lbs.
Their choice of “snow tread” recaps suggest that maybe they drove on lots of rugged back-country roads. But those snow tread recaps didn’t last very long (8,000 miles) before they were replaced with those 8.55 – 15 tires.
In case you’re interested, there’s also the operating instructions for the overdrive. I have this 3-speed and overdrive in mine, but mine was installed later and the overdrive is set up for manual engagement, not via the automatic vacuum-regulated solenoid.
Related CC reading:
Truck Of A Lifetime: 1966 Ford F-100 – Thirty (Six) Years of Hauling Shit, Cheaply by PN
I Take My 1966 F100 On A Road Trip – And Get 21 MPG by PN
My dad bought a 57 Ford 292 V8 Country sedan brand new. Was a traveling salesman. Traded it 2 years later for a 59 Plymouth. The dealer said they had to overhaul the used Ford before they could sell it. I think (I was 12) that he finally admitted that he didn’t change the oil often enough ( let it go to about 5,000 miles). Crankcase breathing on fords were very poor in those days. White milkry substance from water in the oil.
5000 miles is a perfectly acceptable distance between oil changes with no ill effects to the engine.
My dad, a long time mechanic, put our vehicles on a 6000 mile service schedule when I was growing up and my parents typically kept a vehicle for 10 years before trading it in for a newer model, or otherwise selling it off, and all of those vehicles ran just fine at the time they left the family.
It wasn’t until after Dad retired and had some time to “dink around” with the cars, that he started to notice he usually had to put a quart of oil in the engine just before it was time for an O&F service.
Thus, he started to work with a 5000 mile service schedule and held to that until he passed on 10 years later.
Personally, with the tiny little filters that cars come with now, I usually….
A) search out a longer replacement oil filter.
B) work with a 4000 mile service schedule, if that longer filter can be found and utilized. Otherwise, if I have to stick with the stock tiny oil filter, I will work with a 2000 mile service schedule, but will alter the service by changing the oil with every other filter change. At 2000 Miles, the oil is just in too good of shape to toss.
The last truck I did that with, I owned for 21 years with about 17-18 years on the rebuild.
If it were still under warranty, I may have requested a new engine the second time around. Then again, honoring the warranty 332 miles past the limit may have tempered that demand.
I’m aware that the Y-block V8, a decade earlier had the problem with top-end oiling *IF* you let the oil sludge up (and so Ford installed that bypass thing off the oil pan, IIRC?), but I hadn’t heard of any “Big Six” problem.
I’ll make a guess that 24K Rebuild was either for (1) a manufacturing problem that created the lower-end issue, or (2) an owner-neglect thing, BUT that 27K Rebuild was due to a problem with 24K Rebuild (rather than recurring defect or neglect). But what do I know?—–I’ll hope that owner got a fair shake for Ford/dealer, and that the CC Collective Wisdom come up with most-likely solution. Thanks for sharing this today, Paul!
I agree that the service at 27k was almost certainly due to a problem with the work that was previously done. That doesn’t mean it wasn’t a manufacturing defect as that could have been caused by poor workmanship or a problem with the parts installed at 24k.
Paul: I think you told me that the 223 six in my ’58 Ford is related to your 240 and is considered a “bulletproof” engine.
When I bought my ’58 from the original family (2 owners: father and son), I got all the original paperwork: manuals, receipts, etc. Among them was this piece of paper listing engine parts to be replaced. Looks to be a complete engine rebuild, although I have no proof this work was actually done, or when it was done.
At any rate, I have had this car since 2014 and it has been remarkably trouble-free. Regarding the engine, I have only had to rebuild the carb; replace water pump; adjust valves; new spark plugs. In 2024 I replaced the battery which lasted 10 years. This car always starts, and it idles and runs smoothly and consistently. Good power, no smoke, no engine leaks, no overheating. Drives like new!
To me this shows that properly set up (and not abused) these cars are really reliable and durable. (“The Ford Motor Company built it so you know it’s good!”–1958 advertising quote). What did them in was early body rust-out and the fact that the styling fell out of fashion rather quickly.
No, the 240/300 “Big Six” was a completely new engine when it arrived in 1965. But undoubtedly Ford’s experience with the previous generation (215, 223) played some sort of role.
The reality is that the inline sixes from all the manufacturers seem to have been solid engines with very few significant weaknesses. I’m struggling to think of a significant issue with any, except for the Pontiac OHC six which had well known lubrication issues and the Studebaker ohv six, with cracking heads. I’m a big inline six fan, in case that wasn’t obvious!
I quite agree with you Paul.
All of the inline sixes offered by any of the 4 main American auto manufacturers (I’m including AMC in that group), going back to at least the 1950’s where all well thought out and “bulletproof” engines.
With exception to the OHC Pontiac engine, there was absolutely NO “cutting edge” technology with any of those engines. Just good, solid, time proven designs that combined to create a smooth running, efficient and reliable powerplant.
Those engines would always take you there, but more importantly, would always get you home, too.
One thing often forgotten now is those oil spouts that you punctured the top of the oil can with. If they were stored improperly they were magnets for dirt and when used again the new quart of oil washed all of that dirt into the crankcase. Many good engines were done in by them.
That’s a fascinating tidbit about the old puncture spouts being a root-cause of engine failures. Who would have thought that the dust/dirt that was attracted and accumulated to the oil film left on a used spout would ultimately cause engine damage on subsequent oil changes? Only the most fastidious vehicle owner would go to the trouble of wiping/storing the oil spout to prevent it.
And, further, how the problem was ultimately resolved by the use of plastic, disposable oil bottles where no contamination of the new oil occurred.
I hadn’t thought about those cans and spouts in years. When I was an apprentice I worked with a tradesman who had been a mechanic in the RCAF, and he always turned the can over and used the bare metal bottom to put the spout in. He used to tell us that he knew of an engine out forced landing caused by a paint chip from an oil can.
True or not, I picked up the habit and did that until cans went away!
Who knows. In my time I’ve seen a few cases of premature engine failure caused by lack of oil. The most common culprit was failure to remove the old oil filter gasket when doing an oil change. Installing a new filter with a double gasket in place would usually let the new oil filter loosen up after a short period of driving.
Back my garage days, lube tech was a starting position filled by a mechanic trainee. Not all of them were conscientious or well supervised. It was an easy mistake to miss. Of course it is pure speculation to say what caused this particular Ford’s problem. If the engine had been a factory lemon, it would likely have manifest a problem much earlier in its life. I suspect something occurred that was unrelated to the original factory build quality of the engine.
As to the 2nd time, likely a problem with the work not being performed properly the 1st time or the discovery of further damage not noticed during the initial repair.
There may have been a quick fix at 24k that didnt last and the warranty on that job covered the full rebuild, some people should not try to fix engines, I bought a used previously rebuilt engine recently I needed an uncracked block but did the archeology on it as a qualified mechanic had done the rebuild out of sequence conrods were a bad sign drill swarf under no 2 main brg cap explained the rest, oil starvation, some body did a quick fix because somebody else did a poor job initially, I spent the money for a reputable machine shop to create a shortblock for me that runs fine,
Interesting. I’d bet the engine got dusted and the con rod bearings replaced while pistons were out. Followed by a re-do shortly after…..
Even more interesting is the owners manual. F-100 to F-350, gasoline or diesel. Was there a diesel option for these trucks? I’ve never seen or heard of one if so.
I wondered about that too when I picked this manual up. A diesel version? Turns out it was only available on the P-series (panel vans), a 220 inch UK Ford four with 65 hp. I’m slightly surprised Ford didn’t offer it in the F series too, as both Dodge and International were flirting with diesels at the time.
The damage to the pistons and rings had to be due to a lack of lubrication, the cylinder walls are lubricated by oil that is thrown off by the crankshaft as it spins. Likewise the damage to the connecting rod bearings, which was due to lack of oil pressure, which was probably due to a failure of the oil pump. I would hope that the main bearings were also replaced. Damage from excessive wear due to dirt contamination, would be gradual, and would usually show up as reduced engine life as it started burning oil due to loss of compression.
Most oil pumps are driven by a rod that is driven off the camshaft. If this rod breaks or is not seated correctly, the oil pump will not produce any pressure. If the internal workings of the oil pump become jammed by a metal chip that makes its way into the rotating gears, it could seize the pump, which would cause the drive shaft to snap. Now there is no oil pressure.
Of course, the engine could have been run without any oil resulting in this kind of damage. If the mechanic forgot to refill the engine after an oil change, or if they forgot to properly tighten the oil drain plug and it fell off, or as was mentioned, the spin on oil filter was improperly installed and fell off, then the engine could be starved for oil, with dire results.
That happened to my Dad once. I was with him when he noticed that oil pressure light came on, then the lifters started clacking, he pulled over immediately. Luckily it occurred just before we entered a freeway on ramp. We looked up the street and saw a long oil slick, checking underneath we saw that the oil filter was missing! I guess we didn’t tighten it up enough. We walked to an auto supply store and bought a new filter and several quarts of oil. Installed the filter, topped up the oil level, and we were on our way.
It can even happen to a professional mechanic. I once stopped to offer assistance to the driver of a new Jaguar stopped on the side of the road. It turned out that he was a mechanic at the nearby Jaguar dealership that had been working on this car, then took it out for a test drive. He had forgotten to refill the engine with oil! I gave him a ride back to the dealership, but I wondered if he would have a job to go back to after this mistake.
The first engine could have been a s%$t happens deal. I worked in a bodyshop in ’74, the boss bought a new F350 with a Holmes hoist, if memory serves it had a 351 with 2 broken pistons at 4k miles. On the 240, the second failure was more than likely maintenance issue as with the first or residual effect from the first.
My experience with Ford 6 cylinders using oil is from when I pumped gas in the late 60’s, we had a customer with a early to mid 60’s F100 who used to tank up every payday, and always needed 2-3 quarts of oil, and he was always shocked, we had our share of Ford V-8’s that guzzled oil too.
My family bought our first new car in 65 and it was a ford custon 4dr sedan. It had a radio and automatic and the 240 six. Very late one night I had it on I75 and “buried “the speedo at 120. After I hit that I laid off the gas but I don’t thiink it went much faster anyway.
I too am a lifelong i6 lover .
Any of the replies are spot on yet don’t answer the “why ?” .
Bottom end failures back then were usually caused by ‘short shifting’ so the engine was running under load at too slow RPM’s, over time this beat the road bearings out .
Similarly I remember many three speed equipped vehicles that didn’t have overdrive and were run on the open road at 65 + MPH, this used oil like no tomorrow and tended to wear out the top end of the engines .
Lastly most oil back then was paraffin so sludge was always a problem, especially on vehicles used mostly in town and at low speeds for short hops .
I remember those spouts, I found on my my garage last week and didn’t have the heart to toss it in the scrap metal bin where it likely belongs .
-Nate
That may have been the case with old school sixes, but not the modern/new ones that came out in the ’60s. They were fundamentally no different than comparable V8s in terms of tolerating low or high rpm operation.
When did the 24k repair take place? Those engines were designed to run on leaded gas which in my understanding acts a bit like a lubricant. I could be wrong but I swear I read that somewhere. Does not explain the second repair. Just a thought.
Almost certainly at the dealer, under warranty.
I’ve run nothing but unleaded gas in my ’66 F100 240 six since 1987. And leaded gas was banned well before then. Lead does not act as a lubricant. Its deposits on valve seats tended to make them stronger, but that issue is mostly overblown. Every old pre-1970 car on the road has no choice but to run unleaded.
The leaded gas isssue was totally overblown by collector car clubs. I belong to one of the Packard clubs, and for years their news bulletins were filled with handwringing about the leaded gas phaseout. Many general-interest collector magazines were the same. In fact, all gas was unleaded when many Packards were first made, and until the late ’30s at least you had to pay extra for “Ethyl.” In all the fanciful creative advertising exaggerations by the Ethyl Gasoline Corporation back then it’s funny they never thought to mention increased valve life as a benefit, although it would apparently do everything else for you, including getting your grumpy old boss to give you a promotion (I’m not kidding).
Yes. Some, like Amoco Super, never had lead.
I remember all the “hobby hype” about how unleaded gas will ruin your old car’s engine (valve recession). Since 1995 I’ve been using unleaded (no choice) and never had a problem.
Then there was the hysteria over “Crusher Bills”. Year One (the muscle car parts supplier) even put out a VHS tape dramatically showing how EPA cops were going to come to your house, confiscate your ’72 Camaro, and throw it in the crusher. They actually put a very clean, straight, white Camaro into a crusher and crushed it so you could weep and wail over this beautiful car being destroyed!
Endless letters to Hemmings Motor News on both subjects, both of which turned out to be nothing. Which makes me skeptical of a lot of things I hear about.
(I hope this isn’t too far off topic, but I thought it was worth mentioning.)
Maybe someone with a grudge put sugar in the gas tank. It was a thing back then.
In my youth my best friends father had a 61 Mercury with an I6. It was equipped with a canister oil bath oil filter. It was not uncommon for folks to substitute a roll of toilet paper for the filter element. These were notorious for disintegrating and clogging oil passages. In addition the old boot style valve stem seals would harden very quickly. Resulting in increased oil consumption and blue smoke from the tail pipe. In general during those days and even through the early to mid 70s it was quite common for an engine to need fresh rings, valve guides and seals by 60,000 miles.