Why Does My Ford Flathead Keep Overheating??? Hot Rodding 101
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- เผยแพร่เมื่อ 4 ก.ค. 2024
- Join us today for another installment in our Hot Rodding 101 series. Today Matt sits down to talk about the most common reasons why a Ford Flathead overheats. Be sure to comment below with any tips and tricks to keep a Flathead running cool!!!
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Hi, I know you are very busy but I hope you will take the time to read this. Your piece on flat head over heating was spot on. We (family/friends) raced flat heads starting just after WW2, I am 82 now but was always around the garage etc. We were running 59A's from Canada after a Ford rep clued us in. They apparently had a higher nickel content and after switching to them never had a block failure. The way we prepared a block was, as I remember to strip it then clean out all the water passages possible. A long soak (in Muriatic acid??) at a local radiator shop for a boil out. Then a thorough hand scraping, blow out, and more scraping and flush out. then on to porting/relieving etc. Blocks were relatively cheap then. In fact a couple of times we heated them in a wood fire after disassembly prior to hand work/boiling. We even had a partial success with one engine after heating in a wood fire to make the brazing of sleeves (bored through the wall into the water jackets, Chevy 6 cyl sleeves I think Nash pistons). Ran like stink but the process was crude. 2 men with 2 torches brazing away. As the block was now weaker they leaked and didn't last . We did use a Hot Rod splitter in the center exhaust port though. About the over heating: The local rules stated the 1 carb and the engine had to look stock on the outside. After trying the brazed washers in the head to slow down the speed of the flow we made 2 short pieces of exhaust tubing with the correct sized freeze plug welded inside. You are right when you say the water flowed too fast at speed to loose the heat. By slowing it down the engine ran cooler. We tried the removing alternate vanes in the water pumps but that didn't see to have any further effect. We didn't run a fan but used truck radiators. Again local/cheap. Another "stock" trick was to use a Ford schoo lbus fuel pump. Looked the same but pulled the fuel better. Timing was set by elongating the slot on on the side of the distributor and setting upon TDC prior to putting on the head with a notch on the crank pulley. Sure wish I had written down more but at the time who knew. Your show is amust watch for us "old timers".
In our Model A Car Club, We cleaned out engines with Muriatic Acid, we usually mix in very small amounts. About 1/50 to ratio mix. Making extremely sure that the mix does not get into the radiator or on Paint finishes. With that mixture, we let it set overnight. Carefully plugging off the lower outlet to the lower engine outlet. Fill the engine. Let sit overnight. Then drain engine, use caution. Because, the fluid will be nasty! Do not allow to get on the floor of your garage. Do not let any Pets drink of play near the mixture. It will dye it brownish yellow. After it’s out, flush engine until clear water appears. If you wish Neutralize with baking soda. Still do not connect hoses to engine. The Muriatic Acid can make solder come apart. It is important to isolate the mixture from the Radiator. After the baking soda does it’s job, flush a few more times… Clean Hoses and replace any worn parts. With the engine empty of water, mixture and baking soda solution. Reconnect hoses, fill with water and a start engine. Check for leaks. Run engine until warm, and flush out…Then replace Antifreeze/Coolant 50/50. We still use old fashioned green. And in our case, lube water pump bearing grease fitting. Check for leaks and test run it…Thanks… Also, Folks keep tuning into Iron Trap Garage.
I had a long term overheating problem in my 51 Ford F2. Stock V8, but the truck started life as a flathead six. It took me several years of trying everything and getting no improvement. The six radiator had been modified for the V8 hose layout and the center outlet soldered shut. I flushed both engine and radiator, new water pumps, thermostat. I even added the original fan shroud that had been discarded. Still overheated badly. Then someone told me that the sixes had a three row tube layout and the V8s had a four row core. Problem solved. I bought a dead 51 farm truck just to get the radiator.
Make sure you get all the casting sand out of the bottom of the water jackets. I did then I sent the block to a guy in Petaluma to clean the block out further. Mine rarely overheats.
Great episode as usual Matt! I'm 73 years and the old school knowledge you have at your age amazes me. Then I realized you have learned through first hand experience as well as talking to legends like GW. My flathead was a 49 with 59000 miles and newly rebuilt V8. I drove it winter -40 F (Canada) as well as 104 F. It always started in winter with regular glycol mix , electric inline water pump/heater and battery blanket. No that's not cheating the wind chill factor in -40 F in Alberta reaches -70+ F and she never let me down. The only time the flatty overheated was once on a 104 F in Osoyoos BC. lol
Also make sure brakes are not binding. A problem I had in my early days with running flatheads, nothing wrong with them if clean and set up correctly.
Great advice and tips, as usual, Matt. One of my mates, in the early 70s, had a stock '46 Coupe with a
beautiful, quiet flathead in it. Ran it at highway speed, at night, with no dash lights, going to an out-of-town
party. It blew a bottom radiator hose, and ended up with a badly cracked block. He bought a 21 stud motor
for 10 bucks [70s, remember!] we threw it in and he sold the car. [Got his money back] Those were the days!
Dang ten bucks! Haha great
Here in AUS I had a flathead v8 in my ford 37 sedan in the 60s. I agree with all you said , but I still had issues until I replaced the iron heads with alloy , the iron heads get hot spots in them. After that it wasn’t too bad. Having said that we get temps in the 40s (Celsius) and then I used to find the fuel pump being behind the carby used to vaporise the petrol . I still wish I had it still to this day . Great, video
Cooling systems on iron engines are always a pain. I used to use distilled vinegar and water, run it for couple days, flush it out with water, repeat until mostly clean then flush again. Run for a couple days and then flush again, drain it out, flush and refil with good coolant.
I've usually found that its almost always a heat exchanger issue. So radiators are just not flowing enough (necking the coolant flow) or not enough air flow through the rad to take heat out of the coolant etc.
Thanks Matt! Many common sense things that apply to all old motors. I got lucky. My Catalina 57 came with a freshly rebuilt motor (rebuilt, ran then parked for a few decades), rebuilt radiator and a flushed, boiled and sealed fuel tank. Those things alone made the car worth considering.
Trashcan 🗑 Approved
I've used a 1/8" rod to run down the outside of the cylinder walls through the water jackets on a bare block with the plugs removed at the oil pan gasket area. I put it on an engine stand so that I could use gravity and air pressure to dislodge rust and junk. You usually get about a pound of crud!
In addition to blowing out cooling passages using a extendable magnet on a stick helps a lot. The rust is still magnetic!
Yep we do that as well as a first step to get the “big stuff” out. Totally forgot that. Great one!
Agree , beginner here but found my dodgy waterpump was actually hindered by crud .Used a small strong magnet on a piece of fencing wire to probe into the block,certainly very obstructed in the centre .Persuaded myself to do the opposite side as well ,remove probably a mug full of debris each side .I have a 'french' flatty ,so maybe an amount of casting dust in there .👍
Great tutorial on how to keep a flathead cool. I'm sure a lot of this has come from personal experience. Awesome content Matt.
Thanks for the tips Matt! Been battling with a hot engine in a 50 shoebox, tried some youve mentioned, in the middle of all of it, both water pumps died a month apart, gonna try just about everything else
Legend (and Motor City Flathead) said casting sand frequently is/was a factor with hot running flatheads. Motor City Flatheads used to get "pounds" of sand out of bare blocks while preparing for rebuilds using bent up rods, air, actual rolling of the bare block on the ground. Also, a bit of a project , but plugging the jacket surfaces and filling the jackets up with white vinegar and letting it sit for a day or two will dissolve lots of the built up rust. Followed by a good flush and a baking soda solution of course.
I know nothing about flatheads but I read, one time, that the factory didn't clean the sand from casting out of the blocks too well alot of times. Said the same thing you did, that rebuilders find alot of sand in blocks. Extra effort should be made to get the sand out.
Very good helpful tips. Thanks for sharing Matt. I hear a lot about slowing the coolant down but I experienced speeding up the water pump also fixed my problem on a warm running V8. The original water pump pulley was 7” so I installed a 5” pulley I had laying around. Never another issue even on the hottest days. I guess every situation is unique.
An old timer told me to connect the heads together with a 5/8 heater hose. He said that would Ballance flow in the engine and make it run cooler.
Heard about that idea a mate had a 46 coupe that ran hot it eventually ran right but we did try a lot of these ideas.
Excellent advice Matt. Only part where we differ is on coolant. I have been running Evans for 10 years. I have a 286 flattie running a quickfuel 650 manual I drive it hard I have not overheated in the entire 10 years. And no corrosion. Love your videos, Matt you always hit the nail on the head. Clean cooling system is a must.
Good to hear! I’ve never used it so as mentioned my words were just hearsay
Fan shrouds increase the fan cooling effort, and are simple to make.
The advice you give doesn't only concern hotrods, I have an old Russian 4x4 car and an old tractor and have exactly the same problems that you describe
Russian tractors are actually Ford. Just made in Russia, Ford was everywhere.
@@garycamara9955 the tractor isn't that much ford, but the car is identical like a 1930s ford
Thanks for the Tips! Just bought a 51 Merc. The last time I owned a flathead was 1985 so I need to brush up.
Glad to help!
Everytime I rebuilt a flattie the rad was sent to the radiator shop. I used rifle cleaning brushes to clean out the block and no thermostats. Never had a overheating problem. Oh and used green coolant
VERY interesting and instructive Matt! GREAT tips for me to remember! Enjoyed this very much!
Anti- freeze expands when hot. Has to be pressurized. If not you'll run shy on coolant. Old systems need to be full as possible. In my A I run distilled water, 1 qt Napa 1400 (anti rust stuff) and 1 qt anti freeze. Heated garage or just dump in the winter. I live in PA too, so winter driving is so-so anyway. You are 100% correct about condition of the cooling system. That's usually the problem. Very useful video, I hope people pay attention.
Good talk Mate! Exhaust to water heat transfer is a flattie problem like no other engine & the center port is the obvious one but you can reach in there with a long porting shaft & knock off all the chunky bits to help that. The outside ports (1-4-5-8) are a different animal that wrap around the outside of the cylinder so you have limited access to clean them out without taking it to an Extrude Hone company. Most header pipes are built square to the block but that's a mistake on these end ports as it creates a dogleg restriction. Take a minute to eyeball that & you'll see what I'm talking about. Golden rule with headers on any engine, the pipe needs to continue the port angle, the flange is just there to hold it in place.
Great info there! I’m learning myself here! Love it!
Well done, Matt!
I have a 39/40 Mercury 239 engine here that I pulled from an old welder. I took it apart to free up the valves, the pistons weren’t stuck as it’s been rebuilt at some point (.060” over). I let the cooling system dry out and blew it all out with compressed air. Before I put it back together I’m going to flush the block with my pressure washer. I have also found a gentle rub on the exterior of the block with a needle scaler will loosen up crap inside the water jackets so it can be cleaned out. Gentle being the key word.
Thank you Matt for sharing this great information with me !
My father was a mechanic who worked at Ford and Mercury dealerships after WWII. He told of a new Merc that overheated right from the factory. After several attempts to stop it various ways, he pulled the water pumps off and found a bird nest inside the block! Apparently the factory stored the blocks in an area where the birds did their family thing. Irish Jr.
You did a good job missed one big thing & that was when people pull an engine then when the put everything back but leave out the fan shroud. & can't figure out why the engine get hot. Stock flatheads never get hot unless run in extreme conditions. They only need 2 things to stay cool, first, a like new factory radiator & a engine block not just cleaned out but all rust scale down to bare cast iron & then run 50-50 anti-freeze that has distilled water to keep it that way. .Now duel exhaust are great. but in my day never a mouse problem but stuck heat riser was not a good thing. We only worked on stock cars but when modified anything can happen. When Ford tested their cars to find any problem remember those blocks were scale free as the radiators.
Ford did all their testing in winter no hot climate testing plus it was done in flat country
Thanks Matt, Its ben a long time since I ran a Flathead and its good to review the basics
Hello there from the United Kingdom of tea and biscuits 👋
I found FOUR rusty gunky thermostats in my flathead. Two turned sideways in my elbows and two more before the radiator! The steel pipes locked between two sets of thermostats were clogged cavities of restrictive rust stalactites and debris. Surprising I cruised it a year with no issues, it just despised highways 🙃
My first truck was a 51 F3 V8, hot days/heavy loads hung weepy canvas water bag in front of radiator. My flattiy pals avoid hot days and heavy traffic. My flatty and high performance Yblocks/FEs no overheat or vapor lock per: TESTED 165 thermostats (chyna junk). Blocks hot tanked and visually inspect water passages, too many surprises. Block intake heat. American only aluminum radiator no paint. Single electric shrouded fan w/sensor, push/pull fans for AC. Coated headers/2.5" pipes/glass packs. I always tire dyno tune, timing is heat critical but also fear detonation. Happy engines keep me happy.
Neat, koolo, lots of great information on the flatheads.
Also use only distilled water, ground water has a lot of minerals that you don't need in the engine. As far as pressure caps, the older radiators like what you are running don't have a sealing surface for the pressure cap to sit against so in order to run a pressure cap the neck needs to be updated. Not a flathead but I had a Pontiac in my shop that had a muffler completely packed with dog food from a mouse!
I use coolant!
I built a fan shroud for a freinds car, It worked good.
Thanks for the great info. Who do you use for your rad repair/recore?
Very good info , Thankyou
I have a new radiator, a model A with dual outlets for a flathead. The company that made them went out of business just after I got mine. Its a copper and brass radiator.
Through the years I have found that a clean cooling system is the fix for overheating.
The very first thing now is to remove the radiator and have it cleaned and rodded out.
Trying to do it yourself won’t work. A radiator shop is what it says it is . They clean radiators.
Everything else is only frosting on the cake..How many times I said , anew cap, no, new hoses, no, no thermostat, no , trick additive, no. Have the radiator vated and rodded. Then enjoy the ride. 10:53
Big fan of coolant filters..
Having the Block
HOT TANKED & MAGNIFLUX’d before Engine Building. Some are a Ultrasonic
Cleaner on the
Blocks too .
Good information
Good stuff.
Used a trick from the book Thunder Road flathead Guide where you drill a hole in the back of the water pump that matches the hole in the block ran that way for years worked great
I own a 46 Mercury with original rebuilt 239 and radiator with 160 degree thermostats and it has never gone past 180 while driving or idling. It will heat soak to about 205 after shutting down.
Matt on getting rust out of the cooling system could you use a long narrow bottle brush to help knock the rust loose ? Especially if the handle of the brush is a lite metal so you can bend it as you slide it in and out !
Great idea for sure!
Have you ever tried 50/50 parts water and vinegar to remove rust and scale in rusty blocks? That's how to remove scale from household water heaters. However it must be flushed out with fresh water until clear and anti rust solution (Antifreeze) added.
Also helpfull on a clogged heater core caused by using stop leak in engines such as flathead just remember to isolate the heater core from the engine. I've done this on one of my vehicles and it restored heater system perfectly.
The only Ford flathead I ran was a 53 Merc 3/4 race with Wiend head and 3 dueces the problem was trying to get it started again after a brief shutdown like stopping for a coffee. Just would not start. I had to go for a walk for 15-30 minutes.
In this case look at how close the exhaust is to the starter it could be getting hot then could be the timing and then there is the very last thing people miss the carburetor idle mix could be too lean sounds silly but it can cause hard starting
Matt do you recommend a coolant flush chemical treatment ?
I saw an internet show that had a ford flathead v8 expert explain that a lot of these engines came from the factory with some casting sand still in them and caused corrosion and over heating.
Hey I have heard you need the aluminum head with fin's.
I own and have daily driven about 10 flat heads not one had over heating trouble in 60 years
Good morning!
Mood gorning!!!
Matt do you recommend running 2 temp gauges?
There are several additional reasons why most hotrods have "other" engines.
I put 7/8 washers in my 21 stud engine. It immediately ran much hotter. The experiment was an epic fail!
I have no thermostats, I have some washers in mine.
Does hot rodding always involve ford flat head V8's? Are there other engines involved too?
Coolant, corrosion inhibitor must be used in all engines. Rust particles will damage an alloy radiator. If the engine is leaking with fresh coolant, it has cleaned out old rust and old silica build up etc, it is flushing your system.
Do they make 6Volt electric fans? I have never found one.
Yes I’ve seen them on eBay and Amazon actually!
what is the benefit to a restrictor in cooling system?
If coolant flows too quickly through the radiator, it doesn't dissipate heat efficiently. A restrictor ring - or thermostat - will slow down the flow and allow the coolant to cool. Matt mentioned the practice of removing water pump blades to achieve the same. Racers will fit a smaller crank pulley to slow down the pump. All of these things help to achieve the same goal.
Ok that makes sence, thanks Simon@@simonlane1277
Matt, you refer to updated water pumps… I need to get a new set for a Merc I’m building anyway… what do you recommend? Thanks for all the content! You Mike and Steve do a great job promoting old school hot ridding!
Third gen parts sell updated pumps , put 2 on 35 flat head , very satisfied, put 160 degree 8 n ford tractor thermostats inside hoses with clamp work beautiful
Yep third gen and I think Bob Drake also offered them. Or there was a guy on the fordbarn that was redoing them and upgrading them as well.
@@IronTrapGarage George “Skip” Haney rebuilds water pumps. That is the guy you’re thinking of.
Has anyone ran electric water pumps on one
Did the dog fart at 9:40?
Matt,, flathead Ford V8s are designed to boil!! The siamesed exhusts through the block is 'what were they thinking' Clearly they were not!! And then used the design for over 20 years!! The engine really were out of date before they were released. Poured bearings, sidevalve etc etc. Prehistoric crap in 34.
The intake design will leave a LOT to be desired as well. EGTs on one hole will be ok, the next to hot and the next to cool. I suspect twin 97s will help a little. A baby 4 bbl intake and 465 4bbl a good deal more. And will make more power as well.
You need an eficient radiator, meaning in this case a large one. 2 or 3 row max.. Bullshit 5 row ones are useless as they restrict too much air..Wanker tiny ones may be ok for drag racing and nothing else. IF you want to actually drive your hotrod use the original size rad. Or have it overheat all the time.To clean a rad it must be opened up and rodded through, no other way is efficient. And hot tank the block,, then fit a filter in the top hose to collect 50 years of rust even after tanking. Water is to drink and wash the car,, not to cool it. Any premmium coolant should suffice. A good modern alloy radiator is usually better and you can even come down a little in size. Though really with the faults in flatheads within reason larger is better.
Cooling systems MUST be pressurised,, then you can run 230 deg in traffic with no issues OR coolant loss. Later model Fords were ofcourse
A 4 blade tin fan will pull enough air, never bother with flexi fans etc. IF you have enough room a clutch fan will generally be better. But need a shroud. 12volt OEM single fans generally will be ok. And if it is shiny and shiny shrouds probably not. Really fans should be behind the rad pulling air, not in front pushing Not on a road car driven in traffic anyway
Thermostats are imperative in all engines, 180 for those is what they came with and what they should have, colder cracks blocks and heads [as does the siamesed exh]
Restrictors CAN be usefull with race engines,,maybe. 99% of the time a thermostat works best,, this in ALL engines not just Henrys revenge! No thermostat is a total fail.
The engine initially runs too cold, say 140-150 but once you get going then the water circulates way too fast and does not get time to cool, instant boilover.
To me the twin hose deal is less than ideal, yes they can work ok but even Ford worked out for more performance the single system is best.
The best way to fix a flathead cooling is install an OHV, 5 litre Windsor or any SBC is probably best.
Beware of early 289 302s which have the top and bottom hose on one side,, they too are boilers!!. Though use a late waterpump with the bottom hose left and the top right usually fixes them
And I have over 50 years of motorsport, and 50 years of towing them as well. And general automotive repairs.
The reason Ford flatheads are prone to overheating is the result of the poor design of the engine.
Routing the exhaust from the top of the cylinder to the bottom of the block through the water jacket? Not exactly a brilliant design.
The Cadillac flathead, on the other hand, has the exhaust exit directly at the top of the cylinder.
The Ford flathead is simply a gasoline-fueled water heater that can propel a car.