Technical Cured My Flathead’s Occasional Overheating (The Hard Way)!. Updated 1-4

The flattie in my 40 coupe would occasionally overheat and lose coolant. I thought that I found the culprit in a radiator cap with a bad gasket. Replaced it and decided to take the 40 to our club's rod run in Kingsport today.

It was a cool morning and we were purring along. Really happy at how good the little flat motor was running. Pulled a long hill and the temp came on up but stabilized at 195.
A couple miles later, and another long hill, but this time it REALLY got hot.
Turned around to head home when it started to imitate Old Faithful.
Pulled over and it didn't look good.
Hose blown off, paint cooked!
Hate to see what that #5&6 cylinder and piston looks like.
Came home on a rollback, but it still runs on the other 7. LOL.
Figure that it's a boat anchor now.
Glad I have that fresh SBC on the stand.
Before:

After:
Probably had a cracked head and/or block all along and finally tossed the head gasket. Yet to be determined.

 

283 SBC in my 36 Ford 3w Coupe.. V8 Flatheads and I don't get along.. My 49 Ford Business Coupe had a dual carb flathead 6 banger.. never a issue.. ran great. time for a SBC or SBF ( Keeping a Ford in a Ford if preferred)

 

I agree with this post..

 

Well, killing the engine IS one sure way to stop it from overheating again. Creative solution!

 

Flatheads are cool..until they're hot.
SBC on the stand in waiting, sounds like something you had planned for anyway..always nice if it's on your time line though.

 

Why did the hose pop off? Not tight enough? Not on properly? They don't just pop off.
I have always ran with no thermostat and don't over heat even in 100+ degrees. Been doing this for a few decades and I learned this from my Dad and Uncles.
I don't drive mine in freezing weather and might take a little longer to warm up sometimes on cold days.

 

@Flathead Dave. Don’t know why that one side’s hose blew off. Very surprised to see that. Never any sign of a leak there. No thermostat, FWIW.

Replaced the plugs on that bank, and it cranked and ran well enough to pull in the shop.
Blowing oil out the breather and water in the oil.
Milkshake on the dipstick and out the left tailpipe.
Stick a fork in it. It’s done.
BUMMER!

Coming to a fork in the road. Do I
1. install my good running but used ‘63 283 and adapt it to the existing Ford 3 spd. pickup trans?
I have all the pieces to do this
OR
2. Install my freshly rebuilt 350 and automatic and A/C? I also have all the CE pieces to do this.

Decisions, decisions!

 

2. Install my freshly rebuilt 350 and automatic and A/C? I also have all the CE pieces to do this.

You asked
That's what I would do.

 

If I can be forgiven for piggy backing on your post? Going through something similar. Went to a cruise night in my 50 flathead powered A roadster which is recently built. It runs consistently at 165/170 degrees around town with no issues. I was heading to the cruise which was about 20 miles away and was buzzing it along at about 55 for most of it but got up towards 60 or so a few times. As I did it started to push antifreeze out the over flow and the temp headed up into the 195 range. I backed it back down to 55 and the temp came right back down. Sort of attributed it to the engine only having a couple hundred miles on it and not really broken in yet? Am going to install an overflow tank. Running anti freeze and water mix. Water pumps, radiator, cap, hoses, and thermostats are new. No leaks anywhere. Block was pressure tested to 60 psi before engine was built. Any suggestions on what I might look at? What might a normal temp be for a flattie running along at 60 or 65?

 

Had three flatmotors do the samething.....Got tired a spending money and not getting enjoyment out of the car...Blown hemi now...Never any issues..

 

If it did blow the gasket it may have pressurized the cooling system and popped the hose off.

Just a guess, so take it apart and let's see... and see if the nuts were all tight.

 

Not to criticize but that is #5 and 6 cylinder.

 

That’s the only way to fix a Ford. Put a Chevrolet engine in it! I’m partial for the 283 and keeping the stick.

 

Not saying this is your problem, but I've seen a lot of flathead (and other engine) rebuilds on here that totally ignore the corrosion, crap and corruption in the cooling system. The newest (U.S.) flathead block you'll find is now 69 years old. That's a long time to accumulate rust (insulation). Try a system flush.

 

Thanks @Slopok. #5&6

Ironically, I poured over Mart’s video a couple of days ago! Deja Vu, all over again.(Yogi Berra)

Won’t know anything until I pull the head and do a forensic autopsy. (What?)
I’m thinking that I’ve had a weeping head gasket for some time. Thing could sit and idle forever and not overheat. When I did those long hill pulls, it didn’t like it and gave up.
Probably going to need a head.
IF the block is still good, I’ll decide a course of action.
I have Edelbrock heads and Slingshot dual intake sitting on the shelf.

FWIW, a friend had his 40 fry, and blew off BOTH hoses!
Pulled the heads, two new gaskets, a crank driven fan and it runs like an ape.
My results may vary.

 

I wouldn’t be concerned about 195. But your engine will run hotter as it’s new and tight.

 

Those engines (flatheads) back in the day didn't run at the speeds we push them to today. There was no alternative. They were the best money could buy. And they were new at the time. They overheated if pushed past their limit. They were great engines for their time. You just had to know when they were giving you sign's of being abused. We ran a lot of them on the farm in pickups hauling hay, everything you could imagine. Even when the temps were well over a hundred degrees. You have to understand the old timers are wore out at least most of them. I'm just like a flathead ford. I'll run all day long for you but when I don't feel quite right I will lay down. So go ahead and put your SBC in. It's newer. Then you won't have to worry about all the traditional problems a flathead ford can cause. But it's not because it's a bad engine. It's just because it's already been rode hard and put up wet. Just like me. Lippy

 

Back in Jan, our summer, did a 1000 mile round trip with temps in the 90's. Flathead performed faultlessly.
Cruised at 70 mph hour after hour, normally runs about 175, but installed a bra for the trip and it ran about 190.
Even in peak hour traffic after hours on the road, didnt boil or drop any water. Built right they will do the job.
If I could afford a new Ardun I would put it in my coupe instead of the 429 Cad I have now.

 

I really hope the damage to your flathead is minimal and you can save it. Henry would be proud of you for keeping it. If you must switch over to the sbc ( I love them too) I vote for a 283 adapted to the original drivetrain. That is a traditional combo to be respected.

 

The SBC has always been the solution for crappy, under powered, running hot, flathead V8s but the flathead transmissions dont hold up to a SBC. A fully synchronized transmission makes life a lot better

 

Gordon,
It sounds like your rpm’s are pushing antifreeze out of the system at higher speeds. Easy fix without an overflow tank.
Install a 4lb cap on the thing and also a 2-4lb pressure relief valve on the overflow tube.
A brake pressure relief valve works for this.
It will prevent high pressure fluid loss at speed and increase the boiling point slightly at the same time.
Average temp at high speed is dependent on the outside temp.
Mine run usually 100 degrees above.

 

Thanks for the tips guys. Much appreciated!

 

I spent a significant amount of time cleaning the block on the '51 Merc in my car, and paid attention to the overall condition of the gasket surfaces. Never a problem.

 

Hey Tubman! Good to hear from you.

I had spent a lot of time tumbling and probing the block knocking all the scale and build up out of it before I sent it to the builder and they baked it so I think this might be something external to that. Don't really have any leaks anywhere that I can see? Doesn't seem to be burning it either? I'll need to dig into this a bit to see what I can find.

Thanks!

 

Guys & gals do yourself a favor & look into this product. I use it in 3 vehicles & it really helps. Might be snake oil or temp fix but I 'm happy with it enough to give it a shout out.
RMI-25

 

I vote #1.

But if you really want to dig a hole for yourself, 283 to a T170 RTS to an open drive banjo......

 

Good to hear you're on it Gordon. All I can say is that when I had the engine in my '67 Corvette rebuilt, they must have assembled it with all clearances on the tight side. It would run fine down the road, but if I let it sit and idle, it would try to peg the temperature gauge. I lived with it that way for the first 2500 miles, and was just about to pull it and tear it down when it miraculously decided to finally break in, and it now runs right on the thermostat (180 degrees). If you only have 500 miles, I'd just watch it and put some more miles on it and see what happens. It seems engine builders these days are on a mission to get every clearance on the low side.

The engine in my '51 runs right on the thermostats, unless I run extended periods on the hiway at 75+. Then, it starts to creep up towards 200 and I slow down. I chalk that up to the engine just has to work hard pushing that 3200 lb brick through the air at that speed. I just slow down and don't worry about it.

 

HA! Just so happens that I have a T170 RTS.
Unfortunately, the rear end is a 3.00 Maverick and 3.25 and 3.54 center sections are rare and expensive. Would have to buy a gear set and change it out. It certainly would benefit with a gear change and O.D.

I think that pulling the long hills around here contributed to the demise.