Overheating, Part 2

41Fordor

41Fordor

Senior Member
Well, I cruised a little yesterday. It was about 90 degrees, but driving at 50-55 with a nice breeze going through the radiator I was at 220* after a 15 minute drive.

I have a 41 221, bored to 239. Stock intake and exhaust, recored radiator, Skips pumps and hi-flow thermostats. It overheats at highway speeds, even with no thermostats.

So I pulled the 81-A heads today and will have my machinist enlarge these passages over the center exhaust port:

http://www.vanpeltsales.com/FH_web/FH_37-48engine-rebuilding/v8_overhaul-S125-1.htm

I have new Best Graphtite gaskets ordered. I also noticed quite a bit of carbon buildup for only 500 miles:


 
I don't know if I'd be enlarging the passages. Ford not only quit using the head gaskets with the trapezoidal passages, but recommended replacing them with the single small hole. This keeps the water from bypassing the rear two cylinders.

Typically, if you're fine around town, but overheat on the road, it's the radiator. I know you said you had yours re-cored, but that's where I'd be focusing. You've got Skip's pumps, so your flow should be good. You've tried with and without t-stats, so that rules those out. It has to be in the heat transfer which leaves the radiator.

Retarded timing will usually manifest as overheating regardless of speed...it just takes longer when you're going slower (in town). Same with bad head gaskets and combustion leaking into the water.

The only other thing I can think of that will cause your symptoms of overheating on the highway is collapsing lower hoses. With Skip's hi-flow pumps, that's a real possibility.
 
Thanks for all the suggestions. I had previously advanced the timing incrementally with no improvement. I just got my distributor back from Skip and it's at the factory settings. I have springs in the lower radiator hoses and am running 50/50 with purple ice. It's not boiling over, but in a previous thread on how hot is "too hot", the consensus seemed be that a correctly running flatty should stay below 200 when moving down the road, even on a hot day.

The radiator had been suggested previously also. But I'm trying to exhaust all the options before dropping $900 on a Walker radiator...
 
Try running 100% water with a surfactant like purple ice, water wetter, or 40 below along with an anti-corrosion additive. It will cool better than 50/50. In the winter, add only enough anti-freeze to protect your system. For a huge part of the country, 50/50 is overkill.

I don't know that I'd drop $900 on a Walker radiator. I think I'd work with what I have and find out what the problem is. These radiators work fine stock. When you re-cored it, did you add more tubes? Another row?

Also, be sure all of your radiator baffling is in place. On my 40, I even made a small metal plate to cover the top of the grille immediately in front of the radiator so none of the air would go up and over. Run a good shroud and be sure your fan belt isn't slipping.
 
I don't remember part 1. What are we taking temp measurements with?? Digital or analog gauge with an in-block pick up, or point and shoot?? Have you tried a different gauge??
Paul in CT
 
I went for the Walker raditor on the 39 and goes down road below 200 degs, running 180 thermistas runs 190 degs/with out thermistats about 170 on hot day.
Hot in traffic realy needs electric fan.
 
George, a fan shroud will cure the hot in traffic problem. I still have the original split core radiator in mine and cooling is just fine. Never been recored. As Ernie has said, try running water without the anti freeze. Also be sure of your temperature measurements. The fact that it doesn't boil over would lead me to question your temps.
 
41 I would say your pressure cap is not working and or you are not filling the radiator up into the filler neck. If the pressure cap don't work you will loose coolant. 2 gallons of perminent anti freeze along with 2 bottles of purple Ice and a large bottle of Barrs heavy duty aluminum granular stop leak will cure your problem if you don't have a major compression leak. With the coolant filled up into the filler neck and the cap off if you have a major leak you will see the bubbles. Put a large house hold fan against the grill and run it at about 20MPH engine speed. This will give you the same results as you will get driving on the highway. The Barrs will stop small bubbles. G.M.
 
Whether you use antifreeze or not you might want to consider using distilled water, rather than plain tap water, as it is without contaminants, particularly calcium that can build up in the radiator and engine, and is purer to transfer heat better.
 
flatjack9 said:
George, a fan shroud will cure the hot in traffic problem. I still have the original split core radiator in mine and cooling is just fine. Never been recored. As Ernie has said, try running water without the anti freeze. Also be sure of your temperature measurements. The fact that it doesn't boil over would lead me to question your temps.
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I have water only and just got home and goes up the 230 on gauge in 10 minutes idling.
Do you think its safer to boil over with water only,I have a 15 lb cap.
I have been running it few weeks now with water no thermiatats.
Its a new SW electric gauge may be wrong.
 
:) Sounds like some Radiator tubes maybe partially blocked, If you can look thru the filler cap hole & see one or two with debri inside each tube, chances are the top tank needs to come off and have the tubes cleaned.
Take a look !
 
G.M. said:
41 I would say your pressure cap is not working and or you are not filling the radiator up into the filler neck. If the pressure cap don't work you will loose coolant. 2 gallons of perminent anti freeze along with 2 bottles of purple Ice and a large bottle of Barrs heavy duty aluminum granular stop leak will cure your problem if you don't have a major compression leak. With the coolant filled up into the filler neck and the cap off if you have a major leak you will see the bubbles. Put a large house hold fan against the grill and run it at about 20MPH engine speed. This will give you the same results as you will get driving on the highway. The Barrs will stop small bubbles. G.M.
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If you have a good radiator, good air flow, clean block and properly tuned engine, you shoould not have any heating problems. My 39 with a 276 cu. in. engine, stock radiator(no pressure cap)and stock crank mounted fan runs around 180 to 190. I run straight water with rust inhibitors. The radiator is not filled up to the top. I just keep the tubes covered. Just got back from Back to the 50's, around 350 miles one way, and the temperature never got above 190 and it was hot out. I run 65 to 70 mph on the highway. With the overdrive, Im turning around 2300 rpm. And I have never used any Purple Ice or anything like it. By leaving room in the top of the radiator, I never have to add coolant. Oh, and I use stock water pumps.
 
Flat Ernie said:
I don't know if I'd be enlarging the passages. Ford not only quit using the head gaskets with the trapezoidal passages, but recommended replacing them with the single small hole. This keeps the water from bypassing the rear two cylinders.
Click to expand...

I got my Best gaskets yesterday and I noticed they have a notch, which I assume goes to the front. This puts the smaller openings to the front cylinders to direct more water to the back like a small block ford. My old gaskets had trapezoidal openings in the center and had equal size passages around all the cylinders. My machinist thinks I'm getting too worked up about this, but said opening the water passages would be safe.

I use the infrared surface scanning thermometer to check my head and radiator temps. It's within 2-3 degrees of my wife's good candy thermometer. And even if the temps are approximate, they correlate with what I see on my stock 6v dash guage. My gauge still climbs until pegged when moving down the highway; instead of dropping.

My 4# cap is holding pressure, I can feel the hoses when it's hot. If I fill it up to the top it'll puke about a pint. I have an overflow container and the Mac's cap is a coolant recovery cap so it'll suck a little back in and stay about 3/4" below the top.

I really want to take this car on some long distance trips this year, so I want to make sure I don't damage my new engine. The EFV8 club has a meet in Denver in September I'm going to try to make.

Well, have a good 4th everyone!
 
If you fill it to the top and it pukes coolant the pressure cap is not working or you have a small compression leak which Barrs heavy duty stop leak will fix. I live where it's in the 90 degree range most of the year and on 5 or 6 old Fords never add or lose coolant in 6 months or more on any of them. G.M.
 
41Fordor said:
I got my Best gaskets yesterday and I noticed they have a notch, which I assume goes to the front. This puts the smaller openings to the front cylinders to direct more water to the back like a small block ford. My old gaskets had trapezoidal openings in the center and had equal size passages around all the cylinders. My machinist thinks I'm getting too worked up about this, but said opening the water passages would be safe.
Click to expand...
DO NOT DO THIS! Ford changed the passages for a reason. Is your machinist a flathead expert, or an expert machinist? DO NOT DO THIS!

The cooling system on the flatheads was constantly evolving. Pumps got more vanes over the years for more flow and coolant passages were changed to direct and control water flow. The early heads had those big trapezoidal passages, as did the gaskets. The replacement gaskets had large holes for a short while. And then Ford switched to small holes except at the rear. They stayed this way through the end of production. And all replacement gaskets used this configuration. I believe there was even a service bulletin for early engines with cooling issues to change the head gaskets to the later style as a solution. So, again, I will reiterate - DO NOT ENLARGE YOUR PASSAGES ON EITHER YOUR HEAD OR GASKET. It will be a waste of time, money, and it will exacerbate your problem, not help!

41Fordor said:
My 4# cap is holding pressure, I can feel the hoses when it's hot. If I fill it up to the top it'll puke about a pint. I have an overflow container and the Mac's cap is a coolant recovery cap so it'll suck a little back in and stay about 3/4" below the top.
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This is good - it's working as it should.

I really think the issue is your radiator core. For whatever reason it's either not flowing properly or not cooling properly.
 
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Without a coolant recovery system it is natural to lose coolant that is clear full as soon as it gets up to operating temperature - not because the pressure cap isn't working, but because the liquid expands when heated and pushes past the pressure cap. (One of those laws of physics :rolleyes:) That's why it's totally normal to have an inch or two of air in the top of the radiator, even after filling clear up, and will always be there without a coolant recovery system. Mine has always been that way and always will. Works fine. No worries. :)
 
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