The Cooling System...Pushing It's Limitations

[keithb7]

I have been doing a little more investigation into engine cooling issues. Over the past 3 years I have been working to get my car back to spec. I have done all the things I can to address my cooling system. I've rebuilt the engine. Complete hot tank of the block, all sediment removed. New brass water distribution tube. New water pump, rad cap and 170F thermostat. All new hoses and belt. New water pump. Rad re-cored. As mentioned earlier I have learned that my stock temperature gauge is inaccurate. With my fresh new 237, I am not babying the car. I work it now more than before it was rebuilt. Including my recent 300 mile hi-way trip. Over and back a mountainous pass.

 

Yesterday I removed the stock temp gauge capillary tube from the left rear of my head. I installed a new capillary type gauge. I proceeded to work my car hard. Get it really heated up until I notice the oil pressure drops a few pounds. This tells me the oil is good and hot now too.  Then go climb some big hills. Long hills with steep grades. I am talking 15-20 minute climbs with your throttle wide open with the ambient air temps above 80F. So your car is just able to maintain 35-40 mph with all she's got to give. A winding steep 2 lane road. Not a hi-way. This indeed tests the limits of your cooling system. The old cars with no fan shroud, with a belt driven fan, rely on air flow from the car in motion, to help cool it. When you are working the engine hard, a good load,  burning lots of fuel on a steep long hill, airflow becomes an issue. You are traveling slower now. You are making a ton of heat. The engine fan is possibly turning slower depending what gear you are in, dictating engine RPMs. The 80F ambient air is not helping very much. The cards are all stacked against your cooling system now.

 

Most of these old cars did not utilize a shroud around the rad. An open fan is much less efficient than a fan with a shroud. I have read up to 38% less efficient. The fan draws air from all around it, not necessarily from in front of it. Yes some air comes through the rad, not all, efficiently.  In addition to that the outer edges of your rad, outside the span of the fan blade, those fins get little to no air moving through them at lower speed travel.  At stop and go traffic, none.  A fan shroud could help tremendously depending on your driving conditions. A shroud controls the air movement by the fan. It has to come through the rad. A venturi effect is also is created, pulling air through the rad at a higher rate of speed. At low speed, high-load hills, your car could really benefit from a shroud. 

 

The stock system in these old cars was adequate in most all situations. Moving at speed really helped a lot. Yet as each part of the cooling system weakened with age and lack of maintenance, the system may not keep up. Unable to cool adequately in all scenarios. Band-Aids are available. Electric fans. Larger rads. Larger pulleys etc. 

 

My 1938 Plymouth cooling system is not stock. The 23" engine was removed. A 25" 237 is in the car now. A different rad was installed so it could be moved forward in the nose cone and accommodate the longer 25" engine. The fan on my engine is not as close to the rad as I'd like to see. The 237 likely creates a bit more heat than the stock 201 engine.  I am seeing temps a little warmer than I'd like on the long hills.  I am not boiling the coolant. It is 50/50 water and glycol, pressurized with a 7 psi rad cap. The 237 performs awesome in this car. The increased torque and power make it a pleasure to drive. Yet, i am convinced it makes more heat. I suspect I would benefit greatly from a fan shroud.  Building a spacer to to get the fan blade a little closer to the rad.  There are limitations as the crank pulley and generator pulley must all line up.  Moving the rad closer to the fan, would be a good benefit.

 

Hmm...Things to consider.

 

 

 

 

Edited July 3, 2022 by keithb7

[Sniper]

All great points.  Biggest benefit you can get with an engine driven fan is a shroud.  One thing that also helps, though at higher road speeds, is ensuring that all the air coming in the grille is forced thru the radiator, so seal up those air leaks.

[John Fleming]

Keith , If you are currently using a four blade fan consider a fan with a larger number of blades. This change was helpful on my P15. Also what coolant are you using . Many owners in my area use a 50/50 pre mix and ad red line water wetter . This also can be helpful. I live in South West Florida no hills just temps in the mid 90's.  

[capt den]

i have a 54 windsor and the cooling system has always been a sore point with me. hot days, stop and go traffic and the temp needle goes all the way up, but i always stop before it gets to overheat, although maybe it never would.at idle temp always goes up.i have checked the guage and it is accurate, running about 175 normally.at moderate speed, about 45 it seems to stay at temp the best.over 60 it will run up to about 190. makes me guess there is still crud in the block. i have removed the core plugs and cleaned out, but not much came out. the V8 of this year has a shroud, but i do not think it will fit the 265. i guess i would have to fabricate one. new WDT and hoses, 180 thermostat, new hoses, rad recored, rebuilt the original water pump, running water this time of year with purple ice coolant helper. plugged up air leaks around the rad. not much else to do, but a shroud could be next. i think some dodges and plymouths had them for the 6 cylinders. not sure what years. maybe in trucks. anyway, good points there keith. i will be doing my front brakes soon so i will try to learn how to use the brake tool i bought from you. a place near me can cut my drum, but they had no idea what arcing the shoes meant. not sure i can get that done here. just hope the drums are good, they should be.i had them cut about 15,000 miles ago so they might still be good. i have a leak at the front right, so i am replacing shoes and wheel cylinders. just had a carb rebuilt so that will go on too.    capt den

[Worden18]

Just like to throw in my 2 cents Keith.  I would have liked to see put in Evans Waterless Coolant from the very start after your rebuild.  It's guaranteed for the life of the engine, even if you sold the car.  Your radiator and block will never corrode.  You never have to change it.  The boiling point is 375F, freeze point -80F.   My Meadowbrook has had it since the rebuild in 2016.  I've idled stuck at  RR crossing in 97F heat, and driven 55mph in -33F (maintaining approx 165F engine temp with no cardboard in front of the radiator) without issues.  Just my personal experience.  

[Doug&Deb]

Keith my Coronet ran between 190-210 with a 180 stat. Never boiled over just ran hot. My engine was rebuilt about 10,000 miles ago with new pump, hoses, etc. I have a Stewart Warner temperature gauge mounted under dash and I trust the accuracy. I’m currently running a 160 stat for the summer and it’s definitely cooler running. I wonder how they acted when new in rush hour traffic?

[keithb7]

@capt den What PSI radiator cap are you using? 50/50 glycol and water raises the boiling point. So does the pressure maintained by the rad cap. I know anxiety builds when you see that needle pegged. You don’t know where the boiling point is. 
 

Maybe try an experiment. Get your car good and hot. Then drive home. In your driveway leave it idling. Let the gauge pin past 212.  See what happens. If your system the system starts to boil shut her down. Maybe your Windsor cooling system can maintain 215 then it won’t go any higher? 

 

My car can maintain an upper limit cooling point without boiling over. If I leave the rad cap off and try the same? It indeed will boil.  This is why I am pondering my options. Is it necessary to run 180 under all of the toughest conditions? 212 is not a lot higher than 190.  The engine oil can handle 212 on those hot summer days. 
 

For the sake of discussion is 212-215 hard on cylinder heads or gaskets?

[keithb7]

1 hour ago, Worden18 said:

Just like to throw in my 2 cents Keith.  I would have liked to see put in Evans Waterless Coolant from the very start after your rebuild.  It's guaranteed for the life of the engine, even if you sold the car.  Your radiator and block will never corrode.  You never have to change it.  The boiling point is 375F, freeze point -80F.   My Meadowbrook has had it since the rebuild in 2016.  I've idled stuck at  RR crossing in 97F heat, and driven 55mph in -33F (maintaining approx 165F engine temp with no cardboard in front of the radiator) without issues.  Just my personal experience.  

I have not used it…Yet. 

When I first installed my engine I used just water. Figuring I may have to do something to again drain the cooling system.  Like address a leak or something worse. 

 

My first hi-way drive, an expansion plug popped out. I lost a lot of coolant.  I was glad I did not have Evans in there at that point.  I may still switch to Evans. 

Edited July 3, 2022 by keithb7

[Bryan]

Startled me. Thought you had another freeze plug blow.  I'm going to use the suggested JB Weld, just need to find how much of a bead.  I'll probably add a shroud later when I get this motor running. I might run mine with water for the start up and first 30 minutes, then see if any crud comes out, no leaks then use 50/50 antifreeze.

[FarmerJon]

Keith, with the new gauge, what temps are you seeing?

 

A spacer to get the fan closer to the radiator and a shroud would help with the cooling efficiency and also theoretically reduce the horsepower needed to drive the fan. Win/win

Evans coolant is a neat product that I would like to try one day. 

There are also "water wetter" products that are supposed to help with conventional coolant mixes.

 

 

I don't really get why y'all are so freaked out by 180-200 temps. Those are ideal temps to me. I was pretty disappointed to find that my 180 thermostat keeps me around 175 most of the time, and am planning to swap in a 195 stat soon.  160f is great for burning more fuel, making less power, and causing extra sludge to form in that non detergent, straight weight oil you guys all swear by. 

 

[Bryan]

6 hours ago, FarmerJon said:

I don't really get why y'all are so freaked out by 180-200 temps. Those are ideal temps to me. I was pretty disappointed to find that my 180 thermostat keeps me around 175 most of the time, and am planning to swap in a 195 stat soon. 

 

I was considering the 195F stat.  Bought the 180F one but still a long way from getting it running.  Didn't know how that 195F stat would do, being 17F from boiling.   If more people were saying they had used it with success I would.  Let me know how it goes.

[Sam Buchanan]

3 hours ago, Bryan said:

I was considering the 195F stat.  Bought the 180F one but still a long way from getting it running.  Didn't know how that 195F stat would do, being 17F from boiling.   If more people were saying they had used it with success I would.  Let me know how it goes.

 

Running 50/50 antifreeze raises the boiling point to 226*F @ atmospheric pressure (open vent).

Edited July 4, 2022 by Sam Buchanan

[Plymouthy Adams]

couple charts online for antifreeze and boiling points....this one includes many percentage solutions within the common zero pressure systems our older cars are equipped....there is a 4 psi column for early Mopar pressure system, then 8 which is 1 lb over the second pressure system by Mopar....covers good many systems on this chart

 

 

Edited July 4, 2022 by Plymouthy Adams

[James_Douglas]

No shroud. Clean block. Six blade (Dodge Truck) fan. Water wetter. Soluble oil. No antifreeze. Non-pressurized. Car has a 251. Car is about 5000 pounds. 180F Thermostat.

 

95F-100F day climbing out of Yosemite Valley to the north on two lane no shoulder highway. Several thousand feet. No boil over. Car ran to about 210F. Should have boiled by the math on altitude.

 

The only time the temps climb and I cannot stop them is dead still with the fluid coupling engaged for more than 5 to 10 minutes. Then if I clutch it and kick on a 6 volt aux pusher fan I can keep it at 190-200 range on a 100F day which at a dead stop or stop and go.

 

James

 

 

 

[keithb7]

13 hours ago, FarmerJon said:

Keith, with the new gauge, what temps are you seeing?

I don't really get why y'all are so freaked out by 180-200 temps. Those are ideal temps to me. 

 

 

I am not knowledgeable on the long term effects of 200F+ temps on these flathead engines.  Although I have never experienced it, I have heard talk of warped cylinder heads or damaged head gaskets.  I have not researched to learn at what temps this might become a concern.

 

My stock gauge was  pinned to the top under certain hard driving conditions. My Old gauge read to 212, my needle was above that on a steady long slow hill. My new gauge shows I am maxing out at 200F under the same conditions. General around town driving 170-180 . Based on comments here, this seems pretty normal for these era cars. I am not boiling the coolant.

 

I am likely fine to leave well enough alone.  Smaller projects like moving the fan blade ahead with a spacer is easy. Some rubber trim around the outer edges of the rad won't hurt either. I will do these. A shroud, maybe if I lived further south.  I don't think I need one for the brief 100F ambient temps that we generally see around here each summer. It's pretty easy to just enjoy the car in the morning and later evening on those days.

 

I run a thicker viscosity detergent oil. 20W40 or so is my preference in the summer.

 

I've enjoyed the conversation here.  It's great to hear other owners experiences.

Edited July 4, 2022 by keithb7

[keithb7]

I discovered something today. New to me so I thought I’d share. My ‘38 Plymouth had a 15” diameter fan. I noticed a spare fan in my parts pile. 17” diameter. Then I measured my ‘38 Chrysler fan. It’s 18”. I did not stop to ponder various mopar fan diameters.
 

I just installed the 17” in my Plymouth. I performed a simple before and after airflow test. A piece of paper on the front side of the rad. Engine at idle. The 17 is definitely pulling more air. Especially out at the further edges of the rad. Its about 95F here now. Went for a big hill climb test. No better. She cannot keep cool in these ambient temps while climbing slow up the steep winding road. 
 

 

Edited July 30, 2022 by keithb7

[Sniper]

One of the reasons I went to an electric fan, 2400cfm on high speed.  But it's also 12v, I have yet to see a 6v fan who's ratings I believe.  I pull about 27A on high speed, it's a Derale fan.  For the equivalent work at 6v you' be pushing 54 amps.

 

In your case I'd look at a shroud.  Walker radiator works makes (made?) a bunch of black plastic you fit shrouds that might fit the bill.

[wagoneer]

On 7/3/2022 at 1:20 PM, keithb7 said:

 

 

 

 

Generally speaking, I’m not sure whether our vehicles were historically in the day as reliable in all these situations you describe with stock setups. 

All the stories of long trans continental trips or pulling trailers required various upgrades.

 

a couple other things :

 

1. I’m interested in this iequus gauge https://www.iequus.com/5242.html

 

it’s a good find to find a mechanical new gauge. Could you show a bit about how you connected the capillary connector? Did you use the stock connection with an adapter? 
 

2. I have upgraded to a 60 amp alternator and I’m going to replace my stock fan with a 6v pusher fan with a 6v trigger that I found online. 
 

I’d love to find a source for 6v gauges to supplement the stock gauges.

 

 

 

 

 

[kencombs]

My take on the apparent issue:   It seems the problem rears its ugly head at 35-40 mph at full throttle climbing a  steep grade.  Steep enough that it cannot accelerate beyond 40mph.

 

That would meet my definition of 'lugging' an engine.  Often discussed here.  

 

High load, high fuel use rate, low rpm also means low airflow.  Second gear is the solution.   Much better for the engine to have lower crankshaft loading, higher oil, water and air flow.

 

My Dad was a truck driver in the 50s when  90-120HP and 7-9 ton loads were the norm.   That plus the roads of the day mandated lower speeds.  He drilled into me to avoid lugging our wrecker in the 60s.

 

 

Edited July 31, 2022 by kencombs

[keithb7]

Not a bad suggestion Ken, but 2nd gear has been tried as well. To no improvement. Higher RPMS, and no better cooling was offered. I don't lug my engine. 

 

All the factors add up it seems:

Long steep hill up to 11% grade

80F-105F summer weather

New re-cored 2-row rad

Clean rad fins

Clean, good condition stock 4 blade fan

No airflow obstructions

4 blade belt driven fan

7 psi  rad cap

50/50 glycol & water

Sparkling clean brass water distribution Tube

Block removed, hot tanked. Like new inside. Engine rebuilt

New Water pump

New Hoses

New Belt

New Thermostat

Various ignition timing trials, no improvement

No engine lugging

 

It's just dang hot and the engine is working hard. My current cooling system cannot expel BTUs as fast as the engine makes them, under my summer conditions.

On a hot summer day, if I want to drive my car after 9am and before mid-night, something in the cooling system has to be improved. Wetter water is an options but it still gets hot. Just won't boil over. A larger diameter fan pulley would likely help. A new 3 core rad and an electric fan would help. A full shroud would surely help.

I am not against trying these, but a 6V electric fan I am skeptical about. 12V would do much better, yet I am not convinced I want to convert my 6V stock system.

A 6V alternator could likely drive a 6V fan easily. Yet as @Sniper mentions, nobody seems to readily share 6V fan air flow specs. They just want to sell you a fan!

 

It's all over in about another month. The summer heat gone. Then I'll be begging for a reduction in airflow and and hotter thermostat.

 

 

Edited July 31, 2022 by keithb7

[keithb7]

Staying out of the sun today, I got bored so I pulled to rad to consider shroud options. My garage at least offered shade. 

 

 

 

Edited July 31, 2022 by keithb7

[Sniper]

This is the fan I am running.

 

You might want to consider one of these fans.  Might want to see what the center hole diameter is though.

 

Found a 6v fan with specs.  It's rated at 1248 cfm, 15.4A draw.  My fan is rated at 1400 cfm on low and it will cool the coolant to the point the thermostat closes at 100+ degrees.  At idle though, I haven;t road tested it yet.

[Worden18]

An 11% grade in 100F heat I'm thinking would cause problems for most of us.  That's a pretty serious combination.  Today it was about 90F here and I pushed the Meadowbrook hard up some long steep grades.  Got a run at the bottom at 70mph and ended up at 52mph at the crest.  Temp gauge went up, but to the usual 195ish (my guess of reading my stock guage), but it was nothing different from any other performance I've been through with the Meadowbrook.  I wasn't worried about it overheating.  Wish I could run it through your scenario to see how it would do.

[keithb7]

17 hours ago, wagoneer said:

1. I’m interested in this iequus gauge https://www.iequus.com/5242.html

It’s a good find to find a mechanical new gauge. Could you show a bit about how you connected the capillary connector? Did you use the stock connection with an adapter? 

The mechanical temperature gauge that I found appears to work just like the stock one. There is ether gas in the bulb and tube. The new gauge included a couple of different sized gland nuts that thread into the cylinder head port. One gland nut was a perfect fit. I put some Permatex High Performance Pipe Sealant on the threads of the gland nut and the bulb thread and tightened everything up. For my car, there was is nothing difficult about installing this gauge. The gauge utilizes a 12V bulb. My '38 Plymouth has a 6V to 12V converter for my USB charger. Its tucked up behind the glove box at the A-pillar.  I tied-in the 12V light into there. The  12V converter is tied-in to a circuit that is controlled by the ignition key switch.  The fuel gauge circuit. As soon as I turn on the key, the fuel gauge functions, so the 12V converter and the temperature gauge lamp cycles-on then too.

The sensor wire length from the head to the gauge is generous. I rolled it up loosely and zip stripped it up behind the dash. Don't compress it tight and clamp it down tight. You will likely damage the tube and impede ether gas pressure, distorting gauge accuracy, or completely puncture the tube allowing the ether to escape. Then you need another new replacement gauge kit.

 

The Equus gage is low priced and seems to work quite accurately.  It does not come with the chrome gauge mounting plate. I bought it separately. It easily mounted to the bottom edge of the dash. Sure 2 new holes were drilled but not easily seen. Easily removed again if wanted. 

 

 

Edited July 31, 2022 by keithb7

[keithb7]

@Worden18 If I could get a run at this hill starting with a good speed like you mentioned that would likely solve my issues. It's not possible as you make a LH 90 degree turn  at the road at the bottom of the hill. You can't take a 90 turn at much speed in a '38 car. The road is single lane, no shoulder, with winding sharp turns. Blind turns with tall mountains on both the sides of the road. If the grade slope, and limited visibility wasn't enough to slow you down, the early car's handling surely will.  At some spots I can get my speed up to 50 mph, then a steep hill with a combined sharp turn kills your speed. The flathead has HP and torque limitations. Grab a gear and push-on, keeping the revs up. I have sling-shotted and pushed the car hard enough on some turns where I am close braking tire-to-road friction. With the skinny little tires, it doesn't take much. I surely don't want to end up out of control or in the weeds.  On July 1, I was on a 4 lane highway traveling at 50-55 mph up a mountainous pass. It was a hot day. I was able to maintain 50 mph and my temp, same as yours went up to about 190F-195F-ish. Of course hi-ways are designed with wide turns easily navigated at high speed. This goat trail to my house is far from that.

 

Combine the grade of slope. Sharp turns. Lack of a run up entrance. Car's weight and handling. Limited visibility. All the other factors I mention above..I would tend to think any Moapr stock flathead cooling system will suffer a similar fate.

 

I make a decision each time I tackle the hill. Either go as fast as I can up the hill so I get to the flat top as soon as possible. Moving as much air as I can. Staying in top gear of my manual 3 speed as much as I can. That means pushing the car to its handling limits. Putting your safety at risk.  Versus drop to second, lower travel speed. Less air flow. More coolant flow. Higher engine rpms. Solid car handling & control. Safer.  It takes longer to get to the top. Meaning more time for the block and head to really soak up all that heat.  So far, either option is not producing improved cooling results.

 

Anyone wants to try this exercise, you get a free night here in a spare room. Lol. Come on up to Kamloops with your stock flathead! ?

Edited July 31, 2022 by keithb7