Thermostat Question

[nonstop]

Happy Day After Thanksgiving!

I am running a 180 degree stat in my 1954 241 Hemi in place of the 160 that was in there.  I noticed a little better performance all around. Over the summer, I replaced my water pump with a stock one and threw in an aluminum radiator because I got a screaming deal on it and wanted to save my original.  My cooling was great! Now that it’s getting cooler, my engine is running too cool. I leave for work at about 6:30 am, and after my 6 mile commute, the engine doesn’t even reach operating temp. I have a 195 degree stat to throw in, but was wondering if I should try it. I can’t seem to find much, if any info about running a 195 stat in an older engine. Does anybody have experience with it?

Thanks for any input!

Nick

[knuckleharley]

I would definitely use a digital "heat gun" to check the radiator and the engine and get heat readings "At the source" before I did anything else. Could be that your gauge is the problem,not your thermostat. I bought one on Amazon a year or so ago for about 15 bucks. Handy little booger to have.

Once you have hit it with the heat gun and compared those readings to the dash gauge reading you will know if you even have an actual heating problem or if you have a gauge problem.

If the numbers are comparable,why not try the higher temp thermostat? You already have it,so why not?

 

Edited November 24, 2017 by knuckleharley

[nonstop]

Thanks. That’s what I was leaning towards, but was it sure if it would cause any problems on an old  engine (I will still be using a 7 lb cap). I have a infrared temp gun, so I will try that. I couldn’t find any info online about it.

[knuckleharley]

22 minutes ago, nonstop said:

Thanks. That’s what I was leaning towards, but was it sure if it would cause any problems on an old  engine (I will still be using a 7 lb cap). I have a infrared temp gun, so I will try that. I couldn’t find any info online about it.

NO! Never use more than a 4lb pressure cap on these old cars.

If it were me,I would use a digital heat "gun" to check the temps of the radiator after the car is fulling warmed up and still running,and then switch it off,let it cool,put a 4 lb cap on it,and then check the temps again after it is up to operating temperatures.

I suspect you will discover the 7 lb radiator cap is the culprit.

[martybose]

28 minutes ago, knuckleharley said:

NO! Never use more than a 4lb pressure cap on these old cars.

If it were me,I would use a digital heat "gun" to check the temps of the radiator after the car is fulling warmed up and still running,and then switch it off,let it cool,put a 4 lb cap on it,and then check the temps again after it is up to operating temperatures.

I suspect you will discover the 7 lb radiator cap is the culprit.

From his first posting he has already replaced the original radiator with an aluminum one, so I don't see any reason to restrict yourself to just a 4 pound radiator cap.

Marty

[knuckleharley]

3 minutes ago, martybose said:

From his first posting he has already replaced the original radiator with an aluminum one, so I don't see any reason to restrict yourself to just a 4 pound radiator cap.

Marty

The 7 lb cap will put almost twice as much pressure on the system,and that pressure will make the water flow faster. These old flatheads are a LOT thicker and have more cast iron than the more modern engines,and don't lose heat as quickly.

BTW,the 7 lb pressure cap pushing the water faster and reducing cooling is something I suspect,but have zero proof about. I guess we will find out when he swaps caps and hits the radiator with his temp gun.

 

[Don Coatney]

32 minutes ago, knuckleharley said:

The 7 lb cap will put almost twice as much pressure on the system,and that pressure will make the water flow faster. These old flatheads are a LOT thicker and have more cast iron than the more modern engines,and don't lose heat as quickly.

BTW,the 7 lb pressure cap pushing the water faster and reducing cooling is something I suspect,but have zero proof about. I guess we will find out when he swaps caps and hits the radiator with his temp gun.

 

Re read the original posting. Not a flathead. Why will the water flow faster? Increased pressure raises the boiling point only. The water pump control's the speed of flow not the pressure. The weak point with increased pressure is the welsh plugs.

[nonstop]

Wow, thanks guys! I thought the 7lb cap was stock - didn’t know they used a 4 pounder! I will try the thermostat and radiator cap. It has always run a 7lb cap as far as I know. I should be okay, as I have an overflow tank on it now as well (I hope)!

[knuckleharley]

1 hour ago, Don Coatney said:

Re read the original posting. Not a flathead. Why will the water flow faster? Increased pressure raises the boiling point only. The water pump control's the speed of flow not the pressure. The weak point with increased pressure is the welsh plugs.

OOOPS! I read that,and then completely ignored it,

As for the rest,increased  pressure HAS to increase the flow rate,but since this is a semi-modern OHV engine that cools better than the old flatheads,it shouldn't make any difference.

[Plymouthy Adams]

pressure is equal within the sealed system therefore the need for the pump to circulate...IF the pressure was on one end and the flow was exiting at a point along the way only then will pressure affect the flow but not within, only on that which is exiting the sealed system

[nonstop]

Well, just replaced the thermostat. It is still not getting up to temp (at least sitting and running in the driveway for about 15+ minutes).  I took out the digital thermometer and got numbers as follows:

164 at the base of the thermostat housing

126 or so going into the radiator

74 on the hose coming out of the radiator 

144 at the temperature sender

Of course, this is without a test drive. Could a new stock  water pump really make a difference like this? Am I cooling too well? Is the radiator too efficient? Should I just shut up and live with it?

thanks for the helpful so far.....

Edited November 25, 2017 by nonstop

[knuckleharley]

46 minutes ago, nonstop said:

Well, just replaced the thermostat. It is still not getting up to temp (at least sitting and running in the driveway for about 15+ minutes).  I took out the digital thermometer and got numbers as follows:

164 at the base of the thermostat housing

126 or so going into the radiator

74 on the hose coming out of the radiator 

144 at the temperature sender

Of course, this is without a test drive. Could a new stock  water pump really make a difference like this? Am I cooling too well? Is the radiator too efficient? Should I just shut up and live with it?

thanks for the helpful so far.....

WOW! That has me wondering if the thermostat is even closing.

[nonstop]

Well, I would wonder the same thing (especially since I did not test this one -stupid me), but the old one behaved the same way. It was closed when I removed it. They were both Duralast, but I have never had a problem with Duralast thermostats before.

In all fairness, I took the temp readings off the upper tank, but the lower hose if that will make a difference.....

Edited November 25, 2017 by nonstop

[_shel_ny]

Not a fix, but a piece of cardboard covering part of the front of the radiator will get you some heat for your drive to work

[nonstop]

1 hour ago, _shel_ny said:

Not a fix, but a piece of cardboard covering part of the front of the radiator will get you some heat for your drive to work

I agree, the only thing is, I live in the Bay Area. Temperatures have only dropped into the 50’s! I wouldn’t think I needed cardboard - yet!

I dropped in the 195 degree thermostat and went for a 10 mile (at most) drive. It warmed up a little faster, but now my needle sits just a little to the right of the middle. Still not sure how comfortable I feel with that! I think I am going to give it a week or 2 to see how it works out. Worst case is I go back to the 180 degree thermostat and the original radiator.

I never thought I would have the problem of over cooling with this car!

[Plymouthy Adams]

without verifying the readings accurately of the gauge and such you abut really only guessing at what temperature you are running and reporting to the gauge..again, these are old and were never dead on to begin with..

[knuckleharley]

30 minutes ago, nonstop said:

I agree, the only thing is, I live in the Bay Area. Temperatures have only dropped into the 50’s! I wouldn’t think I needed cardboard - yet!

I dropped in the 195 degree thermostat and went for a 10 mile (at most) drive. It warmed up a little faster, but now my needle sits just a little to the right of the middle. Still not sure how comfortable I feel with that! I think I am going to give it a week or 2 to see how it works out. Worst case is I go back to the 180 degree thermostat and the original radiator.

I never thought I would have the problem of over cooling with this car!

What makes you think the dash temp gauge is anything more than a loose estimation? Yeah,some are pretty accurate,but others are off by a bunch.

I was fooling with another project I just bought and was about to panic because once I got it running,the needle on the temp gauge pegged almost half way between the 3rd "peg" on the gauge and the last one. Put a mechanical temp gauge in the block,and it was only running 175 degrees at idle. Judging from the gauge,I was guessing it was on the verge of boiling over.

Screwing a mechanical gauge into the block where the sending unit goes will tell you what it's really doing.

Don't know what to tell you about doing adjustments to the in-dash temp unit.

[Plymouthy Adams]

4 minutes ago, knuckleharley said:

 

Don't know what to tell you about doing adjustments to the in-dash temp unit.

it is possible, read the repair manual...

[Plymouthy Adams]

oh...for those that may ask......brace yourself....seems the books only suggest adjustment if the gauge is off more than +/- .....sit down folks.....are  you ready.....30 degree error

[knuckleharley]

15 minutes ago, Plymouthy Adams said:

oh...for those that may ask......brace yourself....seems the books only suggest adjustment if the gauge is off more than +/- .....sit down folks.....are  you ready.....30 degree error

I suspect if a temp gauge is off that far it's beyond "Adjusting" unless the "Adjustment" to to throw the SOB in the trash and put a mechanical gauge on the engine.

[Plymouthy Adams]

in reality the adjustment would be so little of a bend to correct for 30 degrees....again the gauge is a questimation indication at best...you ball park it and let the big dog eat...I am not sure of it linearity. 

[nonstop]

I totally agree about the gauge being an estimation at best. It was just a little unnerving seeing it past half way. It is raining here, so I may not get to checking temps today. That 30 degree adjustment  thing though is a little surprising!

[DJ194950]

If your thermostat is working it does not matter if the temp is 80 or 40 degrees outside. It should run at the thermostat stated temp. (at least close) unless the cooling parts of the motor cannot keep up with temp. created.

I run this car in the garage here in Modesto,Ca. maybe 60 miles east of you and the temp is not too different between us and my friends 47 Plymouth in my garage gets up to 175-180 in a few minutes minutes just sitting here. It just received a 3 row aluminum radiator with electric fan and adjustable fan thermostat

It has a new style thermostat that comes in two parts with a thick rubber seal that goes on top -as available at Napa and others.

Need to have the owner buy a digital thermometer to check gauge (original) accuracy but from my mechanic experience certainly seems close, but will double check.

Will wait around to see what you find.

DJ

[nonstop]

Do you still have the part number for that newer thermostat? I checked the Napa site but did not find it. I wonder if my problem has to do with the mechanical fan. Since it is always running, it might be causing some of my over cooling, especially since the biggest difference sounds like it is the electric fan.

[DJ194950]

It is a Stant # 13928. or a3926 if you can believe the Ebay sellers, take a look and check the number online at Napa and other With the #.

Many,many available  on Ebay if no where else.

I personally do not think the thermostat is the issue. Check the head back where the temp. sender is with a digital thermometer Before spending more to chase this problem.

Is the thermostat installed with the spring side toward the motor??

Is the heater valve open and not closed for this check? Bypassed heater hoses front to back of motor?

Do you have a motor with the internal bypass setup (later motors) And a water pump to head bypass type thermostat/head hose type setup?

Just throwing some ideas for you to check.

DJ