What is your temperature with a 346 f;athead???

[Richardonly]

Gentlemen,

I installed an aftermarket heat gauge, for the time being, to find out degrees of engine temperature.

Highway in 85 degree temp with humidity shows the gauge reading an average of 210 and then creeping to 220-230, if the air gets warmer.

This is too high for my liking and when shut off, I can hear the antifreeze boiling.  It does loose a LITTLE at this time, but I installed a recovery tank to save the antifreeze.

I have, wrapped the exhaust, flushed the system, opened the fresh air vents into the engine compartment, installed a 6 blade fan and installed a NEW 165 thermostate.

A simple question.........what engine temp should I be trying to acheive?

Thank you, Richard

[gary griffin]

This is a hard one to give a simple answer to. I am sure same of the old timers will have some ideas and their experience will prevail but I have a few comments.

Pressurized radiators were developed to provide a higher boiling point  to make elevation irrelevant in the cooling system and to provide a greater temperature differential between the transfer medium (The water) and the  heat rejection system (The radiator) and with the higher differential greater amounts of heat will be rejected at most conditions.

We all think water boils at 212 degrees but that is only true at sea level on a standard day with barometric pressure of 29.92 inches. Any variation of that pressure will change the poiling point.

Our cooling systems are simply  a heat collection and heat rejection system with water being the transfer medium.

The variables assuming the system is in perfect condition are air temperature, humidity, the make up of the water (What additives are included) velocity of the water flow, and load (The amount of heat being generated by the engine.

Luckily the advent of the pressure cap raising the boiling point of the water and the thermostat stabilizing the water temperature to a preset point take all of the mystery out of problem.

If all is correct we should rarely see temperatures on the thermometer in the car different from the set point of the thermostat after the car warms up.  Chugging up a steep hill with a full load on a hot day with out down shifting would possibly be an exception??

I know this does not fully answer your question but possibly it shines a little light on it??

[CEC #20099]

Richardonly;
You hear the 50/50 antifreeze mix BOILING?  Something is WAY too hot. I suggest you get a laser heat thermometer & scan the whole cooling system externally for temp variations. I did this on my overheating 39 Buick ( Is their any other kind) & found the rear 2 cylinders to be much hotter than the front 6. Obviously , poor water circulation due to rust impacted in cooling jackets. Teardown is next.

CEC #20099

[gary griffin]

Very good and practical answer C. Chelbaun.

Also look for differences in radiator temperature especially around the bottom connections.

Is the water pump operating at peak efficiency?

Has the bottom hose collapsed? (They are supposed to have a coil spring in them to prevent this but often replacements do not have the coil spring.

Only two possibilities, generating too much heat or not collecting it and dispersing it through the radiator. A careful scan with a laser thermometer (Costs about $30 as I recall) will pinpoint the problem. The solution may be simple or complex but the problem needs to be diagnosed first.

[Richardonly]

Gentlemen,

Thank you for your insight.

I did forget to mention that the 1948 flathead had an A/C system installed in the early 1950s and the radiator is restricted by the condensor, so I would assume it would run hotter than one without.  That is the reason for my question as to an average operating temperature.

The A/C does work exceptionaly well and it would be sad to have to remove it.  Perhaps a 6V electric fan in front to provide more cooling to the radiator?

How do you know when the impeller(?) is starting to go?  (The water pump.)  The water IS circulating as I can see it do so at a rapid rate when I flushed out the cooling system.

Thanks again, Richard

[kkarrer]

A question on a related matter...
My temp gauge is not working.  I know that my engine is not running hot because I've checked it with a temp gun, but I'd still like to get the gauge working.  I've replaced the wiring harness and I removed the sensor in the block and cleaned it and reinstalled it without thread sealer or tape.  A vital thing to know is that I've converted the car to 12v neg. ground ( I know that riles some of you guys and I have nothing against a 6v system, but in my case I may want to put AC in this car, etc.) and I've done that once before with a 50 Cadillac coupe (but it was 6v neg. ground).  With the wiring done in the original way.  The gauge does not respond.  With the normal wiring and a Runtz resistor...same result.  With the plarity/wires reversed the gauge pegs all the way over when the key is turned on.  I have another gauge on the way, but I'd like to confirm the wiring (reverse or normal) and get some trouble shooting ideas which might point me to the sender, the gauge, wiring polarity, Runtz/no Runtz etc.  I have the transmission out of my 41 coupe right now and thought I'd solve a few other little problems while I wait for help and parts on that job.  I think in my 50 I just installed a Runtz and left the original wires as they were.  It worked fine.
Thanks,
Ken Karrer 1941 6227D coupe

[TJ Hopland]

Short version:
Unless your radiator is new or has just been professionally cleaned it may be the radiator that just simply cant handle the load.  And by new I mean you just gout it or had it cleaned in the last year or two.   I thought of mine as new and it looked like it could have been new but really it was more than 10 years old.

Long version:
Just finally solved a similar issue with a newer ('73) car.   New radiator.  Old one was around 10 years old and was a Modine copper one that at least to be looked to be in excellent shape.  Just slight crust around the ends of the fins if you looked down in the tank.  No green on the outside.  No leaks.   Could have had my old one cleaned but decided to go with the old time shops recommendation of the new one even bigger aluminum plastic thing instead and its working great.   Shop told me that when cars sit there is some chemical thing that goes on inside that does not happen when they get used.   Its a build up on the inside of the tubes.  Its not the hard crust stuff you see at the edges if you look down in the tank.   I stuck something in one and its almost like a paste and appears to be pretty thin.  I assume it ends up being an insulation layer that does not let the coolant efficiently transfer the heat to the copper.  I asked if he has always seen that and he said it started about 20 years ago and seems to be getting worse.  He suspects is a change in the antifreeze formulas but does not claim to be a chemist, he just knows that in the summer he sees a constant stream of folks just like me that keep him working.  I have always run a 50/50 mix of the green stuff.   I used to use strained rain water to mix but now that they sell the pre mix stuff I just buy that.  Had this car for 15+ years now.   Used to get it flushed yearly but got lazy and only did it 2-3 years for a while.  Did a bunch of engine work a couple years ago that forced it to get changed several times so overall it likely got flushed or at least changed more often than an average collector car does.  One thing I noticed was I let the radiator drain for an hour or so before I started taking things apart then also the time it took to remove it.  It did not appear to have any more coolant in it when I removed it and I dont remember hearing any sloshing when I stood it up on end next to another car in the driveway.   Was busy under the hood with the new one when I noticed a green puddle under my feet.  It was coming from the old radiator!  It was not just a little puddle that you would normally expect, it was like 1/2 gallon.  All I can conclude is this slime stuff must sort of hold on to the coolant which seems weird but I assume cant be a good thing for the flow and heat transfer.   This radiator did not appear to have flow issues, you could see a nice wide stream coming out the end of the tubes if you looked down in the tank when the level was low so I would think it was this slime that was holding the coolant. 

[gary griffin]

If the Air conditioner condenser was the problem I think it would have been diagnosed earlier.   

Most systems are designed with a comfortable margin of safety and I would beleive the Cadillac had a generous margin.

Back to the drawing board?

As an aside we were taught to trn off the air conditioner and turn on the heater in an overheat emergengy. I was driving a non A C 1950 Cadillac in about 1965 in hot climate and it was running hot and I turned on the heater (To reject heat into the cabin) and we made it to Spokane where we had the radiator flushed and all was well. I had never driven the car in real hot weather before.

[Fred Pennington 25635]

You might try a Radiator wetting agent like Purple Ice
It reduces the surface tension in the water (coolant )so it makes better contact with all surfaces and therefore a better heat transfer
I know the off road / rock crawler folks use it to cure cooling issues at slow vehicle / high engine speed conditions
I have heard of 20 degree temperature drops just by adding one of these type agents

My 2 cents
Fred P.

[4860S]

Hi Richard,

As a fellow 48 60S owner maybe I can help. My car sits stubbornly under the half way mark no matter what. With the A/C running the cooling system will be under greater strain but with it off it should be fine. I would check that the radiator is clean, if not have it cleaned, reverse flush the block and check the thermostat and water pump. These things have huge radiators and should not have any issues if its all up to scratch.

However, the A/C does add a new dimension when its on. You might think about an electric pusher fan in front of the condensor that operates when the aircons on, this would certainly help.

Keep us posted!

Regards
John

[Richardonly]

Hello John,

The car always ran on the hotter side in 85 degrees and up.  Normal would be about at least on the upper 1/2 of the middle line to 3/4 and I believed it was because of the restriction caused by the A/C's condensor in front of the fan.

1/2 on the gauge is about 200 degrees.  My normal is about 210.

What scared me was getting stuck in traffic several days ago.  I was stopped in traffic for at least 15 minutes, no where to pull over and the gauge rose to 245.  There was no boil over or steam and suprisingly little or no collant loss.

Upon traffic freeing up and starting to flow again, it dropped to  about 230, but it wasn't too far from where I had to stop.  I would assume it would have returned to about 210.

As much as this forum is helpfull, it strikes me as odd that a simple question cannot be answered.  You wrote that your's is about in the middle of the needle gauge.  That was helpfull.

Twice I asked, where is your temp gauge at, it is in the title, and I did not receive one answer.  A LOT of helpfull ideas, but no answer.

I do thank those gentlemen for reading my post and trying to come up with some solutions, BUT I wanted to know a range of temps such as 1/2 to 3/4 OR 190-220 so I could factor in the A/C blockage to determine if I truly have a problem.

Thank you all once again for your help.

Richard

[Bill Ingler #7799]

Hi Richard: Maybe this will help you. Out here in Arizona, excluding the summer months when it is over 100 and my cars stay in the garage, when the outside temp is 80-85,my 47  gage will show the needle at mid point. That I know is 200. Drop the outside temp to 75 and I run one needle width below the middle. All of the above is down the street at 35-45 mph. Now out on the freeway at 60mph with the temp at 80-85, the temp needle will be one needle width or even at the midpoint between the middle of the gage and H on the gage. Now if I want to go north or east out of Phoenix then I will be climbing out of the valley up the mountains. In the climb I will sometimes have the needle on the H or even to the right of the H. Not one time have I boiled. Even sitting a long time in traffic the needle will approach H but not boil.
       The apprehension of watching the needle rise doesn't`t bother as much now as it did before I had the engine rebuilt. When I did the rebuild, the block was taken to a medal cleaning company that tanked the engine in a electrical charged cleaning solution. When finished,the block both inside and out looked like the day the block was poured at the foundry. A new core was made for the radiator. With both on my 41 and 47 I was told by a radiator shop that there was good flow from the radiators but when the upper tank was removed from both radiators, at least a third of the tubes were plugged and the rest of the tubes, although they were open, they were somewhat restricted. What do you know about your radiator.Unless it has a new core then you are looking at 64 year core. Has it been re-cored?   Bill

[Richardonly]

Hello Bill,

Your responce was extremely helpfull also.  Factoring in the A/C blockage, I don't believe I am too far away from you or John.

The radiator had a new core installed just last summer.  I have also been told that the "timing" is a highway factor, and if it is "off", the temp will be higher on the highway and become cooler at slower speeds.  This is what mine is doing!

So checking the timing, the water pump flow and adding a push fan appear to be in order.

I neglected to mention that the graduated temp gauge I installed was "Made in China."  That could be a 10 degree difference right there AND I find it odd that stuck in traffic, rising to 245 did NOT cause any coolant loss.

The boiling I hear is when the engine is off and I watch the needle rise about 20 degrees.  AGAIN, NO BOIL OVER.   

Thank you, Richard

[gary griffin]

The boiling you heard was contained by the pressure cap.  While we are driving the coolant is moving and there is  a temperature differential between the coolant in the radiator in the engine and the coolant in the radiator and cooling is occurring on a regular basis but when the water is no longer moving and the hot engine is still hot it is not unusual for the coolant in the engine to heat further because it is not being replaced by cooler water. 

Did you rebuild the engine recently. I believe newly rebuilt engines run hotter also until the parts all get acclimated to each other.

As to your post about no one answering your actual question, you got responses from a variety of us and many do not have 346 flatheads. I have one which has not run for two years and cant recall exactly where the temp gauge ran but tried to put in a little general information  about overheating.

[Richardonly]

Gary,

Thank you and that clears up the boiling sound issue.

I just took the car for a 50 mile trip this morning with the outside temperature at 75.  I have been using it lately at between 85-90.

What a difference!  Avg temp was 200 and would raise to 210 on hills, then lower to 200 again as it leveled off or went downhill.  This would put the needle gauge at the middle.

Perhaps my inexperience with flatheads and the unusual heat caused my concern.

That is the problem here in New England as we can have 80 degree summers or 95 degree summers.  Certainly an electric fan would not hurt anything and may be a wise investment.  Still need the timing and water pump checked.

Thanks again, Richard