Over heating - sometimes it really is just the radiator

[m-mman]

The car: 1942 Hudson Commodore 8. 

 

Nice original with restoration and HET club participation from around the 1990s. Runs good, but runs HOT.

 

200 degrees measured with a thermometer. (not 210, not 220 but just 200) This was on a 100+ degree California day.

Hummmmm. . . . maybe somethings is wrong or maybe it just doesnt have any reserve capacity for the summer weather(?)  Try it again when the the air is a cooler 60 degrees and STILL it's idling at 200 degrees. 

 

Its running a 180 thermostat. Switch to a 160. Still goes to 200 

 

Tear into it. 

The heat riser is stuck closed. OK, that will certainly get it hot quickly. Take it apart, open it up and block off the pathway to stop/slow the exhaust gasses. Still running at 200, but now it takes a little longer to get there. 

 

Open the cooling system.

Filled with 100% green antifreeze. (the car is from Maine, guess they wanted to make sure it didnt freeze) 

Remove the water jacket. It looks brand new NO RUST! (hurray!) the water passages in the block are as clean as the outside of the engine. (how often do you see that?) 

Pull the temp sender and put a bore scope into the head, its as clean as the block. 🙂

 

Send the radiator out and the old experienced guy at the shop flushes it, but because of the design and the small leaks on the surface of the core he did not want to attempt to rod it out. Reinstall the radiator and of course its still idling at 200. 

 

Its gotta be the radiator. . . what else could it be???

So pull it again and tell the radiator guy to put in a new core. 

 

New 4 row core. $850(!)  <ouch>  But hey is IS a huge prewar radiator. . . .maybe I should have asked for my old core back? it was probably valuable as scrap copper. 

 

Anyway, today I installed the new radiator and whatta ya know, idling at a perfect 160. 

 

As much as people fight overheating and cooling system issues, sometimes it really "Just needs a radiator". 

Not cheap, but the cost was much easier to bear after I see it working well. 

 

[pmhowe]

I'm glad to see that this worked out.  By the way, a handsome car. I'll bet it is a joy to drive.

Phil

[EmTee]

Thanks for the summary.  I'm currently working through the exact same process on om '38 Century: https://forums.aaca.org/topic/371177-1938-radiator-flow-specification/#comment-2300593

 

I'm at the step where I'm about to send the radiator out for diagnosis and repair.  At this point, my primary suspect is the radiator.

[Larry Schramm]

On 12/3/2021 at 9:08 PM, m-mman said:

New 4 row core. $850(!)  <ouch>  But hey is IS a huge prewar radiator. . . .maybe I should have asked for my old core back? it was probably valuable as scrap copper. 

 

I have been down this path more than once.  In my world, $850 is not expensive.  Fix it right once and done is the easiest thing to do.  IMO.

[trini]

First I  congratulate you for letting us know how you solve the problem. In Tek school I learned there is a test  to check radiator flow per minute and compare it with specks. Cars that are parked for long periods , the rads should be drained (blocks and all ) and filled with Transmission oil. It was possible to clean yours by filling it with vaporust for 2 days. Nice car, Now you can drive with confidence.

 

[Frank DuVal]

On 12/3/2021 at 9:08 PM, m-mman said:

Filled with 100% green antifreeze. (the car is from Maine, guess they wanted to make sure it didnt freeze)

Common statement, but, it WILL freeze with 100% Ethylene Glycol in the system, but, it will not expand like water does, so no damage, unless you are trying to drive it. Freezing point of Ethylene Glycol is 9°F. I'm sure it below that in Main at some point. Antifreeze is designed to be mixed with water to get the lowest possible freezing point.

[hook]

6 hours ago, Frank DuVal said:

Common statement, but, it WILL freeze with 100% Ethylene Glycol in the system, but, it will not expand like water does, so no damage, unless you are trying to drive it. Freezing point of Ethylene Glycol is 9°F. I'm sure it below that in Main at some point. Antifreeze is designed to be mixed with water to get the lowest possible freezing point.

I've never used antifreeze in my car, of course I have a Franklin. Sorry guys I just had to say it. Smack my wrist. just kidding yall! That's a beautiful Hudson. 

Edited December 8, 2021 by hook
left out (see edit history)

[m-mman]

6 hours ago, hook said:

I've never used antifreeze in my car,

Neither have I because I live in Los Angeles :-)

On the left coast coolant is used mostly for its antirust properties. 

[pmhowe]

12 hours ago, hook said:

I've never used antifreeze in my car, of course I have a Franklin. Sorry guys I just had to say it. Smack my wrist. just kidding yall! That's a beautiful Hudson. 

There is nothing like a good gloat! Enjoy!🤣

[Oldtech]

Up here in the country with COLD winters (Canada), you don't dare leave water in a cooling system past Oct 1.  In an extreme cold snap, when it can get below 40 here, even 50-50 antifreeze isn't good enough. It gells at -34.  We typically use about a 60/40 mix of a/f to water.  Just thought i'd balance the conversation.

[Frank DuVal]

[1949 PLYMOUTHP17]

an excellent radiator cleaning tip before you spend the big bucks is to drain the radiator and block the top and bottom hose connections and fill it with vinegar. it will be spotless in a few days. you won't believe how much hard water scale comes out. this is great for a radiator that is too rare to take apart. cost is two gallons of vinegar.

[m-mman]

1 hour ago, 1949 PLYMOUTHP17 said:

an excellent radiator cleaning tip before you spend the big bucks is to drain the radiator and block the top and bottom hose connections and fill it with vinegar.

The car is working and that that makes me happy, BUT since the cure was so instanteous, I have been wondering just exactly how/what makes a radiator "wear out"?

 

Corrosion and rust and scale can plug up the tubes and passages, and perhaps that can be cleaned with chemicals and/or flushing to increase the flow. 

But since it is metal I guess the tubes and fins can also become thin from the corrosion(?) Certainly that would make the system more likely to leak but how does "thin metal" also affect cooling? 

 

A new core would have clear tubes and thick walls on the tubes, (less likely to leak) does this make for better heat transfer?

[DavidMc]

A radiator has many water tubes or passages that provide parallel paths for the coolant to flow through.   Over time some of those become blocked with crud reducing the cooling efficiency.   When the radiator is flushed or a cleaning additive used, it will generally clean out all of the open passages that are reasonably clear but it will bypass any that are heavily blocked.  With so many alternate paths, the flushing liquid will take the paths of least resistance and bypass the blockages.  This can be improved by using a very large flow rate, when that does not work the solution is to remove the top and bottom tanks and rod reach tube until it is clear.  This does not work with old honeycomb radiators where the passages are not straight.  A new core is needed when the old one has too many blocked tubes and/or leaks.

The radiator is designed to cool the water under worst case conditions of full engine power, low air flow and maximum ambient temperature.  Under all other conditions the thermostat restricts the water flow to prevent over cooling.    

[Studeous]

M-Mman: your story just radiates warmth. But indeed sometimes all it takes is money, converted to a radiator. What a handsome Commodore!

[m-mman]

15 minutes ago, Studeous said:

M-Mman: your story just radiates warmth.

Thank you.

And with cold temperatures here (but nothing like in the great white north) I took it out last weekend and tried out the heater and it was very cozy. I guess 160 degrees is good enough to make the inside comfortable.

[MikeC5]

The other thing (I've read) that can happen is over time with expansion and contraction (and corrosion), the tubes and fins lose intimate contact and so loss of heat transfer to the fins results.  

[hook]

Now what's a Franklin acting like that for?

[mfrank]

Quote

The car is working and that that makes me happy, BUT since the cure was so instanteous, I have been wondering just exactly how/what makes a radiator "wear out"?

Two questions, one is, how does a radiator get plugged?, and the second, how does it wear out?

 

The primary culprit in both instances is antifreeze. Traditional Prestone green is a mixture of ethylene glycol and anti-corrosion additives. Specifically, silicate based anticorrosion additives. Silicates do an excellent job of preventing corrosion, because they deposit on bare metal almost instantly. This leaves little opportunity for rust to form. But they are barely soluble. So over time, they tend to fall out of solution, especially if the car isn't in continuous service. Solubility is temperature dependent, so it should come as no surprise that they accumulate in the coolest part of the system...the bottom of the radiator. Over time, they plug the tubes, and it becomes impossible to get a flush solution in to clear them.

 

The radiator wears out by corrosion and mechanical wear. Corrosion will accelerate if glycol coolant is allowed to remain in the car too long. Glycols deteriorate into acidic byproducts under the influence of oxygen and heat, so the longer the coolant remains in service, the more acidic it gets. There are all sorts of old mechanic's methods for identifying worn out coolant, but the simple and scientific way is to use a coolant test strip or litmus paper to determine when it becomes acidic. Or just change it every two years.

 

Mechanical wear accrues from repeated heat/cool cycles. When the coolant gets hot, it expands and pressure rises. When it cools, pressure drops. This pattern of reversing stress causes metal fatigue, and can eventually result in failed seams or burst tubes.  When the system acts up, you get wider temperature swings. So prompt attention to bad thermostats and clogged radiators in necessary to prevent much worse problems.

 

The best coolant for your car is always a 50/50 mix. That's true for any car, even if it lives in a garage and never ventures out in the winter. Glycol coolant accomplishes a lot of things: lower suface tension, corrosion resistance, PH balance, lubricity, extended temperature range.  Reducing surface tension increases the efficiency of fluid/metal contact, which can reduce localized boiling and pump cavitation. Corrosion resistance speaks for itself. PH balance arises from the coolant containing buffering agents which extend the time the coolant can be used without becoming acidic. And finally, extended temperature range helps prevent boilover in hot climates as well as freezing in cold climates.

 

 

 

[viv w]

MMAN,

 When you took off the water jacket from the side of the motor, did you notice if it still had the distribution plate attached to it. I rebuilt a Terraplane years ago. The motor ran very hot and upon removing the water jacket , I found the distribution plate inside was rotten and some of the holes were blocked. This plate has different sized holes in it, to help the water to reach the back cylinders of your motor and without it the rear cylinders are likely to suffer heat damage.

[m-mman]

22 minutes ago, viv w said:

When you took off the water jacket from the side of the motor, did you notice if it still had the distribution plate attached to it.

Yeah it was there.  The car had a HET club history from at least the 1990s and the car went through the owner's estate. The water jacket and baffle was "new" and the block was clean.  I suspected that the owner had been chasing the problem for awhile. 

 

The car came with a bunch of boxes of parts in the trunk. They didnt mean anything to me at first, so I just put them on the shelf. This weekend I wanted to re access what was in there and  I found a little note/check list that pretty much covered everything I have now found the car needing. Sure enough number 3 on the list was "overheating".

 

So they were probably thinking about it in the 1990s replaced a bunch of things, but never figured it out completely. I rechecked everything and as the thread title says "just replaced the radiator" (which they never seemed to have gotten to) and it's all fine now. 

Edited December 21, 2021 by m-mman (see edit history)