[Chrysler300] It ain't the heat, it's the humidity

["Rich Barber" <c300@xxxxxxx>]

The radiator tank on our 1955 C-300 is about 4" X 23".  A 14 psi radiator
cap would limit pressure within the tank to 14 psi and this would generate a
force of up to 1,288 lbs trying to blow the tank top off.  Corroded or
otherwise damaged seams can open up at higher pressure.  If your car does
not ever run hot, a lower pressure cap should work just fine.  

The 14 psi cap allows the coolant temperature to rise by about 36 degrees
before boiling.  Addition of 50% ethylene glycol raises the boiling point
another 36 degrees or so.  Keep in mind the idea is to try and prevent or
minimize boiling at the hottest points in the cooling system--around the
exhaust valves I would assume.  There may be boiling at hot spots without
the entire charge of coolant boiling.  In a new radiator, or in one in as
new shape, a higher pressure radiator cap should accompany a higher
temperature thermostat in order to capture the efficiency associated with
operating at higher temperature without losing coolant.  In an old and
weakened system, one might buy a little life time on the radiator by
lowering the radiator pressure.  Additionally, the pressure is present
throughout the system and impacts the heater core, all hoses and gaskets.

In the design phase, it is a tradeoff of additional cost and weight of a
stronger heat exchanger (radiator) vs. limiting the pressure and temperature
operating levels.  Similarly, more heat exchange surface can be traded for
higher airflow and more parasitic load on the engine.  Some manufacturers
were more generous with their radiators than others.  Our 1955 C-300 runs
just fine at 80 mph in 100 degree temperatures, but warms up at slow speeds
in parades or stop and go traffic.  It needs that forced air from forward
velocity and the fan.

One other thing to consider is that if a cold cooling system is completely
filled, it must dump some of its coolant as it warms up and expands.  The
radiator cap handles this duty, also, and vents the liquid to the road or to
an overflow bottle.

So, has anyone adopted an overflow bottle and radiator cap to a 1955 C-300
radiator?  Ideally, the radiator would suck the coolant back into the
radiator as it cooled and keep oxidizing air out of the cooling system.

-----Original Message-----
From: Chrysler300@xxxxxxxxxxxxxxx [mailto:Chrysler300@xxxxxxxxxxxxxxx] On
Behalf Of Mark Lindahl
Sent: Friday, August 29, 2008 1:27 PM
To: chrysler300@xxxxxxxxxxxxxxx; Knutsen, Mark C
Subject: Re: [Chrysler300] Radiator Re-core, Additional Rows

Hi Mark,

I had my stock radiator recored and the guy suggested to add rows to the max
capacity.
When he did this, it actually made the radiator a little thicker and it
never overheated.
That company is now gone, but one that I know does repairs is listed below.
Give them a call.

Lake Zurich Radiator & Air Conditioning
785 Oakwood Rd 
Lake Zurich, IL 60047 Map

  a.. (847) 438-4334 
There was a small leak between the top tank and they were able to repair it
after the original company went out of business.
One thing he told me was that it is a good idea to slightly reduce the
radiator cap pressure for some of these old radiators.
He said the stock cap (14PSI ?) may actually cause the top tank to separate
under high pressure/heat and he felt that the stock cap pressure was really
not necessary.  

I would be interested in knowing any comments on this.  I still have the
stock cap on there with no problems now.

Regards,
Mark Lindahl
'63 300 Conv.


  ----- Original Message ----- 
  From: Knutsen, Mark C 
  To: chrysler300@xxxxxxxxxxxxxxx 
  Sent: Friday, August 29, 2008 2:57 PM
  Subject: [Chrysler300] Radiator Re-core, Additional Rows


  Any suggestions on radiator shops in the Chicago/Rockford Area for a
  rebuild on a 1961 G?

  Also, any thoughts on adding an additional row of cooling tubes to the
  stock radiator? It was recommended to me by some of the local mechanics
  but curious if anyone has tried it yet.

  Thanks in advance

  Mark Knutsen

  300 G.

  <http://geo.yahoo.com/serv?s=97359714/grpId=3732744/grpspId=1706713852/m
  sgId=23179/stime=1216714814/nc1=4430620/nc2=4507179/nc3=4836044> 


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