DIY Network

1938 Packard: Servicing the Cooling System From "Classic Car Restoration" episode DCR-402

With the front clip and radiator removed from the vehicle, Mark begins the service of the cooling system by disconnecting the radiator hoses.

In this episode of Classic Car Restoration, host Mark Lambert assesses and refurbishes the cooling system on a 1938 Packard. In this segment, he shows how to check the radiator flow, performs a back-flush of the cooling system and replaces worn-out parts.

Materials used in this episode:

Standard automotive tools (socket-wrenches, screwdrivers, nut-drivers, etc.)
Replacement thermostat
Replacement heater valve
Replacement hoses
Gasket scraper
Thermostat-housing gasket
Compression tester
Laser thermometer
Radiator-flush kit and hoses
Garden hose
Catch-basin
Eye protection
Protective gloves

Following is a summary of the major steps in the refurbishment of the cooling system as shown in the episode.

Safety Alert: Always wear eye protection when working with power tools, pneumatic tools and toxic chemicals.

Safety Alert: Always dispose of antifreeze (coolant) and other toxic chemicals responsibly.

Note: This is a summary of steps included in the automotive restoration procedures shown in this episode of Classic Car Restoration. These are general guidelines for restoration procedures on this particular make and model of vehicle, and for the level of restoration selected for this project. There may be variations in procedures depending model, condition of vehicle, level of restoration undertaken and the types of replacement parts or upgrade kits selected. Always follow proper safety precautions, and read and follow manufacturer's guidelines, diagrams and safety notices that come with any replacement parts or kit that you select.

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	Figure A
	Figure B

Cooling System

During our initial test-drive, the temp gauge on our 1938 Packard indicated that it was running hot. This is not unusual or unexpected on a vehicle that has been in storage as long as this one has. It should be noted that after about two years, antifreeze loses its effectiveness and ability to resist corrosion. Since we know just from inspecting the condition of our radiator cap that our cooling system has a substantial amount of corrosion, it's likely that this is effecting the flow of liquid in the system. We begin by checking the flow on the radiator -- which was already removed from the car along with the front clip.

• Upon removing the lower hose from the radiator, we were able to verify a lot of internal corrosion (figure A). In fact, the old radiator spring had come loose and was lodged just inside the hose. This confirms that we will need to flush the system. Since this is a vertical-core radiator, the flow is easy to check.

• We first plugged the top inlet of the radiator by covering it with duct tape. Mark then covered the bottom hose connection with his hand and while the radiator was filled with water.

• When he removed his hand, the water drained out relatively slowly (figure B) confirming that the radiator would need to be removed and sent to a radiator shop for a professional cleaning.
  

• With the radiator removed and tested, the next step is to back-flush the engine's cooling system to clean out any internal corrosion. Before back-flushing can begin, check the condition of the water-pump bearings. Release the tension on the water-pump belt (figure C), then check that the water-pump itself is secure. By grabbing the fan, you can get an idea of the condition of the bearings by the amount of play in the water pump. Ours exhibited little play or "rocking," so was deemed to be in fairly good shape.

• Next, unbolt the thermostat housing from the engine block and remove it, being careful to avoid damaging the gasket if possible. With our housing removed, we discovered that the incorrect type of thermostat had been installed (figure D). The thermostat measures the temperature of the cooling system and also regulates the flow of coolant. An incorrect thermostat may not permit the proper flow of coolant.

  Figure C

  Figure D

  
  

• The correct thermostat for the Packard has a much larger orifice than that of a modern thermostat (figure E).

• We removed the old thermostat from the housing (figure F), and saved the retaining ring for later use.

• Back-flush the system before installing the new thermostat. Back-flushing without the thermostat in place allows the increased water pressure to flush the pipes more thoroughly.

  Figure E

  Figure F

  
  

• For back-flushing the system, Mark simply fashioned a custom inlet from some pieces of old radiator hoses clamped together -- along with a hose-nozzle on the end to control the water pressure. He connected the assembly to the system using hose clamps (figure G), then connected the lower hose as well (figure H).

  Figure G

  Figure H

  
  

• Connect an ordinary garden hose to the hose-nozzle on the incoming radiator hose, and connect a length of old radiator hose to the bottom radiator-outlet to drain the old coolant and water into a bucket. Turn on the water supply and allow the system to flush until the water runs out clear and free of antifreeze, rust and debris (figures I and J). Cupping your hand over the outlet end, then releasing, will help build pressure to help clean the system. Once the water runs out clear, you can turn off the water and disconnect the hose nozzle.

  Figure I

  Figure J

  
  

• To back-flush the heater core, it should be separated from the rest of the cooling system. Cover the cylinders with a clean shop-rag to protect them from any water or debris getting into them, and cut the old heater-supply hose (figure K).

• Connect the back-flush nozzle to the remaining portion of the heater-supply hose -- which normally goes from the engine to the heater (figure L).

  Figure K

  Figure L

  
  

• Unclamp and remove the lower, return heater-hose, and temporarily replace it with a long length of hose to use as a drain hose (figure M).

• To back-flush the heater core, simply turn on the water supply and allow the old coolant and water to flush out into the bucket as before (figure N). Again, allow the water to run until it flows out clear.

  Figure M

  Figure N

  
  

• We replaced all of our cooling-system and heater hoses with new hoses. While doing so, we also replaced the old heater-outlet pipe (actually a makeshift fitting that had been installed at some earlier time) with a new, proper one (figure O).

• To do so, first unclamp and remove the old hose. Then use a screwdriver to provide additional leverage to loosen and remove the old outlet pipe-fitting. Upon removal, we observed that the old fitting was almost completely clogged (figure P).

  Figure O

  Figure P

  
  

• Apply sealant to the threads on the new pipe fitting and carefully install it (figure Q).

• Cut the new heater hose. Remove the old hose at the firewall. Cut the new hose to length and install it.

• Secure the connections with a hose clamps (figure R).

• Tip: Garden pruners work well for cutting hose.

  Figure Q

  Figure R

  
  

• Our Packard had no heater valve installed -- only an open fitting -- so heated water had circulating through the heater core all year-round. The stock replacement would be a Packard heater valve (figure S). However, we opted for an quick-release heater valve (figure T) as an improvement.

  Figure S

  Figure T

  
  

• We removed the old fitting (figure U) and carefully installed the quick-release valve (figure V), being careful to avoid over-tightening.

  Figure U

  Figure V

  
  

  	Figure W
  	Figure X
  	Figure Y
  	Figure Z

• Secure the hose to the firewall, and route the other end to the new valve. Make certain to cut the hose to the appropriate length (figure W) so as to avoid possible kinking. Secure the connections with hose clamps.

• Next, install the correct replacement thermostat into the thermostat housing. Remove the housing from it's mount and clean the mating surface on the housing using a gasket scraper. Also clean the inside of the thermostat housing with a shop rag to remove debris. Position the new thermostat inside the housing so that it rests on the ledge just inside the housing, and so that the bellows is down and the heat-sensor is up (figure X). Secure it in place with the wire retainer.

• Clean the mating surface on the engine.

• Rub some gasket compound onto the new gasket.

  Tip: It's a common mistake, even among shop mechanics, to over-apply the gasket compound (silicon sealent) when replacing a gasket. Very little is actually needed in a situation like this. Simply apply a small amount and work it well into the gasket surface on both sides, leaving a paper-thin layer of silicon.

• Place the gasket in position (figure Y).

• Put the housing, with new thermostat, in place and tighten it down (figure Z). Avoid over-tightening. We torque-tightened our bolts down to about 15 pounds.
  

RESOURCES :


Resources and Special Thanks for Classic Car Restoration 400 series


The Packard Club
Columbus, Ohio
(National & regional clubs, car shows & judging, magazine, resources, etc.)
The Cormorant magazine
The Packard Club
www.packardclub.org

Packards International Motor Car Club
(National owner's club, judging rules, magazine, newsletter and other resources)
Santa Ana, CA
Packardsinternational.com

Packards of Chicagoland
(Regional affiliate of The Packard Club)
Elmhurst, IL
Packards of Chicagoland

America's Packard Museum
Dayton, Ohio
www.americaspackardmuseum.org

The National Packard Museum
Warren, OH (the birthplace of the Packard)
www.warren.org

The Packard Motor Car Foundation
(Foundation for preserving the Packard marque) Restoring the Packard Proving Grounds and other Packard activities.
www.packardmotorfdn.org

Motorbooks International
www.motorbooks.com

Automobile Inspections LLC
(Nationwide automobile appraisal & inspection services, including classic cars)
Hartford, CT
www.automobileinspections.com

Classic Auto Appraisals (Evaluation of Classics, Street Rods, Antiques, Competition Cars, Exotics, Commercial Vehicles and Hand Crafted Vehicles).
www.autoappraisals.com

GUESTS :

Keller Wallace
Keller Wallace Street Rods
Volunteer Street Rod Association
Knoxville, TN