Flossing Fins (Post # 157)

Leading the pack on a glorious New Mexico morning.

 This is the best time of year for road trips in New Mexico. No chance of rain, clear blue cloudless skies, crisp mornings, cool evenings, and trees at higher elevations starting to strut their fall colors. Normally, tourists flock in from Texas and even as far away as Florida, but due to the pandemic the migration this year is reduced. Could be just as well. Unlike New Mexicans, people from those states tend to be somewhat lackadaisical about wearing masks and practicing social distancing in public.  

 

It works, but is it worth it?

According to “The Plan”, The Alfatross and I were supposed to be on the road now, working on refining suspension, steering, engine tuning, and all things related to testing road worthiness. Instead, we are both here in The Shed, me flossing fins on her radiator with pipe cleaners and she impatiently waiting for me to fix everything so she can get back on the road.

Do you know how many fins there are on a 1900C SS radiator?  I do: Cleaning fins is hard work. It helps to pass the time by practicing your math skills. It also helps explain why it takes so long.

Radiator core area = 39.5H X 44L =1,738 cm sq. (one side)

Radiator core fin rows = ca. 4 fins/cm = 158/side

Total length of fins, (both sides) = 158/side X 44 cm X 2 = 13,904 cm

Radiator core tubes (columns) = 28

I mention how many core tubes there are because they break up the 158 rows of fins into 4,424 discrete cleaning areas (each side), thereby compounding the effort it takes to clean them!

 

Virtually invisible, the tiny crack is in the center of the circle.

The delightful opportunity to clean fins was one of those “well, as long as the radiator is  out I might as well go ahead and . . . .  But why is it out? This most recent departure from The Plan, was prompted by the sudden appearance of a radiator leak. Fortunately, it occurred not on the road, but while testing instrument readings at The Shed. Unfortunately, it is still a major bummer, particularly because I pressure-tested the radiator after re-coring and before installation several years ago. The leak appeared as a fine spray of coolant coming from the front of the radiator near the top of the head tank. With the hood off and the engine running, I could see the exact location and snap a photo. 

Angling the radiator and shutter assemblies out together.

 

After sanding the area down to bare metal, I could see what appeared to be an ultra-fine crack at the edge of the soldered joint between the head tank and the new core. After much head-scratching I concluded the best idea would be to remove the radiator, patch the leak, and pressure test it out of the car again in case there might be other weak spots. After all, although the core is new, the tanks are 65 years old!

Andrea Zagato once described the body for the Alfa 1900C SSZ designed by his grandfather as “draped” over the engine and frame . . . and I agree it is a voluptuously seductive design. But . . . just try to get the radiator out without removing the engine first! Tucked up under the car’s nose, it is also firmly attached to the shutter mechanism in front of it that warms the engine up, making the combined assembly twice as thick. 

The thermostat functioned perfectly.

So . . . drain the coolant. Take off the 5 fiendishly fiddly vintage hose bands used to connect the three radiator hoses to the engine. Check the function of the cylinder head thermostat and the other one that operates the shutter. Removing the fan blades will provide another centimeter or two of clearance, but leaves the 5 sharp bolts that hold the blades to the hub exposed. Cover the engine side of the radiator with heavy cardboard to protect it. Take off the 4 bolts, washers and 8 rubber isolators that hold the radiator to the frame and it should come right out. That’s when you discover that it won’t budge unless you first remove two aluminum panels inside the cavity between the body and the radiator bulkhead. To get to them you have to remove the grills with their driving and running lights. As long as you are there anyway, neaten the wiring, thoroughly clean the entire area, and take measurements and photos of the hidden bumper support pipes in case you or the next owner might want to recreate one.

So . . . it is possible after all!

The glossy epoxy patch material matches the radiator's finish.

The extraction itself using an engine hoist was a slow, wiggly, twisty, hold-your-mouth-just-right process but it came out in the end with no damage to itself or the rest of the car. After patching the leak with JB Radiator Weld epoxy, I plugged the openings and pressure tested it to 17 psi without problems. It could have gone back in the car at that point, but the streaks on the fins left by dried coolant bothered me. 

More soul-searching led to the conclusion that there would never be another chance to clean the fins once the radiator goes back in the car, so it’s now or never. It does not have to be spotless, and the front side can’t even be seen once the shutter is in place, so it really isn’t  a big deal. 

It's just frustrating to be removing, patching, cleaning and reinstalling the radiator when on the other side of the overhead door, Legendary Route 66 beckons!