Just cool it

One of the "unknowns" with my 280z that I hadn't explored yet was the radiator.  I knew it was a bit of an eyesore and it was definitely the original unit.  

Given how much gunk came out of my heater core when I cleaned it out, I thought I'd pull the radiator and check out that part of the cooling system.

Pulling the radiator wasn't a very big task.  After draining the coolant I pulled the shroud, hoses and the EGR carbon canister.  I already had the intake and AFM out of the vehicle for other work.  At that point the radiator was ready to come out.

At this point I pulled out my scope camera and began inspecting the tubes on each end of the tank.  They weren't blocked but there was definitely some scale built up in there.

I decided to circulate a vinegar solution through the radiator to remove the scale and corrosion.  I set up a recirculating flow of vinegar and water to begin breaking things down.

As I let this solution circulate through the tank I began other work on the car, taking advantage of the missing radiator.  One task was to clean up the coolant reservoir mount which was beginning to rust.  The mount is to the left of the A/C condenser in the below picture.

It was at this point that I noticed something on the radiator cross brace...

Inspecting the radiator in the same location as the above rust revealed that my radiator had a leak in the seam of the top tank!  As I pondered my options I steered away from a shiny new aluminum radiator as I wanted the engine compartment to retain a factory look.  There are still copper and brass radiators available for my car but they were about $100 more than the aluminum counterparts.  Then I happened upon a clearance item on ZCarDepot's site: a three row copper and brass radiator for $70 that was a direct replacement for my model year!  The item listed cosmetic blemishes that would not affect performance.  I thought the price was worth the risk so I ordered the radiator.  Upon arrival I noted that the only real issue with the radiator was that a column of fins had some damage but the damage did not seem to affect the integrity of the tubes.  These fins would be hidden behind the fan shroud so this seemed to work out perfectly for my needs.

I also ordered a new thermostat inlet, thermostat, stainless mounting hardware, gasket and hoses.  I figured since I'm here I might as well make sure all the components are in good order.

Checking the thermostat turned out to be an interesting endeavor.  The first thing I noticed was the fact that the bolts holding the inlet onto the housing were different sizes; this shouldn't be the case.

When I attempted to remove the inlet I came up with a theory on the reason.  First of all, "offsize" bolt's threads were missing.  There was also quite a bit of corrosion in the hole.

My guess is that corrosion on the original bolt left the threads attached to the aluminum so a smaller bolt was forced into the hole as a quick fix.  Since I had purchased stainless replacements, I needed to clear this out.  I started by using drill bits of increasing sizes, rotating them by hand to clear out the junk in the hole.

I then followed up with several passes with Q-Tips to remove the crud on the very bottom of the hole.  This was in preparation for the next step: cutting new threads.  Being very careful to be straight, I worked the tap in and out of the hole clearing the aluminum shavings as I went.  Once the tap reached the bottom of the hole I cleared it one last time and tested fitment of the new stainless bolt.

Using a Dremel and a wire brush attachment I cleaned the gasket surface around the thermostat.  Attempting to remove the thermostat itself proved to be troublesome as it seemed to be stuck.  Even though I had ordered a replacement I had read that the factory unit was much less prone to failure.  I decided to not risk damaging the original unit which was functioning perfectly so I left it in place.  Using the new hardware and gasket I put the new OE inlet into place.

After prepping and painting the rusty section of the cross brace I was ready to install the new radiator.  The fit was tighter than I expected but the mounting locations were correct for my '76 (in later years the mounting holes were spaced one inch further apart vertically).  Using the new stainless bolts I secured the new radiator into place.

The hoses and shroud attached without issue.  I did make sure to return the anti-collapse spring into the return hose to keep the coolant flowing at all RPM's.

Finally I returned the freshly painted reservoir mount before calling this job done.

What a difference this new radiator has made to the look of the engine compartment!  I am so happy that I did not have to use an aluminum radiator for this replacement.