Flushing the radiator and polishing the gauges

OK, time to get caught up with the blog.  What a great car season this has been.   Before the hot weather driving season I wanted to ensure the cooling system was up to the job.  I thought it would be relatively clear and clean since I drove it over 1,400 miles between Berlin and Milwaukee and it never even came close to running hot.

Funny enough, this is my first non-daily driver car that has a conventional water-cooled engine.  All the other vintage cars I own or have owned are air/oil cooled: Citroen Ami (two of them), Citroen 2CV, Fiat 500 and Porsche 911.  This meant I had to read  up on all the ins and outs of running a vintage water-based cooling system and how to properly maintain it.   In regards to flushing the cooling system, I reached the conclusion that citric acid was the way to go.  It’s what the Mercedes gearheads use and swear by in many threads such as this one: http://www.mbusaforums.com/forums/viewtopic.php?t=499

You can find the stuff locally at health food stores, but at premium prices.  Also at hydroponic supply stores locally or online but the best deal I found was at bio-diesel supply website DudaDiesel, here:  http://www.dudadiesel.com/choose_item.php?id=5ca What they use it for, I have no idea; I didn’t want to look too much into it or next thing I know I’ll be trolling Ebay for a 1980’s MB 300D…  I must confess that as a scrounger, the thought of running a vehicle on ‘free’ fuel is tantalizing.

So I get myself 5 pounds of the stuff, some hose fittings at Lowe’s and start flushing the block, after pulling out the radiator and doing the same to it.  The first picture shows the hose simply stuffed into the upper hose using a steel fitting.  The lower one is the hose with appropriate fittings to connect to the hose and to the block drain.

Flushing the block

Block flush hose

There was so much crud in the block that when I removed the block drain plug, not only did not a single drop come out but I had to poke a screwdriver into the opening many times to break through the crud seal that had formed on the inside.  Here’s what it looked like under the car:

Draining the radiator and block

Cooling system residue

I flushed both the block and radiator 3-4 times and ran water through it for at least 20 minutes each time.  The radiator was not as cruddy and I don’t feel that it needs rodding or boiling out.  While it was out I did paint it using Eastwood’s thin radiator paint in order not to clog the fins.  It was too shiny for the core so I re-coated that area with high temperature satin black.

The same day I pulled the gauges out to properly polish the bezels.  They appeared to have light corrosion on them hat would require refinishing.  I was amazed when 0000 steel wool removed 99% of the ‘corrosion’ and polished them up very nicely.  Over the winter, I’ll be sending the speedo to a guy in Germany that can replace the crazed plastic with glass and a new bezel.

Speedo before polishing bezel

Cluster gauge before polishing bezel

Gauges after polishing bezel

After polishing


It was very cool to see that all the gauges had date stamps of 12/65 or 11/65.  BMW Classic’s records indicate this car was built December 1965.

See also the tags found under the seats; no date codes or anything else I can make sense of on this one.  Does anyone know what the numbers denote?

Under-seat tag

This one is dated 11/65:

Next time, capillary gauge and fuel pump.


3 responses to “Flushing the radiator and polishing the gauges

  1. Hey Luis,

    Glad to see you’re getting the BMW up to snuff (also glad to see you’re still not stuck in Crystal Lake with a non-starting Fiat 500).

    I’ve bought a few things from DudaDiesel as well (viton hose that I’m using for low pressure hydraulic return lines on the SM), so they must be a pretty good deal on many things. Hope to see your 1800 someday. best, andy.

    • Thanks Andy, good to hear from you! Unrelated to the ignition issue that day, the engine suffered from severe piston slap on the trip home and found metal inthe oil and all over the inside so I’m rebuilding it right now. In the process, I’m bumping the displacement to 650cc and putting on a larger Abarth aluminum oil pan to avoid future overheating.

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