This is only my own experience, in a country with less to optimal support available.

My rojo 121 (a B18A engine - one carb) right after buying it (just that help me to adquire it at low price), worked at 120 C and the coolant flow from the reservoir to the floor after 20 minutes of driving.

After changing coolant, headgasket (blowed), add thermostat (car come without it) the problem remain. The drain in the block also was clogged (and not wire cleaning effort worked). Here the public water come with calcium (hard water, many drivers here uses it on radiators :stupid but cheap).

As a last resort, I wash the coolant system using a brute approach (suggested on a old car maintenance handbook coming from the spanish military): on 10 liters of hot water dissolve one kilogram of sosa carbonate (the one used by our granfathers for clogged WCs), and put it on place of coolant just after the engine was hot. After it, I put the engine on idle for two hours.

After shut down the engine and wait for cooling, I take out the metalic plugs(petcocks) available on radiator and engine. A brownish-yellowish mud was out of the holes, seeing it I also take out both radiator hoses.

Also, i take out the thermostat and with a garden hose on the thermostat hole send water into the coolant passage (more mud was out). After the water come clear (no more mud), I make the same washing on the radiator (from down to up, inverse way to usual water circulation).

After it, I set new hoses (sosa damaged the old ones - a toyota hose cut on two fit the bill) and cleaned the thermostat and both petcocks before reinstall. Filled the system with green coolant (prestone) and run the engine with the cap on the radiator open, "burping" the system.

Finally, I capped the radiator and set a new cap on the reservoir (open cap, no pressure type - 0 psi) and check the coolant level up to the middle of the reservoir.

That was the end of my overheating problems.

Of course, this brute cleanup is useful only for iron-made engines. If the sosa solution is put in a aluminium-head engine, the engine will be damaged (on small font: try it at your own risk).

Hope it helps (and as usual, my excuses for my spanglish redaction).




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Joaquin / Rojo 121 / Lima