Coolant Resevoir W123 1982 Turbo

Hi Kent,

I just installed the thermostat on my '82 W123 Turbo and the installation went smooth and easy (except for breaking off the radiator drain plug - got a new one from the dealer). Now I'm at the point of refilling the resevoir with coolant (50/50 mixture with water) and I understand that the capacity is 13.2 quarts. So far I've only put about 4 quarts of coolant and the entire coolant resevoir looks full. Ugh. What have I done wrong, and what do I do next?

Thanks much,

Brook

Forums

Diesel Engine Specific Aid

Chassis Model Number

W123

Refill the radiator first

Refill the radiator first, then run the engine...you'll see the radiator level drop, add until full (takes a couple minutes) - replace radiator cap. Let the engine warm up then shut it off. After it cools down, check the reservoir. It only pulls from the reservoir when cool. If the reservoir is empty, fill it and check the radiator.

You could also have a bad reservoir and/or radiator cap that won't allow the system to pull the coolant in.

Things to consider

When you replace a thermostat you do not lose all the coolant in the system. Some stays in the engine and heater core and hoses. The radiator and radiator hoses usually only hold 6 to 7 quarts. You can potentially get air trapped in the cooling system which could lead to overheating the engine.

To be sure the radiator is full you can remove the top hose from the thermostat housing and pour coolant into the radiator directly through the end of the hose. Once full, hook the hose back up quickly to the radiator neck and tighten. Drive the car around the block to get the engine hot. Watch temp carefully. Then let engine cool down and refill reservoir tank as needed.