Replacing the heat regulator and the anti-freezing liquid – through the example of a 102 engine

I faced the following situation: the engine temperature won’t rise higher than 172-176°F (78-80°C) on the move according to the dashboard. During initial running the temperature quickly rises up to 212°F (100°C), and after I start driving it falls to 176°C (80°C). 

I decided to replace the heat regulator (last replaced five years ago) and the anti-freezing liquid (last changed three years ago). At the same time I decided to rinse the cooling installation (thanks God there’s a lot of cleaning agents nowadays).

Supplies: a new heat regulator, a concentrated anti-freezing liquid, distilled water (plenty of it – see below why), radiator flush.

Regarding the radiator flush: it says that you should pour out the anti-freezing liquid, fill the cooling installation with distilled water (I’ll be saying “water” meaning “distilled water” from now on) while the engine is cool, start the engine, wait for seven minutes, kill the engine, pour out the water once again, repeat the step and then fill the cooling installation with the anti-freezing liquid.

But as the engine is cool (it won’t become warm enough during seven minutes) the heat regulator won’t open and the cooling liquid won’t flow through the radiator – so this procedure makes basically no sense. That’s why we will do it the other way: get rid of the old anti-freezing liquid, remove the thermostat itself (be sure to keep the old rubber spacer) and try to rinse the cooling installation without disassembling anything (except for removing the thermostat cover).

I didn’t like the idea of waiting for the engine to cool down as well as of filling the warm engine with cold water, so I used a hot plate instead. Here how the process looks like (open the heater regulators to the maximum to rinse the heater radiator), the engine is warm:

The heat regulators (the new one on the left) and the radiator flush:

Use a big flat screwdriver to unscrew the plug on the right side of the radiator (when you face the windscreen) and pour out the cooling liquid. On the photo you can see the water after the system has been rinsed twice.

Now look for the screw-bolt that is used to pour out the water out of the engine compartment (under the discharge manifold):

Get rid of the water by unscrewing the bolt. Then screw it up as well as the plug on the right site of the radiator.

Fill the cooling installation with warm water and radiator flush. Some solid substance may appear as well – it is collected on the bottom, yet the instruction doesn’t mention that you should shake the can before use. I added some water to the can and got the solid substances dissolve.

Start the engine. They say you should wait for seven minutes, I decided to wait for fifteen to be sure. Unscrew the plug, the bolt and pour out the water. As a matter of fact, it doesn’t really look like water:

Something muddy…

Now pour in some warm water and start the engine once more. Wait for about fifteen minutes and pour the water out. Something muddy once again. So we’ve got to repeat the whole procedure one more time and wait for fifteen more minutes.

I decided to leave the water inside of the cooling installation till tomorrow. In the morning I poured it out and was glad to see how pure it was:

Install the new heat regulator (it is placed angle-wise and the air ejection valve should be at the very top position):

1,5-2 liters of water still remain inside of the cooling installation (you can’t get rid of this water anyway) so add 4 more liters of concentrated anti-freezing liquid:

And add more water until you fill the whole installation.

Let’s wash the radiator from outside as well: purchase asphalt stains cleanser (hand operated one in a plastic jar), set the head to the spraying mode and spray it over the radiator. Be sure not to spray if over the engine through the radiator. Wait for about ten minutes (the black mud will be flowing down the radiator) and rinse the radiator from a water hose (in the opposite direction from where the engine is located).

As a result the engine temperature is about 194°F (90°C) and it’s stable regardless of the speed (40-70-100-120 mph). In traffic jams the temperature rises up to 212 F (100°C) much slower than it used to. After I start driving (when out of the traffic jam) the temperature falls to 185 F (85°C) but then rises back up to 194°F. It’s even boring – always those 194°F.

Regarding the heater: earlier the heater sliders were open by one third and the air was barely warm. Now they are hardly open by one fourth and the air is warmer yet!

Provided by ZoMer

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1 Response

  1. August 10, 2016

    […] I faced the following situation: the engine temperature won’t rise higher than 172-176°F (78-80°C) on the move according to the dashboard. During initial running the temperature quickly rises up to 212°F (100°C), and after I start driving it falls to 176°C (80°C). More on http://www.oldmerc.net/replacing-the-heat-regulator-and-the-anti-freezing-liquid-through-the-example… […]

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