Coolant fill procedure

spederman · Nov 19, 2009

There isnt a special way to fill the coolant on our cars is there? I lost the belt on my car which caused it to overheat and loose a lot of coolant.

Ive always just started the engine when its cold and opened the coolant resevoir cap and just poured coolant in until the full line on the resevoir.

Some dude at work told me to make sure i open the vent on some hose while filling the coolant?? I wasnt aware of any vent to be opened.

Rickyll7 · Nov 19, 2009

Don't think you need to open any vent on the 2v cars or fill it while its running either. I always fill it up, run it until it get to operating temp for a few minutes, then check the level again after I shut it off and fill it up again. Never had a problem.

bdcardinal · Nov 19, 2009

i fill through the overflow bottle and the thermostat housing if i have that off. i lift the front end and add coolant to the overflow bottle while its running until it looks like its at a good level.

spederman · Nov 19, 2009

Cool,thanks guys, thats what i thought.

GDawg · Nov 19, 2009

Don't quote me on this but I thought you had to somehow "back fill" it or do it at the thermostat so you don't get an air bubble in the system. Do a search cause I'm not sure.

Rickyll7 · Nov 19, 2009

Why fill it while the engine is running?

GDawg · Nov 19, 2009

Rickyll7 said:
Why fill it while the engine is running?

Maybe to push out the air... That's why I think you are supposed to "back fill" it.

wmburns · Nov 20, 2009

The absolute fastest way to refill any coolant system is to pull a vacuum and refill. However, very few of us have the equipment to do that.

On my 2V SOHC, I will disconnect the heater line or the upper radiator hose. The reason this is done is to allow the coolant to enter the engine and displace the max amount of air. This reduces the number of heat/cool cycles are needed for the air to fully migrate to the degass bottle.

There are some engine designs that will almost never purge all of the air unless something else is done. The DOHC and 3.8 V6 come to mind. Which is why each engine came from the factory with a means to purge/check air from the crossover.

It is important to remember that some of the procedures used are for dealer techs. The average customer is expecting to drive the car away without any issues. Can you image telling a customer to watch the temperature guage and if it starts to over heat, pull over and let it cool? The cooling creates the partial vacuum needed to aid in air migration.

The other problems dealers have is with the high cost of labor. It is time consuming to allow a car to fully heat up (needed to make t-stat open), and full cool down (needed to create partial vacuum).

The tricks I have been taught to use after a coolant refill is to run the heater for that 1st test drive. If the heat output stops, there are steam bubbles in the line. Pull over. Over heating is happening.

The other tick I have been taught is to watch the temperature guage. If it is abnormally slow to warm up, that means air is trapped right around the t-stat/cross over. Pull over.

Rickyll7 · Nov 20, 2009

wmburns said:
The absolute fastest way to refill any coolant system is to pull a vacuum and refill. However, very few of us have the equipment to do that.

On my 2V SOHC, I will disconnect the heater line or the upper radiator hose. The reason this is done is to allow the coolant to enter the engine and displace the max amount of air. This reduces the number of heat/cool cycles are needed for the air to fully migrate to the degass bottle.

There are some engine designs that will almost never purge all of the air unless something else is done. The DOHC and 3.8 V6 come to mind. Which is why each engine came from the factory with a means to purge/check air from the crossover.

It is important to remember that some of the procedures used are for dealer techs. The average customer is expecting to drive the car away without any issues. Can you image telling a customer to watch the temperature guage and if it starts to over heat, pull over and let it cool? The cooling creates the partial vacuum needed to aid in air migration.

The other problems dealers have is with the high cost of labor. It is time consuming to allow a car to fully heat up (needed to make t-stat open), and full cool down (needed to create partial vacuum).

The tricks I have been taught to use after a coolant refill is to run the heater for that 1st test drive. If the heat output stops, there are steam bubbles in the line. Pull over. Over heating is happening.

The other tick I have been taught is to watch the temperature guage. If it is abnormally slow to warm up, that means air is trapped right around the t-stat/cross over. Pull over.

Nice post. That clears up all my questions.

Coolant fill procedure

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GDawg

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