1978 MK1 Golf GLS 1.6 Coolant Change

Hi

I have 1978 1.6 GLS.

I want to drain the coolant and replace it.
I removed the bottom hose from the radiator side and some liquid came out. But no where  near the 5-6 ltr that I was told I would need to replace it once all drained.

I then attached the hose back again. Then I  remove the top hose on the radiator side. I started the engine and more liquid started pumping out but not much more.

I then also did a wash with a radiator wash solution.

I re-attached all the hoses made sure all secure and filled the radiator with pre-mixed coolant from the top of the radiator.

But…. I am very worried

A: I was told once i drain it I will need 5-6 L to fill it back up and I used at push 3L. so why did i not use 5-6 ltr??
B: I have done something wrong and two types of coolant have mixed as not all of the old one came out..
C: I have not got enough of my water and cleaning solution out of the engine and now it will either freeze or cause corrosion  to my engine. Especially as it is getting very cold.
Please can someone help and tell me if i  a have done something wrong.


 

Welcome along,

You have to have the heater set to hot in the car when re filling, otherwise you may end up with the a air lock in the system.

Do you have a top fill rad or a header tank?

Ian

When you remove the bottom hose from the radiator you also need to remove the thermostat housing (bottom hose fixes to it on the engine end of the hose) then pull the thermostat out, that will empty the engine off coolant.

Hi
Thank you for your help l!

The car does not have a header tank so I  fill from from the top of the radiator.

Also If I did not remove the thermostat which means the whole engine did not flush is there a risk the cleaning solution and the water may be around the engine. Or would they have never got there if i never removed the thermostat when i applied them?

Thank you






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If you used a flush product, and it says to run the engine till warm, then you have it sitting in your engine.

To properly flush and back flush it you need to pop the t-stat out, then reconnect the cover.

Loosen the upper radiator hose both sides.
From the upper hose you force water from a garden hose in to the hose towards the radiator and the outlet on the engine will blow out until clear.

You then reverse the hose and fill it to the engine side till it blow out clear on the radiator.

Do this at least 3 times.

Use a new t-stat, and prior to replacing you drill a 1/16 or 1/8 inch hole in the lip of it.

Fill the radiator from the upper hose till t dribbles out.
Then fill the block side of the engine till it dribbles out.

Reconnect the hose and tighten the clamps fill the res jug 1/2 full start the car and allow it to get warm (cap off the res), once the t-stat gets warm and opens the radiator res will go down a wee bit, fill to the full mark and replace the cap.

How-to-flush-your radiator | Volkswagen Owners Club Forum

Before you do your engine, Take the two hoses off the heater matrix, and flush and back flush that from lower hose to upper and upper to lower about 3 times or 4.

Reconnect the upper hose to the Valve and tighten the clamps.  Replace the barbed plastic fitting on the lower hose with a 5/8 brass hose mender that you can get at a Hardware store…replace the hoses tighten the clamps.

Then proceed to flush and back flush your radiator.

With a top fill radiator its really easy to get an air lock so when you connect everything back up and run the engine keep an eye on the temperature gauge and feel the hoses to make sure they all get hot, the bottom radiator hose should be last hose to get hot. Also check the heater blows out hot air once warm.

If you do get an air lock remove the top radiator hose at the radiator end and pour coolant directly into the engine.

5l is plenty of coolant as you will struggle to get that much in the car, don't know who told you 6l in a car with a top fill radiator…      

Drilling the hole in the t-stat prevents the air bubble, that plagues the VW and other cars.

Some Makers placed a bleeder screw on the top of the head, VW did this on latter mk3's with the heater core hoses having a bleeder port other makers placed the t-stat at the top of the head with a bleeder port.

Proper filling of the system is the key even on expansion less systems.  Fill the Radiator from the top hose, and let it slightly dribble out of the radiator,  Then Fill the block side from the water outlet.

The hole in the lip allows the Radiator lower hose to bleed trapped air in to the block, and then filling the block side forces most of the air up.

Some  makers of t-stats have this "hole" in the lip as a Design mod from the manufacturers….

Then while the Engine is Running you Burp the Upper hose as that usually forces the air to the expansion tank.

As in every Radiator I have done I have opened the caps and watched the level go down, as the t-stat is opened and fluid is fully moving through the system (heater core (matrix) on full hot.  Once you see this, then you can top things off and cap it as you are done.

If you have an expansion less system, then you usually have an over flow jug, and I usually fill that above the full mark as when the system cools off it will drain back in to the system and fill it fully.  

The reason that you don't totally fill the system at the start is that as the water is getting warm and being pressurized by the t-stat not opening it will over flow.

I never had a "air" bubble from hades as even with my Diesel in the 80's I filled the system from both sides.

On the 90's with the plastic flanges for the Digi, you can remove a sensor and totally fill the upper head and radiator then re-fit the sensor.  

When I have to play with things, I usually use a meat baster to suck out the Expansion Tank, then remove a sensor to suck out most of the fluid from the outlet.  When I had Plastic flanges on it that cracked or leaked this is what I would do prior to replacing it to prevent excessive loos of coolant.  I also used a plastic bag around the Dizzy to keep water migration to a minimum.

Knowing why, and how to stop it is better than just guessing.  The only really sad part is that before I started drilling the t-stats, replacing a radiator only caused minimum loss of coolant.  Or a single douching.

When you flushed a system you got a douching when removing the lower hose, then another when you popped the t-stat out….

With the hole in the t-stat you get a constant dribble out of the t-stat cover hose connection.

Briano1234 said

Drilling the hole in the t-stat prevents the air bubble, that plagues the VW and other

With the hole in the t-stat you get a constant dribble out of the t-stat cover hose connection.

Amen to that!