Hi All,

 

It has been a very very long time since I've had to back flush a coolant system, and wanted to get some advice on how to do it on my AE82 Twin Cam.

 

Had an overheating issue (found to be a dead thermo fan switch - thanks to Thomo - who if you're reading please check your PM) so figure while I'm replacing the fan switch I might as well replace the thermostat and radiator cap, flush the coolant and put in new coolant so I have a known quantity.

 

Any advice appreciated.

 

Cheers,

Todd

hey hey

 

If your radiator hoses seem to be a little ratty and crappy looking replace them too. Hoses splitting is not fun and can be dangerous.

 

cheers des

hey hey

 

If your radiator hoses seem to be a little ratty and crappy looking replace them too. Hoses splitting is not fun and can be dangerous.

 

cheers des

 

Not a bad plan either... Thanks!

How To Flush Cooling System:

 

1. Remove thermostat housing

2. Remove thermostat

3. Replace thermostat housing without thermostat

4. Disconnect top (inlet) radiator hose from radiator

5. Disconnect bottom (outlet) radiator hose from waterpump or water inlet.

6. Connect flush gun or hose to top (inlet) radiator hose.

7. Flush with water until system is clean.

8. Flush radiator in the reverse flow direction, same as the block.

9. Reinstall thermostat with new gasket/ o-ring (make sure surfaces are clean) and reinstall hoses.

10. Fill cooling system with a 50% mix of coolant and water or manufacturers specs.

11. Run to operating temperature, check for air locks and correct level.

 

 

If the 4age is the same cooling system setup as the 4ac, the direction of normal flow is from the bottom of the radiator to the top.

 

I reccomend Holden Coolant

Removing the thermostat is definately overkill.

 

1. Turn the heater in the car to HOT

2. Disconnect the bottom heater hose

3. Put the garden hose is the heater hose and turn it on as hard as you can without it popping off

4. Blow out as much of the water you have just sprayed through the system as you can

5. Leave the heater hose of and poor coolant into the radiator until it starts coming out of the heater tap as green

6. Put the heater hose back on and top up the system

7. Warm the car up and check coolant/water level

 

don't forget to give your over flow bottle a quick flush aswell and don't forget to set the heater to hot.

Edited September 4, 200620 yr by mitch13

He's replacing the thermostat anyway, which is a good idea, so it should be ok

Removing the thermostat is definately overkill.

 

1. Turn the heater in the car to HOT

2. Disconnect the bottom heater hose

3. Put the garden hose is the heater hose and turn it on as hard as you can without it popping off

4. Blow out as much of the water you have just sprayed through the system as you can

5. Leave the heater hose of and poor coolant into the radiator until it starts coming out of the heater tap as green

6. Put the heater hose back on and top up the system

7. Warm the car up and check coolant/water level

 

don't forget to give your over flow bottle a quick flush aswell and don't forget to set the heater to hot.

 

Its not overkill, removing the thermostat and flushing in the reverse flow removes shit that has become stuck in the normal direction of flow.

 

If your technique is used, the system will not be completely flushed and if any other type of coolant is used besides the type that was originally in there, it will be useless.

 

If your in a hurry and are using the same type/brand of coolant that is already in the system, use mitch13's method.

 

If you have got time and want to do the flush correctly, use the method I said earlier.

 

Do not mix coolants.

Edited September 4, 200620 yr by Robert

Do not mix coolants.

 

 

That is 100% correct. He did say he was replacing the thermostat anyway, so it will be out.

Big thanks to all who have replied - enough info there, should be able to manage it.

 

Sourced most of the bits now, just need to get hold of some new hoses.

 

As an aside - had a bit of a gotcha with getting the thermo fan switch. Repco had the AE82 TC listed with a twin prong switch and the single cam listed with the single prong. My car is a pretty original unplayed with 87 TC - it had a single prong switch. Luckily they had got both in...

 

Cheers,

Todd

Out of curiosity how much was the switch? retail price thanks

 

Cheers, Rob

Out of curiosity how much was the switch? retail price thanks

 

Cheers, Rob

 

Just under $68 I think.

i picked up my thermo adjustable switch thingy from the wreckers for $15 a bit more fiddleing and adjusting but it works nice. ;)