glmoore0001

Hello.

I am changing the the Antifreeze in a 1985 928 ROW from Green to Zerex G05 and want to make remove as much of the green as possible before refilling.

I have purchased a new radiator bottom plug, metal gaskets for the block plugs and a new expansion tank cap from Roger.

It was suggested by a wise person to flush the heater core before the fluid change. I just want to make sure I am grabbing the correct hoses.

So, a couple questions...

(1) Am I correct in saying that the hose that runs from the front of the water bridge( about 1" o.d.) to the Y pipe goes to the heater core?
If so, where does the other part of the y go?

(2) The vacuum actuated Heater Control Valve when in its resting state with the motor off, is that open or closed?

Thanks... Gary Moore

Bertrand Daoust

1) Yes. The other side goes to the bottom of the expansion tank.
2) Open.

glmoore0001

Thank you very much sir! Gary

Bertrand Daoust

You're welcome Gary.

Here's a pic of all the coolant hoses for my car.

Mrmerlin

Gary to drain the system and flush the heater core

first drain the radiator, about 1.2 gallons
then the drain the block, each side holds about 1.4 gallons.
Then,
remove the heater control valve short hose from its port.
remove the 1 inch line at the water bridge and put into a bucket add clean water to the HCV short hose with a charged hose this will flush the heater core and the coolant bottel.
Then plug the HCV short hose and add some clean water to the coolant bottle,
this will flush the tank,
once the tank is empty,
reconnect the short hose to the head,
then the 1 inch line to the water bridge fill the system through the coolant tank.

I suggest to not flush the block as it could remove deposits on the head gaskets, this then could cause a leak