jej3

Agreed

Stromius

@RPetty and Jeff : https://rennlist.com/forums/928-foru...rol-valve.html

(Jim's thread response above): Napa P/N 6601410


Mine is failing too so it's time to go with a metal one for a bit. $16 at any NAPA

928porschemangreg

Any advice on the heater hose back there? I think regular 3/4" heater hose should work.

mickster

It's a special size-I think 5/8" to 3/4" but 3/4" with clamps works fine.

Mrmerlin

once again this topic pops up.

Here is my take on the HCV.
I suggest that you replace the HCV with the factory part as well as using the correctly sized short hose,
they get swapped out together.


Here is why...

The Porsche HCV is made of plastic ,it has a vacuum operated gate valve with seals on the sides of the gate,
its common for the seals to fail on the gate thus causing coolant to continue to flow when the valve has been shut off.

The flow will be greatly reduced but it will still flow with bad seals.

The valve will also fail to the open position when it loses its vacuum supply.

NOTE this is also an important feature as it will also let you know that you have a vacuum leak in your HVAC system ,
if the valve wont shut off when commanded,
the loss of vacuum will also affect the cruise control operation.

Now the best part about this seemingly weak plastic valve is that its made to be the weakest part of the coolant system,
and combined with the short hose acts as a fuse of sorts for the cooling system.

It is also placed in a spot where if it should fail most of the 4 gallons of coolant will remain in the engine,
in other words if you were to have coolant leak this is where you would want it to happen.

Why would the HCV/hose fail ,
could be from overpressure of the coolant system usually a HG failure.
Hydrocarbons or various cleaners being leaked or put into into the coolant thus degrading the plastic
Overtightening of the clamps thus crushing the plastic
Overpressure due to bad cap, instead of the coolant bottle failing

Thats is why I suggest to use the factory parts, install a new HCV and short hose.
They can last a long time if the engine doesnt overheat from other issues ,
otherwise replacement every 8 to 10 years would be a good idea as well as adding the short hose.

Swapping in a petcock or metal valve will change the design idea ,
thus may create other issues that could be more damaging to the engine than a plastic HCV failure.

When installing the HCV make sure the black side faces to the front of the car,
Dont overtighten the clamps on the HCV as this will deform the plastic and cause possibly early failure.

When replacing the HCV and short hose Its also a good time to consider swapping out the thermostat and the rear seal and O ring as well as installing a new coolant bottle cap.

ilikebig928butts

Resurrecting for n00bs like myself...
On an '84, the HCV is on the passenger side and roughly around here right? I just received the part from 928intl but it doesn't quite match the look of it. If this is indeed the right thing to replace, which hose goes where?

9two8

Never seen an HCV in that position before although my car is RHD. Mines located just to the left of the bell housing and under the air cleaner housing ?

Ken
80 928 S
5 Speed

UK

westija

That is not it. That is part of the air diverter system / emissions and is connected to the inside of the fender well. The Heater Control Valve is further to the driver side under the air filter box. Remove the air filter box and you will see it

westija

This is a picture when I started my Intake Refresh (I am glad it is very nice now).
Have a look at the valve and how it is located somewhat close to the Fuel Cooler...

ilikebig928butts

Ah! Capice. need to remove the air filter assembly 1st and on the driver side. Danke.

westija

It is still on the passenger side, but not too much to the side