how do you add coolant?

[idopps]

Hey, I am trying to add some coolant to my 928s. I can not get any room to remove a cap or put it in. Any advice?

[Britwrench]

928 coolant tank caps are difficult to undo, but use a pair of grips and you should be able to release it. Obviously make sure the engine is cold when you do this. Check the cap and renew it if the rubber washer is perished. Use only the proper BEHR cap, US caps have the wrong pressure.

[Wayne 962]

"US caps have the wrong pressure"

I don't quite understand this statement?

???

-Wayne

[Britwrench]

Sorry Wayne, I should have been clearer. Porsche run the cooling system at a higher pressure than most US cars; therefore if you fit a pressure cap from the local auto-parts store it will allow coolant to leak out due to the opening pressure being too low.

[Wayne 962]

Coolant pressure? Do you mean that the cap (which is sometimes designed be pressure relief?) would break at a different pressure?

-Wayne

[Britwrench]

Yes, the pressure that the cap operates at is higher for Porsche models than most domestic cars.
Usual auto-parts cap pressure; 7 - 10 psi
Porsche 15-20 psi

[rich]

How interesting.. I never noticed that.. great info.

[Roland Kunz]

Hello

Most Mercedes use a similar cap.

Grüsse