Dear U.S. Diver,

Hope you're well. I can't recall having seen an all-metal heater control valve for a 940. I have a couple that are mostly metal: one hose nipple is plastic.

The problem with plastic is that it embrittles with time and heat. When such a valve fails, it is usually "catastrophic". One of the hose nipples separates from the valve body. Coolant is lost in a minute or so.

An all-steel valve will corrode, given enough time. But as the metal rusts, the valve is likely to leak. A gradual loss of coolant is noticeable. The valve can then be replaced before it fails completely.

I suggest use of Volvo brand heater hoses. These mission-critical hoses last reliably for about 15 years, where ambient temperatures are not for long periods above 90⁰F (32.2⁰C). It is hard to install and to inspect heater hoses, so using the best-quality part is money well-spent.

Hope this helps.

Yours faithfully,

Spook