940 Turbo Heater Control Valve

[Forrest]

I discovered the other day that the original heater control valve was starting to leak on my 1994 Wentworth after 28 years and 275k miles. I wonder whether this might have been a factor in the drivability problems I was having a year ago since its failure mode is to spray the distributor with hot liquid.

Anyway, I replaced it today with a Professional Parts Sweden all plastic jobby bought earlier in the year from eBay for £20. I’m sure this is nowhere near the quality of the original but it’s better than one that’s falling apart - literally, see photo.

This was actually quite a straightforward job despite the ridiculous location Volvo chose to install this part. I didn’t replace the hoses which are also original but appear to be reinforced, unlike the emergency spares I bought recently from Skandix.

The heater valve is in the lower of the two hoses to the heater matrix. I found disconnecting it at the firewall and then pulling the whole caboodle through to the inlet manifold side of the engine the easiest way to gain access without any dismantling beyond removing the transmission fluid dipstick.

In order to remove the original hose from the heater matrix for the first time in 28 years I first cleaned up around it to remove grime and traces of dried coolant. I sprayed a bit of maintenance spray onto the jubilee clip and then fully loosened it and pulled it right out of the way down the hose. I then gently twisted the hose from side to side using Knipex pliers adjusted to grip it gently without crushing anything and got it started by gently prising with a screwdriver. It then slipped off really easily with no damage to either hose or spigot. Phew!

For reassembly I first attached the short (downstream) hose to the valve and tightened the jubilee clip and then assembled and aligned the remaining connections and tightened them in situ. I found the original rubber vacuum connector too loose a fit on the new valve. It is a tight friction fit on the hard, white plastic vacuum pipe and can be pulled off. I replaced it with a short length of 1/8” ID braided vacuum hose.