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John Davies · Dec 23rd, 2009, 01:03

Over the years I have had several cars need a new 't' piece in the screenwash hose, which on most Volvos is combined with a one way valve. This sits about 4" away from the nozzles under the bonnet, sometimes hidden behind sound deadening.

It is an untypically poor design by Volvo standards.

The normal problem is a rubber diaphragm in the one way valve which rots, meaning that water can leak out of the small hole drilled in the 't' piece to allow air in and soak the distributor cap every time the screen washers are used. I had one car stop on the road in bad weather due to this very fault.

A further problem is that any rubbish, including rubber from a failing pump, can block the nozzles; also, the 't' piece can fail on one side only, leading to the incorrect conclusion that the nozzles are blocked.

The answer is to replace the combination 't' piece with a standard one from an accessory shop, and then put in a one way valve from the same source just forward of the bonnet hinge. I go one better than this by putting a small torpedo type fuel filter just by the hinge so any rubber which does come off the one way valve or the pump doesn't find its way to the nozzles but is filtered out with any other debris. Saves lots of fiddling for an outlay of only a couple of pounds. Well worth it!

John Davies

Dec 23rd, 2009, 01:03	#1
John Davies VOC Member Last Online: Sep 26th, 2015 22:56 Join Date: Dec 2002 Location: Walsall	Screenwash improvements. Over the years I have had several cars need a new 't' piece in the screenwash hose, which on most Volvos is combined with a one way valve. This sits about 4" away from the nozzles under the bonnet, sometimes hidden behind sound deadening. It is an untypically poor design by Volvo standards. The normal problem is a rubber diaphragm in the one way valve which rots, meaning that water can leak out of the small hole drilled in the 't' piece to allow air in and soak the distributor cap every time the screen washers are used. I had one car stop on the road in bad weather due to this very fault. A further problem is that any rubbish, including rubber from a failing pump, can block the nozzles; also, the 't' piece can fail on one side only, leading to the incorrect conclusion that the nozzles are blocked. The answer is to replace the combination 't' piece with a standard one from an accessory shop, and then put in a one way valve from the same source just forward of the bonnet hinge. I go one better than this by putting a small torpedo type fuel filter just by the hinge so any rubber which does come off the one way valve or the pump doesn't find its way to the nozzles but is filtered out with any other debris. Saves lots of fiddling for an outlay of only a couple of pounds. Well worth it! John Davies __________________ Volvo 760 GLE turbodiesel estate 1989 (auto). Ford Mondeo 2001 mk. 3 Ghia X petrol estate. Austin A60 Cambridge 1966 (auto) . Austin A60 Cambridge 1967 (manual) undergoing restoration. Last edited by cumbrianmale; Dec 27th, 2009 at 03:14.