XJS ( X27 ) 1975 - 1996 3.6 4.0 5.3 6.0

Screenwashers inconsistent

Old Apr 6, 2026 | 11:01 AM
  #1  
Greg in France's Avatar
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Default Screenwashers inconsistent

Guys
While the car was terrific on my recent UK trip, a couple of days ago the screenwashers started to get weak. Sometimes OK and sometimes nothing. Now I have a home made reservoir as the OEM one (pre-ABS in rear of the engine bay opposite the brake booster) has been replaced by my header tank, which greatly simplifies the coolant circuitry. Anyone interested, as it was posted several years ago, see the attached pdf.
Consequently my washer fluid reservoir is hidden in the LHS wing cavity behind the front LHS roadwheel. Pics here:
Empty wing cavity behind the LHS front wheel
Empty wing cavity behind the LHS front wheel

Washer reservoir in place with headlight  washer pump. The wing stoneguard covers this all up
Washer reservoir in place with headlight washer pump used for extra pressure. The wing stoneguard covers this all up

GiF coolant header tank where OEM washer reservoir used to be:
GiF coolant header: Rad bleed horizintal red pipe, atmo tank top curving down to the left pipe, feed to system plumbed into the heater return, blue pipe.
GiF coolant header: Rad bleed horizintal red pipe, atmo tank top curving down to the left pipe, feed to system plumbed into the heater return, blue pipe.

Now to the washer problem. They would work, having fitted new jets, and then not work, endless trials and whatnot failed to provide any consistency, with lots of false dawns and fruitless pump changes etc etc ; the 'master mechanic' fooled around for HOURS until he gave up, and then just before going to sleep, his subconscious made him murmer to Madame: "I wonder if the OEM feed is not delivering enough amps?". (For our younger readers, this is the sort of wasted opportunity that old age brings when alongside one's true love).

So the next morning the tractor battery that was just charged up was lugged to the pump and rigged up, result: fine strong streams of fluid! Now the pump was wired up to the OEM system and I am guessing that either the OEM wiring was corroded somewhere, or the pump was going home, not sure which as it had been working perfectly for nearly 10 years. Either way I fitted a relay, triggered by the oEM wiring and delivering battery firewall post power to the pump. Problem solved. And as I had a spare slot in my electric fan fusebox, it was pretty straightforward.

Extra fusebox slot all ready for washer pump relay power feed. This box is for the twin circuits to the main electric fan, one automatic from the water pump inlet switch, one cabin-switched, with two completely separate circuits and relays. It is fed from the firewall post.
Extra fusebox slot all ready for washer pump relay power feed. This box is for the twin circuits to the main electric fan, one automatic from the water pump inlet switch, one cabin-switched, with two completely separate circuits and relays. It is fed from the firewall post.

So if your washer system gets weak, this may save you some time!
 
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Old Apr 6, 2026 | 11:52 AM
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Mac Allan's Avatar
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You know your XJS is well sorted when you even notice, let alone have time to attend to the windscreen washer performance!

Cheers
 
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Old Apr 7, 2026 | 03:21 AM
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Grant Francis's Avatar
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Luv those murmurings, maybe I do the same, but my Managing Director is now deaf, oops.

Good job Greg, boredom kept at bay for 2 days.
 
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Old Apr 10, 2026 | 01:00 PM
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Good idea but I'm not sure about the Heath Robinson appearance though.
 

Last edited by rgp; Apr 10, 2026 at 01:18 PM.
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