Windshield Washer System (Part II)

Hi Guys,

I posted sometime back how my windshield jets suddenly “dried up” on me, not emitting wiper fluid at all anymore despite the running of the pump and plenty of fluid in the reservoir. :angry: So, I finally took the plunge last night (all night, no less) and dug further into things.

I decided to investigate the plenum area under the WW grill. After taking off the wiper arms (and yes, one of the brittle old nut covers crumbled apart in the process - have to get a new one, now :confounded:) I discovered that the 4 screws (with captive washers) holding the grill in place was NOT Pozi-Drive but Torxhead (for once on a Jag, imagine that :roll_eyes: ). I think #20s. They had apparently not been removed since the car came out of the factory, as one of them required copious amounts of PB Blaster to finally and slightly loosen up. After removing the grill (be sure to first squeeze both jets fore and aft and push down through their respective mounting holes in the grill), I checked the plenum drains, and was very pleasantly surprised to find them not only clear, but quite over-sized, vs. those used on the sedans/saloons (which is probably why they were clear) :smile: . I still remember the nightmares caused by the small drain hoses in that area on my XJ40s, X-300, etc., particularly the dreaded “duckbill hose” on the XJ40s. :angry: Jag finally smartened up with the XJS and changed to 2" diameter “radiator main”-sized hoses on either end of the plenum chamber. These drain down and through the front wheel arches. To double check free flow, I poured about a gallon of distilled water into the chamber and nearly all of it quickly drained off. :+1: The bad news is then that I’m still puzzled about the water on my driver’s side floorboard after a hard rain, as me and a convertible owner both posted about earlier. Oh well.

Anyway, the set up for the WW jets is that each has a separate water feed hose that converge at about the mid-point of the chamber via a “3-way connector” (i.e. “Y”) to hook up with the common main feed hose. Shortly after the connector is a one-way valve in the main feed hose. The main hose goes from there to disappear out of sight at the passenger end of the chamber and then, IIRC, travels down the passenger aft side of the engine compartment to run forward from there to the reservoir and pump(s).

The first thing I did to try to find out where the blockage was was to disconnect the one-way valve from the main feed hose, intending to thread my (large E) guitar string down the hose from there as far as possible to see if any obstacle was encountered. I’ve posted before on here how I use a standard (cheap) set of guitar strings to clear out blockages in the tiny water drain or feed hoses on my Jags. IMHO, it’s safer than trying to blow them clear with compressed air, as no risk of blowing apart the hose at some weak point. :triumph: Before I could do that, though, the feed hose was so hard and brittle (I guess with age + the high heat that builds up inside the chamber in the summer and in the winter as well, being located above the heater core?) that it snapped apart off one side of the one-way valve rather than pull free of the valve’s “barb” fitting on that side. O.K., no biggie, but then when I tried to pull off the hose on the other side’s barb it too snapped apart at that point. :rage: Soooo, sticking the one-way valve off to the side for the time being, un-phased I went ahead and threaded the guitar string down the main feed hose (think “performing an angioplasty on your Jag”). By yanking it back and forth many times, I was able to get a little over 2’ of it through the hose until I could get it to go no further. My hunch at this point is that further progress of the string was not hampered by some foreign obstacle in the hose but possibly due to other factors, such as lack of flexibility of the string, dryness of the inside of the hose, “twists and turns” of the hose, etc… I decided to withdraw the string at that point and instead check out the one-way valve more closely. But first, I tuned on my key and tried the wash pump, to see if water flows out the end of the main feed hose. Sure enough, it did, although I was surprised it was not high pressure - more like that of the stream of water that comes out of a store drinking fountain. Assuming that is in fact the correct pressure, then I guess the one-way valve, when working properly, along with the narrow exit holes of the WW jets, creates the high pressure streams (?) The presence of the water stream further makes me suspect the one-way valve is at fault, rather than an obstruction further down in the main feed hose.

Inside, I first tried blowing air through the valve from either side, like blowing a straw. I noticed that NO air was getting through it, either way. So, is that “normal”, or does that show something wrong with the valve? :confused: I have never had a new one of those valves, so I have nothing to compare it to.

On the hunch that the valve is in fact blocked up, I tried soaking and shaking it around in a cup of rubbing alcohol, then a cup of 409 Spray Cleaner, and, finally, a cup of hot sudsy soap water. Still, no air will blow through it from either port. :slightly_frowning_face:

At that point, I had no choice but to put everything back together until I can find out more about and, if needed, replace the one-way valve. I’m hoping that was the culprit all along. :thinking: I’ll also have to buy a couple of feet of fresh water feed hose (hopefully one of the local auto stores carries it in that size) and some of those double-barbed connectors, so that I can splice the fresh pieces into the old system with them.

btw, I did make a mistake following the Jaguar Factory materials when it came time to replace the windshield wiper arms. Note that they advise how the driver’s side arm should locate about 2" above the bottom edge of the windshield when parked, and the passenger’s side arm at about 1 3/8", both measured near the upper end of the blades where the sub-arm attaches the rubber of the blade to the rest of the blade. That MAY be correct for the pre-face lifts, but it is NOT correct for our face-lifts. When I went to test the wipers afterward there was a slight movement down followed by a CLUNK, with the arms refusing to budge after that point. :open_mouth: I thought for sure I had damaged something, but when I reset the arms to where they were before I removed them (I had marked that position on my windshield with a couple of pieces of blue painters’ tape) they operated normally once again. :relieved:

Anyone??? re: one-way valve operation and pressure of water stream from washer pump … :confused:

I’m not sure what info you are looking for. The following is quite general.

One-way valves are fitted to prevent back flow of the washer fluid, which would create a dead time after activating the wipers while the lines refilled. There is, mainly in older designs, an additional reason–to avoid the pump having to prime itself if it happens to be separated from the reservoir (to avoid this, most pumps since the 80s are located within the reservoir, not remotely).

The issue of pressure is simple physics. A given pump can deliver a certain maximum pressure, and a certain maximum flow. Some automotive pumps (like oil pumps) are designed to deliver a particular flow, and will supply, within reason, whatever pressure is required to achieve this. Others (like water pumps) will create a given pressure head, but not mind whether flow occurs or not. The washer pump is in between. It delivers a certain flow (liters/hour, say), and, if into a relatively large hose, won’t need to generate much pressure to do so. But fit restrictions at the end (the nozzles) and the pressure will rise in order to pump the water through–although not as much as when the nozzles aren’t there.

It’s similar to an ordinary large-diameter domestic water hose. Turn it on, and water pours out, but not under pressure. Fit a nozzle, and the pressure rises to whatever is available.

Sorry if I’m missing the point of your question entirely. IMHO of course.

Thanks, Robert. Yes, that answered question #2, so it appears that I do have correct water pressure from the main feed hose (and therefore apparently the one-way valve was bad). My other question is how to tell if a one-way valve is good – by blowing like a straw on the fitting on either side, first one then the other, should air flow out one way/side but not the other? If so, then my one-way valve is definitely bad (i.e. blocked up) in that I can’t get air to flow out either side by blowing on either opposite side.

Exactly that Paul, blow one way and you get flow, blow the other way and it should NOT flow any air/water.

Oh boy. :frowning_face: I wish I could take it apart and repair it, if that is possible, but it looks like a sealed/molded uni-piece construction. So what keeps the water from flowing back in the other direction - is there a movable diaphragm, ball, etc. inside it? I can shake it, but don’t hear or otherwise detect anything else inside of it. Reason I ask about repairing it is I have searched exhaustively online, and found only ONE of them, and that’s a used one, in the U.K… Apparently Jaguar stopped making them long ago and there’s no aftermarket (interest?) in making them. I have run across a few aftermarket non-return WW valves for other makes, but I note that the “disc” part on those is mounted vertically in the line instead of horizontally. More importantly though, it could be the case that the hose fittings are not the correct diameter for the Jag feed hose. :confused: And yet w/o one I take it the WW spray system will not operate … What a nightmare … :grimacing:

As has been explained its there to stop the fluid flowing back into the pump, you would get away with removing the valve and just running a hose straight through. There would just be a delay in water reaching the windscreen.

SNG sells this one (for $39.00 - yikes :flushed:), which they claim will fit, e.g. “facelift XJS”, although note that the Jag part # is not even close to the one for the facelift XJS valve shown on the Jag Classic website:!/English/parts/5058b1c9-ff57-4eec-9e69-21f2f5855762

btw, JagDaim in Australia also sells that same valve, claiming too that it will work for, e.g. “XJS”, but they want $32.00 U.S. + another $15.00 to ship to the U.S. Seems kinda steep for a little plastic bit like that! :open_mouth:

I did also find out that JagBits has a used OEM one as well.

You’d think one of those shrewd Chinese after-market auto parts manufacturers would be cranking these things out for, say, under $10.00 or so. :wink:

That’s a standard part. Line diameter is certainly standardized. Take the valve to any shop or junkyard. Inside is uncomplicated, just a spring and a gasket, disc of some sort. These valves should be ubiquitous. You can also look for ebay one-way valves that fit and in the meantime just leave the hose connected without the valve. See ebay, 3-4 bucks, small form factor, any size.