Ern

I am trying to figure out why my windshield washer will not spray on the windshield but will wash the headlights on my 1979. I have the original set of manuals and under sec. 92, it only covers aligning the nozzles and installing a rear window wiper. There is no hose and pump schematic or any reference as to how it works. It is rather difficult figuring out how this is all to work from the wiring diagram. In the Archives, Dr. Bob discussed the problem and mentions a picture of the hoses, pumps, etc. but I could not find it. If anyone has a schematic, I would appreciate a look at it. The wiring diagram doesn't show clearly which contact closes when one pulls forward on the wiper switch to activate the windshield pump so I can't trace the wire. It is hard to figure how one pump can acheive both functions of washing the windshield and the headlights separately unless there is a electrical diverter valve somewhere in the system or two pumps under the reservoir. I pulled the resovior and there is only one pump. I know there is another pump on the intensive washer system, but that is another area that should only come to play when the button under the dash is pressed. It works but also does not spray on the windshield. I would assume that the check valves just come to play when using the intensive cleaner rather than the regular cleaner operation. This is quite a complex system for such a simple task. I have owned the car since nearly new and it has never worked. I never drive the car in the rain so I don't need this fixed, but it is a matter of principal. This form is great and I hope that I can return the favor of help in the future. Ern

Donald

If the MYs were the same, they have different pumps & resevoirs.
Here is the headlight set-up: <a href="http://members.rennlist.com/v1uhoh/underww.htm" target="_blank">http://members.rennlist.com/v1uhoh/underww.htm</a>
and here is the windshield system:
<a href="http://members.rennlist.com/v1uhoh/windshie.htm" target="_blank">http://members.rennlist.com/v1uhoh/windshie.htm</a>

On the 90 MY, the washer/wiper stick is pulled to spray the windshield, pushed to wash the headlights.

Good luck,
Donald


(Good job, Tony)

Erik - Denmark

Ern,
See Tony's homepage: members.rennlist.com.v1uhoh
there you will find good diagrams for the window washer system.
There is three pumps - a separate one for the headlight washer activated when you push forwards - The windscreen washer when you 'push' backwards

Sab

If you hear the pumps going but get no water it's probably the check valves. With the bad check valves you would only be pumping water from the main water tank to the high intensity washer reservoir and I assume the headlight washer could still work. I changed mine and used Tony's suggestion with the simplified plumming under the hood about a year ago. It has worked great ever since.
When I fixed mine, the PO must have had the same water in there for years. Very interesting smell when I used it the first time to say the least.
regards,
Sab.

Ern

Wow, what great information! Thanks for all the help. I didn't pull the washer fluid tank completely out looking for the second pump, so I must have missed the pump that is causing the problem. There must be two pumps on the bottom of the in-the-fender washer tank. The mention of two resevoirs must refer to one, in the fender, for regular fluid and one, in front of the radiator, for intensive fluid. If there are two reseviors for regular washer fluid, I have one to find yet. Well, here we go again, wheel off, guard off and out comes the washer fluid tank, completely, this time. Ern

Erik - Denmark

Ern,
The third pump is placed in the engine compartment, below the cooling resevoir tank - Difficult to get in to - I think Tony's homepage had an instruction about this job.
Good luck

Randy V

How's that for a coincidence - two separate assistance replies from Donald and Erik referencing Tony's site, both posted at the exact same time!

Erik - Denmark

Randy,
Two different people in two different places are thinking exactly the same thought at exactly the same time - That must be the correct answer! and one thing more: Small world!
I must say you are 'awake' recognising even the time! Well done!

Donald

Erik-
Then the odds are that you are not only smart but good-looking as well!
Cheers,
Donald

Ern

Thanks to all for the help and especially to Eric for the tip on the location of the windshield pump which is under the radiator reservoir. I would never have found that one without spending hours of time searching. I got it out from under the car and it wasn't too bad as I could get enough slack in the hoses and electrical lines to get them off and on. The rubber mounts quickly broke so getting the pump down was easy. The rubber was old and hard. This pump has not worked since the car was almost new. It turns out that the free gear in the pump was binding in its plastic bearing causing so much torque that the motor couldn't turn the gears. I spun the shaft on some emery cloth for a while and then the pump worked perfectly. I first cleaned the gears with a fine wire brush on my Dremel so there was no gear interference.

Now everything is perfect except my intensive cleaner doesn't put out enough liquid. I think that pump is marginal due to it being quite corroded when I cleaned it up. I don't quite understand its operation. The pump and reservior on the 79 is located in front of the radiator in plain view. The pump is located under the reservoir and pumps solution into a line that within a foot of length has a tee. One line from the tee goes right to the top of the reservior and the other changes to a small diameter plastic line and goes to the winshield (through those check valves and all). It seems that most of the liquid just recirculates back into the reservior. Is the pump suppose to be so powerful that it can recirculate all this liquid and still have enough for the windshield? Mine will only provide liquid to the windshield if I block this hose going to the top of the reservior. There is also one more hose that comes out of the top of the reservior and it also changes from rubber to a small diameter plastic hose, but this small plastic hose just ends in the harness close to the radiator reservoir. The end is open so it is only venting right now. All very strange! Anybody know the fine details on these issues? Ern

Erik - Denmark

Ern,
Glad I could help you,
Your analyse of the incentive washing system is correct.
I cannot tell you why it is made in this strange way, and I am like you, looking forwards to 'the answer'
I have been 'playing' with this strange system for years, and have almost 'given up' (forgotten it)- It is very dependant of the non-return valves - Maybe it will work if we use Tony's simplified system with less non-return valve.
I am looking forwards to 'the answer'

Ern

Erik, The non-return valves offer quite a bit of resistance to flow and I think my marginal pump can't overcome this resistance, since most of the flow goes right back into the reservoir from the tee in the supply line. Like you, I can make mine work by changing the disign, but I just can't figure out the design plan as done by the porsche engineers. I wonder if anyone has this odd design figured out. Ern

Erik - Denmark

Ern,
I was wondering why, and what to do.
The reason for the design with the return line to tank can only be, the pump is a gear pump - i.e. a positive pump - If we imagine a blockade in the line to the nozzles the pressure will increase and blow the hose (or disconnect the hose in one of the connections, therefore the return line (This is only my theory)
What can we do? - Place an restriction in the return line (Play with the size of the hole)
(I think I have seen a similar return line from the main pump too, but not 100% sure)

Ern

Erik, I think you are right about the pump having a return line in case the main line gets blocked. When you pull down the pump for the windshield washer, there is a tee in that line also. I followed the line to get it free enough to get the pump down. That line went to the top of the tank in the fender. It looks like it also has the bypass, most likely for the same reason as you describe. Now the only line that we don't understand is the extra line from the intensive cleaner tank that ends in the wiring harness acting like a vent. Ern

Erik - Denmark

Ern,
It is a vent.
Where the return and vent hoses go to the tank there is a plastic fixture to hold the hoses, easy to place something under the return hose here, to give the needed restriction.
I did, but have not tested yet (I am repairing engine with new gaskets)