Washing fluid reservoir heating
 

Hello everyone.

Today I changed the engine cutoff valve which was a rather nice job. I had to remove the cruise control and also the washing fluid reservoir. You certainly know this feeling that after putting something apart and then together you begin to have your doubts whether that certain part is working the way it should. Having my doubts I found out that the spiral in the reservoir doesn't heat up and seem to recall that the fluid inside the reservoir used to be hot after even a short drive.

There are two rubber hoses from the cooling system fluid connected to each end of the spiral. They are not interchangeable - one is wider (left) and one is narrower (right). I pulled them off the metal spiral and tried blowing/sucking in them. They feel very easy for the flow, there is nothing stuck in them.

I then tried blowing/sucking in the metal spiral inside the reservoir. When I suck at the wider (left) end then the passage for flow is free. But when I blow then there is a rattle sound as if there was a ball valve and the flow closes. Nothing comes thru. Alternatively, when I blow at the narrow end the flow is OK but when I suck at it that 'something' closes the flow.

Is this the way it is supposed to be? Because when the engine is running the cooland flow comes from the wider end and can't flow through the spiral because there is some sort of a one way valve. This way, however, the reservoir will never heat up and I remember it did.

Am I doing something wrong? If there is a valve (which there clearly is) - is it supposed to work this way or is it stuck the incorrect way? Or will the valve open after a certain time or ... or what? :)

Thank you for your suggestions!

Please add to your signature the model and year of your car so we don't have to ask, "What kind of car are you asking about?"

Oh I am sorry, I've had that in my profile for years. The car is a W124 300D 2.5 Turbo. I also thought the heating spiral was the same on almost any model that featured it.

Anyhow, in the meantime I found this: There is a thermovalve in the heat exchanger (spiral) that maintains an uniform temperature of + 20 to + 30 degrees Centigrade.

So there is a valve. I will investigate further.

I had a look at the spiral element in a 300E reservoir
It has a thermostat valve in it, down near the bottom and that could be plugged up or something. I would think there is a bleed hole that allows hot fluid to get to the thermo valve otherwise it would never open

The tubing looks like stainless steel so I doubt its rusted
While at a dealer I priced one of those and it was a staggering amount, $195 or something. You definitely want to try repairing yours instead of replacing it, or look on eBay or a scrap yard for one.

I tried blowing in the spiral tubes. The valve doesn't seem stuck. One way it closes, blow the other way and it easily opens. Alas it closes in the direction of heating action. You can 'feel' the ball open/close.

Because it is thermostatically operated there must be a bimetallic strip and should something be wrong on the valve it must be this strip. I am having hard time finding out if it works or not.

I remember the water in reservoir being hot after a long drive. But... that was in summer and the whole engine compartment was hot and so must have been the reservoir no matter whether the valve worked or not. The manual says the water is kept at 20 - 30 degrees Celsius which isn't hot or even warm because luke-warm would be something like 36-37 degrees.

I think I need to wait till winter when there is freezing weather outside and then check for the temperature of the water inside.

There is a sort of a plastic dimple outside on the reservoir but it looks it is either welded or glued solidly.


At that price ordering a new one is a no-question. I best wait till winter and then see whether the valve works or not. If not scrap yard is the way to go. Even if the heating doesn't work it won't be too much of a problem - the engine heat will heat up the fluid sooner or later anyway and besides - I use winter fluid which takes some low temps before freezing up.

Valve renewed
 

OK, I found out the valve was bad. I was reluctant a bit to take the reservoir system apart but after asking at a local scrapyard the nice person there showed me how to make that procedure.

It is very easy and straightforward and takes about a minute to take the entire spiral (including the valve) out. No catches there. The valve needed was held by a simple nut and asked for replacement. The nice guy sold me a used valve also, for $10. Alas, after I got home to replace the valve, I found it was cracked around the orifice. When I tightened the nut fully and blew in the tube there was a leak. Had I installed the valve this way I would have ended up with coolant in my washing fluid reservoir :)

A temporary solution was to loosen the nut slightly. The crack receded and the leak stopped. Of course this was only a short-time solution. Had this happened in summer with engine temps running around 100 or more the crack would open I think.

So I called the dealership, ordered a brand new valve ($23) and installed it once again. While on the phone ordering I also ordered all rubber gaskets that go on the reservoir - 2 for washer pump motors, 2 for the heating spiral tubes, 1 cap and 1 for the fluid level indicator. The overall cost for gaskets was about $2. I replaced them all and now, even when the reservoir is top full, it doesn't leak anywhere. Before I was bothered that the washer motors dripped constantly. Because they only dropped a drop every now and then I couldn't get to be bothered enough to do anything about it. Now the entire reservoir is perfectly dry and this all for a negligible cost.

Needles to say I rinsed and cleaned the reservoir's inside also.

Related topic
 

Whats the best way to clean the windshield washer nozzles when they get plugged up?

Good write-up, Jassper! Makes me want to check mine out to see if it's working.

I now realize why the setup has a thermovalve - you don't want 100 degree C washer fluid hitting a -10 degree C windshield...

I think it is more the fact that water boils at 100 degrees (C) and on a hot day (or even cold) with your temp running at 100 or more, the fluid would just boil off and you wouldn't be left with anything. Also alcohol in antifreeze washing fluid mixtures for winter has a much lower boiling point. It would be a terrible lost to have all that booze escape to be left with water and detergent that would freeze in the end :)

But you are also definitely right, boiling water hitting windscreen is no good idea.

Have never done that but would I need to I would use a pin (such as tailors use), (or a single straight thread of steel cable) while someone else would push at the washer so that you have pressure to blow out any dislodged matter.

If there is still no improvement I would remove the nozzle, use the same pin while blowing in the nozzle (use a rubber hose or anything you find) and hope for the best.

Doh
 

Without the thermovalve, you will have 225 fahrenheit washer fluid hitting subzero glass, been there, done that, replaced the fractured glass (one of my cars).

Note:
Windshield washer fluid, boils off very fast at 225 fahrenheit, and stinks.

Answer:
 

Compressed air...

Sometimes it is better if you remove them to soak in water over night.

In the worst case, use sewing needles to break the grit, then compressed air to clear the passage.

Remember to blow in the direction of flow, most MB have a one way check valve in the windshield washer line that will block the air flow or break.

A thought would be to use "The Works" cleaner. It has a mild acid in it. the gunk in the nozzles are usually just lime build up and The Works eats those up. Just don't leave it on too long.

I guess I could use the same thing for the tank.