WRD Feeler’s Pin Length

[alchemist]

The length of my original feeler pin equipped for IP R20Y is 23 mm (0.9055”), taken from the base of the feeler to the end of the pin. It won’t shrink in the freezer and it won’t extend beyond the 23 mm in boiled water. I bought a new one, German made from AutohauseAz website and it behaved exactly the same as the old one. As I read in the Forum, it only retracts when it is under pressure from the spring. So, I measured the height from the air valve to the bottom of the feeler in the WRD and came up with the following: 24 mm (0.945”) when the air valve is open and 32 mm (1.26”) when the air valve is closed and it is at the bottom of the WRD. These figures mean that I need my feeler to extend an extra 8 mm to close the valve. Is anyone has made similar measurements and why the feeler won’t extend beyond 23 mm even when it is hot?

[ja17]

Seems like these pins will not retract on their own. They need some pressure to send them back home.  It may just be an air lock in the unit, the seal around the pin is very tight.

[alchemist]

Joe, Thank you for your comments. Have you measured the length of the feeler’s pin cold and hot? I am trying to establish the standard pin length so I can determine if my 2 feelers (old and new) are Ok, then I can focus on why the feeler is not able to close the air valve. There is another possibility that the spring under air valve is not sitting right. I disassembled the spring and re-assembled it, now it rest at the bottom of the WRD which is different than what I see in the manual’s schematics. The schematics show that the spring rest few mms above the bottom. If this is the case, then this is where my problem lies. The question is what kind of retainer used to hold the spring above the bottom of the WRD? I would appreciate your expertise in this matter. Thanks again.

[garymand]

Its a little difficult understanding what you are measuring and how.   But it is more exact to measure it as an assembly.  When I want to know if the WRD is working right, I take it off the FIP, as an assembly.  Do not take it apart, just disconnect the two hoses and remove the two long attachement screws that hold it to the pump body.  To test it you need a thermometer and a pan of watger in which you can submerge the WRD, heat the water and watch the temperature as the air valve opens.  Two birds: At RT the piston should be just at the 'hole wide open' position and at 80C, it hould be just fully closed.  I think the exact # is 79 but my thermometer is +- a few.

Sneak into the kitchen, put the wrd and thermometer in the water at room temp.  Heat up the water while watching the termometer.  The WRD air valve should start with the air hole fully open.  As you heat the water the air valve closes the hole.  At 80C the hole should be fully closed. 

The new thermostat should have come with a retainer clip that holds the pin in.  Don't remove it until you are ready to install it.  Don't mess with the pin.  If you pull it out, you will probably not get it to function right again.  I did that once and couldn't find a satisfactory way to get all the air out of the rubber pocket.  It wasn't a good one to start.  I'm told that behind the rubber is wax.  as the ampule is heated and the rubber expands.  As it expands it pushes the pin out.  As it cools, the pin is sucked back in by the vacuum in the pocket behind the pin.  If you break that vacuum pulling the pin out, it would be technically very difficult to reestablish complete vacuum.   Fortunately they are still available for the newer pumps and not too expensive.

[alchemist]

Gary: Thank you for your input. I did a test similar to what you suggested, but in a different way. I let the engine ran to the normal operating temperature, then I loosened the WRD’s lower 2 screws and moved the whole WRD upward and measured the length of the pin. The pin was barely showing from the bottom hole, which gave me the idea that my feeler is the problem. I have 2 feelers, an old one and a new one and both are behaving the same. They are stuck on 23 mm pin length, they won’t retract in the freezer and they won’t extend in hot water. The new feelers are sold with a clip; the length of the pin with the clip is 23 mm. This is may be the maximum length, However, I pushed the old feeler pin in and it did shrink to 18 mm. In hot water, it came out to 23 mm. So, I am trying to determine if 23 mm is the minimum or the maximum pin length for IP R20. There are some posting in the forum for the older feeler (IP R11) and not for the IP R20 feeler. These postings on the R11 feeler state that the pin extend up to 60 mm, two third of my feeler’s pin length. Do you know of any posting regarding the measurement of R20 feeler’s pin? Thank you.

[Jordan]

What is it you are trying to determine, other than the length of the pin.  Do you want to know if your WRD is working?  A simple test is to remove the air filter on the side of the WRD.  Start the car cold and put your finger briefly over the hole where the filter sits.  You should feel good suction, enough to hold your finger there, but don't or the car will stall.  As the car warms up the suction should decrease until there is no more suction when the car has warmed up.  If it isn't happening like this then your WRD is not working properly, otherwise it's working.  If it's not working properly then yes it might be the pin is not extending properly or maybe the valve is sticking.

[jeffc280sl]

I agree with Jordan.  This is a good test.  Have used it on my car in the past.

Br,

jeff

[alchemist]

Thank you Jeff and Jordan for your input to my posting. I have done all what you suggested and found that the WRD is not working. The valve is not sticking, but the feeler is not pushing far enough to close the valve. Even when I bought a new one, it behaved the same as the old one. So, I posted this thread to establish if anyone measured of the feeler’s pin. This information is vital to me to determine if my 2 feelers are OK. You can depress the pin back and it comes out in hot water, but it won’t extend beyond 23 mm. Is this length enough to push the air valve to a closing position? It does not seem that such measurements were reported by the group yet and the manual does not state any pin length. There are some positing for R11 pump feeler stating that the pin extend 60 mm. My pump is R20 and it has a different length feeler. I am trying to find out if such information is correct. Thank you again.

[Jordan]

I have the older style thermometer so unfortunately I can't help you with the pin length.  You are sure that coolant is circulating around the thermostat when the car is running?   Maybe the new one you purchased is defective.  It's certainly not unheard of for new parts not to work properly.