WRD Valve is Stubborn

[alchemist]

My 67 230SL WRD is sucking air even at 185 F. I disassembled the WRD and found the aluminum looking valve in the lower part stuck and won’t move. I also found engine coolant in the lower part of the WRD when I removed the tower with the hoses on and the thermostat. I do not know if this normal? If so, then the coolant will go into the injection pump and mix with oil. If this is not normal, would this mean that my tower is leaking and is in need of replacement?  I soaked the lower part of the WRD in a penetrating fluid for a week and the valve is still stuck. I even used a sonication which applies heat that did not leash the valve from its seat. It is possible that the coolant has caused the aluminum valve to chemically react with its seat. Any suggestion on this issue will be appreciated.

[wwheeler]

Zach,

You should not have coolant below the tower. Coolant that gets on the WRD piston will wash away oil and cause corrosion. This could cause the piston to become stuck. And as you mentioned, will get coolant into the engine oil. Not a good situation.

The coolant seal is made on an angled seat between the tower and the thermostat body. http://www.sl113.org/wiki/Engine/WarmRunningDevice  If your tower seat has corrosion, it may not be able to create a good seal. Check it out.

When you tighten down the tower to the WRD body, it compresses the thermostat (with spacer ring below) and creates a seal. I used a small bead of high temp, ultra strength silicone on this angled seat to ensure sealing and to keep a seal even when the tower is removed for shim adjustment. If you do not use a sealer, coolant will rush out every time you remove the tower for a round WRD shim change.

You may need to get a used WRD assembly from a salvage yard if yours is too far gone. Others may have help for loosening up the seized piston.

Good luck!

[garymand]

Correct, if you took it apart with the hoxes still connected And without cleaning the coolant out of the tower, and you removed the top screws holding the thermostat,  then you will easily (unavoidably) get coolant leaking past the thermostat into the aluminum air piston area.  Its normal. 

Check the oil level in the pump with the dipstick, very carefully!  It is probably fine.  Get the piston unstuck, clean it oil it lightlt, put it back together and put it in a pan of water and a thermometer on the stove.  Heat it up to 87 degrees F and the piston should close the air hole completely.

[alchemist]

Thank you Wallace & Gary for your suggestions. My problem is that the air piston stuck and won’t come out. With one week soaking with sonication cleaning which applies heat, there is not sign of easing. What if I fabricate an extraction tool with a screw that goes into the center of the air valve to extract it? By screwing the screw clockwise, it pushes on a hollow small pipe, this way; it should lift the air valve out. The only concern is that the center of the air valve will be threaded. Is anyone tried this method? Would threading the center of the valve affect its function? Thank you.

[wwheeler]

I guess my concern is that if the piston is stuck this bad, either the cylinder, piston or both are so badly corroded that they will never seal well again.

This device may have sealed well brand new. But with years of wear, mine doesn't ever COMPLETELY stop sucking in air. There is always a very small amount air that escapes past. And both my cylinder and piston have a nice surface finish on them. So my concern is that even if you can get the piston out, the surface finishes will be so bad that air will easily get past.

I would look for a working salvage part at this point. Shouldn't be hard to find. MHO.

I was thinking the shut off point for the WRD thermostat was more like 150*F???

[Jordan]

Zach, your valve sounds like mine use to be, wouldn't move even after spending days in a penetrating fluid bath.  Problem is the penetrating fluid is not getting past the dried up gunk inside the valve. I don't think the piston/valve is corroded so much as the coolant has gotten in and dried up, basically acting like a glue.  I ended up putting the entire unit in a vise (don't clamp the body) and then tapping the stem that sticks out the bottom with a hammer.  You need to break the seal so the penetrating fluid can get in.  I ended up having to pound on the stem so hard that it started to mushroom.  I just cringe thinking about it (don't know if I would have the courage to do it again today) and probably others reading this are cringing right now.  Too bad they don't make micro vibratory hammers (think pile driving).  Once it started to move it went back in the bath.  It took another week of slowly moving it back and forth to get it freed up.  When you can get it to move with your fingers just keep sliding it back and forth and pour lots of fluid on it.  You need to wash out all the crap.  I ground off the sides of the mushroomed stem and removed a few shims to compensate for the marginally shorter stem (less than a mm). It now works as it should.  I don't think you can get parts for the WRD so if you end up needing parts you would have to salvage what you can from an old one if you can find one.  Don't forget to check that your thermostat is working.  I boiled some water, turned it off, let it sit for a few minutes and them dropped the thermostat into the water.  You should see the needle move out a few mm's.

[ja17]

Use a little heat on it also. Not too much. You can put it in the oven at 250 degrees F if you don't have a propane torch. 

[garymand]

I like your screw, tap and pull idea.  Creative.  The fit is not that critical.  I had a piston that had been sanded by some idiot.  the ends were rolled off and all the surface had been scratched.  It still shut the air off significantly to just a very small flow.  Sure not perfect, point is you aren't going to injure it that badly pressing it out.  Put it in a vise and use a short extension to push it out.  Oil it up a bit first.  You don't have much choice, you have to un-stick it, they are very rare.

An additional thought: the big air hose at the intake butter fly cracks and allows dirty air into the intake.  It is conceiled in the accordian folds of the $100 pipe.  When I got my car the whole intake was gritty due to the oil mixing in from the blow by.  If grit got to the WRD piston and wall, you will have to force the piston past the grit and it won't feel or sound great.  But again. you don't have much choice.

Alu expands at about 13 millionths / in / degree f.  I would also torch the out side evenly getting it pretty hot quickly then press.  With 200 degrees on the outside the bore will expand 2,600 Uin (just under .003.  That should be enough to minimize injury to the walls and piston.

If it is just antifreeze glueing the piston, the heat and expansion is all it needs to unglue it.

[alchemist]

My 67 230SL WRD is sucking air even at 185 F. I disassembled the WRD and found the aluminum looking valve in the lower part stuck and won’t move. I also found engine coolant in the lower part of the WRD when I removed the tower with the hoses on and the thermostat. I do not know if this normal? If so, then the coolant will go into the injection pump and mix with oil. If this is not normal, would this mean that my tower is leaking and is in need of replacement?  I soaked the lower part of the WRD in a penetrating fluid for a week and the valve is still stuck. I even used a sonication which applies heat that did not leash the valve from its seat. It is possible that the coolant has caused the aluminum valve to chemically react with its seat. Any suggestion on this issue will be appreciated.

Progress Report:
After soaking the WRD in PB Blaster for 3 weeks with occasional sonication, the air piston would not move. Although, the sonication applies heat as well as the sonic action, that did not release the air valve. However, noticeable amount of debris came out indicating that the WRD was never been serviced since the inception of my 1967 230SL. So, I devised an extraction tool (I have pictures, but I do not know how to upload them). I threaded the central hole of the air valve with 10 mm thread and screwed a bolt. I put 2 flat wide washers, one at top of the WRD to protect the surface and the second on top of a large nut. As you screw clockwise, the nut presses on the nut pulling the air valve upward. One has to be careful not to be forceful to avoid damaging the thread, but, slowly and surely, the air valve came out. There was damage to the lower part of the seat. I had to hone it similar to the procedure practiced in honing engine cylinders. Using an abrasive paste as chrome cleaner, the honing method was successful and the air valve is sliding comfortably in its seat with lubrication. I am glad to have a happy ending that I can share with SL’s community.

[alchemist]

I posting pictures about the extraction tool that used to pull a stubborn air valve from its seat.