warm running device

[n/a]

Hi all from a long-time lurker. I have gleaned much useful information over the last couple of years, but have generally had a fairly easy time maintenance-wise, but have encountered some issues whilst trying to improve running generally.

Car is a 1969 280SL (RHD) manual.

I decided to pull the warm-running device to bits to r&r, and I immediately noticed that the housing that bolts the thermostat down was a good 5 mm apart (ie. not done up tight and flush) - is this correct, or has the spring slowly forced it apart?

On pulling the thermostat out, I also (foolishly?) pulled the plunger out of the thermostat. It was fairly securely wedged in - now it seems to move in and out freely. If you compress it in, it will slowly work it's way out. Which of these is correct? Is there any way of checking the function of the thermostat?

Finally, on pulling the (aluminium?) valve out of the body, I notice on one side (the deepest recessed) there appears to be the remains of a rubber seal - does this need to be replaced? There is also a sort of circlip above that with a bit protruding a couple of mm. I think that this is the side that should mate with the spring, but if that is so, the protrusion is preventing the top of the piston (with spring) from seating as it looks like it should?

I realise there are lots of questions, and believe me there are many more to come, so thanks in advance for your answers,

Matt
Edinburgh

[George Davis]

Matt,

unfortunately I don't have the WRD apart to confirm any of this, but I believe the end of the piston with the bit of rubber in it goes toward the thermostat (i.e., faces up).  The rubber may be the remains of a small seal that is on the end of the thermostat.

Pulling the rod out of the thermostat was probably not a good thing to do.  I'd guess that now there is a small pocket of air trapped under the rod, and that is what makes it slowly extend when you push the rod in.  It might work just fine as it is, but the 280 thermostat isn't terribly expensive, so replacement might be the best way to go.

Thermostats can be tested by heating in a pan of water.  As the temp rises toward about 80 C, the rod will push out.  In your case, that bit of air in there will make it hard to test.

Don't know if the attached pic is helpful, but here it is:



Download Attachment: WRD4.JPG
76.26 KB

George Davis
'69 280 SL Euro manual