water tempreature guage.

[andy]

My tempreature guage has stopped working,is there any tests i can carry out to find out what part,or parts are the cause.
Or is it just a case of replacing the guage,sensor,and wire.
Have had the head off,recently,but worked fine for a week after,
car is a 71 280sl U.S.
Thanks,Andy.

[Jonny B]

Andy,

The gauge is a one piece unit, from the sensor to the gauge face. You can try pulling the sensor out of the head, and using hot water to test it, but generally if it is not working there is not much you can do except take the unit out and get it repaired at a place that does this kind of work. There have been a number of discussions on the site about the temperature gauge, and you should be able to use the search function, limit to the "General Discussion" topics to find out more information. You may have knicked the tube when you had the head off, and had a slow leak of the capillary tube.

Jonny B
1967 250SL Auto

[glennard]

Hi, If it is a 'filled thermal system', they probably broke the tubing when 'they' did the head work.  The place where the tubing meets the bulb on the head mounting is where it usually is over-flexed and breaks.

[glennard]

Hi, If it is a 'filled thermal system', they probably broke the tubing when 'they' did the head work.  The place where the tubing meets the bulb on the head mounting is where it usually is over-flexed and breaks.

[andy]

Cheers for the help,mine looks like the one piece type.I was just wondering if there could be any other reason for it to pack up,bad earth?some relay somewhere or another? (not fuse) Jonny been a full member for a few years now and have used the search system many a time,but got back zero info on this subject,even tried different phrases?
Thanks again.

[merrill]

andy,
if the 280 is anything like the 230 then there are no electronics involved.
I sent mine off to palo alto speedometer for rebuild.  works great now.  

matt

Matt
Austin Tx
66 230 sl - "white"
78 300 D - Blue
98 C230

[rwmastel]

quote:Originally posted by merrill

If the 280 is anything like the 230 then there are no electronics involved.  I sent mine off to palo alto speedometer for rebuild.  works great now.

Andy,

Matt is right, it's not an eletronic gage, it's all mechanical.  The gas in the tube that runs from the engine to the gage get's hot and moves the needle.  As suggested, do a search on "capillary tube" and you'll see what everyone else has to say about this issue.

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[ja17]

Hello,

Head removal, can result in straining or crimping the capilary tube. Vibration from the running engine afterward may have finished off the damaged tube. Once the gas escapes the guage will no longer function. Drop the sending bulb in boiling water to test the unit.

The fix is very tricky, most often left to a repair service. Check you MB dealer first since repairing a bad unit can be cosrly also consider the shipping back and forth to a repair shop in the final cost. The dealer will  charge only for the new part. Get a discount from a MB dealer if possible.

Joe Alexander
Blacklick, Ohio