Why does CO level go out?

[jaymanek]

Just curious... I noticed excess fuel consumption, poor warm starting and occasional puffs of smoke behind me recently with the W123 (Carb Model)... checked the CO level and it was 5%

I set it two years ago at 1.5-2% so what caused it to go out?

I have reset it again so ill see how it performs...

 

[Dieselman]

It shouldn't normally drift out. Check the small breather pipe isn't blocked and that there is either a reasonable amount of friction on the mixture control screw or a spring to hold it.

 

[grober]

Worn valve stem O ring seals? They can go hard and allow oil to enter the combustion chamber. Known problem on the w123 engine.

 

[jaymanek]

there isnt a mixture control screw, you have to undo a 22mm nut and then you turn the shut off valve body which moves the height of the jet?

Thanks Grober, something i did not want to hear... hasnt been burning much oil, but i do get through a couple of litres between annual oil changes..

 

[Dieselman]

Ah, yes forgetting it's a Stomberg/Pierburg 175cd.

First thing check the diaphragm and all the vacuum ports/lines, then the float height.

If it was the valve guide seals it would be smoking blue on the over-run.

Does your car have auto choke, if so check that first.

 

[jaymanek]

well im going to see how it performs now...

I have stripped these carbs a few times, but must admit its been a few years, last time was after jimmys GTG!

Auto Choke is over complicated on these, you could be right that one of the springs or plungers could have gotten stuck..

 

[Dieselman]

Probably the hot water waxstat element has jammed partially on due to lack of use.
If it's jammed apply some heat as that will free it off.