1975 w115 240d Questions.

[Benji Chemist]

Howdy!

Ive just bought a 1975 w115 240d and for the life of me cant figure out a few things! Ive been searching several forums over the last week but i just cant seem to find out the answers to a few things that are bugging me so any help would be massively appreciated.

Firstly, can anyone tell me what the combo is on the heater controls, its fine atm but i cant seem to figure out what does what exactly. I realise the central turn nob adjusts the front vent defroster but the vents in the centre dash seem to only blow cold (whilst the defroster blows hot). Also the footwell are getting warm air.

Secondly, i seem to have a leak of oil coming from the top of what looks like the power steering reservoir, its a reddish liquid that is making its way out of the top fly nut and coating everything round it. Any guesses on the best way to fix this, ive read that replacing the standard washer with a rubber one may help?

thirdly, whats the right level for the engine coolant? i open the radiator and liquid is sitting just about the metal but i cant see any line or anything to figure out where it should be.

Lastly, i have a small oil leak sitting just behind the sump. the previous owner seems to think its a leak from the servo but it looks like engine oil to me. There seems to be a rubber gasket on the backside of the sump (drainage i guess) so im wondering if this may be the problem. Need to fill her up again and see exactly where its coming from...in the meantime whats the best oil for her? i live in norway so it gets cold here pretty soon so was thinking 10 40 for the oil, that sound right?

Any help greatly appreciated!

[gmog220d]

Hi Benji,

Welcome to the forums! We'd love to see some pics of your car. There are a few W115 fans around here.

The center dash vent lets in fresh air all the time. If you don't want cold/fresh air coming through it simply close it by using the slider/lever. Then you should have heat coming in through the other vents as you choose by operating the control panel sliders, and the levers on the side vents. I've attached a couple .pdfs that should help you understand what does what.

I like the center fresh air vent. After the interior gets good and warm it's nice to let in some fresh air.

Not sure about the power steering reservoir. My '74's reservoir develops a layer of oil over time, but it doesn't pool anywhere. There is no washer of any kind between the thumb screw and cap (need to check that in the parts list). I wipe it down with a towel when it needs it. Maybe yours is over-filled?

Fill the radiator up to the bottom of the opening. It will come to a level on its own. This system lacks a external expansion tank, so some air in the radiator is normal. The level should be well over the core.

Post a photo of the oil leak, if you can.

[Shortsguy1]

You can read the entire owners manual here:
Mercedes-Benz Model 114/115

and the official MB workshop manual is here:
Mercedes-Benz Model 114/115

Sorry those links appear the same. They take you to slightly different websites.

[Sugar Bear]

The power steering reservoir has a filter in the bottom. It is probably clogged. Try removing it for now and get a replacement. Good luck !

[Idle]

Originally Posted by Sugar Bear

The power steering reservoir has a filter in the bottom. It is probably clogged. Try removing it for now and get a replacement. Good luck !

When you open the top you will not see the filter. Look for a filter online before you do this and you will likely see a photo of one somewhere. They don't look like a 'filter' as they are just a ring of fiber that drops into the P/S tank.

But filter they do, and when they get clogged up, and they will, then need to be replaced.

The good thing is they are cheap and last for years. They are also simple to replace. The only bad part is getting the power steering fluid off of you fingers after you are finished.