300 SDL mistery leak: What is this? - PeachParts Mercedes-Benz Forum

julio.garcia.fc · #1 08-20-2011, 12:13 PM

Hi,

I am very new to my car and still trying to learn. I hope my questions are not too dumb. I am chasing a leak and I think I traced it to this brown cap, which seems to be loose.

What is it?
Is it OK to just tighten it?
I do not think I can get the tab all the way around to tighten it all the way down, which puzzles me.
Should I worry about it?

The leak, if coming from here, is a clear'ish, oily liquid, but it does not smell like diesel. My fluids seem to be OK. Any clues?

Here are a couple of pictures of the location of the cap and the brown cap itself:

sixto · #2 08-20-2011, 12:30 PM

That is the connector for the control rod sensor in the IP. It is common for the o-ring to fail allowing engine oil to seep out. It has a bayonet collar holding it to the IP. It might be the collar that feels loose to you. Otherwise, turn the collar clockwise until it clicks to be sure it's properly in place. The position of the bayonet lock has no influence on the o-ring. If it's leaking, it's leaking. There is no practical solution other than wiping the leak since the o-ring is replaced from inside the IP. As mentioned, there is engine oil on the other side of the o-ring. If you see clear fluid, it's not coming from that connector. In fact the closest clear fluids to that connector are coolant and brake fluid.

Sixto
87 300D

julio.garcia.fc · #3 08-20-2011, 12:59 PM

My brake and coolant are perfect. Don't think that is leaking. There is definitely a very slight seeping out of that area. I will not worry about it just keep it clean'ish. I tightened the cap.

The fluid also did not quite smell like the coolant and brake fluid. It did seem to have a peculiar smell. Where it had pooled, is too high to be transmission fluid. I should have take a picture before cleaning it. It will be a couple of weeks before it collects again.

sixto · #4 08-20-2011, 02:24 PM

I was being facetious about coolant and brake fluid. If there is clear fluid, it has to be fuel from the injector lines that pass above that connector. But you say it doesn't smell of fuel.

Sixto
87 300D

julio.garcia.fc · #5 08-20-2011, 11:36 PM

Ouch