tank collapse
 

fuel tank in my 1983 300d collapsed ,, i used some tank sealer to hopefully stop the leak that was created(small crack where the tank bent in) so far no leak...all due to vent line totally blocked...still a very little woosh sound when i remove fuel cap...supposed to be like this? tried searching forums...thanks again everyone...clean your vent line!!!

wow im going to actually unclog mine this weekend, no more putting that one off :eek:

Sounds like you have a very good lift pump!! :eek:
I didn't know the tank would collapse like that.....

crazy!!! supposed to be a slight release of air when removing cap?...way better now than used to be but now i'm on the paranoid side

Note that I've driven the same model for 25 years.
Never heard a whoosh sound when removing fuel cap.

Any airflow sound means the breather is still restricted. The tank should have less than 1psi pressure or 1"Hg vacuum if the breather and tank cap are working correctly. If you have the plain engine oil style cap you should get the correct cap made for the fuel tank that has a pressure relief vent built in.

Oil:
http://12.153.160.115/images/catalog...244700005A.jpg

Fuel:
http://12.153.160.115/images/catalog...44700005OE.jpg

Seems strange mercedes would even have the vent under the car where it is. think it would be up higher.

My 82 Datsun Diesel PU, they run the vent line along the supply and return line into the engine compartment. the vent line then runs across the fire wall over to the pass side and bends down.

The only problem I had with it was a check valve at the fuel tank.
when I would open the fuel cap it would WHOOOSH.
removed the check valve and everything has been normal.

on the MB I have taken the end piece off the vent line and cleaned it a couple yrs ago. just checking things, and to see what it was.
seems like it would pick up dust and dirt as the tank draws in air.

thats my vent on things :D.

Charlie

Are you sure those are not just early and late styles? The Oil caps say 'Oel' on them. My fuel cap looks like the first one and has a mercedes star on it.

Yeah, the tank cap on all of our cars looks like the upper picture, and they all have a star on them, and seem to work fine. My dad's SD had a whooshing problem, but we cleared out the tank vent and it solved the issue...

From the cd shop manual for 602/603 , section 47-0030. With normal system operation pressure of up to 50mb can be developed in the tank.The pressure part of the vent valve should open between 30-50mb.Should the vent valve fail to open the fuel tank cap will release the pressure if it reaches 100mb.The vacuum valve of the vent should open at 1-16 mb of vacuum. So a pretty good "woosh" when you remove the cap is not an indication of a problem. Don

same here with the top pic, my Fuel cap looks like the top one. Is that lower one a upgrade or newer model that may have came on newer models.