Air leak on 1989 300se .

[parkman1]

Hi, I wonder if some-one might be online who would know what is going on under my 300se. It is an '89 300se and when I parked it this evening and got out, with the engine still running, I could hear what seems to be an air leak somewhere around the rear axle on the drivers [left hand side. looking at the car from the front] side of the car.

I looked under the car but all I could see were two what appear to be round canisters just behind the axle near the back wheel, and I think that the air leak is coming from that area somewhere. When the engine is turned off there is nothing to be heard, only when the engine is running. As far as I am aware the car doesn't have air suspension, or am I wrong ?

Maybe someone might have an answer, please?

parkman

 

[stwat]

Hi.

It is probably just the fuel pump you can hear running.

 

[parkman1]

Air leak

Hi stwat, would the fuel pump be that noisy and noticeable ? It is a hissing sound that you can hear when at the rear of the car, and, as I posted on the MB owners forum, it sounds like a bad puncture, or maybe the exhaust blowing.

I think that I will take it to an Indie Mercedes garage and see what they say.

Best regards,parkman

 

[parkman1]

Air leak

Hi, thanks are due to stwat - you were absolutely right about the hissing sound at the back of the car ['89 300se], I spoke to MB in Hoylake, an independent Merc garage, and spoke to Steve. He confirmed that the noise was normal and that it is indeed the fuel pump, and that I should hear it. If I don't hear it then there is a problem, and he said that [a] I should hear it from the rear of the car, that I should not hear it in the car, and [c] if I don't hear it from outside and I do hear it from inside the car then there is a problem with the fuel pump.

So thanks again stwat, and thanks also to Steve in MB, Hoylake.

parkman

 

[stwat]

I'm more that happy to have helped parkman

I just knew it had to be the pump as they are quite noisy. And yer man is exactly correct. You should just about be able to hear the pump prime when you switch on the ignition. Once engine is running you should not be able to hear it at all unless it is struggling due to either being on it's way out, or from a blocked filter. They are very noticeable from outside the car, especially the back.

If you have problems starting and you can't hear the pump prime, then it is 99.9% of the time, a fault with the fuel pump relay. Either bad/dirty connections on the pins or internal cracks to the solder joints on the circuit board.

By the way, the guys over on Mercedes 126 S Class Club - Welcome always know good sources for 126 parts.

Cheers,

Stu