R107 500 SL over fueling

[lambo911]

Hi All,

My 1982 500SL it starts fine and idles ok at 650 rpm but the exhaust smells of fuel. When accelerating from low rpm it bogs down a bit but as the rev picks up it is fine. The oil smells a bit petrolly as well.

The cold start valve is working ok and not leaking. And as the idle is fine I don't think it is a vacuum leak.

I am thinking it maybe the injectors leaking and they are probably the originals looking at them, they are Bosch 0437 502 010 and are grey in colour.

Do you think I should just change them all anyway ? They are about £40 each and I'll need the rubber seals too so not cheap to do if that isn't the problem.

Cheers
Richard

 

[lambo911]

Can anyone help please ?

 

[Larkone]

Cant you get then tested before spending out on new ones - can they be refurbed?

 

[Doug1234]

A 1982 engine is always going to smell of fuel , they just do not run as lean as modern cars and if you ran them as lean then they would probably start melting pistons etc.
Any time you get a classic car be it a Mg midget or morris minor or your Mercedes in front of you when driving you will smell petrol fumes it’s just the way they are.
You could just pop into a garage and ask them to take an exhaust reading to confirm if it is an injector issue but I think you will find it’s normal behaviour.

 

[Kudly]

A 1982 engine is always going to smell of fuel , they just do not run as lean as modern cars and if you ran them as lean then they would probably start melting pistons etc.
Any time you get a classic car be it a Mg midget or morris minor or your Mercedes in front of you when driving you will smell petrol fumes it’s just the way they are.
You could just pop into a garage and ask them to take an exhaust reading to confirm if it is an injector issue but I think you will find it’s normal behaviour.

I miss that smell
Do the plugs indicate over-rich mix?

 

[lambo911]

Thank you.

A tester is pretty cheap so I might buy one and check them myself. I also have an ultrasonic cleaner so I could give that a go too.

My car smells of fuel more than it should and with the poor pick up I am sure there is an issue there somewhere.

 

[mattkh]

The cold start valve is working ok and not leaking.

But is it stopping the fuel when the temperature is reached..????

 

[lambo911]

But is it stopping the fuel when the temperature is reached..????

Hi, if I unplug it then it should turn off ? I did unplug it but it didn't make any difference

 

[lambo911]

So I have tested all the injectors and they were absolutely fine. I gave them a sonic clean as well. All the injectors are in and it is running the same

 

[ajlsl600]

A 1982 engine is always going to smell of fuel , they just do not run as lean as modern cars and if you ran them as lean then they would probably start melting pistons etc.
Any time you get a classic car be it a Mg midget or morris minor or your Mercedes in front of you when driving you will smell petrol fumes it’s just the way they are.
You could just pop into a garage and ask them to take an exhaust reading to confirm if it is an injector issue but I think you will find it’s normal behaviour.

My mg 1800 did smell of petrol but once mixture sorted it dont and tail pipe is not dirty. Plugs are all straw coloured. It does require regular setting tho.

 

[Larkone]

A faulty MAF could cause over fuelling and hesitation - had exactly that issue on mid 90s Alfa V6 and an Audi V6. Damn difficult to diagnose. You could try some MAF / Carb cleaner.

 

[lambo911]

I think I have fixed the problem.

So the injectors were fine.
The cold start valve was fine.
I then tested the warm up regulator using a fuel pressure gauge and that was also working as it should.

I pulled one of the spark plugs and it wasn't in a good way, they had never been changed during my ownership so I put a new set of Bosch ones in it and it's now running properly with no hesitation on acceleration.

I say that I think I have fixed it because the new plugs might be coping with over-fueling if that is still happening so I am going to have to run it for a while to see how it goes.

Thanks all for you inputs.

Cheers

 

[mattkh]

I say that I think I have fixed it

I am 100% sure you have fixed it. Well done.
The old plugs were giving you an incomplete combustion, hence the smell of petol in th oil.
Next job.... change the engine oil.

 

[lambo911]

Oil now changed! Running like a dream