300 SL-24 M104 non-return valve?

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Active Member
Jul 18, 2010
Borough, London
94 300 SL-24 in Bornite, 2010 Smart Fortwo Passion
Afternoon all.

Quick couple of questions - I've got a 75,000 mile one of the above. Recently parked the car on a sideways slope after a long run and the tappets rattled for a few seconds when starting the engine again.

Guess the oil had run out of some of the tappets, perhaps due to the parking angle? Quietened down after a second or so but it's not something that sounds nice when you think of the tappets clanking around without oil. :crazy:

Does the oil filter have a non-return valve like VW's used to ensure there was oil there from startup, or do they all do this? Not going to cause any harm is it? It's done it once more after a week of being left in my basement car park, but was quieter this time. The engine normally runs very smoothly and very quietly.

Any views greatly appreciated - I know these engines are capable of huge mileages judging by other forum members cars - and hope mine will do the same!

Have a relaxing Sunday,

It is something that sometimes happens - my M103 300TE used to make this noise from startup - but always went away within 3 or 4 seconds of starting - the car ran to 198K and had to part with it due to diff failure in the end - but engine was fine .

My 300TE-24 was on its second engine when I had it , with 60K on the new engine , the original having been replaced at 380K due to high oil consumption . The low mileage engine never made this noise .

I don't know about the non return valve , but as long as the noise stops within a few seconds , the hydraulic tappets seem to be fine - I have heard of people dismantling them and cleaning them out to stop this , but they seem to survive as they are .
Thanks as always guys!

It did cross my mind that there might be something in one of the galleries blocking it a bit, however, the inside of the engine through the filler is spotless with just golden oil, and it's got a full Merc and specialist service history.

As I live in central London and don't have garage faciltiies (communal basement car park) I can't change the oil and filter - but it's only just been done. Is it possible that the non return valve in the filter is failing and therefore the oil runs out?

Am I right in thinking that the filter is in the housing at the back of the engine with the black cover? If so, can one change it without having to empty the sump, and therefore avoid an oil change? Otherwise I'll have to take it to national tyres and provide an original MB filter.....

What do you reckon? Sods law it won't make any difference!

Yes - you should be able to change the filter without draining the sump . You may lose the small amount of oil left in the filter , but this will not be much .

If your main concern is not soiling the floor of the basement car park when doing oil changes etc - perhaps you can put an oil proof tarpaulin down in your parking space before parking on top of it - so as to catch any spillage ? Of course , if T&C of the car park prohibit such activities then it can't be helped . There is at least one DIY garage in London , where you book a bay for the required number of hours and go along to work on your own car - tools are available to rent as well as a qualified mechanic in case customers 'get stuck' . I think only paint spraying , welding and draining petrol are prohibited for obvious reasons . Sorry I can't remember the name of the place - it was mentioned on one or other of the car forums I frequent - but a Google search ought to turn it up .
Just found it - pit start garage - great for reference but I think I'll leave it to national tyres as it's cheaper sending it there than doing it myself! I'll just make sure that when it is changed it's done properly..

You're right re downstairs - my car's next to BD6's, a Ferrari etc and I will get some very odd looks and will be in contravention of my long leasehold if I start doing any more work then polishing it down there! I already get looks for doing that. Bloody bankers :)

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