104 Engine Help ?!

[Essexbenz86]

Hi Guys ,

Great Forum , proved really helpful on my E220 . Now i have a new car and new issues lol and being only my second Merc would appreciate some advice?

I have just bought a 96 w140 S320 , 149k.

Now i have had a number of issues in a short space of time and im hoping someone more familiar with the model maybe be able to point me in the direction of the cause of them and maybe how severe they might be.

OK ,

1) The car has stalled on me during parking manoeuvres more than once , on one occasion 2/3 times in a 30sec-2min period.

2)when staionary if i rev the car as i come off the throttle there is an odd hissing sound as it comes back down the rev range , normal? cause for concern?

3) Today after standing for 3 hours the car refused to start for a few mins , i must have turned it over 5/6 times , then it burst into life and was fine on my 30 mile trip home , first time its done it ...

4) The temperature gets very close to 120 when stationary for a small amount of time , It always returns to normal , again is this normal?

I appreciate anyone with superior knowledge on the model giving me any ideas lol ?

But despite the niggles , i love this car !!

Thanks Guys,

 

[television]

I am wondering if the MAF could be at fault for the stalling, it the same engine as used in the other cars of the same year.


The heating up possible suggest a blocked rad


See what others think

 

[Myros]

in addition to Malcolm

the viscous fan might not be kicking in at the higher temps. or a combination of both.

The non-start sounds symptomatic of an OVP fault. My old 280 occasionally did the same until the relay was replaced.

 

[MechPhil]

You have a vacuum leak. Plain and simple. That's the hissing sound and the stalling.

Finding the vacuum leak can be difficult, and there may be more than one hose or pot leaking, so I suggest finding a reputable Indie (possibly someone known to the other guys on the forum).

The starting problem sounds like flooding. It was very common with the older KE-Jetronic systems, but shouldn't happen with you fully electronic system. It may also be prevented by curing the vacuum leak.

Overheating has many causes, but getting up to 120 is cause for concern. It's either a stuck thermostat, knackered visco coupling, blocked rad or corroded water pump. Personally, on a 12 year old car I'd have the rad removed and cleaned and flush the system as a matter of course. Fisrt test the visco coupling though. When the motor gets up to near 120, stop it and then try to spin the radiator fan. It should be pretty stiff (you should be able to turn it slowly by hand, using a fair amount of force on the fan blades). If it spins freely, the visco coupling is knackered. If the coupling checks out and the rad is clean and it still overheats, it will probably be the thermostat.

If you want to have a go at the vacuum leak, see if you can pinpoint the source of the hissing. It will probably hiss when idling as well, just not as loudly, so get your head right in there and jiggle the hoses round to see if the hissing changes at all. Replace any vacuum hoses that look suspect.

Good luck
Phil