380SLC - 1980 model- auto gearbox

[devsi]

Hi I have a Mercedes C107 -380SLC- a 1980 model: the car holds 3 bar oil pressure when driving however when in gear at idle with the brakes on , the pressure drops to 1 bar and car seems to 'shake' and it seems as if the engine wants to stalls. Please advise how to cure this.

 

[Druk]

1bar is common oil pressure at idle and nothing to be concerned at. It might need the CO checked which has a significant effect on idle speed, or there is an air/vacuum leak at the manifold but get the CO checked first.

 

[grober]

It sounds as if the engine fuel injection system is failing to compensate for the extra load placed on it by the torque converter when the car is in gear. This is causing the engine RPM to drop and a consequent drop in oil pressure. you need to check why this is happening. Many of the cars of this age systems depend on manifold generated vacuum for operation. Thes can often develop leaks and cause problems- This might be a good place to start? this is a good book.
Product: Mercedes-Benz 350 and 450 (71 - 80) (USA)

 

[devsi]

Thanks Gents-i have no tools etc: can anyone recommend a classic car MBZ mechanic in Bishops Stortford, Herts area? Thanks

 

[219]

What RPM is showing on the Rev counter when the car is idling in neutral and in drive ?

 

[devsi]

Went out for a drive to recheck and it's after driving 15 mins or so when this happens: when in gear at idle its at about 700rpm and just slightly over 1 bar pressure and the car starts to 'shake'

 

[grober]

After 15 minutes the engine will have warmed up fully meaning that any initial mixture enrichment which the engine injection system will have imposed during warm up will have ceased------ which points to a weak mixture--- this means the engine is not being fed the correct air/fuel ratio when its idling when fully warmed up.----- which implies an air leak somewhere in the inlet system or the vacuum system attached to it. As Druk suggested a CO measurement would show this up.

 

[devsi]

Graeme- many thanks. Regards Devsi

 

[claggy001]

Thanks Gents-i have no tools etc: can anyone recommend a classic car MBZ mechanic in Bishops Stortford, Herts area? Thanks

For a MB indy I can thoroughly recommend Alex Crow who is based in Stowmarket; he's about the same distance from you as he is from me.
However, as your car isn't full of modern electrickery you may be just as well to try a good classic car garage. I've previously used Richard Shrive, who is based in Greenfield, Beds - in fact he rebuilt a TR6 for me a few years ago.
He often has 'Youngtimer' cars in stock & often sells W107s.
Hope you get it sorted.

 

[devsi]

Thanks for the info