Date registered: Dec 2002
Location: Lawrenceville, GA
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RE: 1970 280 se
As you are smelling gas in the oil the first thing you need to do is change that oil! Gas washed oil will do wonders for your bearings, rings, and cam. After changing the oil you then need to ascertain the cause for the gas washing of your oil. The only plus side is that it makes for an excellent engine flush, but the risks and costs are horrendous.
If you let your car idle for long periods of time they are known to do this as an FYI.
Likely culprits for this are leaking cold start valves. Also, if the injection pump is set too rich that too can cause this to happen. Ensure you have the proper spark plugs installed (I recoomend NGK BP6ES provided you have the venerable m130) and that you are getting a strong enough spark. Resistor plugs and a weak spark will cause incomplete combustion and thus lead to gas washing.
Chances are if you have a high mileage car your injection pump is out of calibration and needs to be checked/calibrated by a competent shop. These shops are far and few in between. I trust only one facility in the US.
There is the unlikely chance that the thermostat in the IP is sticking, but generally this will cause the car to flood out when hot as there will be too much fuel for it to stay running.
Lead additives are not necessary as your motor has hardened valve seats.
Mathieu J. Cama
Old World Automotive
Vintage Mercedes Repair and Mechanical Restoration
Serving the Mercedes community since 1986
1961 Unimog 404S
1967 250s (for sale)
1971 280se 5 speed
1978 280slc 4 speed
1983 240d 3.0 4 speed
1984 300d 5 speed (sold)
1985 500sel Euro w/ hydromat
1986 190e 2.3-16
1989 560sec AMG