Date registered: Sep 2014
Vehicle: 1975 Mercedes 450 SEL
Mentioned: 0 Post(s)
Quoted: 14 Post(s)
(1) Motor warmed up spray water over intake ( outside naturally ) parts , Intake Manifold , Carb base , all vacuum lines .
Just use a garden hose with low flow and direct the water. If the motor slows its sucking water in a Vacuum leak .
Vacuum Leaks cause poor running and backfire
(2)check the valve clearance . If to tight on intake can cause this backfire
(3) Re Check Compression with a good gauge motor warmed up Dry Test first then a wet test . ( wet test add a little oil to cylinders that are low to wet test wait for oil to spread before testing )
(4) Check for blue spark from spark plug wires to ground when disconnected from plug running . bad change wires .
(5) Distributor Cap