126 engine problems and questions!

[kartman]

I`ve just bought a nice 500 but it seems to have a few mechanical issues
 After a 25 minute drive at speed the cabin was filling with burning oil fumes, when i went to the back of the car a lot of oil smoke was coming from under the engine cover, this was coming from the oil filler cap. The oil breather pipe has a kink in it but is not completly closed, all the oil was gone in the engine!
Anything other than piston rings i could check, the dipstick hadn`t blown out.
Also what are the plug and point gap, it is a Marrelli distributer. I`m not sure if it has a 600 or 650 engine fitted, i know the 650 has a `650` casting in the head but is that at the visible end or in the far end of the engine behind the carb?  Many thanks.............Martin

[GTMaster]

Hi,
The point gap is around 0.5mm, the spark plug gap is ok at 0.7mm.
Try and see where the oil started to leak out from. If it came out from underneath the thermostat housing on the right of the block then it may be the push rod tube seals. Check the air filter too. Could also be that the breather pipe was blocked (or the flame trap was clogged) and the crankcase pressure was too big and pushed out the oil somewhere (oil filler cap?). Check around the muffler backets as oil can leak out from the bolts that go into the engine block ( they can rattle out).

[kartman]

Many thanks for the reply, the oil is blowing out from under the oil filler cap and has left a `misting` of oil in parts of the engine bay and all over the rocker cover
..........Martin

[GTMaster]

Check the bottom of the filler cap. There should be a spring and a plastic plate on the shaft. Also check the seal under the cap to see if it's still like rubber or if it's gone hard or broken.

[kartman]

Many thanks, you may have hit the nail on the head, the plastic disk that should be on the bottom of the filler cap assembly is missing so nothing to stop the oil etc going past. I will try a new cap first........Martin