Oil spray

[John Hughes]

I have noticed that when driving especially when it's cool in the evening a fine spray of "oil" seems to eminate from the carbs (1700 XF with 40DCOE's). This coats the offside wings F&R occasionally the screen and the K&N covers. The performance has not gone off (recent RR no probs), oil consumption has not changed etc. The "Oil" is certainly comming out of the carbs / air filters (doesn't appear to be K&N air filter oil)

The "oil" has a strong smell of petrol

The car is run on ESSO LRP.

The only thing I can think of is blow back from the carbs of additives in the petrol

Any other ideas / possible causes ??

[Peter Carmichael]

The oil *is* petrol.

 

At certain rpm, when the engine is just coming on cam, you get a phenomenon called "stand-off". This is when the carbs are at their noisiest (about 3500-4000rpm). There are strong pulses in the inlet tract and the mixture gets bounced out of the carbs and you can see a cloud of petrol vapour just outside the filters. In cold weather, this is more likely to condense into visible droplets.

 

This is perfectly normal for a carb-fed car with a reasonably hot cam. As long as the jetting is OK the engine will be running fine and this is perfectly normal.

[Roger King]

I'll second Peter on his reply, but just add that anything allows the engine to go off tune - ignition timing, poor compressions, mixture problems, etc, can make the problem worse. You can see the phenomonen sometimes when an engine is on dyno test without it's air filters - there can be what looks like a cloud hanging around near the ram pipes.

 

Sometimes it can be reduced by changing the induction length, but this may or may not lead to other problems.

[John Hughes]

Many thanks for the reassurance

[Morrison]

I have a similar car and have had the same problem a couple of times. Mine was after sustained revs on the Motorway so when the engine was kept warm. Is the same thing and is it ok ?

 

 

[Robster]

I have found this but it usually becomes noticable (oiled windscreen) when one of the carbs rattles itself out of balance. Careful balancing every so often seems to control it reasonably.