HI All, i have a 2008 1.2 9N3 and a 2010 1.2 6R 

i have noticed on both of them, if they are ticking over and you open the oil cap the revs drop so low they almost stall,  is this normal? Just wondering if something is wrong? Or a breather is blocked? 

The 9n3 is the 70BHP with 98k on the clock, the 6r is a 60BHP with 117k 

 

any thoughts or suggestions? 

 

Also i am new on here, no idea what the tags part is all about….

Cheers Dean

Normal behaviour on these engines, I think.

 

The breather system is designed to keep the crankcase at a slight negative (below atmospheric) pressure. Because of the way this is achieved, a large air leak into the crankcase is created if the oil cap is removed, and the engine management can't figure out why, as it hasn't changed anything to cause such an influx.

There is a small diameter 'fresh air intake' hose on top of the rocker cover which lets in a trickle, but the oil filler is huge diameter in comparison.

 

If you just loosen the cap without completely removing it, and then pull it gently upwards, you should be able to feel this slight negative pressure in the crankcase, pulling the cap back down against your lifting. 

 

Tags are about improving the searchability of threads by making a couple of key words more easily found by search engines, as I understand it. 

 

 

Cheers thanks