white smoke burning rubber smell
 

i have a 2001 chevy s10 that sometimes get a burning rubber smell with white smoke. the oil level is fine and has not changed in about a month. also when the smell starts there is white smoke coming from under the hood. it looks like it is coming from under the exhaust manifold heat shield. the weird thing is this only happens periodically but any suggestions would be nice it is a 2.2l 5 speed manual transmission.