On N7 and R7s check the fuel return on very top center of engine where it is secured with a clamp to see it isn't wearing threw and also check the fuel supply lines to pump that there clamps are not wearing threw line. Also on them machines check the bolts right in between the two heads to see that the washer or flange on the bolts are not cracked. You should scrape with oring pick to verify there is no crack for if they are cracked the head gasket may blow. On all machines check battery positive cables to see they are not rubbing on anything and wearing thin. Keep engine free of any leaks and keep engine compartment clean of any straw, chaff, or oil buildup. Drag a chain to help prevent static buildup especially with flax in the right conditions. Doing all this will drastically reduce chance of FIRE. Have a great day. Dan