i have a 7.5 onam diesel generator that runs for 15 min and shuts down i get a code 33 (overheating)I change coolant,cap and thermostat also checked air flow Still no luck.any ideas anyone
If it has a waterpump you might need to change that.
The onan fault code 33 is high engine coolant temperature fault
This may sound stupid, but check the belt. Make sure it's actually on there. The Onan QD's sometimes throw a belt. I have seen them break too. Make sure that's on. You may have an internal water pump issue as well - impeller fell off, etc (rare but possible). Another issue could be a blocked radiator. If your radiator is blocked with sludge, you may not even know. I usually check various spots on the block, thermostat housing and radiator while running with a infrared temperature probe to see if it's actually getting hot BUT BE CAREFUL doing that because there's a risk of damaging your unit. That's actually a last resort thing. It may just be a bad high temp switch. But make sure everything else is right first. Full radiator, belt, t-stat (you already did). Oh, I just thought - make sure you have the right temp t-stat in there. The one I have in the shop (1997 7.5 Kw HDKAJ Spec D) takes a 71 Degree C (160 degree F) one. Anything higher will set off the high temp system I believe.
