Hey everyone i have a 2009 G37s sedan. The engine has around 100k miles on it. and my brother just gave me this car. For the last 2-3 years he's been running water through it because it had a coolant leak and it would burn and smell. Its my car now and while driving on the AZ freeway the cars radiator blew up and instantly overheated and shut off before I had a chance to pull over. I towed it home and changed the Radiator and filled it with coolant and it still overheats, I changed the thermostat and it still overheats, I also changed the radiator cap but no effect. So as a last resort I put a stuck open thermostat to see if I just had a faulty one. I think its the water pump but I want to be sure is there any way to test it? or from what I explained is it likely that it is the water pump? Any advice would be great I've only owned the car for like 2 months now.

 

You are using half water half coolant right?

 

1) Have you checked to make sure both of your fans are running normally? IPDM/er Fan Test
2) Prior to replacing the radiators did you run any coolant flush to clean the system?
3) Are you using a 50/50 coolant?
4) Did you ensure there is absolutely NO air in the system? These cars are a PITA to fully bleed air out.
5) When you run the heater is it fully hot or barely warm?

Normally I would say that the water pump is likely fine. These Aisin pumps are extremely reliable and have really low failure rates. However, if your brother ran the car "for 2-3 years" adding plain "tap" water, there could be some residual scale buildup on the impeller fins. Unlikely, but possible.

Unfortunately, my "old school" tricks are useless with these internal water pumps. Maybe someone else will have some ideas.