My 1993 SC400 is overheating. The thermostat was replaced with new oem but it still overheats. The top coolant hose that connects to thermostat housing is cold while engine is running. After disconnecting the coolant hose and removing the thermostat I do not see any coolant flow even though the coolant level is fine. I suspect that the water pump does not pump the coolant and should be replaced.

Should I check anything else? Please suggest.

 

Did you burp the system?? my suspicion is air in the system therefore you're overheating

 

If it does need burping as Tally has mentioned it would help to raise the front end maybe drive it up on ramps. This helps get the air bubbles to the highest point for burping. Good luck.
Bill

 

Thanks for the suggestions. I will follow your directions this weekend to let the air out from the system and let you know about the results. Cheers!

 

Make sure you have heater full blast

 

yes, assume air in coolant system to blame first, read up on all the tips to remove it, and do it carefully and completely. Smallish investment in no-spill radiator funnel kit is great idea to do it easiest and most effectively.

harbor freight has one from Pittsburg brand that has worked for me across my sc300, rx330 and Volvo s60 for last few years. Probably not much cheaper than brands like lisle on Amazon.

in sc300 layout, thermostat is located where lower coolant hose meets engine block and when open, it allows flow from block into bottom of radiator. If thermostat stuck closed and or air pocket in system, it’s probably also blocking that channel. Your lower hose will be cool or a little warm and upper will be scalding—sign of air pocket or stuck closed thermostat as first likely guess.

you also gotta have working radiator, coolant in system, operating radiator cooling fan, working water pump, maybe coolant temp sensor as small issue, working fan clutch. There’s chance u got bad thermostat or you put thermostat in wrong orientation too. Chance for bad radiator cap as issue also!

You have an sc400 but … it seems easy for air to get into our sc300s and cause problems. I’m convinced air can enter system by cracking open radiator cap while system partially pressurized, but that just my experience.

 

The engine stoped overheating. This issue was caused by the water pump impeller. It wasn’t spinning. Since we replaced the WP the engine temp stays normal.