danbob79

Hi, Recently I got my old LS400 up and running. It had been sitting for about a year and just needed a new alternator to get it running. However, after a couple short drives I noticed it was overheating. I've now replaced the temp sender (thermostat) on the radiator and the whole radiator itself but it is still overheating. Also if it gets very hot it will smoke white (from the engine bay not the exhaust). I'm kind of lost as to what could be wrong with it at this point. The oil and transmission fluid levels are good and I haven't seen anything in the dipstick that would indicate a heat gasket. Any advice would be much appreciated.

deanshark

Did you change the thermostat, or just the sensor on the radiator? If thermostat is old it could be stuck closed and not letting the coolant flow through. If you changed it hopefully it's not backwards and it's in the correct position.
The white smoke ya see, is it just steam? You could have a cracked hose somewhere and the coolant is leaking on the exhaust causing the smoke. (steam) Or it could be coolant that was spilled. Which side of the engine does it come from?
Did you bleed all the air out of the system when you changed the radiator? It's hard to get all of it out sometimes. If there's air in the system the temp gauge will rise to the top when it's not even hot. Have the car facing up hill a bit, get car to operating temp, turn the heat on high and make sure the heater valve in engine bay opens up, crack open the fill hole on top of the engine just a touch and the air should release from that spot. Fill coolant tank as needed.
If you have a clog somewhere you can tell by touching the hoses to see if they're hot, or cooler, when supposed to be. Such as the inlet and outlet of the heater core, top and bottom hoses on the radiator, and so on.

CLLEXUSS

If you replaced the radiator, you probably checked everything else like the fan clutch, the thermostat, things like that. White smoke from engine is weird. You can also test the coolant, there are test kits available to determine if exhaust gas is getting into the coolant itself. That's an option to look at. Hopefully you don't have a clogged catalectic converter, but wouldn't make that assumption. But if the coolant is not circulating, the upper radiator hose will be hot and the lower one much much cooler or cold after its warmed up as mentioned. That is for sure a sign that the fluid is not circulating. If it is circulating, then the next thing is the fan, if its not the fan check the coolant for exhaust gasses, if its not that, hmm something is weird, hopefully no the cats. But the white smoke is for sure weird so...if its not steam, maybe test the coolant for exhaust gas.

400fanboy

Where is the white smoke coming from? Need to be more specific about where and what is leaking from the engine. Is it a coolant leak flashing to steam on the exhaust manifold? Is it burning coolant? Oil?

Water pump is possible reason for the overheating. Agree with the above poster about the inlet\outlet hoses from the radiator as a way to test whether it's actually circulating throughout the engine. When was the timing belt done last? This car, for some reason, is systemic for ignoring timing belt service intervals. And\or not replacing the water pump & other typical parts during that time.

timmy0tool

iTrader: (7)

anytime you open the coolant system (such as to replace the radiator) the system will need to be burped of air (bleed) which is not as easy as other vehicles. air in the system will cause overheating!

check out the process in the latter half of the procedure here:
http://www.lexls.com/tutorials/cooling/coolant.html

i found that you need to hold the idle high for 10-15mins to get all the air bubbles thoroughly out. even leaving the water inlet housing open helps the air escape and you can even have the car at an incline nose up. lastly of course you need to have your heater on a full max when burping.

i hope the white smoke is not getting confused for power steering fluid. check the reservoir level!