I have a 92 ls400 and just finished replacing the timing belt,water pump. I used the lexls tutorial and followed it to the T, after I started the car everything runs fine but after 15 minutes of running the car started to run alittle hot. Then smoke and I checked the hoses and the top was hot but the hose with the thermostat wasnt. I really don't know were to start and would hate to take everything apart cause the pump is bad. Help!

 

did you install a new thermostat or the old one? have you checked the radiator fluid level after running it?

 

It's the same thermostat, as for the fluid I filled the radiator and the resevoir and it didnt go down any.

 

might be a bad thermostat, take it out and run it without it and see if thats it.

 

Great idea. It couldn't be the water pump could it, its new and I checked it before I put it on just not after.

 

i doubt it, unless it is a defective part, wrong part, or you got something into the pump system that clogged it. there are only a few things that cause it to over heat: low fluid, no fluid, or fluid not circulating properly (thats the complicated one). Or a bad sensor or gauge which would give you a false positive..

 

I definitely know its not circulating that's why I think the thermostat is stuck closed. Does anyone know the direction of flow.

 

Is there anyone out there that can give me more advice.

 

Generally, coolant circulates through a radiator from top to bottom. In your 1992, the coolant exits the radiator at the bottom on the PAX side and flows to the engine inlet located just under to right side coil. Your thermostat is located in this inlet. Coolant exits the engine at the crossover pipe at the top front of the engine on the driver side and flows to the top of the radiator on driver side. Here are the pages from the RM showing operation of the system.

 

Just took the thermostat out and tested it in boiling water and it didn't open. I hope a new one solves my problem. I turned the crank to see if the pump was turning and it is, the only other thing I guess it could be is a clog but there shouldn't be nothing clogging it.

 

Same symptoms as when my T-stat was stuck closed. For future reference, for you or anyone, you could have just taken out the bolt on top of the thermostat housing and seen if the coolant was flowing. That's how I determined mine was bad.
Also, when you start a new thread put the actual problem in the title, something like "over heating after timing belt change", that way when people search in the future it will be easier for them to find an answer for thier problem. I know when I search and see "huge problem" I don't think thermostat. Thanks for the cooperation.

 

Well it was the thermostat and thank god it was cause I need my car for work. Thanks for all the help guys.

 

Just bleed the coolant and you be fine . You probaly have air pockets in your cooling system. If upper house hot and lower is cold the thermostat is not open, doesnt nessarily mean the t is bad. You might need more coolant because the thermostat open on water temp and pressure.