thermostat

[bongli]

Hello everyone,
I've been troubleshooting an overheating problem and one mechanic here suggested to remove the thermostat. The bighorn was overheating before during stop and go traffic and climbing hills. I have removed the thermostat. Tested the bighorn again in more or less the same condition of traffic and hills. I noticed the temp gauge does not go more than half of the gauge anymore. What are the consequences of my action? I dont really notice the difference in warm up time before and after. Thanks!

[geeves]

lay money on the real cause being a faulty viscous fan. You can buy replacement fluid. It could also be a blocked radiator either inside with rust etc or outside with mud. It could be a faulty water pump.
Thermostat is more about emissions and a faster warm up in colder countries. Not recomended to remove it but not that damaging either.
Also a leaky head can cause this but I dont think its your problem

[bongli]

Thanks Geeves, its good to know that removing the thermostat won't give me future troubles. Warming up has never been a problem here in the Philippines. I do not notice any black smoke coming out except when I suddenly step on the pedal. I recently did, some 5000 kms ago, cleaning of the radiator when we changed the timing belt. The remaining suspects are water pump and thermostat. I tried to boil the thermostat and it open before the water boiled. I guess the openning temp was correct at 82 deg C. Its hard to find bnew water pump and thermostat here. I'll try harder. Is it correct to assume if i have a broken head, i will lose coolant and this coolant will go to the oil sump?

[bongli]

Also, the viscous fan was hard to rotate when the engine was warm.

[geeves]

common head problems are bubbles in radiator and possible coolant loss. Its rare on this engine to get coolant in the oil.

[bongli]

Thanks again geeves. I'll watch for those bubbles.

[BrianR]

Hi, I have a 1994 Elf truck with a motorhome conversion, 4Jg2 3l diesel engine. Maybe a member can help. It runs fine all day at around 80Ks but on long hills the temp gauge goes up to high(not in the red) but as soon as I level out it drops back to mid range. The vehicle is a Japanese import to Australia in 2014. Is this a problem? I was thinking that the thermostat may be designed for Japan and it may require a different one to handle the higher temperatures in Qld. Regards, Brian R

[geeves]

Options are failing viscous fan. You can replace the fluid in these. Blocked radiator either internally or externally corroded water pump. Is it Auto? A failing auto can cause overheating

[BrianR]

Hi Geeves, Can you tell me where is the viscous fan and where do you check the fluid level? sorry to be a dummy. The vehicle has a 4JG2 engine. Brian

[geeves]

The fan on the front of the engine is probably a viscous fan. I dont know for sure in the Elf. If its plastic and turns with the engine its probably viscous. Cant check the level in it but the fluid is more likely to burn than leak. If the fan turns easily the fluid needs replacing