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thermostat

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thermostat

Postby bongli » Sat May 17, 2014 2:22 pm

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!
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Re: thermostat

Postby geeves » Sat May 17, 2014 2:43 pm

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
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: thermostat

Postby bongli » Sat May 17, 2014 3:07 pm

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?
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Re: thermostat

Postby bongli » Sat May 17, 2014 3:19 pm

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

Postby geeves » Sat May 17, 2014 9:21 pm

common head problems are bubbles in radiator and possible coolant loss. Its rare on this engine to get coolant in the oil.
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: thermostat

Postby bongli » Sun May 18, 2014 4:09 pm

Thanks again geeves. I'll watch for those bubbles.
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Re: thermostat

Postby BrianR » Mon Oct 12, 2020 4:54 pm

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
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Re: thermostat

Postby geeves » Tue Oct 13, 2020 5:44 am

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
Sanding your knuckles before starting work can help. That way you cant skin them
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what is the viscous fan

Postby BrianR » Fri Nov 20, 2020 10:51 am

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
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Re: thermostat

Postby geeves » Fri Nov 20, 2020 3:26 pm

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
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: thermostat

Postby BrianR » Mon Nov 23, 2020 6:43 am

Hi Geeves, Thanks for that information. The fan is plastic and it does turn fairly easily by hand. Checked the copy of the manual I have but cant find any info on the fluid. I cant see any obvious place to put the fluid but will have another look and what fluid do you use? Kind regards, Brian
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Re: thermostat

Postby geeves » Mon Nov 23, 2020 4:27 pm

They are not designed to be routinely refilled. The first thing to look at is whether the 2 halves are riveted or screwed together. If its riveted replace as a unit. If its screwed first find soomewhere that sells viscous clutch fluid. Only place I know in NZ is BNT but over there ? Take the fan off remove the fan from the unit and then undo all the screws and place both parts overnight on thick newspaper. This will drain out most of the burnt fluid. Its like runny honey in viscosity. Then take the fluid which is probably supplied in a syringe and squeeze as much as you can into both halves then quickly put the 2 parts together and put all the screws back etc
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: thermostat

Postby BrianR » Tue Nov 24, 2020 5:49 am

Hi geeves, Thanks so much for all your help and information. Kind regards Brian
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