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ratty

Inaccurate Temp Gauge ?

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I can't tell exactly what is going on. It started a couple of weeks ago, but while sitting in traffic, my temp gauge will start to rise pretty quickly and climb. While driving, my temp goes back to normal operating temp. I checked my hoses and water pump with an infrared thermometer and they were different from what the gauge read. Any other test I can do? I have a new radiator and triple electric fan set up. The water pump is new and I'm pretty sure the thermostat was replaced when the engine was rebuilt. 

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Do you have a temp gauge with numbers or just a C and H?

 

If its number what is it actually reading? Have you ever let it sit and idle to see how high it goes? 

 

The temp gauge reads from a sender located in the very way back of the cylinder head where it is hottest.

 

How are your fans controlled? Do they push or pull air through the radiator?

 

 

This is slightly on the cold side of normal. Any where between this and 210 is normal running temp. 195° being ideal.

 

 

IMG_0293.jpg

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Cooling requires air movement through the radiator. The condition you describe (heating up when stopped, colling down when moving) usually indicates that the viscous fan clutch isn't doing its job and turning the fan fast enough to move the amount of air needed for cooling when the vehicle isn't moving. Since you have triple electric fans, I assume you don't have a mechanical fan with (or without) a viscous clutch. But ...

 

The MJ radiator is only wide enough for two fans of the stock size, so if you have three they must be smaller. How many normally run at the same time? Have you verified that they're working? The symptoms suggest that your fans aren't moving the air through the radiator.

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Sounds like you have air in the cooling system or are low on coolant.  Try adding some coolant and burping it.  

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The gauge may not be accurate to a scientific level, but it is accurate enough. What it is showing you is that the temp is fluctuating at a stop.
The laser temp guns are neat but you’ve got to find the right spot to get readings consistently because they usually read all over from one extreme to another.

My guess would be your not getting enough air flow at a stop, and the temperature rises, factory gauges can be off a few degrees but normally they are accurate over all.

If the radiator is clogged or the water passageways are gunked up there might be other issues causing the fluctuations.

If you coolant is good and clean, water pump is good and belt is tight, I’d assume it’s air flow related, unless I could see some problem with the radiator.

Of course if you have trapped air in the system you’ll see temp spikes at idle, which can just be a pocket of air to the extreme of head gasket allowing gas in.






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19 hours ago, ftpiercecracker1 said:

Do you have a temp gauge with numbers or just a C and H?

 

If its number what is it actually reading? Have you ever let it sit and idle to see how high it goes? 

 

The temp gauge reads from a sender located in the very way back of the cylinder head where it is hottest.

 

How are your fans controlled? Do they push or pull air through the radiator?

 

 

This is slightly on the cold side of normal. Any where between this and 210 is normal running temp. 195° being ideal.

 

 

IMG_0293.jpg

 

I have a gauge with numbers. I'm running my truck at about 190/195. When in traffic, it starts to rise to 210 and above. I haven't let it rise too much passed that without movement or blasting the heater. Haven't let it sit at idle for too long. When it's parked I don't have the issue. The fans seem to kick on. My fans are controlled by a thermometer resting in the radiator and they pull air through.

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19 hours ago, Eagle said:

Cooling requires air movement through the radiator. The condition you describe (heating up when stopped, colling down when moving) usually indicates that the viscous fan clutch isn't doing its job and turning the fan fast enough to move the amount of air needed for cooling when the vehicle isn't moving. Since you have triple electric fans, I assume you don't have a mechanical fan with (or without) a viscous clutch. But ...

 

The MJ radiator is only wide enough for two fans of the stock size, so if you have three they must be smaller. How many normally run at the same time? Have you verified that they're working? The symptoms suggest that your fans aren't moving the air through the radiator.

 

All three are on all the time usually. They seem to be working, but maybe not fast enough. 

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It doesnt get hot when parked, but does when in traffic. Hmmm. 

 

Can we get a picture of your fan setup?

 

How many miles do you have on the rebuild? A fresh engine can run a little hot until its fully broke in.

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On 3/5/2019 at 6:27 PM, ftpiercecracker1 said:

It doesnt get hot when parked, but does when in traffic. Hmmm. 

 

Can we get a picture of your fan setup?

 

How many miles do you have on the rebuild? A fresh engine can run a little hot until its fully broke in.

 

I can't grab a picture right now but its the triple threat fan set up from FF Dynamics. I have about 11,000 on the rebuild. 

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9 minutes ago, ratty said:

 

I can't grab a picture right now but its the triple threat fan set up from FF Dynamics. I have about 11,000 on the rebuild. 

 

Wow!

 

rs=w:600,h:600

 

Three tiny little fans, and they claim that it will maximize cooling and increase air flow by 30 percent. Which is ridiculous, since it's the same radiator. It looks to me like that setup will reduce the airflow by at least 30 percent compared to a factory double fan setup.

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1 minute ago, Eagle said:

 

Wow!

 

rs=w:600,h:600

 

Three tiny little fans, and they claim that it will maximize cooling and increase air flow by 30 percent. Which is ridiculous, since it's the same radiator. It looks to me like that setup will reduce the airflow by at least 30 percent compared to a factory double fan setup.

 

That's the one. The radiator already failed and I couldn't repair it because it's aluminum. Already had to replace the control module too because it shorted. Can't say I'm really happy with that purchase, but I didn't know what I was doing. I was thinking about sticking the stock fan system back on. Don't have time and money to keep messing with it. 

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