overheating issue

yesterday as i was sitting at a light, in traffic, i glanced down to see my coolant temps a lot higher then usual.
the guage didn't hit the red but had i sat there a little longer it probably would have.
so once i seen it i turned off the a/c, turned into the the u-turn lane and went into the nearest parking lot.
but even before i got there the gauge dropped back down to normal driving temps.
i put the truck in park and i sat there for a moment, then raised the hood, no steam coming out, to see if could see a leak or anything.
no leaks or anything.
get back into the truck and get on my way.
i left the a/c off and the temps never raised again.
a guy on another forum said something about checking my wp but how do i do that?
but would it even be that if the temps stayed down after turning off the a/c?
btw, i still have the clutch fan.
maybe my fan clutch is going out?
i've replaced it once already with a used unit and never had temp problems until now.

ya thats an interesting problem, might possibly be a fan issue. not sure really, i have e-fans so one is on constantly when the A/C is turned on.

I'm sure someone on here can tell you how to check that.

Otherwise its time to get E-fans and call nelson performance up.

how hot out was it when this happened?

what mods do you have? i am fully bolted with H\C with e fans, sat in traffic today cause of a accident up the road sat for like 10 to 15 minutes before i decided to turn truck off temps came up to 230-240 decided to start truck back up to see how high the temps would rise, well it never passed the 240 mark.. but once i started moving temps went back down, remind you i have NO ac, lmao and it was freaking hot this morning..

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Originally Posted by 99sierra4x4

how hot out was it when this happened?

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my mirror temp was changing between 101 and 97 degrees

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Originally Posted by skeet

what mods do you have? i am fully bolted with H\C with e fans, sat in traffic today cause of a accident up the road sat for like 10 to 15 minutes before i decided to turn truck off temps came up to 230-240 decided to start truck back up to see how high the temps would rise, well it never passed the 240 mark.. but once i started moving temps went back down, remind you i have NO ac, lmao and it was freaking hot this morning..

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cammed w/ cai, pulley, exhaust

Don't the pulleys slow down the water pump?

only has a crank pulley so i don't know if it slows down the wp.

Since everything runs off the crank pulley slowing it down slows everything down.

i thought that a smaller pulley would speed up the crank????

drove the truck in this morning w/o problems.
the only thing is it wasn't as hot outside as it was that day.
so this afternoon we will see how it handles the heat.

That happened to me at about 130k miles and it turned out to be blockage in the Radiator. Maybe hit it with a heat gun and see if yuo get any hotspots. Mine would only get hot at hwy speeds and only on some occassions.

dont know what to tell ya, i have a cam, and headers, and e-fans, i run mine all day long, in traffic, it was like 96 out the other day, and never even went past the normal operating temp. i would definately check to see what your coolant level is like, maybe try flushing the system with a hose.

I have to work on my heater core, its getting down to the 50's at night and im going to need heat when the snow hits.

The crank is what drives everything else...

Check the thermostat.They sometimes hang up.If there is a shiny spot on the inner pole replace it.

well i checked my fluid level and it was a little low.
i wouldn't think that being less that a cup low would make it start overheating.
since i filled it up i haven't seen the temps go up.

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Originally Posted by GasGuzzler

The crank is what drives everything else...

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correct but by putting a smaller crank pulley doesn't that speed up the other pullies?
maybe i'm not getting the science behind the UD pulley.
can you explain to me how the UD pulley works? (very serious)
i'm here at work asking a co-worker and both of us are a little stumped. LOL

Think of it this way...if two cars are going around the same corner, the one on the outside has to travel a little faster to stay in the same relative position as the other car. If you increase the size (radius) of the corner, the outside car has to travel even faster to keep up. On a UD pulley, you are effectively decreasing the "size of the corner"...since the outside diameter of the pulley has to travel the same speed as the inside diameter, making the pulley smaller effectively reduces the "outside velocity". That's why UD pulleys are popular...you don't use as much energy/hp turning them.

so the rotating speed of the crank is constant?
but the speed of the pulley is changed....correct?
am i getting warm or i am cold? lol

The crank speed will obviously change with the speed of the engine, but the crank pulley speed will also change appropriately. Regardless if it's spinning at 1 rpm or 6000, the outside edge of a smaller crank pulley will travel slower than the outside edge of a larger crank pulley. Since this is where the belt travels, the belt will travel slower around a smaller crank pulley than a larger one. Here's a link to some good info on underdrive pulleys: Underdrive pulleys - Wikipedia, the free encyclopedia

cool thanks for the link!

in the past when i had problems like that i would turn my heater on high/hot to help remove any heat from the engine. not pleasant in 100F weather but if the air coming out of my heat was not burning hot i knew the coolant was really low.

i would say get it hot like that again and pop the hood to see if the fan is running fast. if you get elec fans and have an overide switch to get both fans on high it would probably get rid of the issue.

but i would also change the thermostat because it sounds like it wasnt fully opening. full flush and new thermo cant hurt.

When the DRIVE gear or pulley is decreased in size, everything it runs will slow down. If the DRIVE gear or pulley is increased in size, everything it drives will speed up.

If a DRIVEN item gets a larger pulley, it (and only it) will slow. If a DRIVEN item gets a smaller pulley it (and only it) will speed up.

^^^yeah, that too! Big difference betwen driven and driving when it comes to pullies...thanks for the clarification

Quote:

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Originally Posted by GasGuzzler

When the DRIVE gear or pulley is decreased in size, everything it runs will slow down. If the DRIVE gear or pulley is increased in size, everything it drives will speed up.

If a DRIVEN item gets a larger pulley, it (and only it) will slow. If a DRIVEN item gets a smaller pulley it (and only it) will speed up.

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so DRIVE pulley = crank pulley
and DRIVEN pulley = accessory pullies
got it!
thanks

That's it.