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Over heating

R

Rodd

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Location
Antelope, CA
I was just up in the mountains with my kids doing some off roading nothing extreme. Forest service roads that need 4x4 to get through. I was doing about 5 mph up the steep rocky roads and on my way down I noticed my check gauges light was on and my temp was on the next longest line between 210 and 260. As I climbed hills it got higher. We were between 4 & 5k feet elevation and the temp was between 85-90. I did replace the water pump and flushed the whole system about 10 months ago so everything was good there. I was also running my A/C which probably contributed to the overheating. Is this a normal thing for you guy's that use your 4x4 in the heat?

Thanks!
 
I hit 230 in my '95 on a boulder hopping crawl up Lightning Gulch peak (9500') east of Big Bear. Ambient temp was in the high '70s that was pre Heath cooling upgrade. Just not enough airflow with the stock fan combined hard work and low speed. My son is reporting that it's staying waaay cool now with the Heath cooling kit. Just need to get the ATT and chip to finish it.
 
Big T said:
I hit 230 in my '95 on a boulder hopping crawl up Lightning Gulch peak (9500') east of Big Bear. Ambient temp was in the high '70s that was pre Heath cooling upgrade. Just not enough airflow with the stock fan combined hard work and low speed. My son is reporting that it's staying waaay cool now with the Heath cooling kit. Just need to get the ATT and chip to finish it.
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That is what I was hoping was the problem. It hit 260 for a minute I think when I notice it.
 
Not good, wouldnt do that again. You need the Dmax fan and new fan clutch, shouldnt ever get to 260.

If youre not going to be in freezing temperatures you can flush the coolant and just refill with water, 10% coolant, and a bottle of watter wetter or hyperlube stuff. This will cool much more efficiently.
 
How clean is the radiator? How old is the fan clutch? A new clutch and the DIY fan clutch mod should help.Stock fan moves a lot of air if fully engauged and rad. is clean.
 
bk95td said:
How clean is the radiator? How old is the fan clutch? A new clutch and the DIY fan clutch mod should help.Stock fan moves a lot of air if fully engauged and rad. is clean.
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Yep - that's on my mind, also.

If your rad isn't amazingly clean (and if you haven't pulled it out and cleaned it, it isn't), then you will overheat.

If the spring on the front of your fan clutch has any crap on it ... you'll overheat.

In both cases, air has to get through the rad to get to the fanclutch to activate the bimetal strip to make your fan kick in... and that's doubly important when you're going slow, because all you HAVE is the fan to keep things cool.

If your fan is kicking in, your temps wouldn't be that high. Ergo, you have either a cleaning problem or a fanclutch problem. Both are easily fixable for not much $$.

Running these engines at anything over 210 is really cruising for a bruising, though... new motors are not cheap at all.
 
External cleaning is what we are talking about here to do it properly takes 3 hrs and using a pressure washer even low pressure is not the way, that either bends the fins or forces the crud deeper.

"Foaming cleaner" like you get at a AC & R supply house, lots of water from garden hose nozzle, I like to use the hot water drain off the bottom of the hot water heater, that also lets you get the crud off the bottom of your hot water tank so 2 maintenance items at same time.

make THIN bladed plastic tool to mechanically remove the bigger stuff to really clean the rad and A/C condenser takes about 3 hrs
 
I pulled mine right outta the truck and laid it face-down on top of 2 sawhorses. Took about 3 hrs of soaking with cleaner, spraying with garden hose, (blowing it out with leaf blower is good, too) to get the fins clean. OMG... you can't believe the crud that keeps coming out!! (little rocks, fluff, dirt, bugs, feathers, slow hitchikers, pieces of Prius, etc)

It's also amazing what gets lodged in between the rad and the AC condenser.. mine looked clean from the outside, and yes, I used a pressure washer on it, but jeez, it looked like a woolen blanket in between... cottonwood fluff, bugs, etc.

There is a thread here where somebody (who was doing this) also showed the bimetal thermostat coil on the front of his fan clutch - it was covered with grime, effectively insulating it from the hot air.
 
You might look into your thermostat....I had a 195 in my 93 and it ran 210 NO problem...BUT im not 100% if that over heating problem was related to my turbo or my thermostat..I changed the thermostat to a good 190 and opened my wastegate up on the turbo(it was stuck shut and boostin ALL the time 14psi wasnt hard to get, saving for an att to fix that!!) So take it how you feel, i feel both had something to do with it..Now I can haul my trailer is 90 degree hot sun and block hardly reaches 200 if im trying hard and my IP is cranked all the way up with only 4psi boost if Im running her hard and EGT's are spiking to 1200 and trying to run north(they settle out near 1200 if turbo makes boost)!!! Before my block temp would run to 210 and start WAY north if the EGT's went past 900 degrees!!! ive had my block temp up to prolly 230ish on flat level ground in 60 degree weather!! and im sure my radiator isnt super clean, but i did spend about 20 minutes washing it with a garden hose and do that every once in a while just to say yes ive atleast washed it some.....
 
Although for the mopst opart I am against them..Low speed off roading can benifit from an electric pusher fan. The engine fan does not keep enough consistent RPMs even with a good clutch and not enough air from low speed natuarlly. If your gonna do ALOT of off roading i would consider that option. electric pushers won't help with towing or higway but they will help alot in off road low speed climbing. I got alot of years under my belt busting stuff off road....:D
It wasn't a good night 4 wheeling unless you got towed home...:D
 
Acesneights1 said:
Although for the mopst opart I am against them..Low speed off roading can benifit from an electric pusher fan. The engine fan does not keep enough consistent RPMs even with a good clutch and not enough air from low speed natuarlly. If your gonna do ALOT of off roading i would consider that option. electric pushers won't help with towing or higway but they will help alot in off road low speed climbing. I got alot of years under my belt busting stuff off road....:D
It wasn't a good night 4 wheeling unless you got towed home...:D
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That DMax fan pulls a lot of air at idle even, without the clutch engaged. So I think that is a good compromise vs electric fans. Although yes the electric would be good because you could switch them on whenever. Might not be good for our crappy alternators though, at near idle, may need a CS144 or AD244 upgrade.
 
Turbine Doc said:
Great minds eh Jim, I used the exhaust side of my shop vac for hi volume low pressure warm air, it was a little more manageable than my leaf blower
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To be honest, I was improvising with the leaf-blower...

See, my shop-vac was at my son's house, and I was trying to sneak Alicia's Vacuum cleaner out of the house but I got caught.

Apparently, blurring the lines between house tools and shop tools is a bad thing. ):h
 
Thanks for the advise guy's. It looks like another project is coming. When I replaced my oil cooler a couple years back I pressure washed it in place. I guess I need to pull it out to get it good and clean.
 
3 hours is pretty accurate once the radiator is on the saw horses.I just did the rad for my "599"project truck. I spent almost a hour blowing the big hunks out:eek: with a air hose before washing. I used scrubbing bubbles bathroom cleaner.:thumbsup: Made the whole shop smell fresh when I brought it back in:rolleyes5:
 
buddy said:
My shop vac exhaust is a leaf blower :D
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Ridgid? I have the same one! Works ok... Great for this type of stuff. Decent for leaves :)

The fan clutch mod and just as importantly the Dmax fan blade must increase idle and low rpm airflow by at least 2 - 3 times... May be enough to battle low speed 4x4 'ing without need for electric make over.

When I start my truck up in the morning, I do it from outside i open the door and reach in. I instantly feel the air blowing on my feet.

Also, when letting it do the 2-3 minute cooldown, I jump out of the truck and the airflow is so great its pushing that super hot underhood air right out... hot to the feet and legs.

That Dmax fan is awesome.
 
JiFaire said:
...
There is a thread here where somebody (who was doing this) also showed the bimetal thermostat coil on the front of his fan clutch - it was covered with grime, effectively insulating it from the hot air.
Click to expand...

You can send your radiator to a radiator shop to be hot tanked and cleaned. You would do this because of external airflow plugging issues as the others above describe 'home' cleaning methods for. Depends on your budget and free time. :thumbsup:

The gunk on the fan clutch spring comes from the "working fluid" in the fan clutch. Effectively the clutch is bleeding to death and will reach a point where there is not enough fluid to lock in the fan clutch. This clutch is not a metal to clutch material, rather, the working fluid is what drives the fan. The fluid allows less than 100% lockup to save fuel when just a little fan is needed rather than 100% fan.

Regardless the expected service life on a fan clutch is 5 years as they loose 200 RPM per year.

I have already scuffed and cracked a 6.5 piston over using an old fan clutch. Yup, got hot and then a defective radiator cap, new one, let go suddenly and shock cooled the block. As water flow is to the #1 cyl first and more flow to that side - that caused the #1 cyl to shrink the most with a hot piston and hot thin oil. This chain of events scuffed the piston severely and cracked it. (per oil samples saying overheated oil (fist sample) and fix the egr due to soot on the next samples - no EGR on that engine...) The new fan clutch was on the way. I got another 7000 hard towing miles out of the engine before the crack burned through and required the engine to be replaced. The engine was a zero blowby engine when I got it and has idle blowby after that day and high oil consumption till it failed.

4x4 is harder use than towing because the road speed and ram air is less. for example electric fans can keep a 395 HP LS2 V-8 Trailblazer SS (not for off road use- see the track) cool enough. The same electric fans can not keep a 6 cylinder Trailblazer cool in 4 Low WOT up hills.

Hopefully you were in 4 Low to keep fan and water pump speed up.

The 6 blade fan is garbage for this body style. Worked fine for the pre 1988 OBS with a non-turbo 6.2. Our airflow issues dictate that this fan be replaced as GM did for later years with a 20" 9 blade steel fan or the better 21" Duramax composite fan. Both fans will do the job with a clean stack, HO pump, and working fan clutch. Lower temp t-stats and low turn on fan clutches also help when you get real extreme with towing or in AZ 115+ degree weather. MPG may suffer though with lower setpoints as others claim - never made a difference for me towing.
 
Exactly why I stand by my idea(well Missys) that what these trucks really need is a Horton electric Clutch. ONe of our vendors needs to step up to the plate here and get together with Horton. They used to supposedly make one but no longer offer it.
 
I pulled the top of the fan shroud off so I could get between the condenser and the radiator. I used a shop vac to pull out about four hand fulls of bugs and stuff. Then I soaked the all the exchangers with a garden house and shot at a low psi - 60 I think - from the compressor nozzle. It was enough to blast water and bits and though I'm sure it didn't turn out as well as if I'd removed it, I do think I got it pretty clean.
 
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