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Discussion Starter · #1 ·
I have a 2006 LBZ dually stock with 160,000 miles. I have a Lance cabover camper that weighs 3,700 lbs on the truck. On days that the ambient temperature is under 90 degrees the truck engine runs at 186-200 degrees up any hill where I have the throttle over 50%. But on 90+ degrees days the temperature will raise past 200 and keep going until the super fan engages or I back off the accelerator.
Local mechanic wants to replace the radiator.
Is this the right fix?
 

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Discussion Starter · #2 ·
Although I have never removed the stack and cleaned it, I have cleaned it with garden hose and motor running. A lot of water came through the stack and even a mouse fell out.
 

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You need to clean the cooling stack, all the pieces, with a mild degreaser or dish detergent from the back of each piece to the front of each piece. Do not use a pressure sprayer unless you are VERY CAREFUL not to bend any fins, and they are VERY easy to bend with a pressure washer. The problematic dirt collects in the same area as the fan clutch, a circle about 1-1 1/2 ft in diameter, that blocks hot air from the radiator from reaching the fan clutch until you are way hotter than you want to be. If that hot air would not be blocked, your truck would be cooling down much sooner, not later.

Sure a new radiator will be clean and will provide the same benefits as a washed radiator will. But the cost is way different IF you do your own work. You might inquire at a radiator shop what they would charge to pull and clean the radiator (and intercooler which is directly attached to the radiator) and compare the mechanic. I don't think many charge the $125/hr that mechanics charge. It's your choice.
 

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Discussion Starter · #4 ·
You need to clean the cooling stack, all the pieces, with a mild degreaser or dish detergent from the back of each piece to the front of each piece. Do not use a pressure sprayer unless you are VERY CAREFUL not to bend any fins, and they are VERY easy to bend with a pressure washer. The problematic dirt collects in the same area as the fan clutch, a circle about 1-1 1/2 ft in diameter, that blocks hot air from the radiator from reaching the fan clutch until you are way hotter than you want to be. If that hot air would not be blocked, your truck would be cooling down much sooner, not later.

Sure a new radiator will be clean and will provide the same benefits as a washed radiator will. But the cost is way different IF you do your own work. You might inquire at a radiator shop what they would charge to pull and clean the radiator (and intercooler which is directly attached to the radiator) and compare the mechanic. I don't think many charge the $125/hr that mechanics charge. It's your choice.
thank you for the alternative suggestion. I am not at a location where I can do that level of work and instead have to pay someone to do it. Gave up the house and garage...
 

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Cleaning the stack is what you should try first. Use Simple Green to spray it down. If you want to pull the radiator it is kind of a pain in the butt. There is two bolts way down low that if I remember correctly the one on the passenger side is horrible to get loose. I would also replace the idler pullies and maybe the belt if you haven't done it. Soon enough when that fan kicks in they will start to squeel.

I would note that 200 degrees is not overheating nor is the fan coming on saying it is over heating. Really if you see 260 then of course your overheating. Water boils at 212 at atmospheric pressure but add antifreeze and pressure 260 is about where your in deep trouble and 225 or 230 is where you start to worry.

What gets the LBZ hot is a combination of load and then the air getting reduced coming over the stack. Consider your pulling up a long hill. Your loading the engine and at the same time going slower. So your adding more heat and reducing the air speed going over the radiator. Get it hot enough then the fan kicks on to bring that air speed up again. Towed many a miles with a 5th wheel with my old LBZ going up many a hills. DON'T RACE UP THE HILLS!! You should notice that 18 wheelers don't either. Often you can keep the fan from coming on.
 

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I have done the conventional ( lazyman clean with coil cleaner and detergents without removal ) and always walked away more wet than satisfied anything got clean. So a month ago, I followed some instruction here with printed photos and the 7 tools required and pulled it in the driveway. As stated above my past attempts were less than stellar because this is is what was unveiled. I can now say I have a cool running truck.
1087936
 

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Discussion Starter · #7 ·
Thank you everyone.
I will have the stack removed and cleaned Monday. I only wish I had a place I could do the work instead of paying a mechanic.
 

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So a month ago, I followed some instruction here with printed photos and the 7 tools required and pulled it in the driveway.
Mind sharing what walkthru you used, and any comments on how long it took and lessons learned?

I will have the stack removed and cleaned Monday. I only wish I had a place I could do the work instead of paying a mechanic.
Please report back the time & expense involved... I'm still trying to decide if I should do this project myself or have a mechanic or radiator shop handle it.
 

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I do not understand what the problem is. Sounds to me, like the truck is working as designed. I HAVE cleaned the stack on my 2006 and even on an 80* day, towing a steep hill, will get the fan on. Thats what its designed to do. Its not a malfunction, its just the oil filled fan working as designed. Now, if the temps keep rising, into the overheat zone there might be other issues.

When you say "keep going", how high does it go?

Also, depending on how long, how steep the hill, and how heavy the load, ANY diesel truck will reach a point where you have to back off the throttle. If you are pulling a 6-7000lb trailer up a 5% grade for a mile and it overheats, that's an issue.

If its, like here, a 12,000lb 5th wheel up a 3 mile long 7% grade, then expect to back off the throttle a bit. Pulling a grade with a decent load at 180* sounds to me like your thermostats might not be working right. My stats are both new and when towing 200-210* is normal, even on fairly level roads.
 
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Pulling a grade with a decent load at 180* sounds to me like your thermostats might not be working right. My stats are both new and when towing 200-210* is normal, even on fairly level roads.
if you see 180 towing up a grade i would think they are stuck open and you are in freezing weather. wouldnt expect the temp to stay low in that scenario.
I saw 185* pulling a 2 ton empty dump trailer through flat/gentle hills in 75*/60% RH running my tow tune with tow/haul on. My tstats are stock.
 

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Where do you guys go to figure out what % grade a particular stretch of hill is? I'm a flatlander from the Midwest so not accustomed to any real climbs until a drive down through MO and OK this Spring while towing our trailer to TX. And even those bigger (to me) hills were less than a mile upward at any given time, and probably nothing compared to mountain passes.
 

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Often, the steeper grades will have signs posted, telling what the grade is.

I don't really consider 4000 lbs much of a load for these trucks. I was meaning something in the 7K plus range. GM doesn't even recommend using tow-haul, until you are around 70% of rated tow capacity.
 

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Mind sharing what walkthru you used, and any comments on how long it took and lessons learned?



Please report back the time & expense involved... I'm still trying to decide if I should do this project myself or have a mechanic or radiator shop handle it.

Procedure I followed. I Had a full day in it, I did not use a power washer As I did NOT want to bend the fins. I have done HVAC work in past like and fixing fins with a fin COMB suck. How To: Radiator Stack Removal and Install

Things learned,
1) GM Engineers that removed the radiator drain on the LBZ UP are assholes.
2) make sure the lower radiator snout is clean many report it leaking and I think mine still weeps.

Yesterday was the first day I got to tow with mine 83Deg temp 80% Humidity pulling 15,000# of Fifth wheel not fully loaded. locked in 5th Tow haul mode on Highest temp I saw was 204 heading out to the HWY main road has long lite grade and 2 Fricking stop signs. Once on the HWY 60-72 flowing with traffic temps cycles 192-197 and the Trans 171-175 once I got back off the hwy heading into town the trans went up to 184. I was on the Heavy tow tune #2 Idaho Rob tunes. Pretty happy with what I saw, test is this coming weekend when we have a full 9 hour drive to our destination.
 
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Both LBZs I've owned have been like clockwork. Pull a grade watch the ECT come up to around 230, clutch fan locks up, sounds like a freight train, and temps drop back down into the 210s. Rinse and repeat. Seems like intended operation to me.
 

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Discussion Starter · #16 ·
Mind sharing what walkthru you used, and any comments on how long it took and lessons learned?



Please report back the time & expense involved... I'm still trying to decide if I should do this project myself or have a mechanic or radiator shop handle it.
I had a replacement radiator installed on Monday. Including 6 gallons of dexcool, it cost $700. $240 in labor.
The stack was clean without any bugs or mater blocking the vents. You could see right through them. However, the old radiator weighed 2x times as much as the old one. So it is believed there was blockage inside.

First test in 85 degrees weather, never got above 195 on 6% grades. The old radiator would have gone to 210.

we will have 95 degrees weather later this week so I will test again.
 

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Discussion Starter · #18 ·
I do not understand what the problem is. Sounds to me, like the truck is working as designed. I HAVE cleaned the stack on my 2006 and even on an 80* day, towing a steep hill, will get the fan on. Thats what its designed to do. Its not a malfunction, its just the oil filled fan working as designed. Now, if the temps keep rising, into the overheat zone there might be other issues.

When you say "keep going", how high does it go?

Also, depending on how long, how steep the hill, and how heavy the load, ANY diesel truck will reach a point where you have to back off the throttle. If you are pulling a 6-7000lb trailer up a 5% grade for a mile and it overheats, that's an issue.

If its, like here, a 12,000lb 5th wheel up a 3 mile long 7% grade, then expect to back off the throttle a bit. Pulling a grade with a decent load at 180* sounds to me like your thermostats might not be working right. My stats are both new and when towing 200-210* is normal, even on fairly level roads.
Sorry for delay response...

last hot day we drove it, it was 95 ambient temperature, truck and 3700lbs slide in camper. The road was 12 miles up with flat and 3 percent grades for a 3000’ elevation change at 45 mph. At about 3 miles truck hit 238 degrees and fan did not turn on. Pulled over to let cool. Truck cooled to 192, start up again and in 1 mile 240 fan turns on so we keep going. Fan stops and it returns to 240, but no fan so pull over. When this happens I keep it in lower gear to stay at 2000+ rpms.

On other trips, the warning center has says “coolant hot” and it can’t be good for the truck to keep getting this hot.
 

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Sorry for delay response...

last hot day we drove it, it was 95 ambient temperature, truck and 3700lbs slide in camper. The road was 12 miles up with flat and 3 percent grades for a 3000’ elevation change at 45 mph. At about 3 miles truck hit 238 degrees and fan did not turn on. Pulled over to let cool. Truck cooled to 192, start up again and in 1 mile 240 fan turns on so we keep going. Fan stops and it returns to 240, but no fan so pull over. When this happens I keep it in lower gear to stay at 2000+ rpms.

On other trips, the warning center has says “coolant hot” and it can’t be good for the truck to keep getting this hot.
You need to check into that cooling fan operation then. If that truck was truly hitting 240 degrees with no cooling fan intervention, then you got issues with that fan clutch.
 
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