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If your truck ''runs hot'',clean your radiator fins

dmaxx3500

dmaxx3500

Deputy
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chicago,
well ever since i bought this truck,it ran 210degs everywere,and when towing anything up hills ,it would climb to 225-230degs,

well i got pissed[nobody knew what was wrong]so i started looking at things myself,i replaced the cooling fan clutch,thermastats,flushed cooling system

nothing made any difference,so today i took out the radiator,intercooler,a/c condenser,trans cooler,then after seeing the radiator was full of dirt-bugs-2 mud bee nests,i flushed the rad,a/c condenser,intercooler,trans cooler,it took 1hr to flush everything,but it took 5 hrs to r&r the front bumper,grille,h-lights,battery,air-box,and coolers

now after driving the truck 30 miles in traffic and up/down hills,it runs 20+degs cooler and the coolent temp gauge moves up/down like it should,,we will see how it runs next week

''IF YOUR TRUCK RUNS HOT,SPEND A DAY AND DO THIS''
 
Don't forget to Flush it from the INSIDE > OUT. So from the Engine Bay side Forward, otherwise you're just gonna push the Junk deeper into the Cooling Fins.
 
"when towing anything up hills ,it would climb to 225-230degs"
I found the Allison likes to lug the hell out of the engine in 6th gear towing to the point ECT rises a lot. You know the grade that isn't hard enough to require a lot of throttle to downshift?
I kept the temp from rising by manually selecting 5th for those slight grades. Harder grades would shift by itself.

Just another reason to explain some of what you may be seeing.
 
1.i flushed it with a garden hose
2.i flushed it front to back and back to front,then blew it out with air,then shined a light thru it,,it was clear
3.yes i down shift to 5th 0r 4th,i try to keep the eng at 2000-2500 up hills,i don't like it lugging
4.my 06' LBZ never did this
5.this truck has 64k on it,
6.i recharged the a/c today and it now blows 45-48degs at idle and 50degs going down the road,i'll keep using a laser temp guage to ck things
 
The 2008 has a huge 25" fan over the 2006. It also has the DPF 'engine heat retention system' that requires a new bodystyle with massive grille and that huge fan.
We used a 2 quart aftermarket oil cooler and were still nearly ruining the engine oil at the 9K change oil light. The have reformulated the low emission oil since, but, 2008 is a good setup to think about synthetic in.
The heater hoses appear to be the first hose to fail from excessive constant heat. The passenger side battery is the first casualty. You should rotate your batteries.
 
The funny thing is we all get the validity of rotating the batteries for extending the life due to the heat. Could you imagine a shop trying to tell someone "pay me for 1/4 hour to rotate your batteries". Maybe it's just me, but it sounds funny.
 
I don't know when they went to the 25" fan. The 2008 has lots of shrouding and some air deflectors as I recall.
 
dmaxx3500 said:
1.i flushed it with a garden hose
2.i flushed it front to back and back to front,then blew it out with air,then shined a light thru it,,it was clear
3.yes i down shift to 5th 0r 4th,i try to keep the eng at 2000-2500 up hills,i don't like it lugging
4.my 06' LBZ never did this
5.this truck has 64k on it,
6.i recharged the a/c today and it now blows 45-48degs at idle and 50degs going down the road,i'll keep using a laser temp guage to ck things
Click to expand...

Thank you

As far as the lugging the Allison goes, use the tow/haul switch. It downshifts quicker and keeps the engine RPM's in the sweet spot and keeps the revs higher which in turn, keeps the fluid flowing thus keeping the temps a little cooler.

The 2006's on up have the larger cooling fan already.
 
Take the time and 'stand up' any fins that are smooshed as a result of too much water pressure (over zealous power washer operator) and/or things rubbing/hitting (knuckles perhaps) the core.
 
Will L. said:
The funny thing is we all get the validity of rotating the batteries for extending the life due to the heat. Could you imagine a shop trying to tell someone "pay me for 1/4 hour to rotate your batteries". Maybe it's just me, but it sounds funny.
Click to expand...

Being I work for a shop, I can see how that would go.

Mechanic- We recommend you rotate your batteries for more life. This will keep the heat from just hitting one battery all the time.
Customer- No thanks maybe next time, I'm in a hurry today. (In the customers head he is really saying . Go pound sand, I'm going to another shop. You are just trying to rob me.)
 
RI Chevy Silveradoman said:
Thank you

As far as the lugging the Allison goes, use the tow/haul switch. It downshifts quicker and keeps the engine RPM's in the sweet spot and keeps the revs higher which in turn, keeps the fluid flowing thus keeping the temps a little cooler.

The 2006's on up have the larger cooling fan already.
Click to expand...

Thanks for the fan info. The Tow/Haul still doesn't solve the lug in 6th till ECT rises problem with a 28' full height cargo trailer. It is just an area in the tables where it doesn't shift and nothing is looking at ECT to notice the extended time load is warming things up. Even with the programmed numb temp gauge would move to 3/4 scale when we were on grades like this.
 
WarWagon said:
Thanks for the fan info. The Tow/Haul still doesn't solve the lug in 6th till ECT rises problem with a 28' full height cargo trailer. It is just an area in the tables where it doesn't shift and nothing is looking at ECT to notice the extended time load is warming things up. Even with the programmed numb temp gauge would move to 3/4 scale when we were on grades like this.
Click to expand...

What are you basing this on? What year truck? I would venture to say that the tow/haul is not working correctly. My truck downshifts much earlier when in tow/haul mode. Actually much earlier than I would prefer, but then again, I am not an engineer, so I will leave it to them if they feel it is best for the engine.
 
06-10 all use the same fan blade, and I believe it is a 22 inch blade. I know 01-05 used the 21" blade, and the 06-10 blade doesn't look that much bigger. And I have never heard of anybody except for ww have any troubles with the 6 speed lugging down and overheating. Most people complain it kicks down to soon and races the RPM's up instead of using the engines torque. The only time I have heard of any complaints with them is when they get poor tuning installed. 2011 I think got the 25" fan, an even bigger intercooler, and a radiator that looks like it belongs in a semi crammed into the stack.
 
update2

hooked a trailer up[35' 2-car open],put 250 miles on it,84degs-70%humidty,sunny,4-5 little hills-[less then 1 mile long],tail wind and side winds
1.no over heating,ran 195-210 on the factory guage[never over]
2.a/c runs 52-56degs
3.coolant guage goes down 1-2 needle widths on down-hills and down-shifts
4.a/c condenser 125degs after running 45mins,facing wind sitting still 5mins 112degs
 
THEFERMANATOR said:
06-10 all use the same fan blade, and I believe it is a 22 inch blade. I know 01-05 used the 21" blade, and the 06-10 blade doesn't look that much bigger. And I have never heard of anybody except for ww have any troubles with the 6 speed lugging down and overheating. Most people complain it kicks down to soon and races the RPM's up instead of using the engines torque. The only time I have heard of any complaints with them is when they get poor tuning installed. 2011 I think got the 25" fan, an even bigger intercooler, and a radiator that looks like it belongs in a semi crammed into the stack.
Click to expand...

2008 for sure has 25" as I measured it out of curiosity back in the day. (Don't think I messed up measuring, but maybe, as there was a lot of stuff in the way.) Running hotter than a wet pistol is not 'overheating'. That is a subjective POV that GM wants to define as coolant boiling out the cap with overheat alarms going off. There are several 'old' posts over on the other place of these engines running hot enough while towing to move the numb GM temp gauge. The conclusion was bumping it out of double overdrive on some grades kept the temp from climbing as much. 230 was more or less normal for my 2008 to see every day towing as seen by HPtuners and factory gauge movement. Only tune change it had later in life was a mod to use B99 without flooding the crankcase with fuel from exhaust stroke injection events.

Possible GM was running a fine line of not wanting to downshift - but the trade off for using low RPM torque is lack of fan and water pump RPM. When the grade goes on long enough it catches up with you. Especially when GM gave up decent ECT control by using the obsolete spring thermal fan clutch and all it's delays before kicking in rather than the EV computer controlled fan clutch the marketing promised and was dropped before 2008 production. Yes, it has the torque to pull the hill in double over drive. No, it doesn't have the cooling to do it very long.

The peak ECT was lower if I started the grade in manual 5th rather than lug it all the way in 6th. Most days we didn't bother to manually downshift. Split heater hose at 102K, bad less than 1 year old battery at 88K, and oil analysis bordering on the need for synthetic every 10K miles was the result. Headwinds would make the ECT higher and in one case we had to drive 55 MPH at 7MPG towing a 37' RV watching the high ECT to keep it from getting too high. (It was going over the 3/4 point on the gauge.) This was between storms in the middle of the country that had very high winds. The gamble paid off as we weren't caught underwater as the second storm flooded the country badly. Again this is with extra oil cooling installed.

Not only did mine run hot you could hear the effects of temperature on the diesel ignition delay. The engine would start to literary ping as the timing became too advanced for everything that was getting hot including IAT rise from a heat soaked intercooler. #2 and B99 both did this, but, less noise with B99. Maybe their more recent ECM's in new trucks have tables to reduce timing when temperatures start to climb from sustained loads?

I think the OP conclusion of cleaning the stack is the same tried and true advice we use on 6.5's. I additionally suggest that 2008 was 6 years ago and pushing the 5 year lifespan of the fan clutch as they loose 200 RPM per year.
 
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