First a big thanks to Nate for putting together a great thread. Second to all those that supported Nate and added other items that can also affect cooling. I am in the process of doing the stack cleaning as I am writing this. I am going to try and do it without dumping the charge in the A/C system. I have been having problems with cooling when I tow my travel trailer (10K). If ambient temp stays under 80*F no problem but anything over and temps start to climb. I am going to install a baffle for the A/C condenser and try not to trash out the engine compartment. The CAC and Rad will be completely removed and hopefully I will get them cleaned well. I will post some pics when I am done to add to this great thread.

 

I haven't got to the pics to post yet but, My cooling problems are gone after cleaning the stack. I tried to use degreaser and cleaners to get the gunk out between the fins but it didn't work. I went to Utube and found a video of Merchants Automotive showing them cleaning with a pressure washer. The really important thing to do if you use a pressure washer is to make sure the spray is in line with the fins and they say to use a 25 degree nozzle. Yes, it worked great and I got 100% of the debris moved from between the fins.

 

Follow his instructions and you will be fine. I used them a couple of years ago and had no problems other than removing headlights and grille LOL. If you remove the radiator and intercooler as a unit you won't lose freon and makes cleaning much easier IMHO. Have some available to help, because the stack is heavy and awkward to handle and could damage something trying to do t by yourself. It will take you about 10 hours to do the job if you have all the tools needed. Before cleaning, my fan clutch engaged all the time and my AC would not cool at low RPM's. After cleaning, it will freeze you out anytime. Now the only time my fan clutch engages is occasionally when pulling my 15K fifth wheel at low speed in heavy traffic in the summer, and it will only engage for 30 seconds or so. At 208K, it was really nasty and probably over 75% blocked. Well worth the time and effort if you have any cooling issues at all.

 

Thanks for this excellent write up

Thank you for this write up. I am doing mine over the weekend and I really appreciate all the instructions, pictures and bolt locations, etc. I can't wait to see if this helps my transmission and coolant temps while towing. I only tow a camper that weighs about 5000 pounds but it seems to run hotter than it should and I know I should be able to tow way heavier without running hot.

 

Great write up! Seeing those plugged up coolers spurred me into action. I spent a couple of hours one morning putting a bug screen on my Denali. I've put a bug screen on every truck I've ever owned.

 

Looks nice.
However, note that the debris collected between the coils over time, comes from other directions than thru the grill. You'll still have the buildup seen in the pics in this thread.

 

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This was in between the Stack.

 

I was able to pull everything apart enough to get a wand in there and blow it out. I didn't have any big stuff in there just dirt.

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Did that fix your cooling problem?

 

When I did mine it didn't come clean but looked like it did. I held both of them up so I could shine a light on the back side and they both were at least 50% clogged where I couldn't see the light. So I did some more research and pressure washed them until they were completely clear. Temps still at 185-190 but when I load to 11K lbs temps just stay within the thermostat range. Problem gone.

 

Thanks

Just wanted to drop a quick note saying thanks for posting this up. I used this thread to remove the entire cooling stack this past weekend and clean everything out and it was a huge help. I had been planning this for a few months now and finally found time to do it and change the fan clutch, serpentine belt, water pump, and thermostats while the intercooler and radiator were out (made it much easier). One thing to note is it was easier for us to take out the intercooler and radiator together before separating them - requires two people but made life easier. Thanks for posting this!

 

Just wanted to drop a quick note saying thanks for posting this up. I used this thread to remove the entire cooling stack this past weekend and clean everything out and it was a huge help. I had been planning this for a few months now and finally found time to do it and change the fan clutch, serpentine belt, water pump, and thermostats while the intercooler and radiator were out (made it much easier). One thing to note is it was easier for us to take out the intercooler and radiator together before separating them - requires two people but made life easier. Thanks for posting this!

no problem, and I am glad it worked out for you on several aspects.

 

First off thank u for ur service and nice write up. I will b doin this stack cleanout very soon. But I gotta few questions. I just flushed my coolant and changed both t-stats last year just before we went on a trip to Colorado haulin 2 rangers (week of July 4th). The whole way there and back I fought my temps. Engine 215-230. Trans 210-220. (read off of my edge monitor). My fan hardly ever kicked on and when it did it didn’t last long. Got the engine down to 195 a few times. Leavin Santa Fe my engine got up to 245 before I got pulled over and then the fan kicked on. I’m just wondering if while my cooling stack is out should I go ahead and change my fan clutch and water pump? My 07 classic has 192k miles on the clock now.

 

CA88 - I always encourage Duramax owners to periodically clean all their coolers, not just spray them with a garden hose, though that helps a little if the stack isn't too dirty. When you say Colorado, I'm assuming high altitude Colorado. You need to remember that at high altitudes the air is 'thinner' meaning less dense, and air that is less dense does not have the same the same capacity to remove heat from your cooling stack compared to more dense air, like at sea level. Also, humidity comes into play and Colorado high altitude generally has lower humidity than sea level. So I'm not surprised to see the temp levels you experienced. And I wouldn't be concerned as long as your fan clutch kicks on fully at some point and the engine cools down. If my engine went to 245, that's just too hot and I would strongly suspect the fan clutch to be defective. I think the highest my truck has ever been is 236 (high altitude, steep grade, pulling 5th wheel) and then lockup occurred and cooled down.


Another thing to remember is that your fan clutch lock up temp is not directly tied to your coolant temp. If your cooling stack is clean, the air flows equally through all parts of the stack and hits the fan clutch equally as well. If your cooling stack isn't clean, it will most likely block the airflow to the fan clutch and the fan clutch won't see the temps that the rest of the air coming thru the stack has, and consequently your fan clutch doesn't lock up when you think it should. Enough preaching.

 

i think the highest my truck has ever been is 136 (high altitude, steep grade, pulling 5th wheel) and then lockup occurred and cooled down.

136?

 

Thanks Ron. Sounds like a good time to replace the fan clutch. I guess I shoulda said southern Colorado. Pagosa springs. Still higher elevation but prolly not too crazy. Like I said earlier. The engine temp hovered around 220-230 almost the whole 12 hr trip and would engage randomly. Of course when temps were high. But not everytime they got up there and some of those times it would not stay engaged long enough for temps to go down enough. Which is what led me to think the clutch is goin out. And bout the water pump. I was just askin bout that since I’m almost to 200k miles and I’ll have the cooling stack outta the way. Didn’t know if it’s a ‘run it till it goes out’ type of thing.

 

IMO it would be a good time to do the water pump along with the fan clutch.

If you do change the pump, you have 1 of 2 routes to go if my memory serves me correctly......stockish/oem or aftermarket pinned.

Several diesel performance shops sell complete replacement sets

 

Finally got to mine. Should have done it last winter when I did the injectors. I think a lot of it is from a drive across ND in the fall & the cat tail fuzz was blowing around IC doesn't look bad but the radiator had some build up.

 

I did my stack at 129K when I did the EGR delete and turbo swap. It needed cleaning too.
The coolant should be changed every 100K anyway.
If the water pump makes it I'm at 199K now... My plan for 229K is drop the coolant, break down the stack for cleaning, replace the water pump, idlers, belt, fan clutch then put it back together with fresh coolant.

 

Thanks Nate.

 

Is there any special tools I would need to replace my fan clutch and water pump?

 

If you can rent or borrow a 4 to 1 Torque Multiplier, like the one in the link, it will reduce the force required to break the bolt loose from 275 FP to 63 FP.

It will make getting it re-torqued to 275 just as easy.

https://www.ebay.com/itm/X4-Torque-...ltiplier-and-Handle-Snap-On/392278230384?hash=item5b559ac570:g:yVEAAOSwisZctjA9

 

Spanner wrench for breaking loose the fan.

Water pump, nothing special...except that one of the bolts is behind the lower pulley....Sold as a pair (amazoid?) is the socket to fit and the flywheel lock tool. Not expensive.

Then you need something for that socket....I borrowed a 4' long 3/4 drive 600 ftlb torque wrench to break it loose. It's a beast, you need some leverage.

However, since you ask in this thread.....having removed the Rad and CAC, you'd have enough room where you could then use an impact wrench on it, vs the socket & breaker bar plus the neighbors two mules to pull on it.

 

Lol. Ok thanks hook.

 

I've posted all those part numbers up on threads in the past....maybe $50 for the wrench, socket and lock tool. Can't find 'em in my email....Search threads on the WP, they're posted several times in several threads.
IIRC, the socket/tool was a Lisle product.

 

Lisle 22100 Flywheel Locking Tool for 6.6L Duramax https://www.amazon.com/dp/B002MCVPOO/ref=cm_sw_r_cp_apa_i_sK5TCb88XWSTC

TEKTON 3/4-Inch Drive x 40-Inch Breaker Bar | SBH00340 https://www.amazon.com/dp/B07H3KJQ83/ref=cm_sw_r_cp_apa_i_6M5TCbM7S93F4

https://www.merchant-automotive.com/10358-Fan-Clutch-Wrench.aspx


Have a cheater bar on the breaker bar and it will be easier.

Torque wrenches and time.

Don't forget gaskets and o-rings. If you have an LBZ go with the oem pump with the plastic impeller.

Merchant has a nice kit already put together with everything you need for water pump and gaskets

 

Bypass hose is 1/2 id about 4 inches of coolant hose will work to replace it. Might as well replace your thermostats too.

 

Rock Auto has an oem pump with cover for about 152$. You can get a gasket kit from merchant.

 

Pump should come with the oil cooler gasket and both O-rings, no?
Mine did.

Two new hose clamps for that new 4" crossover piece feeding the Turbo (off small Y tube on #15 below)....unless you like those stock spring clamps. :|

Also, don't know the size, but be prepared to replace the small O-ring (#190) on the pipe (#15) feeding that short hose and the T-stats...disturbing it, it will fall apart.
#191 is one of the two that should come with the pump.

Careful with #60 and you should be able to reuse it.

 

Pump should come with the oil cooler gasket and both O-rings, no?

Mine did.



Two new hose clamps for that new 4" crossover piece feeding the Turbo (off small Y tube on #15 below)....unless you like those stock spring clamps. :|



Also, don't know the size, but be prepared to replace the small O-ring (#190) on the pipe (#15) feeding that short hose and the T-stats...disturbing it, it will fall apart.

#191 is one of the two that should come with the pump.



Careful with #60 and you should be able to reuse it.

Not sure hook. I got my water pump kit from merchant when they had welded pumps. No more now.bAll o-rings came with it.They been finding out the oem pumps for the LBZ are good and holding up. You can look on there webpage and look up all the gaskets and o-rings you need to do the job or just buy the o-ring kit for 40$. Buy the oem pump from Rock Auto and be done. Or just buy the pump kit from merchant it will come with everything you need. Even the flywheel lock. They have good customer service and support from my experience. I would say it's way above average.

I bought a welded water pump kit from them. Two years later I install it. 4 months later it started leaking. They replaced it for free. Sucks I had to do the job again but they took care of me.

 

Thanks hook and mike for the links and the diagram.