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OverHeating Issues!! What Am I Missing?????

D

DieselDonutz

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Carlisle Pa
Hi All!!

Happy Easter!! I am hoping to get some help here. I am at a complete loss. from the beginning. I bought truck about a year and a half ago. It would easily overheat going up a hill unloaded. this is what I have done to the truck since purchase. new cylinder heads, new 4" exhaust, computer upgrade, hx40 turbo mod, newer upgraded water pump, newer upgraded fan clutch, duramax fan, new thermostats (185's) dual stats setup, brand new 4 row radiator, replaced duramax and fan clutch with twin Taurus electric fan setup. new custom air box. at this point I still cant drive up the mountain unloaded without overheating. At this point I am ready to throw in the towel on this one. the truck runs out of this world. It has tons of power. no missing, no hard starts, no other issues. just the heating problem. if you have any ideas please let me know. and no there is no build up in between the rad's. its all clean. what am I missing?????? HELP HELP HELP!!!
 
I'll ask the dumb ???

Overheating as in the gauge is climbing/pegging or actually bowing coolant out the reservoir...???

From all you have listed you should be running ok. other than a blockage in the block, heads or heater box....??? and even if something was in the heater box it shouldnt cause the over heat. Speaking of the heater..... when the temp gauge starts to climb, have you run the heater on high to try and help the system cool down...??

How many miles on the new motor???
 
ok, as far as the gauge, it will gradually climb until I just pull over and let the fans do their job. if I don't stop if will eventually bubble over (which I try very very hard not to do). this is only under heavy load on straight aways or unloaded driving up a steep long hill. the tune was done but Bill Heath. the Heating issue was there long before the tune. As I said in my first post, I bought the truck with the heating issue. Originally I replaced the heads because it had blown head gaskets when I bought it. the truck actually didn't run bad when I bought it even with the blown head gasket. I just assumed that was why it got hot. then I started replacing and upgrading everything. as far as the timing, I hate to say it but... I don't know. I am currently working on picking up either some software capable of checking timing or a tech 2. so I cant answer that. but if the timing was off so bad as to cause overheating wouldn't I see a noticeable loss of power and other symptoms? oh and to add to the list. I also replaced the timing chain and gears. I will say that I am going to pull the stats out tomorrow and take it for another run just to see if it makes any difference. One more thing that I would like to mention. when it does start to cool back down, it is always a very slow process. almost as if it is restricted. but my question is where. everything is new. again, I feel that I have to be missing something.
 
Did it boil over with the DMax clutch and fan? The reason I ask is I don't think electric fans will cool as well. My first thought was a bad temp sender, but the boiling over rules that out.
 
NVW said:
Did it boil over with the DMax clutch and fan? The reason I ask is I don't think electric fans will cool as well. My first thought was a bad temp sender, but the boiling over rules that out.
Click to expand...

Electric fans will NEVER touch what the DURAMAX 21" blade and a good clutch will move. Even the TAURUS fans can only move about 2000-2500 CFM each of actual airflow through a cooling stack. The DURAMAX fan blade is capable of moving over 8000 CFM of air. You do NOT want to use a DURAMAX fan clutch, it is calibrated for a higher temp than the 6.5 clutches are. If you are running the 99+ spin on fan clutch, then you want to use the associated 6.5 spin on fan clutch. The DURAMAX fan clutch isn't meant to come on until 225-235 engine temp, and that is with the extra heat of the intercooler up there as well. The 6.5 fan clutch should come on in the 215-220 range. And this may sound stupid, but have you swapped out the coolant bottle cap? You need to run a GOOD 15-16 PSI non vented style cap. If your not holding pressure you WILL overheat.

And if you pull the stats, don't be surprised if it overheats even worse. Coolant needs to have time to actually absorb heat to work. Without the stats the coolant could move through quick enough that it won't be absorbing the heat as well.

Also where is your boost set at? I see you have a HX40II on it, so where did you set your boost at with it? Have ou tried dropping your boost down some?
 
Just a few thoughts...

- Leroy's question is important; the wrong brand of thermostats will cause you grief. The problem isn't as severe as in a 1-tstat system, but it still exists.

- Ferm's observation is important, too ... the right fan clutch and fan make a huge difference, and I've never seen electric fans work as well as a proper mechanical fan setup. Ever.

- When your temp is climbing, is your TCC locked? A 4L80e can generate a huge amount of heat when the TCC is unlocked, and that heat transfers directly to the rad. If you can't get up to a speed where the TCC stays locked, rather than running in OD (unlocked), try running in 3 (locked) on the same hill. If you aren't sure if it's locked or not, just touch the brake with your left foot... if the rpms don't increase, you were unlocked.

- Adding a couple bottles of Water-Wetter is never a bad idea, although it won't help if the physical issue is severe enough.

- I almost hate to ask, but is the water pump the right one? Some of the aftermarket ones are designed for a different pulley system that turns the other way... (only seen that once, but I just had to ask). When the water circulates the wrong way, things still work, but not very well.

- I think you're onto something with the comment about taking a long time to cool down... that alone tells me something isn't right. Once you remove the heat load, things should normalize fairly quickly.
 
T stats in in the right direction? They are confusing. They say "radiator" on one side but if you put it in with that side pointing at the radiator its wrong because the housing is backwards. The side with the stamp needs to be facing the back of the truck/exit of the housing/flow of coolant to the radiator. Did that make sense?

Sent from my ADR6350 using Tapatalk 2
 
wow, lots of helpful info. let me start by thanks to all. now to answer some Q's it will boil over regardless of what fan setup I have. I just stop before it happens. I was running the dmax fan, with the 6.5 upgraded pump and clutch. now electric fans with same result. the rad bottle cap is replace with new. boost was set at 10 now I have it set at 15 with no change. torque is locked, 3rd or overdrive. either way is the same. as far as the T stats, they were the new fail safe style but previously were from dealer. I checked the water pump and to the best of my knowledge it is correct. I am going to reconfirm the stats and their direction tonight. I will post my findings. thanks
 
I would get a inexpensive IR temp gun and verify the gauge is good. A bad cap as suggested is possible and the IR temp reading would prove it. It can also let you know if the transmission cooler liner are the source of the heat trouble.

Have you specifically removed the oil coolers and cleaned the mat of debris off the A/C condenser that builds up behind the oil coolers? Bent fins on the condenser or air flow plugged oil coolers? Plugged up condenser? Did you take the 'caps' off the new radiator inlet and outlet - yeah I have seen this not done and the engine was well done... :rolleyes5:

X2 on exhaust restriction being a possible cause - too much boost, plugged cat, collapsed pipe.

Possible you have blown head gaskets or a cracked head(s) filling the cooling system with 'air'. (Maybe even crack in the block at top of cylinder) Remove t stat crossover and belt. Start engine and watch for bubbles indicating cracks or head gasket issues. Bonus is bubbles tell you what side is leaking.

I personally measured a 21" Trailblazer SS clutch cooling fan move 10,000 CFM through the stack on a Trailblazer. The same 10,000 CFM fan on the 6.5 diesel isn't enough towing. I tried it. Therefore the 19" steel or 21" Duramax fan is worth over 10,000 CFM.

Electric fans on a IDI diesel are a bad joke. Nuff said. Get them off the truck. You are going the wrong way with electrics to solve the issue. :nonod:
 
One thought I have seen only one. But a mud upped block. This usually results in the cooling system not being taken care of. Back flush the block.
 
I know that electric fans aren't moving the same air. I know that the dmax and upgraded pump and clutch are the way to go. BUT BUT BUT. I am grasping at straws now. the engine had 30,000 miles on it when I bought it. When I bought it, it had a blown head gasket (because it was overheating on the previous owner). I did not rebuild the heads, I put BRAND NEW heads on the truck. keep in mind that the heating issue has been there from day 1 a year and 1/2 ago. new heads, new exhaust, new turbo, new computer (with heath tune) new 4row radiator. changed tstats 3 times. not to mention the cooling upgrade (then downgrade) It does not have a blown head gasket. Diesel nut, you may be on to something with the mudded up block. I cant see how but what else is left ALL PARTS I replaced were brand new. lets just humor the idea that I have a clogged up block. Is there a way to back flush that will not do any harm to the new rad I just put in? just fyi, coolant is clean, not mucked up.
 
I know that electric fans aren't moving the same air. I know that the dmax and upgraded pump and clutch are the way to go. BUT BUT BUT. I am grasping at straws now. I am trying every different avenue I can think of. the engine had 30,000 miles on it when I bought it. When I bought it, it had a blown head gasket (because it was overheating on the previous owner). I did not rebuild the heads, I put BRAND NEW heads on the truck. keep in mind that the heating issue has been there from day 1 a year and 1/2 ago. new heads, new exhaust, new turbo, new computer (with heath tune) new 4row radiator. changed tstats 3 times. not to mention the cooling upgrade (then downgrade) It does not have a blown head gasket. Diesel nut, you may be on to something with the mudded up block. I cant see how but what else is left ALL PARTS I replaced were brand new. lets just humor the idea that I have a clogged up block. Is there a way to back flush that will not do any harm to the new rad I just put in? just fyi, coolant is clean, not mucked up.
 
Pull both radiator hoses off the radiator and remove the thermostats. Flow water through the bottom radiator hose and up. One thought, was the block a reman or a new block. It could have sand left in it from manufacturing. Are you losing coolant? Does it ever overheat when your in stop and go traffic?
 
The cooling upgrade didn't solve the problem so you have another problem or bad parts. Electric fans didn't help, and it is known this body style needs more not less airflow. No, it will not solve the major issue you have, but, you will need the better cooling setup when you finally do solve the issue. Load an IDI on a hill and it needs airflow across the radiator stack. This includes looking for any restrictions like mats, bug screens, etc.

New parts don't mean good parts. Less likely they are bad, but, never rule them out as the continuing source of your problem.

Again I would check the AC condenser as it wasn't mentioned and a common debris restriction behind oil coolers.

Then I would check coolant flow in case the water pump impeller is slipping. This system is difficult to see flow through the heater return in the radiator. Feel the upper radiator hose with the cap off and t-stats open for flow. Pot holders as it will be hot... I had a 1995 350 with a bad water pump that would boil over the passenger side of the block while ECT (measured on the driver's side sensor) wasn't rising much with less than 50K on the clock. Known bad water pump design/flaw (balance flow) from the factory for those years. GM dealer had a re-designed pump to be installed that had better flow through the passenger side. 6.5 Diesels suffer from the same issue.

Next is getting a temp gauge on the transmission although slipping transmission 250+ degrees never pushed my ECT up.


What else keeps heat in the engine or adds heat to the stack?

Exhaust. Exhaust valves opening late from a flat cam, restrictions in the exhaust etc. Possible the turbo has issues with a flaw or damage in context of exhaust restriction.

What is the IAT on the manifold? Possible the turbo is generating extreme IAT for some strange reason. Have you removed the fender intake snorkel?

Something really hot in the block or a combustion gas leak causing an air/steam pocket that stops coolant flow - including not getting the air out of the system.

Excessive load like a brake hanging up would not show up as the upgraded cooling system should be able to handle extended WOT time.
 
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