Overheating on long pulls?

[Mingoglia]

My '01 runs considerably cooler in both EGT (about 350 degrees cooler post turbo) and coolant temperature. My truck has to run 20 degrees cooler coolant temp... I have a Edge EZ and running completely stock other than that. If I were to add injectors I'm sure I would run warmer than stock, but with just the EZ I definitely run considerably cooler.



Mike

 

[RustyJC]

Primarily because of timing advance and boost increase associated with the EZ, but I was talking in general terms. More BHP = more fuel = more heat = more heat rejection (measured in terms of BTU/hour [absolute] or BTU/BHP-hour [brake specific]). My point is this - my truck was rated 245/505 at the flywheel. I'm making 347/762 at the rear wheels which, for the sake of discussion, lets call it 380/800 at the flywheel. All else being equal (which it's admittedly not), my heat rejection is 380/245, or 155% that of my stock truck. Even if, because the brake specific heat rejection of the BOMBed truck is slightly better (as with the EZ), the absolute heat rejection delta is only 40% instead of 55%, is it realistic to think my stock cooling system was sized with a 40% safety margin? Probably not!!



Rusty

 

[rweis]

Rusty,



To keep the entire truck running as a system, we bomb the engine air, we bomb the engine fuel, we bomb the engine timing,



how do we bomb the enging cooling?



to keep the system balanced as we bomb the horspower?



Don't remember reading threads on bombing the cooling system. Not as much fun as bombing the horsepower I would imagine.



Interesting idea and I certainly do agree with the idea that the horsepower is pushed up significantly but the cooling system is still stock.



Bob Weis



ps Did the antifreeze (Fleetguard ES Compleat 50/50 premix) change and thermostat change. Will pull a short run with the 5er this weekend and see how it goes.

 

[RustyJC]

Bob,



I think the only reasons we get away with it are (1. ) Dodge must have been pretty conservative on their safety margin in designing the cooling system - knowing we're gonna be working the heck out of the Cummins powered trucks and (2. ) we normally don't use maximum BHP long enough to drive coolant temps out of sight. The situation I'm concerned with is the guy with the 450 BHP truck who drags a 20,000 lb 5ver up a 10 mile 8% grade with the throttle floored. I don't see how the stock cooling system would be able to handle that situation! The easiest solution - lift the right foot, but where's the fun in that?



Rusty

 

[rweis]

- lift the right foot, but where's the fun in that?



Yeah, really. The vagaries of bombing.



Bob Weis

 

[C Schomer]

I've been having heating problems too. New radiator(and antifreeze) last summer after it sprung a leak - still overheats on hard pulls. Beings the t-stat only had 40k miles on it, I replaced the fan clutch - helped a little but still doesn't get the old roar out of the fan and overheats a little, yet. Took the stat out yesterday and tested on the stove - stat stuck open. Stat is screwed up and might not be opening all the way either! Makes sense - if the stat doesn't open far enough the radiator won't put out enough heat to make the clutch fully engage. New napa stat and a trip to the mtns tomorrow. I don't have full faith in the napa stat tho - MUCH smaller port. Just had a brain-fart... maybe my origonal fanbelt is slipping too! Craig

 

[Eric_77]

Here are a couple things that can help alot that we have learned from racing.



1. pure distilled H2O it carries heat much easier and transfers it more quickly. downside the boiling point is much less (this is normally not an issue as the coolant remains cooler since it operates more effinceintly) and no corrosion or freeze protection.



2. Add Red Line Water Wetter it breaks down the surface tension and allows better transfer of heat. (also adds some corrsion and water pump lube when used in pure H2O)



3. Evans NPG this is a non water based coolant, pain to change over to but much higher boiling point and non-toxic. Engine runs at higher temp but hot spots and actual overheating are almost non-existent.



Websites

http://www.redlineoil.com/

http://www.evanscooling.com/

 

[rblomquist]

I thought pure (distilled) water didn't boil because it had no impurities in it?



The Mythbuster TV show just did a thing on it. They timed how long it took to boil tap water in the mircowave and then put a cup of distilled in it for the same time; only when they introduced an impurity to the distilled water (sugar cube in this test) did the water boil/errupt.



If someone can explain it differently please post what the real deal is.

 

[yogibear]

I used the Evans NPG+ in my 00. It protects to -40*F doesn't boil till 375*F, and is a low pressure system, change rad. cap to 5#, so hose life is much greater. It cost about 30. 00 per gal. , I'm changing over to it in my 03 as soon as it gets here.



Larry

 

[CFast]

How old is your radiator? When was the last time it was rodded out?

 

[Blue Thunder]

Outside the box...

Usually the obvious thing we think of when our truck is overheating is the cooling system. However, if you go back and look at the signatures, you'll find a common thread. Those with autos are the one's overheating. The reason is because of the auto not locking up in second gear, causing heat to build in the transmission. Once the trans temp rises above the engine coolant temp (usually about 210*) the stacked coolers at the front of our trucks work against us. Since the trans cooler is in front of the intercooler in front of the radiator, the hot air from the trans. heats the intake air which makes the EGT's rise, which make the engine run hotter, which is trying to be cooled by the hot air coming from the hot trans cooler. Does that make sense???



That being said, the first thing we with autos need to do is make sure we are getting lock-up in 2nd. As long as the valve body is set up for it, all you need is a lock-up device. most trans builders have one available for about $300, or you could use some sort of mystery switch.



My new trans (with 2nd lock-up) is going in next week. I'll know then if my findings prove true.



Granted, our cooling system is likely inadequate for the power levels we are running. So, it would be good to check all the aforementioned devices (fan clutch, t-stat, coolant etc. ).



I am no expert, but you may find this info helpful.

 

[jimnance]

Originally posted by RustyJC

Bob,



I think the only reasons we get away with it are (1. ) Dodge must have been pretty conservative on their safety margin in designing the cooling system - knowing we're gonna be working the heck out of the Cummins powered trucks and (2. ) we normally don't use maximum BHP long enough to drive coolant temps out of sight. The situation I'm concerned with is the guy with the 450 BHP truck who drags a 20,000 lb 5ver up a 10 mile 8% grade with the throttle floored. I don't see how the stock cooling system would be able to handle that situation! The easiest solution - lift the right foot, but where's the fun in that?



Rusty

I'm not nearly that extreme, but I'm 22,500 GCVW going over 6% grades with an Edge EZ and I never get over 210 F. As soon as the fan clutch kicks in the temps come down.



My '99 had the thermostat fail at 70K. I'd put money on the thermostat or fan clutch.

 

[Eric_77]

Distilled water boils. I think the point that myth busters missed is the impurities they added lowered the boiling point of water below 100c or maybe the point is the water does not boil in a microwave??? I have never tried that we did all our experiments over gas heat in HS/college.

 

[Houser]

Have you tried a new thermostat. I was having a similar problem wih heating up on hill this spring. Going up the engine got hot and going down the enging cooled way down. With the new termostat my temps don't fluctuate more than 5degrees.



Houser

Anchorage

 

[alaskax]

Houser,

Maybe it's time for me to get a new thermostat, as my truck is doing the same as yours did.



Blue Thunder,

With my ATS transmission with Commander, I lock up in 2nd, but my start/stops going up was enough to heat up the transmission anyway, to about 200 to 230 deg. It too goes down on when going down the hills!



Still seems wierd that I had the worst problems with overheating in lower gears, locked up, not stressing the engine, egt's fine. Simply needed high "ram" air to keep engine temp down. Guess I have a few things to check out!

 

[Turboman]

Mine gets hot too

I'm at about 22k lbs with my fiver. On long mountain passes in NM/CO it will climb up to about 220*. This is on 8-10* passes at about 30-45mph. It's a bum having the power to go faster but ahving to slow down with Furds to keep the heat down. I figure it a combo of 300+ hp and a 245hp radiator, slow speed so no ram air cooling, and high boost/ egt for extended period. I have been looking for a better radiator. I remembered a thread about a high performance radiator for our trucks a while back but have not see anything in a while.

 

[geusterman]

My guess is fan, thermo and radiator plugging, in that order. That done, I would add a 5 core or larger radiator and see if there is a way to increase gal per minute with a different water pump.



As long as you obey the speed limit and weight limits there should not be an egt or water temp issue unless the first three things are not working. If speed and weight are exceeded then the extra egt could be handled with increased cooling. After increase radiator and water flow then inter cooler increased for cooler intake air (providing exhaust size is not limiting factor). My take and what I would do (and have done). George

 

[Mingoglia]

I was a little lighter than normal this past weekend but I was around 19,000 gross combined. I pulled the several mile 7% grades at 50mph with it to the floor with my '01 5sp 3. 55 Edge EZ. The hottest I got it was 210 degrees. I was pulling in 105 degree Arizona weather. The hottest I got my EGT was 900 post turbo. This is with a stock air filter and exhaust.



Mike

 

[dcamilleri]

I am also having cooling problems with my 24v conversion, but I also had similar problems with my 300 hp 6. 5. I am currently running a 19 inch flex fan that I believe is not flowing enough air. Tommorrow a 22 inch flexalite class 5 truck fan should be showing up on my door step and we should see a dramatic increase in air flow.



As to those of you experiencing heating problems I would point to the fan clutch. Fan clutch lock up temps are not very predictable. While they might be designed to lock at 208 some might lock at 200, while others might not be locked at 220. I have bombed some fan clutches in the past by cutting a different groove for the bi metal spring to rest in thus lowering the lock up temp. This worked outstanding at getting the fan to roar and do it's thing. However, if after modifying it still does not roar, then there is a problem internally with the clutch.



The way a fan clutch works is that a bi metal spring turns a valve as it gets hot thus creating more resistance to movement creating close to mechanical lock up. At high engine temps your fan should make a definate roar(very noticeable,loud).



If it is determined that your fan clutch is defective DO NOT BUY A REPLACEMENT FROM AN AUTO PARTS STORE!!!!!! Their quality is poor and lock up is very unpredictable. Buy the real thing from Cummins or DC.



Also remember that radiator caps only keep pressure in the cooling system. When coolant is under pressure the boiling tempature is raised(I. E. water boils at 212F at sea level, with 15 pounds of pressure in the system it will boil at 235+-) keeping the inside of the engine from having steam pockets.



For those instances when pulling long mountain passes and coolant temp is going through the roof, TURN OFF A/C, ROLL DOWN WINDOWS AND TURN HEATER ON HOT WITH FAN ON HIGH. This will help. The A/C condenser in front of the radiator is very hot while running the A/C and takes away from cooling ability. The heater is another radiator and effectively increases cooling capacity.



I will post if my cooling problems diminish with the install of my new fan. Hopefully it won't rob too much H. P.

 

[dcamilleri]

Just received and installed my new flexalite 4600 series, 22 inch fan. The fan is black nylon with an aluminum center hub. This fan is designed for class 5 trucks. When I rev the engine now it REALLY sucks air! I hope the fuel mileage does not drop too severely. Temps are starting to get hot here in the Rockies now so I need to hook up to the trailer and see what happens. I think the fan is going to make a huge difference.