Cooling System Upgrade/Fix

I am currently looking for some advise/suggestions on a replacement and/or upgrade to my engine cooling system. Also, for anyone who is experiencing similar issues, this story may provide you some useful info. I have a 2006 SR5 DC 4WD.

Here's the backstory:

I recently had an issue with my coolant boiling out of the radiator. I was towing a pontoon boat and then let my truck idle with the AC on to keep the dogs cool in the back while unhooking the boat. I walked back towards the truck and realized there was coolant gushing out onto the ground. Luckily I turned off the truck before excessive smoking and steam.

I was two hours from home so I got the truck towed and taken to a local shop. They did a pressure test and a die test and found that there was no damage or lead to the coolant loop or at the head gasket (pretty happy with that). We determined that the likely cause was that I worked the truck pretty hard while towing, then couldn't reject enough heat while stationary (especially with AC on). While there are *technically* no issues with the truck as long as I'm driving it properly and cautiously, I am looking to upgrade a few items with either OEM or upgraded aftermarket replacements.

Based on the fact that I'm at 217k miles on a 15 year old truck, it is likely time to go ahead and replace the radiator due to normal internal fouling. Also, from what I have read, the fan clutch could also be the culprit.

What I'm going to replace:
Radiator
Fan Clutch
Hoses

Possible replacements:
Upgraded fan - anyone have a recommendation
Coolant reservoir - preferably not plastic if possible
Anything else???

I hope some of you can find this useful and also let me know if you have any suggestions.

 

stock components will be fine, they lasted 15 years and over 200k....no there would be no concern replacing whatever is needed with factory stuff. You are on track with rad, fan clutch(which often is overlooked) and hoses.

Only other thing I would check is to make sure the fan shroud is secure. Sometimes the lower section comes loose, so reduces airflow are low speed, idle, etc.

 

Seems like a good plan. I'd order a new OEM radiator cap and thermostat while you're at it.

 

Aluminum radiator will cool more efficient

 

I assumed the OEM would be Al, is this not the case?

 

Good call. I'll check out the shroud while I'm at it.

 

Bigger core…all aluminum radiator

 

You could also consider adding an air to liquid oil cooler if the truck doesn’t have one.

 

Little known fact: Radiators (all radiators) only need air moving through them at 7 mph to reach their maximum cooling capacity.
It's just how the physics of heat transfer works. If you're travelling more than 7 mph your fan and shroud aren't contributing to the cooling at all (assuming you don't have a tail wind.)

There's some missing info that could help us answer you more effectively.

• Have you towed this boat in similar conditions in the past without overheating?
  
• How much does the pontoon boat & trailer weigh?
• Towing on flat ground, hills, mountains?
• Auto or Manual Trans? (Sorry, no so familiar with 1st Gen options.)
• How fast and in what gear were you driving?
• Were you using overdrive or did you keep it in a lower gear?
• Tow/haul mode?
• What was the outside temp? (80's, 90's, 100's?)
• Does your truck have the towing package? (factory trailer light plug & transmission cooler)

 

He is stationary, unhooking the boat, idle with AC on

 

Not many options for our 1st gens and they are extremely expensive. It's best to just get a Denso OEM equivalent.

 

Call the dealership and get the OEM part number then use Google to find it cheaper. I want to say my 06 DC radiator was about $125 a few years back for a Denso

 

It’s depends if he tow a lot and weather conditions in his area. If it hella hot and he always towing max load up a mountain, I’ll go for a bigger core radiator for sure.
And new engine or head gasket job cost way more then a radiator
Factory is like 1-½” core, but the all aluminum one comes in 2-7/16” that’s 1.25x bigger

 

The truck was sitting still and idling after arriving at his destination when he first noticed it overheating, but I guarantee that it didn't tow the boat just fine with no heat issue then suddenly start overheating shortly after he stopped unless the fan clutch is toast.

A reliable estimate for an automotive cooling system heat loading is that it's roughly equal to the current power output of the engine. In the case of the 1st gens if the transmission cooler is built into the radiator then you have to add that heat load to it as well.

I think that it's unlikely that his cooling system effectively kept the engine at 190-195°F for the whole trip and then just almost immediately fell on its face once he arrived and started idling. I would expect it to already be on the verge of blowing to cap when he stopped for it to happen before he could even finish unhooking the trailer.

I asked all of those questions to find out if my suspicions are legitimate or if something else is going on.

I pulled a heavy, bulky trailer for 3k miles through the mountains in the summer in my 2nd gen with 180k miles on the original cooling system and never had the cooling temp get above 193°F. I don't think these trucks are prone to overheating if they aren't severely abused or in need of repair.

 

Maybe u are right, cause I don’t tow and I’m fairly new to trucks, but I go to HPDS when I’m young, a normal car without any issues will overheat at the track. It’s only a 20 min section in the heat and almost every car without a aluminum radiator will overheat. So I’m used to upgrading full aluminum radiator with 2.5” core.

 

We need to know more details about the operating conditions before we can provide any truly helpful suggestion.

Until then we're just guessing and wasting someone else's money.

 

If your pulling all of this out, great time to do the timing belt if it's within half of it's usable service life. You'll get a new water pump and thermostat during this as well. Coolant flush will happen since your draining the whole system. Replace all of your hoses including the ones to the TB and the heater core while you're at it. Could an overheated transmission be contributing to this scenario? It cools through the radiator as well.

 

Here's some answers to your questions:

• Have you towed this boat in similar conditions in the past without overheating? - Yes, I've towed this boat in very similar conditions minus the part where I idled with the A/C on since I did not have the dogs with me previously.
• How much does the pontoon boat & trailer weigh? - I don't know but I'd guess trailer and all we're talking 4500lbs. It's a 27' pontoon with a 115hp on the back. See below these questions for a bit more info on past towing w/ this truck.
• Towing on flat ground, hills, mountains? - Some small hills at medium/low elevation - It's at Lake Raystown in Central PA
• Auto or Manual Trans? (Sorry, no so familiar with 1st Gen options.) - Auto. As far as the engine goes it's the 4.7.
• How fast and in what gear were you driving? - Up to 50-55mph for 3-4 miles plus 20-30 minutes of idling between the ramp and drop off location.
• Were you using overdrive or did you keep it in a lower gear? - Honestly I keep it on all the time. Open to tips on when to change this.
• Tow/haul mode? Doesn't have this feature.
• What was the outside temp? (80's, 90's, 100's?) Low 90's, somewhere between 90-93 I'd say.
• Does your truck have the towing package? (factory trailer light plug & transmission cooler) - Yes it does.

Some additional comments that seem pretty applicable:

I drove this truck from Pennsylvania to Washington State while pulling a camper last year in late June, experiencing temperatures up to the high 90's for much of the way (Mid-West) as well as climbing some serious mountains (You know, the Rockies). My trailer has a dry weight of 3500lbs, plus I had another several hundred pounds in the bed and cab. After driving it all the way out and back I had no issues with engine temp or performance. When on a steep climb in Montana, I'd be able to hold 55-60mph for 5+ minutes up steep grade. Going across the flats of Montana, I'd be pushing 80 to try to keep up with the speed limit and not add to my ETA on Google Maps. I've towed some trailers around town in PA recently and had no issue. This was truly a surprise when it happened, because prior to this past weekend the old thing seemed bulletproof.

Based on some of your feedback, especially what you say about 7mph airflow, I'd have to guess fan clutch too. The shop that checked out my system told me that these engine driven fans w/ hydraulic clutches (pretty sure that's what I've got) are hard to diagnose with a visual inspection. Since you're relying on your eyes to tell you if the fan speed matches the engine speed, it seems like more of a pass/fail than a true performance measure.

 

Does the trans still cool through the radiator even when there is a second transmission fluid cooler due to having the OEM tow package?

 

Mine does.

 

Yes, the auxiliary transmission cooler loop and radiator supplement the capacity of the transmission cooling done by the main radiator.

When were your timing belt and water pump last replaced? Just curious if a water pump that isn’t flowing well at idle would lead to a cooling issue as well immediately after being under load on a hot day.

The engine fan needs to pull air through the radiator, and the water pump needs to circulate coolant with a high enough flow rate to carry heat away from the engine.

 

That's an easy one to diagnose. Just wait until the engine gets warm then use an air hose to blow against the rotation of the fan. If the air hose can nearly/completely stop the fan rotation the fan clutch is bad.

I would suggest that you don't tow in overdrive. It's really hard on your engine and your transmission. Pull the gear shift past Drive and put it in 4th when towing. The RPM will be higher, but you'll also have more engine power an higher transmission pump speed to increase clamping force on the clutch packs to reduce slipping.

 

After what all I'm reading here, I think it'd be smart to do a few preventative maintenance items. Replacing the radiator is easy enough for me to do myself and its only $100-150. I think I'm about due for a coolant flush anyway, so I will go ahead and do both of these items together.

What I would also like to do is the fan clutch. It does not seem difficult to do, especially while the rad is out, but I've read some stuff saying you may want to consider water pump at the same time... then while the water pump is out do the timing belts... Unfortunately, these items aren't all as simple, so I can't just knock it out in an afternoon by myself. Has anyone here just replaced fan clutch/radiator without doing water pump/timing belt? If not, does anyone have any advise on whether or not it is a good idea or not to just do radiator and fan clutch?

 

Has your timing belt been replaced recently?

If it’s past it’s due date the whole engine is a ticking time bomb.

 

If you're not experienced at changing timing belts and there's no one experienced that can walk you through then pay an experienced mechanic do it.

If you don't use the right procedure to change the timing belt the cams can rotate when you remove the old belt. Then you'll have to reset the camshaft timing which is not a job for a novice wrench turner.

 

I'm definitely looking into getting a professional to due timing belt. While they're in there I'll get them to do the water pump as well. I am trying to get some service records as well as quotes regarding this. I can definitely do the fan clutch, radiator, and coolant flush, so if this does not impact my water pump or timing belt I will treat them as independent projects.

 

They are independent. The fan clutch bolts onto the water pump, but not in any way that would require you to disturb the water pump when you remove it.

Just a tip on the fan clutch: leave all of the nuts on the fan clutch until you get them all loose. You'll need to wedge a large flathead screwdriver between a nut and the center of the water pump pulley to use it as a lever to keep the pulley from spinning while you loosen the nut on the opposite side of bolt the circle. There are probably only four 10 mm or 12 mm nuts holding it on.

That's not a very clear description of what you'll have to do so just search for youtube videos on how to remove a fan clutch to get an idea before you start.

 

Good point !

 

On that one you may have to put the flat of the screwdriver on the inside of one stud and the shaft of the screwdriver on the outside of the next stud. Just make sure the nuts are still on the studs so you don't ruin the threads.

 

Not trying to hijack, but this seemed the logical place for my question:
Does anyone know the hose diameter for the stock transmission cooler? Thinking about replacing mine and was considering an upgrade to a B&M. Does anyone know the specs on the stock cooler (BTU rating)?
I'm looking at replacing it with the B&M 70273.