Hey guys, so a few months ago I was towing the bass boat to the lake and the temp started shooting up on my Cummins (230-240degrees) and then lowering back down. So I immediately replaced the thermostat and no issues for a little while. This past weekend I was on my way back from a road trip with the family and it started doing it again about 10 miles from the house so I just nursed it home and let it cool off. I did some research and thought it might be the electric Fan Clutch, so I replaced that little PITA and took it for a test drive and low and behold it started doing the exact same thing. This is a 2010 Mega Cab Laramie 2500 6.7, deleted and tuned using a H&S mini maxx, and I typically run it on the street tune and not performance, but am not beating on it hard at all. Any help would be appreciated as to what is causing it to run hot.

 

Thanks 

What is your EGT's like?

 

What size tires are you running?

 

What temperature thermostat are you running? Where did you buy the thermostat?

 

 

295/70/17's and 190 degree thermostat from AutoZone. Apparently the EGT is not hooked up because the Tuner has Pyro 1 & 2, which to my understanding means they aren't reading anything, but Pyro 1 is reading 300 plus at idle (180 degrees coolant) and the Pyro 2 is reading 90's, but I didnt have those on while running, I usually run the fuel rail pressure, trans temp, and boost... 

Also, I have noticed it started bubbling after shutoff the past couple of months, not sure if that helps any. The head studs and all work were done before I bought this truck, so I am working blind here somewhat

How is the air flow over the radiator cooling fins, rat nest or other obstructions between it and the intercooler?

How is the coolant flow through the radiator cooling tubes.  No blockage with calcium deposits or other debris?

You might switch up and watch Pyro 1. Lets check and see if the large tires are not building more heat.

 

Like myself I'm studying the effect of using smaller tires.

 

IBMobile is right check for debris.the common spots is the bottom half typically can get block and you can't see it.

If it's boiling, it's ether really really hot or you may be getting exhaust gases in your cooling system. What mix of antifreeze/water do you use and what pressure on radiator cap. 

I'm just guessing here, maybe verify temp with a Lazer thermometer in few spots too. And your truck should have an electronically controlled fan, maybe a sensor isn't functioning properly and fan is not fully on. 

 

38 minutes ago, Dieselfuture said:

And your truck should have an electronically controlled fan, maybe a sensor isn't functioning properly and fan is not fully on.

 

It's possible to have an electric fan clutch fail too. I've got 3rd Gen I've got to change fan clutch on really soon. Same kind of overheat issues as well. If I'm not mistaken the fan clutch is controlled from ECT (Engine Coolant Temperature) sensor so if the data is coming through and the gauge is showing it then I would have to think fan clutch next step. 

Tires aren't going to cause that much of an overheat, even towing. That's pretty darn hot for a Cummins. 

 

Rapid rise in temp with a light load and no real hills (Assuming you were in NC, not the Rockies), tells me that either you have air in the cooling system or your thermostat isn't working properly. A plugged radiator shouldn't shoot temps up and down rapidly, but rather run hot and stay there. 

 

The thermostat could very well be the culprit, even with the new one. Stick with genuine Cummins thermostats, as the rest have a pretty lousy reputation. 

 

Your 2010 should have a 200° thermostat from the factory. A 190° thermostat is fine for most uses, but the fan is calibrated for a 200° thermostat and while towing the fan won't come on early enough to keep the 190° thermostat where it should be, but a bass boat and tires shouldn't cause that much heat. I'd replace the autozone thermostat with a Cummins 200° thermostat. If you tow above 18K GCW often I'd see about a 190° thermostat and a custom tune to adjust the fan, as this will reduce your oil temps to a better level... but unless you're doing that often I'd stick with the 200° thermostat so that when you do tow the fan is working at the appropriate temps. I'd also run a synthetic oil so it can handle the higher oil temps better. 

 

What is your coolant level? With a cold motor, sitting overnight, what level is the radiator at? How does it look?

 

Pyro 1 may be hooked up. Before you start the truck in the morning see what the Pyro 1 temp is, and it should be similar to coolant and intake air temp. If it is, then start the truck. If it starts to go up then it's likely hooked up. Look underhood for a probe in the exhaust manifold or turbine oulet pipe. If the PO put studs and MM on the truck it likely has Pryo 1 hooked up. 

 

If Pyro 1 is working you need to monitor it, more so than boost or rail pressure. Pyro temp will give you limitations where boost/rail pressure are just fun to watch and won't be extreme unless something has failed. 

 

The fan clutch will throw soft codes, set's a code in the ECM but doesn't like the CEL, and the MM should be able to check for those. 

 

It's been a while since I have played with a MM, but can you select fan speed on it?

 

 

Just now, Mopar1973Man said:

 

It's possible to have an electric fan clutch fail too. I've got 3rd Gen I've got to change fan clutch on really soon. Same kind of overheat issues as well. If I'm not mistaken the fan clutch is controlled from ECT (Engine Coolant Temperature) sensor so if the data is coming through and the gauge is showing it then I would have to think fan clutch next step. 

 

The 3rd gen, and 4th gen, have a LOT of parameters for fan speed. It's fully controlled by the ECM which means it will throw a code, but not normally a CEL, for underspeed operation. 

 

The OP already replaced the fan clutch, but it doesn't seem to me like that's his issue. My non-UDC programming never engaged my fan much and I'd top out at about 215-218° at 20K GCW on a 6% grade at 65 mph on a 100° day. Now with my fan programming I've only seen 211° once for 5 seconds, the rest of the time the fan engages at 208° and keeps the coolant to a max of 209-210°. 

Just now, AH64ID said:

Tires aren't going to cause that much of an overheat, even towing.

 

Some people blindly tow large loads with 37" tires with 3.42 gearing and hold their foot to the floor. No pyrometer. Seen this a few times where people are stopped along the road trying to cool down their truck. Like today here it just about reached 100*F and I know its even hotter in Riggins. Yeah, it does happen blindly assume the truck can handle the load with 37" tires. 

 

I've even seen a few burn down on Whitebird grade from this. Yes, it possible. 

It's possible, but we're talking about the OP's truck with 295's, not 37's. He monitors trans temp, so it's a 68RFE and they will not let you lug the motor to that point, as it will downshift.  

 

So while it's possible for some people to do it, that's not the issue with the guys asking the questions and having the issues in this thread. 

56 minutes ago, Mopar1973Man said:

 

It's possible to have an electric fan clutch fail too. I've got 3rd Gen I've got to change fan clutch on really soon. Same kind of overheat issues as well. If I'm not mistaken the fan clutch is controlled from ECT (Engine Coolant Temperature) sensor so if the data is coming through and the gauge is showing it then I would have to think fan clutch next step. 

 

55 minutes ago, AH64ID said:

Tires aren't going to cause that much of an overheat, even towing. That's pretty darn hot for a Cummins. 

 

Rapid rise in temp with a light load and no real hills (Assuming you were in NC, not the Rockies), tells me that either you have air in the cooling system or your thermostat isn't working properly. A plugged radiator shouldn't shoot temps up and down rapidly, but rather run hot and stay there. 

 

 The thermostat could very well be the culprit, even with the new one. Stick with genuine Cummins thermostats, as the rest have a pretty lousy reputation. 

 

Your 2010 should have a 200° thermostat from the factory. A 190° thermostat is fine for most uses, but the fan is calibrated for a 200° thermostat and while towing the fan won't come on early enough to keep the 190° thermostat where it should be, but a bass boat and tires shouldn't cause that much heat. I'd replace the autozone thermostat with a Cummins 200° thermostat. If you tow above 18K GCW often I'd see about a 190° thermostat and a custom tune to adjust the fan, as this will reduce your oil temps to a better level... but unless you're doing that often I'd stick with the 200° thermostat so that when you do tow the fan is working at the appropriate temps. I'd also run a synthetic oil so it can handle the higher oil temps better. 

 

What is your coolant level? With a cold motor, sitting overnight, what level is the radiator at? How does it look?

 

Pyro 1 may be hooked up. Before you start the truck in the morning see what the Pyro 1 temp is, and it should be similar to coolant and intake air temp. If it is, then start the truck. If it starts to go up then it's likely hooked up. Look underhood for a probe in the exhaust manifold or turbine oulet pipe. If the PO put studs and MM on the truck it likely has Pryo 1 hooked up. 

 

If Pyro 1 is working you need to monitor it, more so than boost or rail pressure. Pyro temp will give you limitations where boost/rail pressure are just fun to watch and won't be extreme unless something has failed. 

 

The fan clutch will throw soft codes, set's a code in the ECM but doesn't like the CEL, and the MM should be able to check for those. 

 

It's been a while since I have played with a MM, but can you select fan speed on it?

 

 

 

The 3rd gen, and 4th gen, have a LOT of parameters for fan speed. It's fully controlled by the ECM which means it will throw a code, but not normally a CEL, for underspeed operation. 

 

The OP already replaced the fan clutch, but it doesn't seem to me like that's his issue. My non-UDC programming never engaged my fan much and I'd top out at about 215-218° at 20K GCW on a 6% grade at 65 mph on a 100° day. Now with my fan programming I've only seen 211° once for 5 seconds, the rest of the time the fan engages at 208° and keeps the coolant to a max of 209-210°. 

Thanks guys, lots of good information. I replaced the Fan Clutch and flushed the coolant and that seems to have fixed it. The coolant was low and had a pretty good air pocket burp when I took the radiator cap off, so I think that had a lot to do with the temps as well. It's running strong again and keeping steady at 190, so I appreciate the insight and help figuring this out and wish you all the best.

Thank you

14 hours ago, Mopar1973Man said:

Some people blindly tow large loads with 37" tires with 3.42 gearing and hold their foot to the floor. No pyrometer.

Ignorance is bliss!

That it is, but I'm not one of them.. A) I'm not running 37's, and/or trying to haul heavy with the wrong setup, I tow a 5k lb center console to the coast a few times a year, a fiberglass bass boat <1500lbs, and a horse trailer occasionally that is 8500, so I'm not beating on this truck at all and B) given that this issue isn't across the board and sporadically started happening is what led me to believe it was a failure somewhere else and not a simple obstruction in front of the grill or the tire setup. I was born at night, but it wasn't last night...

Edited July 6, 20186 yr by MtnManMegaCab

That wasn't directed at you @MtnManMegaCab....

3 hours ago, MtnManMegaCab said:

 

Thanks guys, lots of good information. I replaced the Fan Clutch and flushed the coolant and that seems to have fixed it. The coolant was low and had a pretty good air pocket burp when I took the radiator cap off, so I think that had a lot to do with the temps as well. It's running strong again and keeping steady at 190, so I appreciate the insight and help figuring this out and wish you all the best.

Thank you

 

Good deal!

 

One of the downfalls of the non-OEM thermostats is they often don't let the block purge the air as well. It's very possible the original thermostat was the 1st issue and air was the 2nd. 

 

 

2 hours ago, AH64ID said:

 

Good deal!

 

One of the downfalls of the non-OEM thermostats is they often don't let the block purge the air as well. It's very possible the original thermostat was the 1st issue and air was the 2nd. 

 

 

 

Suggestion. Doing reloading with coolant. I typically leave the thermostat out and fill till the coolant just about ready to spill out. Then Install the thermostat. 

 

4 hours ago, MtnManMegaCab said:

I was born at night, but it wasn't last night...

 

Not directed at you either...

 

Just I've witnessed quite a few really "dumb moves" by people with diesel trucks. I tend to bring the worst cases to the table. I tend to be kept from saying "never" because there is always one out there dumb enough to reach for the stupid ring yet. Again not directed at you but just pointing out they are out there.