Why does my Duramax diesel engine keep overheating?

I and 3 friends with duramax diesels are having same issues. The top radiator hose is collapsing ,preventing flow of coolant to engine. Replacing hose seems to fix problem for a while but need to figure out why the hose is collapsing when engine is under heavy load ,pulling trailer up long grades.

What should the temp be in a tow truck?

However, when I tow an 8000lb 5th wheel on 100F days at 60MPH up 6% grades, mine goes to 240F, the fan comes (around 225 but it takes a several seconds to have an affect) and then the temps drop like a rock to 190-195, the fan goes off and it starts all over again.

Why does my truck run cooler in SRW?

Be prepared for a ton of reading.Good Luck. I have the same truck in SRW. You are implying it ran much cooler at one time under the same conditions (load, temps, speed, hills). If so, then it might be a clogged radiator (internal or external), the fan slipping, head gasket, etc. Something changed.

When does the cooling fan engage on a Duramax LLY?

After towing for a few hours, I could very easily predict the behavior of the cooling fan. With every short hill I pulled, the fan clutch would engage for about three to five minutes near the top or after I crested the hill.

Why is my Duramax LLY overheating at 50 mph?

The fan clutch on that old gasser would never engage at speeds above 50 MPH, even in the hottest ambient temperatures and towing the heaviest loads. Above that speed, there was always enough airflow over the radiator to keep the engine quite cool.

What should the temperature be in a Duramax LLY?

I noted on my digital gauges that the engine temperature was running between 198 and 220°F, a significant jump from the typical 190 to 194°F when running empty.

How much horsepower does a Duramax LLY have?

My first experience towing with my 2005 LLY Duramax was a thrill – and a disappointment. In stock form, other than some gauges and a power program that added about 100 crankshaft horsepower and roughly 180 foot-pounds of torque, there was no disappointment with the power – it was awesome!

How to keep my truck from overheating when towing?

The fan always pulls the coolant temps down but the intake air temps keep slowly rising. I have tried everything suggested and more. I am installing a auxiliary cooler and be done with it. At high loads, the radiator isn’t big enough and there isn’t enough room to install a bigger radiator.

Are there any problems with the 6.6L LLY Duramax?

Thankfully, the LB7 injector problems were resolved, but some new problems revealed themselves. Some of these 6.6L LLY Duramax engine problems stem from the fact that it has significantly more horsepower and torque compared to the original Dmax.

What causes a Duramax diesel truck to overheat?

Its restrictions cause excess heat and force the turbocharger to work harder than necessary. The LLY experiences more overheating compared to other generations of the Duramax diesel because of its inadequate cooling system. They have the smallest radiators and fans found on any Duramax diesel truck.

What to do if your Duramax cooler goes bad?

Lastly we replace a fair amount of glow plug controllers as well. You will usually get a diagnostic trouble code for the cooler when they go bad. Head Gaskets – As these truck reach the 100,000-150,000 miles we are seeing more and more head gasket issues. The Duramax has a multi-layer steel head gasket.

When does a LLY Duramax water pump fail?

While the seal issues found on LB7 trucks have been largely solved, the LLY Duramax can still suffer from water pump failure. Over time and at higher mileage, the seals in the factory water pumps can fail. This frequently occurs after 80-100,000 miles.

How to repair a LB7 6.6 Duramax engine?

We carry a full line of repair and performance parts for these engines that we install in our shop on a regular basis. Odds are we have run across your problem before and would be glad to help. Call us at 1-877-367-9351.

What should the temperature be on a Duramax LB7?

I’ve got a new to me LB7 and I think that the temperature is a little low. On all of my other vehicles (mostly GM), operating temp is 210, however I cant get the Duramax above 170 (according to the gauge it is 180). I took the reading via my OBDII reader, it is 170-172F.

What should the temperature be in a GMC Duramax 04?

My 04 runs this cool also. In town it is 160-170 all the time. If I drive it a little bit harder than normal it will warm up or if I get on the highway at 65-70 it will warm up. Not sure what the low side thermostat is but I would bet its a 165-170 since this is where they like to run.

How long does it take for a Chevy Duramax to warm up?

Mine now takes about 5 miles at highway speeds to come up to full temp. It still won’t warm up a whole lot just idling, but it is much better with the new thermostats and will now put out heat. I got my thermostats at the local parts store in a kit that had both thermostats and the rubber gaskets. Merchant also has them.

Why does my Duramax diesel engine keep overheating?