Hey everyone, I have a 95 1500 with the 5.9 and im having some problems with my cooling system. in town it seems to do alright, it hangs out around 200 degrees but as soon as i get on the freeway or highway or start pulling a long hill the temp pops up to 230+. I have replaced the radiator cap, put in a 180 degree thermostat and put in a new fan clutch. and its still doing it. Any ideas?

 

Air bubble in cooling system? Too much crap floating around in the system? Blocked radiator? (insufficient air flow) Temp gauge lying to you?

 

Is it blowing coolant through the overflow? If so, then it sounds like the timing needs to be adjusted, which means programming the PCM.

 

When you replaced the cap (or before), did you check your coolant level?

After getting it warmed up, park it on an incline (engine towards the top of the incline) or put it on ramps (or jack up the front end). After waiting several minutes (or more), letting the engine begin to cool down, take off the radiator cap (use a glove, it will be hot). Some coolant will come probably come shooting out, and it'll be hot, so be very careful. I always have a set of thick work gloves in my garage for such occasions. Close the hood, let it sit for several hours (I usually let it sit overnight) with the cap off. This should "burp" any air out of the system. Before you drive it the next morning, fill it up with coolant, as the air bubbles being gone means it'll be low and take more, and then put the cap back on.

If it still doesn't cool after that, you probably have more serious issues.

 

I really can't recommend opening a hot (under pressure...) cooling system. That is just a recipe for a trip to the emergency room.

 

before i did anything yes the coolant levels were good, since i replaced the thermostat i have been checking it daily making sure any air bubbles that work their way up get replaced with coolant, but i may try the incline thing and see if that helps...

and if i do have to open a hot radiator i use a lever type radiator cap with a towel draped over the cap to catch any overflow, im not into the being burned thing, haha

 

I apologize, when I went back and did some proof reading before I posted, I must have deleted a bit to much and forgot to add some back in. I meant to state to wait several minutes or more for the engine to begin to cool down. I will edit the post to fix it.

However, like I stated, coolant may still pop out a bit, so make sure you are wearing hand protection.

 

I'm no expert but take this as you will.

When you changed your thermostat, did you check to see if what color the fluids were? where they bright green or a yellow green.

Have you checked your radiator to make sure its got all its fins or at least a good proportion of it.

Have you thought about doing a fluid flush?

Have you thought about blasting the AC condenser and radiator from the front, sometimes those things get blocked with dirt and bugs.

 

I did test the a fluid and it was good, the radiator looks in good shape fin wise from the outside. I think im going to try a flush next and just see if there is any blockage inside.

 

Use chemicals. A descaler would be a good idea too.