So let me start by saying hello, long time lurker first time user. You all have helped in the past quite a bit with my Expy; FPDM, CJB, Plugs.

So recently I had an issue with my radiator. While driving to work, there was a loud pop from my engine bay. At first i thought a piston had blown out, but since it was driving normally, I figured that wasn't the case. So fast-forward 2.5 miles down the road, alarms start going off, so I look down and my check gauge lights on. Not really seeing anything until I look at my temp gauge, which is all the way on hot. I get the truck to work about a mile and a half later and pop the hood. The engine bay is covered in coolant. Looking around I cant find the source of the coolant leak until I look at the fan shroud on the drivers side. There is now a nice sized hole in the shroud. Below that i see that roughly 20 - 30 of the cooling tubes have been damaged. I also notice that there are now two fan blades almost completely gone. Call my wife and tell her that when I'm done with work she will need to bring the other truck down to tow me the 17 miles home. This all happened about 8 days ago.

So today I drop in the new radiator, get coolant and distilled water and put that in. Charged the battery, and drop that back in. Turn her on, and she fires up but shakes now. I let the truck idle for a bit and make sure that the coolant is flowing and the hoses are tight to the squeeze. check the A/C to make sure it works since I live in Vegas and it gets a bit warm outside. i also check the heater because it is close to our cold season. No heat, only cold.

Now i get curious to see if this is all due to the fact that its been sitting for 8 days with no coolant and just needs time to work into the system. So i let the wife take it around the block to see if the roughness goes away. She returns less than two minutes later as the gauge says the truck is again overheating. So i pop the hood to make sure no coolant has blown out again. No coolant spills that i can see, and radiator cold to the touch.

Now here is where i am at a loss. Is it possible that there could be damage to an internal component of the engine? Or could it be something simple like the thermostat? Any help or insight would be extremely appreciated.

 

If you didn't replace the thermostat, you can start by replacing it. It could have been damaged during the overheating, or might even be the cause of the first overheat. They're cheap and takes only minutes to replace.

 

You didn't say so I'll ask the obvious question, did you also replace the broken fan? Also, since the fan had physical damage there is a high probability the water pump shaft got bent and is the source of the shaking.

 

There is a ways the possibility that driving for 1.5 miles while overheating blew the head gaskets and warped the heads. I would go to auto zone and borrow a head gasket test kit.

 

If the radiator was still cool to the touch, it wasn't circulating as you noted. I'd first start with a thermostat and I hope you would have replaced the fan as alloro asked but if not, an easy place to start.
Once you heard that "pop," not pulling over and inspecting was probably not a good idea. Then once you did and found this issue, driving another mile and a half and overheating more, could have blown a head gasket among other possibilities.
I take it you mean a compression tester for the head gasket?

 

So I changed the thermostat yesterday as mentioned. Fired the truck up, shaking is now 85% gone. I didn't get a chance to replace the fan as I will need to order one. I'm getting that through a pic-a-part type place as in a few months I plan on installing dual electric fans on it. Does the fan do any form of balancing? if so would losing two blades cause the shaking?

The heater now works as well, blows warm. But that's probably because I tested in 98 degree heat. A/C still works, blows ice cold.

I still need to figure out why the RPM's drop by about 200 or so when i turn on the climate controls.

I don't think my head gasket went out. Of course I'm basing that off no creamy white fluid in the oil like when my Suburbans head gasket went out. I can pick up a compression tester next weekend after pay day

 

The fan doesn't balance the motor if that's what you are asking, but it does need to be balanced itself. Anything that rotates needs to be balanced. Are you doing all of this missing two fan blades?????

 

If the fan is missing a blade or two, it will cause inbalance in it and lead to shaking in the engine. It will also wreak havoc on your water pump and cause premature failure of the bearing in the water pump if you drive it like that.

 

Yea its missing two blades. Well half of two blades anyways. I haven't been driving it too far from home because of the radiator/thermostat/fan issues, testing is less than a mile round trip. During the testing I've had no overheating warnings. After the radiator felt hot to the touch, but that's possible because i didn't reattach the shroud because I would be removing it constantly and i haven't replaced the fan.

This has by far been my most problematic truck, possibly as the previous owners only changed oil and brake pads. Any repairs have been due to their negligence.

 

Sticky IAC valve.
What year is this vehicle?

 

Its a 2006 XLT

 

Then scratch the IAC valve suggestion, you don't have one in 06. I believe yours is drive by wire.

 

Yea its drive by wire. I did have two codes related to throttle body actuator and sensor a couple months back but those cleared after a power cycle

 

I'd kiss that water pump goodbye. You are only going to foul more things up by driving like that.

 

Which is why in the entire repair process its been driven less than 1.5 miles. If the pump goes, I'll replace that with a part that I would keep on the truck for more than six months.

This is the first time I've ever had a radiator/thermostat/fan fail on me. My Chevys are all at 200k miles with originals still on them. So far on the Expy I've replaced plugs, four FPDM, three fuel pumps, two CJBs, taken to Ford who found bad grounds, in addition to the upgrades I've put on it.

I'd love to keep the truck up to 400k - 600k miles if possible