Overdue for a coolant flush, what parts should be replaced?

[DJPepper]

I've got a '08 Sierra 1500 5.3 LY5 afm with 143k on it. I bought it used from a dealership with 98k on it in 2017 and as far as I can tell no 100k maintenance has been done so I'm getting ready to flush out the cooling system and change plugs and wires. I was just wondering about changing out coolant hoses, lines, thermostat and how much life I can expect out of the radiator. I think I'll put a new thermostat and new radiator hoses on while I'm at it. I was just wondering what everyone's experience is with these parts failing (really any part of the cooling system) (mileage, age, etc at time of failure). Any heater hose leaks? As old as the coolant is it only shows a voltage of 30-35ma with the truck off, so as I understand it, it isn't overly acidic, but I can see micro particulate in it.

 

Also what are these 2 lines in the pic? It looks like they go to the radiator, but it could be to the tranny cooler. It looks like one of them has a slow leak by the damp crud collected on the line and the wet spot on the skid plate. Any experience with that condition? I haven't noticed any low levels on coolant or tranny fluid. It does burn a good amount of oil, I guess due to the afm. I'd like to shut that off permanently.

 

Here's a shot in the dark: Is this the original plug wire? I've watched some plugs and wires change vids on the webs and other original wires are red. I'm assuming these are the original plugs and wires because the wire part #(8997) doesn't turn anything up on the web (due to age?), and if you were going to trade this truck in at 100k why would you spend money on the scheduled maintenance. Wire color must vary between years, motors, GM/Chevy). I suppose the definitive way to tell would be to pull a plug and see if it has the original part number.

[davester]

I would not replace cooling system bits until you have a problem (thermostat/hoses/radiator/etc).  They last a long while.

 

The smaller lines in the center of the first pic are probably the transmission cooler lines.  They typically don't fail, just weep/leak oil over time from where all the crimped connections are between rubber hose and metal line.  Same with the oil cooler lines and the power steering lines.

 

I would change all the fluids (engine/transmission/transfer case/front&rear diff oil, brake fluid, power steering fluid, engine coolant).

Maybe also take off the serpentine belt and examine it, and spin the pulleys to check for any noises.  You may be the range where you want to just replace the belts and idlers/tensioners...

[Black02Silverado]

For the cost and ease I would change the belts and idler pulleys.  If the belt goes you get stranded since they drive the water pump.  Don't forget the AC belt.

 

I changed out the coolant on my 2002 and the hoses around 160k I think.  Just wanted to do the hoses since it had more age on it than anything.  I'm still running the original thermostat.  Now that I'm thinking of it, I'm probably over 6yrs on the coolant and need to change it out again. 

[DJPepper]

Appreciate the responses guys. At 12-13 years old,  age is what worries me about the hoses, and they seem worn. I think I can get the 2 main hoses for under $20, and I've got to take them half way off to do the flush anyway so I'm thinking I'll just go ahead and do those.

 

Davester, are you saying your '04 Sierra 3500 still has the original cooling system parts?

I've put new fluid in the differentials and transfer case in the last year, my transmission fluid still looks really clean, and my brake fluid tests good for water and pH. I'll add a power steering fluid, belts, and pulleys to my list.

[davester]

I've only had it for about 6 years now, I don't know what previous work was done to the truck.  It appeared to have a new water pump when I bought the truck but the hoses all looked unchanged, and I did replace the water pump & thermostat last year due to it leaking from the weep hole, but the hoses I disconnected to do it all looked fine on the inside when I changed it.  I've only had to replace a small hose (bleeder hose I believe) because the PO didn't proper secure it when they changed the water pump, and the fan rubbed a hole in it.

 

I replaced the transmission, oil, and power steering lines over time because they were weeping/leaking.

[Black02Silverado]

Rock Auto usually has good prices on parts if you can't find them locally.

[sefiroxx]

My trucks all had problems with heater hose / connections here in Texas. Lost them on each vehicle around the 150-200k. For some reason, the quick connect eventually goes brittle.