Some of you may have seen my various distraught overheating comments throughout the forums. But today was the last straw, I'm starting my own thread.

Here's what happening: The truck warms up fine to operating temperature with or without air on. The truck will linger around 180 degrees for 4 to 5 minutes before deciding to take off. When I say take off, it's not that drastic, the temperature slowly climbs, idle versus driving has no tremendous effects on overheating I don't see. Now, the truck gets to 220 degrees within ten minutes after that 180 degree mark, then, it stays. For example; today, I was in Fastenal and left the truck running with A/C on outside to see how it went. When I parked, the truck was around 190 degrees and about 8 minutes later when I got back in the truck it had reached its 219-221 mark, every now and then it would touch 224 but not for any extended amount of time. In the past, my lower radiator hose was popping a leak from where it slips over the radiator. The leak was not in the hose. The two times that happened I simply tightened up the old clamp (I really should get new clamps) and haven't had any problems. Once, when my truck got a little hot the lower rad hose plus a random heater hose sprung a leak, I replaced that hose and haven't had any problems with it. But today, when I came out I noticed the upper thermo to rad hose had a stream of antifreeze also coming out where it slips over. I am almost ruling out the overpressurizing thing due to the old clamps, but I know better. I limped Landy home as she stayed at 220ish degrees all the way home, air on. One consideration, as I was limping her home the temperature gauge in the gauge cluster was going wild, similar to what a gauge does with air in the system. I assume air entered via the leak in that upper hose I was talking about; but I just kept an eye on Ultra on the way home, stayed around 224 the entire time. Later today I drove her again, the stock gauge seemed fine.

For what I've done; replaced every single cooling system hose, Chevy fan clutch, correct belt routing, 180 degree thermostat, rodded out radiator, coolant flush, green O'Reilly's premixed coolant. The only thing I haven't replaced, water pump. Let's all keep in mind, the entire cooling system was overhauled last year (Heads, fan clutch, thermo) Only non-replaced cooling part was the radiator before I had it rodded out.

I have two theories; I need a new water pump (it was replaced last summer, damn it) or my radiator wasn't rodded out as well as it should have been. I'm not ruling out head gaskets, though I don't think it's pressurizing enough to make sense for those. That's all there is to fix cooling-wise

When I got home I got a temperature gun on the radiator. Ten minutes after shut down; 200 degrees at the top and around 115 degrees at the bottom of the radiator.

I love my truck, it's modified. I'm not the typical 5 post kinda guy inquiring about "my truck I just bought for $500 is overheating, help me!" I'll do anything for this stupid money pit.

I believe I'll replace that water pump, maybe the teeth are worn down. I also prefer speaking than typing, so if someone besides Mike could give me their phone number I'd love to talk Rover.....Savannah Buzz

 

Sounds like a radiator to me. I know you said you had it rodded not too long ago, but 200 top vs 115 bottom is a big difference, and it fits with your description of coming up to operating temp, lingering, and rising up again. I'd check the temps up and down the radiator when running hot, they should be fairly close (I think Spike says 10-20 degrees difference top to bottom).

 

I've heard that too! I've heard Buzz mention the 10 to 20 degree thing, also. This radiator guy is the only one in town and has been doing radiators as long as I can remember, so I don't know why he would/or did half *** mine

 

i think its a rad issues. also one thing that can go wrong is that the fins inside your pump wear out so it still pump water through but not the volume it needs. but you pump is newer so that my not be the case. if you want to call 530-321-5834 text before calling. i work at a bank so i can't always get to my phone.

 

I tend to agree with the radiator. If it can't get rid of the heat, then system slowly warms up, and just can't get rid of it. At speed engine makes even more heat, and just not enough air moving to get rid of it. I think you may be a candidate for the $235 aluminum replacement that has done well for those who have swapped it out recently. Sometimes they just can't get all the gunk out. The difference top to bottom shows that water flow is slow or not at all in the bottom.

 

What about head gaskets? It could be even a small leak causing pressure. Does it boil out through the cap?

 

True, and the exhaust gas in coolant test could point to that. But if it was HG, I don't think it would stop at 220 and sit there. I think the rad is "undersized" because the blocked or coated tubes have chocked it off and the truck just reaches that temp. The big difference between top fins temp and lower fins temp also points at that. The hot coolant enters the driver side (NAS) amd flows across in parallel tubes, so temp top/bottom on the side tank is not a good indicator. Really need to look at the fins temp. If it was HG (and that could be part of it) and not the rad, the rad would read a more even temp top to bottom.

 

No boiling. Maybe e blockage in radiator was pressuring up the hoses. Time to remove my radiator

 

Wen you measure rad with IR I would do it when just turned off. Letting it sit allows convection to change heat readings somewhat. You can also reverse flush it, or flush both ways.

 

Its getting rodded, again, as we speak