Dapper

Yeah, I don't disagree with your response, but you shifted your stance a bit. Your original comment was along the lines of "as it gets older it won't cool as well". I still disagree with that. Of course, it COULD be true with calcium build up, a rotted water pump impeller and stuff like that. But it can all be fixed for the most part. Otherwise, I understand I could split the planetary gears or pop a head gasket. Sounds like we both understand that risk. We just react differently... you rent your pullers and I stay prepared for an adventure with my title in hand. All that to say, if you have an old vehicle that has been taken care of and has a healthy cooling system, non slipping tranny and a healthy air conditioner, it won't run hotter with age. Obviously your head gaskets and iron/aluminum can't be leaking.

Well guys, appreciate the time. I still say that that pump behavior is suspect. But I found a huge problem and I wasted a bunch of time by not covering the basics. High side AC pressures are 500psi+ (my gauge only goes that high).

Agree on never fully trusting the gauge. 210 is nothing to worry about for sure. In theory, 230 would still be OK. But the issue was that it would climb until I backed off. For anyone reading this, a chevy block can take 230 consistently... the issue is temp swings that cause the block and heads to expand and contract. If you thermostat is set to open at 190, and the engine runs there, it can swing from 190 to 210 and take it under the chin. But swinging from 190 to 230 is bad really hard. Keeping the engine at 230 is near impossible. You will have downhill coasts and slow traffic. I apologize that my post sounds like I was worried about 210 temps. I wasn't. I am worried because I can make it go higher easily.

Fan clutch roars. I am on board with a trans cooler, but I don't want to mask a problem. This thing went from fine, to overheating after a new water pump. If anyone is reading this, the reason not to mix colors is because the two turn to jelly and plug up your radiator. Not losing coolant. And the dash is dead nuts on, but that is always a great thing to consider with a Chevy. I've learned that. The sensor gets real excited at around 215 and jumps up to the "oh crap" range on the gauge. "Even at highway speeds the fan is used when the temp gets high enough." <-- I am really curious about this. I have seen some pretty good tests that claim to debunk this. But I am curious because people keep saying this. What do you know? Genuinely curious, not looking for a debate.

Not sure I entirely agree. The inside of the engine is clean and with a new radiator and water pump, it should be able to cool as efficiently as it did new. If the tranny is slipping, that would create a TON of heat, and that certainly is a possibility. I've got a 94 pickup that can pull anything it used to be able to. I just can't fit the kids in it.

You thought my post was long, imagine if I had actually been thorough enough to say, that I already did ALL that LOL. I really appreciate the input thought. Side note: Antifreeze doesn't transfer heat as efficiently as water. Straight antifreeze can cause over heats and water works the best other than it doesn't lubricate very well. We saw this in a race car I worked on. We know when the cooling system got saturated and with straight antifreeze (we put it in so it didn't freeze in storage and didn't have a chance to take it out before a quick practice) the cooling system got saturated much easier. However, most mechanics, and I know a lot of good ones, have never seen it actually happen. In AZ a few mechanics there have see over heats in the 120 degree ambient temp range. I am totally on board with installing a tranny cooler but I don't want to mask a problem. What I. and all my friends were hoping for, is someone whose actually yanked the hose off before to see if I might be barking up the right tree with this new water pump being inferior.

Hi everyone, Thanks in advance for your help. I am not sure this is going to be an easy one. I have a 5000lb loaded camper that I pull with my Suburban. Last year, I towed it during a pretty hot spell although I don't know exactly how hot it was. It towed fine with zero issues. I don't have a tranny temp gauge but I lasered the pan often and it was always under 160. It does not have a tranny cooler either. I planned to put one on, but the truck has 240k and we are raising 5 foster kids on a single income. I am grateful for every trip with get and I bring the title with me every time just in case. This winter, the water pump started leaking so a replaced it with a NAPA premium pump, with new hoses and thermostat. Last weekend we took a 6 hour trip and the truck started run hot when the ambient temps hit 95 degrees. By a little hot, I mean, just on the other side of 210, where normally is sits right at 205 on the gauge. I know you might be OK with this, but I am not. I backed off and turned the AC off on hills and accelerating. Later in the day, as it got hotter, I definitely had to wrestle it quite a bit to keep the temp down... mostly by leaving the AC off and once I ran the heater. During stops, I checked the tranny temps via the pan. I was seeing about 10 degrees of difference across the radiator (not great in my opinion). But it wasn't overly cool like a clogged radiator either. At our destination I changed the radiator and stat (again) on a whim, and also noticed that I had mixed the coolant a bit rich when I did the pump. I had high hopes things would be better on the way home, but they weren't... About the same for the most part. The fan clutch is working well, even though most of the issue is on the highway so I think it is irrelevant. The shroud is good and the radiator and condenser are clean. I too Since then I have been tinkering quite a bit and I found something strange. When the engine is running and the water is circulating through the block (stat closed and the stat is located on the inlet of the block which is the lower hose) if I unhook the top hose, I don't get much flow if any out of the top hose. There is a little static pressure but otherwise not much flow. It seems to me that the water pump is only capable of just enough flow to circulate through the block. Now if I start the engine with the hose unhooked, it will flow out the hose (path of the least resistance compared to getting the block circulating). Has anyone on here ever removed their hose and can tell me what you'd expect to see? This behaviour is pretty suspect but I've been doing this long enough to know that engineers have stuff doing all kinds of funky things. I am ready to snag a different pump but it is really hard to believe this this thing would only half work. If the impeller fell of, it would just not work at all. Other than the pump, my next plan of attack is something I didn't think of until tonight. One time my AC system popped off a high pressure valve on the compressor. It kept working fine so I thought maybe it got oil locked or something. But I need to throw the gauges on it and make sure the condenser isn't running at 1000 degrees or something like that. After that, I might take my tranny cooler off my work truck and remove the tranny lines completely from the radiator temporarily just to see what happens. Maybe the tranny is slipping and heating up the radiator but returning to the pan cool? I will leave the fan shrouds off so I can get a better sense as to what the radiator is doing. Does anyone have any other suggestions? Any experience with actually water flow. I want to duplicate my tests for fear I am air locking the pump. But I doubt it. Also, if you aren't familiar with the 5.3 liter, the thermostat is out of the picture for this test. There is a straight shot from the reservoir to the pump and out the top radiator hose. I know if I were reading this or watching the videos, I'd be thinking how stupid it is because the thermostat is blocking the flow... it isn't. You should be able to see the flow, or lack of flow here (scroll down, there are 4 videos) : https://www.icloud.com/sharedalbum/#B0NG4TcsmEobPhttps://www.icloud.com/sharedalbum/#B0NG4TcsmEobP