99 Chevy Silverado 1500 4x4 Overheating PLEASE HELP!

JoshWalkerMedia · October 6, 2014

Ok so I am stumped on this and spent to much money and my own time I am at my whits end.

I have a 1999 Chevy Silverado 1500 4x4 5.3l v8 Single cab Short Wide
It is over heating I have no clue why.

This all started with a plastic nippe broke off my heater core since then it hasn't ran at normal temp.

We first by passed it and just spliced the hoses together that didn't work then we got a new thermostat that didn't work next came the new water pump then all new hoses and a new plastic nipple for the heater core.

I have flushed the block, radiator and the heater core everything was fine the water that came out was clean as could be ( Other than what LITTLE antifreeze was in the heater core)

I have replaced the following
Upper radiator hose

Lower radiator hose
The Y hose that come from the holding tank to the heater core and the water pump
The one hose that connects directly from water pump to heater core.
Went through 2 Thermostats both brand new one a cheap one and one a more expensive one different brand as well.

New water pump and water pump gaskets

I belive that is everything radiator is less than a year old had to replace that awhile back as the old one cracked

So to recap i have replaced all this and it still over heats I've tried filling up everything first and running it the holding tank just fills and doesn't seem to want to let anything pass the thermo stat all the hoses get hot the lower one is bairly warm and the hoses to the heater core don't get very hot either.

As a side not i did notice when i turn my defroster on or my heater or even the ac *My ac has no belt so it just blows air* But my truck ( I assume the blower fan ) makes an insane rattling and vibrating noise coming from the dash and i can't get hot hair to blow out of my truck either.

Also truck has 270k miles on it

if you need more info ask

If anyone knows how to fix this i am in dire need please and thank you.

brucelimerick · October 7, 2014

Sounds like a t-stat to me. Ignore all the heater and defrost stuff for now. I would take the t-stat our and put it in a pot on the stove in water. It should open slowly as the water nears boiling. If you have a thermometer even better. It should be full open around 180 or 190F. Sounds strange you get no heat though, that hose comes directly off the engine so if the engine is hot your heater core should be hot. T-stat just controls the fluid going to the rad for cooling. The cartridge should face the engine on the t-stat.

JoshWalkerMedia · October 7, 2014

Sounds like a t-stat to me. Ignore all the heater and defrost stuff for now. I would take the t-stat our and put it in a pot on the stove in water. It should open slowly as the water nears boiling. If you have a thermometer even better. It should be full open around 180 or 190F. Sounds strange you get no heat though, that hose comes directly off the engine so if the engine is hot your heater core should be hot. T-stat just controls the fluid going to the rad for cooling. The cartridge should face the engine on the t-stat.

Ive replaced the t stat twice

brucelimerick · October 7, 2014

The way to check them is to put them in water and heat them up. Then you can see with your own eyes they are working properly. You have a real strange set of circumstances. You have replaced everything. Something is still not right. So many parts are just cheap crap. You really need to start serious troubleshooting.

When the piece broke on the heater core did all the pieces match up. No chunks missing?

JoshWalkerMedia · October 7, 2014

The way to check them is to put them in water and heat them up. Then you can see with your own eyes they are working properly. You have a real strange set of circumstances. You have replaced everything. Something is still not right. So many parts are just cheap crap. You really need to start serious troubleshooting.

When the piece broke on the heater core did all the pieces match up. No chunks missing?

nope the thing that broke was the plastic end piece that they make a tool for to remove them to pur a new one on and we did that with the old thermo and thought ehh doesn't seem like its opening up very wide so we got this new one and i somehow doubt that we keep getting bad stats from orileys

JoshWalkerMedia · October 7, 2014

anyone else have any suggestions please?

Duelin · October 7, 2014

I have seen rebuilt water pumps that had the wrong impeller installed in them. Which caused the impellers to run backwards. Have you check to make sure you have good circulation? Is the radiator getting hot all over or does it have cold spots?

JoshWalkerMedia · October 7, 2014

I have seen rebuilt water pumps that had the wrong impeller installed in them. Which caused the impellers to run backwards. Have you check to make sure you have good circulation? Is the radiator getting hot all over or does it have cold spots?

the water pump isn't a rebuild its brand new and the radiator warms all over from what i can tell like i said though its not circulating the upper hose will get hot as hell but the lower ons stays kinda warm WHICH usually would mean the stat isn't opening but this is the second stat we've put into it so i have no clue what is wrong with it anymore there is no blockage in anything not the heater core not the block and not the radiator

brucelimerick · October 8, 2014

I would pull the stat and put the hose back on without it. Boil the stat, check it and run the engine without it. Both rad hoses should run about the same temperature and the engine won't get very hot. The rad should be over cooling it. You could also have a problem with the rad fan but your heater hoses are cold.

The hottest water comes out the top of the engine, rad cools it and cooler water goes in the bottom.

Your heater core hoses should be as hot as the engine, they are on the engine circuit not the rad circuit.

Your overflow tank should come off the top of the rad.

One other thing to try is to leave your rad cap off. I assume you are just running water right now, let the overflow tank drain out. If your pump is running backwards the water should gush out the rad cap. The whole system should run with no overflow tank and unpressurized. Typically the rad cap will hold the system at about 15 psi. The main purpose of the expansion tank is to keep air out of the system.

With the stat out you should see flow in the water through the cap hole. Be real careful if it is in and sticking. By the time it unsticks it will blow steam out the rad cap and if you are looking into, it kiss your eyes goodbye.

To me, I would still think the t-stat is bad or it is in backwards. If not those then a pump running backwards though I have never heard of that happening. But stranger things have happened. Nothing surprises me anymore.

Stevens03 · October 9, 2014

Dumb question but your pitting the stat I'm the correct side up? Also there could be air trapped in the system that cause it to not circulate.

yodahunter · October 9, 2014

Sure there is no air in system? While cool and running, squeeze a hose to see if it's full of water.

Snow White · October 9, 2014

dumber question, is the belt going around the water pump going the right way.... i ask this because you have no belt on the ac and i believe that is 1 serpantine belt meaning it is possible you ran the belt around the water pump around the wrong side of the pulley.... it's also possible the thermostat is in upside down. otherwise, you'd be left with air in the system. If the radiator is full and it's overheating the pump is not working, the t-stat isn't working, or there's a blockage.

tramz · October 9, 2014

^{Pull the thermostat and drive it for a few miles. Is the overflow tank boiling or the gauge reading hot?}

JoshWalkerMedia · October 9, 2014

^{Pull the thermostat and drive it for a few miles. Is the overflow tank boiling or the gauge reading hot?}

we did it just idling and only drove it once when we thought it was working fine and the gauge is maxing out light coming on saying check coolant and the lower hose isn't hot but like I've said several times we've already went through 2 stats a new water pump all new hoses and flushed everything

brucelimerick · October 10, 2014

Your water isn't circulating properly, actually it doesn't seem like it is circulating at all. With the t-sat out it has to be the pump. I would check the serpentine belt idea. A good pump turning the wrong way is a no good pump. There should be a diagram of your serpentine system on the rad housing. You can check whether taking out the AC has changed the direction of the water pump.

Another quick check is to take your top rad house off, duct tape off the top inlet of the rad, t-stat out, and start it cold. The pump should blow water out the top hose. It should only take a couple of seconds to know. If the water comes out the rad cap the pump is running backwards. I don't know the efficiency of a water pump running backwards but if it is an air fan, FC or BI, it is less than 50%. They are both centrifugal. Problem is, if the pump is running backwards the hot water is on the wrong side of the t-stat and it won't open.