need help with cooling system

[David Mahuka]

I have a 2004 yukon 5.3 and I don't understand why the top radiator hose is really hot and I can't hold it for only a few seconds and the bottom hose is just warm that I can hold it for a while. I have change the pump and the thermostat and its bothering me. I feel like it not circulating enough or something. The temp stays between 200 and 210. I don't wanna be driving long distance and something happen...please help

[Jsdirt]

Your system is working normally. Congratulations! 

 

Coolant leaves the engine for the radiator via the top hose. The radiator expels heat in that coolant, and the water pump pulls it back into the engine through the lower hose. You've got a properly functioning radiator, and water pump.

[davester]

Yeah, that sounds fine.  If you are doing long trips, and you haven't replaced these parts recently (in the last 100k miles), you might consider replacing the belt/idlers/tensions, or even just having new parts in the truck with you on the trip.  They aren't hard to replace.

[David Mahuka]

On 6/16/2020 at 8:20 PM, Jsdirt said:

Your system is working normally. Congratulations! 

 

Coolant leaves the engine for the radiator via the top hose. The radiator expels heat in that coolant, and the water pump pulls it back into the engine through the lower hose. You've got a properly functioning radiator, and water pump.

Thanks I'm going on a 4 hour road trip and just wasn't sure if that is normal. I didn't want to be stuck on the road going camping with the fam and get stuck. Thanks 

[Jsdirt]

You're welcome. Have fun on the trip!

 

When I question whether a thermostat is working or not, I'll fire up the engine first thing in the morning with the hood up, and feel the upper hose, cylinder heads, and t-stat housing and note the temperatures as they warm up. If the upper hose immediately gets warm, the t-stat has failed, and is leaking flow past it. If the heads seem to get hotter than I was expecting, I throw the infrared thermometer at it. 210° plus or minus is what I want to see. Anything much over 240° and I start to get concerned. Nearing 260° I'm frantically feeling around for where the problem might lie, so I can shut the engine down quick. If the upper hose is hot but the radiator is ambient, along with the lower hose, then I suspect the pump isn't pumping. The heater hoses should warm up first - usually if both are warm quickly, then the pump is working.

 

The gauge in the cluster typically reads 210° , needle straight up, but the actual engine temp varies between 185° - 230° with little movement of the needle, according to the temp sensor reading in the scan tool.

 

Bottom line, as long as the engine isn't literally smoking hot, you're fine.

Edited June 18, 2020 by Jsdirt

[David Mahuka]

12 minutes ago, Jsdirt said:

You're welcome. Have fun on the trip!

 

When I question whether a thermostat is working or not, I'll fire up the engine first thing in the morning with the hood up, and feel the upper hose, cylinder heads, and t-stat housing and note the temperatures as they warm up. If the upper hose immediately gets warm, the t-stat has failed, and is leaking flow past it. If the heads seem to get hotter than I was expecting, I throw the infrared thermometer at it. 210° plus or minus is what I want to see. Anything much over 240° and I start to get concerned. Nearing 260° I'm frantically feeling around for where the problem might lie, so I can shut the engine down quick. If the upper hose is hot but the radiator is ambient, along with the lower hose, then I suspect the pump isn't pumping. The heater hoses should warm up first - usually if both are warm quickly, then the pump is working.

 

The gauge in the cluster typically reads 210° , needle straight up, but the actual engine temp varies between 185° - 230° with little movement of the needle, according to the temp sensor reading in the scan tool.

 

Bottom line, as long as the engine isn't literally smoking hot, you're fine.

I dont have an infrared thermometer, I keep smelling coolant when I'm stopped at a light. Even on short trips thats why I'm kinda trippin on it.

[Jsdirt]

There's a leak somewhere, in that case. Probably small if you can't see it dripping anywhere. It could be running down the back of the engine and evaporating, or out from one of the heads, or a pinhole in a hose. You'd have to have it warmed up and the hoses nice and hard with pressure, then crawl around underneath with a good flashlight. If it still has the orange Dexcool in it, you'll see dark orange crust wherever the leak is, especially if it's been happening for a while.

[David Mahuka]

16 minutes ago, Jsdirt said:

There's a leak somewhere, in that case. Probably small if you can't see it dripping anywhere. It could be running down the back of the engine and evaporating, or out from one of the heads, or a pinhole in a hose. You'd have to have it warmed up and the hoses nice and hard with pressure, then crawl around underneath with a good flashlight. If it still has the orange Dexcool in it, you'll see dark orange crust wherever the leak is, especially if it's been happening for a while.

Ya thats the problem should I just take it to a shop and have them inspect it

[txab]

Did you have the smell prior to replacing the pump and 'stat? You could have a slight leak at any hose connection, especially if you re-used old hoses with spring clamps. I'd be looking there first. Some replacement pump gaskets are very poor and I've seen guys screw 'em up putting in the pump. You've got a throttle body that has coolant flowing through it, check the connections on those hoses. Driver's side is a short hose and can leak. Again any hose that was re-used can be leaking. Checking operation of your fan clutch is important too for temps. If it's original consider replacing because they do get weak over time

[David Mahuka]

55 minutes ago, txab said:

Did you have the smell prior to replacing the pump and 'stat? You could have a slight leak at any hose connection, especially if you re-used old hoses with spring clamps. I'd be looking there first. Some replacement pump gaskets are very poor and I've seen guys screw 'em up putting in the pump. You've got a throttle body that has coolant flowing through it, check the connections on those hoses. Driver's side is a short hose and can leak. Again any hose that was re-used can be leaking. Checking operation of your fan clutch is important too for temps. If it's original consider replacing because they do get weak over time

I think the leak is coming from the black heater hose connector, I've changed it before but put it back on in the wrong order .I should've put it on the metal pipe then into the fire wall connection, instead I put on the opposite and struggled with it after that I seen a few drops from that connector...although I haven't seen any drops from there recently I have a sneaky suspicion that ,that could be the issue cuz it drops directly onto the manifold. I just can't see any trace of coolant anywhere else. 

[Jsdirt]

Oh, those stupid black connectors? Common problem on these trucks going all the way back to the 90's (then, it was the plastic insert on the other end, on the intake manifold). I usually just break the stupid things off, and clamp the hose to what is underneath. Fits perfect, and cheaper than buying another heap of plastic that will fail the same way eventually.

 

Just break that outer shell - not the whole connection. 

Edited June 19, 2020 by Jsdirt

[David Mahuka]

5 minutes ago, Jsdirt said:

Oh, those stupid black connectors? Common problem on these trucks going all the way back to the 90's (then, it was the plastic insert on the other end, on the intake manifold). I usually just break the stupid things off, and clamp the hose to what is underneath. Fits perfect, and cheaper than buying another heap of plastic that will fail the same way eventually.

 

Just break that outer shell - not the whole connection. 

I usually break the whole thing taking it Off. Is that a pressurized hose. I kinda wanna put hoses with clamps and a metal Tinstaed of this plastic stuff.

[Jsdirt]

That's what I always do. Get a worm clamp, or better yet, a "fuel injection hose" clamp - a little better quality, and grabs in a full circle around what you're trying to clamp, with minimal gaps.

[txab]

I would suggest removing the plastic disconnects from the heater core properly with the correct tool. Then you can do whatever you wish to them. No need to risk damaging the heater core. If your hoses are factory, never replaced, I'd replace all of them now.

 

If you OEM style connectors or Dorman then this is the tool

 

 

 

 

Edited June 19, 2020 by txab