Heat

[BraveHeart]

Hello everyone!

Now i have swapped my 06 Hummer h3 since the last one went broken, the new used engine i have replaced seems good and no issues with it.

Only what bofgers me is that temp goes up very fast, i mean within 10 to 20 minutes it will go up to half the gauge and as i drive it goes up slowly to med ways between ½ and ¾ and. If i stop or park while engine is running or even rev up a bit it goes to ¾ right away.

It never crosses that but it is worrying to be hknest since it wasn't like that before.

Notes:
• Change the radiator to Aluminum one almost 3 weeks ago.
 • i use the same th
he same thermostat i had in my older engine (because i know it was fine).
•i used the same fan and clutch i had, again because the temp was fine in there.
• the water pump i used the one came with new/used engine.

Ready to hear you kind Suggestions

 

[Doc Olds]

Welcome. 3/4 is no big deal on the temp gauge as it is not accurate, more like an idiot light with a pointer. You have to scan it and see what the actual coolant temp is which is related to the ambient outside air temp. If it is 100F outside, the temp will be higher than if it is 70F outside. If the target temp is 195F, when very hot outside, it may end up at 205F. When you stop = less air on the nose and less cooling mass so temp on gauge goes up.

BTW the temp is supposed to go up quickly so the engine can run at the set full operating temp and switch from open loop cold start strategy (rich fuel mixture) to closed loop and normal fuel ratio for increase efficiency.

While scanning, look at the Trans Temp when the temp gauge is at its highest. If your trans is worn and slipping, dirty fluid and filter, it can run hot it will increase the coolant temp as the trans has a cooling loop through the radiator if you have an auto transmission.

 

[EndeavoredH3]

Did you reuse the coolant temp sensor from the original motor or did you use one that came with the new motor.

If it’s the latter it’s difference in sensor sensitivity. Verify coolant temp with a temp gun. Basically anything between 190F - 220F is normal at idle. Depends heavily on ambient.

 

[H3Hummer]

Like Doc Olds said, don't just look at that dump gauge, I changed mine too with a permanent 195 thermostat years ago (which never let my engine goes overheated ) and my dumb gauge is still a bit over the middle all time that I stop .....

 

[3Hummers]

Our H3 Alpha gauge always settled at about the 3/4 mark. Car never overheated.

 

[BraveHeart]

Wow, your replies are all rich, thank you guys...

Must of what you said is known to me and have tried it already, only the trans temp thing that doc old said was interestingly new to me!

Don't get me wrong guys, but thing is, my vehicle's temp never been up to the ¾ mark even in the middle of August, so what is happening is bizzare to me! And might be because i have done that motor thing, i am all suspecious and already ready to relate everything to that

A MAJOR SURPRISING UPDATE:
Gauge pointer was at ½ and then I put my small scanner to the OBD and went to live data > engine coolant temp > and it reads 210 f / 99 c.
Then i did some revs and it went up to ¾, but the temp read on the scanner only went up to 230F / 110c

So are you thinking the same, temp sensor is bad?

 

[650Hawk]

I would expect the gauge to go up 1/4 with a 20 degree temp increase; seems like the sensor is working fine.

 

[BraveHeart]

I would expect the gauge to go up 1/4 with a 20 degree temp increase; seems like the sensor is working fine.

My point was that at ¾ it should at least read 250 F to 260 F not 210 or 230

 

[Jeepwalker]

Did you ever put an infrared temp gun at the engine outlet hose and see what it's actually running at? You can simply ohm out the temp sensor and compare the readings to a temp chart (for Colorado/H3). Do it engine cold/engine hot. Also ensure the body grounds are solid.

Unless there was some debris in the process of changing your engine that got into your T-stat or the T-stat happened to plug the cooling system somewhere. Eventually if nothing else panned out, I'd probably stick a new t-stat in it.

 

[Teahead]

bad fan clutch?

If it overheats while driving on the highway: radiator
If it overheats while only idling, bad fan clutch.

If the latter, I'd maybe convert to electric?

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HERE IT IS. KEEP ENGINE RUNNING COOLER FOR MORE HP, YOU DECIDE WHAT TEMP YOU WANT YOUR ENGINE TO RUN AT.FULLY STAND ALONE UNIT THAT YOU CAN DIAL IN YOURSELF. NO MORE FANS NOISE UNDER THE HOOD. BETTER MPG.

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[650Hawk]

My point was that at ¾ it should at least read 250 F to 260 F not 210 or 230

Based on what?

 

[BraveHeart]

Based on what?

Based on normal thing!

Still it is what i believe and you might know better, so please enlighten me if i am wrong

 

[Jeepwalker]

You almost got to get a 'real solid' temp reading with, ideally, a separate mechanical gauge, or at least an IR gun, so you know what you're dealing with in real numbers that are trustworthy. Is the temp in the right neighborhood, or not ...I think is what it comes down to. There could be a number of reasons if not: ...fan belt slipping, worn pulley grooves, glazed belt, wonky new radiator with restricted flow, Lower radiator hose sucking in while driving down the road. Water pump with a loose or broken impeller, flaked-out thermostat. You're just going to have to make a list of possibilities and cross them off one at a time. Did you ever do a compression check on the new engine? And have a look at the spark plugs, in case there's indication of a flaky head gasket with the new engine (that can make temps ride all over the place too). Is there excessive milky substance on the top of the oil fill cap. Electric fan would just be masking the problem. Shouldn't need it. It robs energy anyway (adds strain/drag via the alt).

You're doing the right thing asking questions and trying to drill down to the bottom of it though. Nobody w/o being there step by step is going to do more than arm-chair QB it. You'll have to dig in to each possibility and rule out one by one till you find the culprit. You will. Keep looking at things. Best of luck.

 

[Teahead]

So if temps were fine w/the OLD engine, and the only thing you replaced was the engine and radiator, then maybe the radiator is bad.

What about the temp sensor; are you using the same one from your old engine?

 

[650Hawk]

My point was that at ¾ it should at least read 250 F to 260 F not 210 or 230

Based on what?

Based on normal thing!

Still it is what i believe and you might know better, so please enlighten me if i am wrong

And my point is that you have no reference for how many degrees each 1/4 of the gauge represents on an H3, except what your scan gauge told you (and you disagree with that). If 1/2 is 210, should 3/4 be 220? or 250? or 280? I have no idea what GM specs out for each quarter of gauge reading; do you? If so, show us your source.

BTW, 1/2 on MY Alpha's gauge is about 195-200, not 210.

 

[08H3]

GM temperature gauges have never been linear, at least not one I have ever encountered. As an example, you say 1/2 is 210 on yours. Two of mine, 1/2 is exactly 190. If it's not in the red, don't sweat it.

 

[wpage]

Get a scan gauge for accurate measurement.

 

[JPaul]

Get a scan gauge for accurate measurement.

This, or an Ultragauge. The computer knows what the actual temperature is, the gauge on the dash is just to give the average person a general idea of how hot the coolant is. None of the gauges, save maybe the tachometer, will give you an accurate reading. Even the speedometer can be off slightly, even with factory sized tires.