Coolant Flush

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
You sure it's the ECT? I had the same thing happen to me halfway to DC and the ECT was loose. Tightened it up and was good to go. You did use the aluminum sealing washer? Maybe the seal around the t-stat is leaking or it's loose.
 
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RTTBLT1

Original poster
Member
Jan 25, 2016
512
Louisburg, KS
You sure it's the ECT? I had the same thing happen to me halfway to DC and the ECT was loose. Tightened it up and was good to go. You did use the aluminum sealing washer? Maybe the seal around the t-stat is leaking or it's loose.

I'm guessing it is the ECT Sensor still but don't know yet as I have not removed the Alt for the 3rd time to check things out. But i will check the T-Stat bolts, I checked them last time but didn't get to crazy as I didn't want to over tighten them. The 2nd (last) time I opened things up to look, you could see that the Fluid was running from the ECT Sensor down around the T-Stat and down the side of the block.

I did use the Aluminum Sealing Washer...if you are referring to the oblong shaped Washer that came on the end of it.

Also, forgot to mention this in my last post...for some reason it only leaks when the engine is running.

Is it normal for the new ECT Sensor to loosen after a few engine warm ups and cool downs?...the first time I tighten it tight and when I checked it the 2nd (last) time it was loose. Is that because it is made from Brass and the engine Metal?


Do you suggest I purchased another one and try replacing it again?
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
Oblong? Maybe the washer is borked? It should have been round. Maybe replace it with a copper washer unless you can find an aluminum one.
 

RTTBLT1

Original poster
Member
Jan 25, 2016
512
Louisburg, KS
Hi, everyone.

So I still have not looked into the small leak after doing the Flush, T-Stat, ECT Sensor ect...but will be soon.

But I have a few concerns...

I noticed with the AC On my Temperature Guage on the dash is going almost one tick passed 210. With the AC Off it stays right at 210.

I used the Torque App and found with the AC On it's getting up to 226-228F but with AC Off its around 202-208F. Both readings are with outside temperatures of 96-101F and real feel of 102-110F.

1. Is this normal for this Engine?

2. To determine if the T-Stat is functioning properly I touch the Lower Radiator Hose ( which should be slightly cooler) and the Upper Radiator Hose ( which should be very hot)...correct?

Thanks in advance for any help!
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON

RTTBLT1

Original poster
Member
Jan 25, 2016
512
Louisburg, KS
Ok so I did the Fan Clutch test per the link...

I stopped the Fan with a rag which was hard to stop. I had to push down fairly hard and it took a few seconds to bring it to a stop. Is this a good or bad sign?

Also I do not have the roaring/jet sound coming from the Fan. It does the roaring/jet sound at cold start but goes away very fast, like around 5 seconds.

Edit: forgot to mention...while I held the Fan I could feel like a light thumping in the assembly as if someone was hit the Fan while holding it. Is this the resistance I was looking for?
 
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Blckshdw

Moderator
Nov 20, 2011
10,665
Tampa Bay Area, FL
Edit: forgot to mention...while I held the Fan I could feel like a light thumping in the assembly as if someone was hit the Fan while holding it. Is this the resistance I was looking for?

:yes: That's the pulse signal of the clutch engaging, to get the fan to spin.
 
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RTTBLT1

Original poster
Member
Jan 25, 2016
512
Louisburg, KS
:yes: That's the pulse signal of the clutch engaging, to get the fan to spin.

Ok so I'm guessing that is a good sign.

And after I let go of the Fan it immediately started to spin slowly and went back to normal speed. I didn't help it get back to spinning like the person in the video did, it did it on its own will...Is this also a sign of a normal functioning Fan Clutch?
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
Sounds like it's good to me. The one in the video was dead, just freewheeling.
 
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RTTBLT1

Original poster
Member
Jan 25, 2016
512
Louisburg, KS
So since I can rule out the Fan Clutch...what do you guys suggest I should look into next?...

1. Possible weak Water Pump?
2. Wrong mix of Coolant?
3. Restricted Coolant flow/circulation?
4. Defective (new) T-Stat?

Also, with outside temperatures around 100F Degrees and AC On...what should the highest Coolant Temperature reading be for this Engine?...never over 210F?

Edit: I forgot to do the extra test for the Water Pump wobble/slop but I plan to check it soon also.
 
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AzTruckGuy

Member
Dec 1, 2015
501
scottsdale, az
So since I can rule out the Fan Clutch...what do you guys suggest I should look into next?...

1. Possible weak Water Pump?
2. Wrong mix of Coolant?
3. Restricted Coolant flow/circulation?
4. Defective (new) T-Stat?

Also, with outside temperatures around 100F Degrees and AC On...what should the highest Coolant Temperature reading be for this Engine?...never over 210F?

1. I researched this and it seems some experienced issues with the old water pump leaking after a full flush, when I changed mine out I didn't bother with the Preston flush stuff, just did garden hose flush and drain and then did purified water and ran and then drained 2 times.

2. You should be fine since you have 2 gallons of Preston Dexcool, I only had 1 gallon and I will getting another gallon tomorrow to fill mine up.

3. If you had restrictive flow, I would assume the engine would get really hot and be in the red?

4. Researched this myself, some have experienced issues with the thread tape that comes with the sensor, which caused some leaking. If your sensor is reading correctly it should be fine.

FYI you replied to my thread, I was wrong about my sensor leaking near the wires, I forgot I had sprayed some water on the block to remove some gunk. If the sensor were leaking it would be from the thread tape areas, I realized this as the wire area don't come in contact with the water in the block, just the tip of the sensor comes in contact with the water.
 
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Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
I'd say it's normal to run a little warmer on hot days with A/C on but just slightly to the right of 210. Fan will engage more as the temp goes up. It will be really going if it were to get near the halfway to overheat. Just make sure your condenser and radiator are clear of bugs and dirt.

It is quite possible you have a defective new t-stat. It has happened before and IIRC, it was even an ACDelco. It happens. Maybe we should start testing them in boiling water before installing them.

Coolant mix in your part of the continent should be 50/50 for better heat transfer performance. You could also add some Water Wetter, which does help in heat transfer. I have used it in my snowmobile and have noticed a difference. Can't hurt to try it.

GM went cheap on the radiator putting in one that was barely adequate, hence the reason they went overboard with the clutch fan (and no efans like the other trucks).
 

RTTBLT1

Original poster
Member
Jan 25, 2016
512
Louisburg, KS
I'd say it's normal to run a little warmer on hot days with A/C on but just slightly to the right of 210. Fan will engage more as the temp goes up. It will be really going if it were to get near the halfway to overheat. Just make sure your condenser and radiator are clear of bugs and dirt.

It is quite possible you have a defective new t-stat. It has happened before and IIRC, it was even an ACDelco. It happens. Maybe we should start testing them in boiling water before installing them.

Coolant mix in your part of the continent should be 50/50 for better heat transfer performance. You could also add some Water Wetter, which does help in heat transfer. I have used it in my snowmobile and have noticed a difference. Can't hurt to try it.

GM went cheap on the radiator putting in one that was barely adequate, hence the reason they went overboard with the clutch fan (and no efans like the other trucks).

Ok, i will have to look into all of the mention items.

The Temperature Guage has been going slightly over the 210F mark, almost one tick to the right of 210F. But only when outside temperatures are around 90-100F and with the AC On. All other occasions it has been sitting right on 210F, like it should.

If I had a faulty/bad T-Stat, wouldn't both Radiator Hoses be the same Temperature?...the other day when I noticed the Guage slightly over 210F, I grasped both Hoses and the Lower Radiator Hose was cooler than the Upper Radiator Hose...I was thinking this was a sign of the T-Stat functioning properly...???
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
That is normal as the cooled coolant flows from top to bottom. It's a reverse flow system.
 
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AzTruckGuy

Member
Dec 1, 2015
501
scottsdale, az
is
The Temperature Guage has been going slightly over the 210F mark, almost one tick to the right of 210F. But only when outside temperatures are around 90-100F and with the AC On. All other occasions it has been sitting right on 210F, like it should.

Ok since I changed mine out too, the 210F mark is where mine is at around the 90-100F mark as well, drove in 107F with the AC on...it went maybe 1 mark to the right of 210F and stayed there. Now that I know this normal, the TB is at operating temps now. I wouldn't worry too much about this...
 
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RTTBLT1

Original poster
Member
Jan 25, 2016
512
Louisburg, KS
That is normal as the cooled coolant flows from top to bottom. It's a reverse flow system.

Ok, that's what I was thinking...my 06 Impala with the 3900 (3.9L) is the same way.

is

Ok since I changed mine out too, the 210F mark is where mine is at around the 90-100F mark as well, drove in 107F with the AC on...it went maybe 1 mark to the right of 210F and stayed there. Now that I know this normal, the TB is at operating temps now. I wouldn't worry too much about this...

Ok, good to know. If that is how it is suppose to be...then ok. Mine also didn't get any higher than 1 tick (if even that, maybe between 210F and the next tick to the right) over the 210F.

I was starting to wonder if my Coolant mix was off.

Thanks again @Mooseman, @Blckshdw and @AzTruckGuy for the input/help.
 

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