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Water - COOLANT

Christian

Christian

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Joined
Mar 25, 2024
Messages
7
Hello,
I own a 2005 Chevrolet Avalanche and my problem is that when the water reaches 160 degrees Fahrenheit the water escapes through the overflow pipe from the expansion tank.
Can you help me.
Because here in France there are no longer any Chevrolet sellers.
THANKS
 
Sorry.

But, I am having difficulty understanding exactly what is going on here with the information given.

How full do you try to keep the overflow tank?

Around the middle seam in the tank is a good level for your coolant.

I actually keep mine slightly above that level with no issues.

Are you certain the temperature reading you are seeing is correct?

If your engine coolant is actually at 160 degrees F, then the coolant is no where near overheating, especially if you have the proper ratio of coolant and water.

Also, are you seeing any large gas "bubbles" appearing in the overflow tank as the engine is running?

There should be only a light flow of liquid coolant coming into the tank with no gurgling or bubbles present.

If you are seeing bubbles and such, that can indicate a blown head gasket that is allowing exhaust gases to enter the cooling system and making more pressure inside the system than it is designed to hold.

An over pressurized system could certainly push coolant out of the overflow tube.

There are test kits available to test for exhaust gases in the cooling system.

Do you have access to a radiator pressure test kit?

If you do, then install the test kit and pump up the pressure to 15 PSI.

Perform this pressure test on a cold engine.

Your system should hold that pressure for hours.

If the pressure drops off over time or quickly, begin looking for a leak.

If you see no leaks outside the engine, then you may have a blown head gasket and coolant is going into a cylinder.

Do you notice any white smoke coming from the exhaust pipe while the engine is running?

That can be another sign of a blown head gasket.
 
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probably have a bad cap.
The cap is design to hold in I think 15 PSI and as they age they open sooner and let out steam aka coolant.

Go to any mechanic in France and have then test cap or just get a replacement if original.

2005 CHEVROLET AVALANCHE 1500 5.3L V8 Coolant Reservoir Cap | RockAuto

RockAuto ships auto parts and body parts from over 300 manufacturers to customers' doors worldwide, all at warehouse prices. Easy to use parts catalog.
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Hello,
thank you for all this very precise information. I'm going to look at all of this and I'm going to start by changing the cap.
My level is around middle seam in the tank.
My coolant is well at 160 degrees Fahrenheit and it does not overheat.
I don't have any bubbles in the overflow tank when the engine is running.
I don't have access to a radiator pressure test kit. I will inform him.
I don't have any white smoke coming from the exhaust pipe while the engine is running.
I will keep you informed
 
I still do not see how coolant is escaping from the overflow at the top of the tank if the normal coolant level is at mid-tank.

Can you get a video of this happening?
 
the water escapes through the small overflow pipe which is on the upper part of the tank.

I can't post a photo.
 
I know what the tank looks like.

I have two of them.

I was hoping to see a video of your actual tank in operation and overflowing.

In order for coolant to flow out of the overflow you are pointing to, the coolant must rise to the top of the tank under pressure and exceed the pressure setting of the tank cap, which is a little over 15 PSI.

This can happen in an overheating situation, but not if the engine is a 160 degrees F, which is well below the normal operating temperature of 195 degrees F when fully warmed up.

Your thermostat should open around 185 degrees F.

Coolant staying at the mid-level mark of the tank can not reach the overflow tube.

Coolant at 160 degrees F and at the mid tank level is never going to reach the overflow tube port.

Something is not right here.

Take the tank cap off of the cold tank and then start the engine and let it fully warm up (which if it only gets to 160 degrees F, it is never fully warming up and that in itself is a different issue.)

Once the engine is fully warm, you should see a slight flow of coolant in the tank, from the larger hose coming from the radiator into the side of the tank, but the level most likely will not rise much above the cold level.

If the coolant is sloshing and gurgling about wildly and the coolant begins to flow out of the open tank, start looking for a blown head gasket or something else.

This is just a strange situation, but I am sure there is an answer.

We just have to find it.

NEVER open the cap if the coolant is warmed up and especially not if the coolant is hot.
 
Just a thought, is it possible the temperature gauge or associated wiring is off and it is in fact running much hotter than the 160 degrees you reference?
 
1. If water is coming out of that hose, then I believe it's the pressure cap if you have no bubbles or the water is dark or dirty looking it could be a head gasket...
2. If the temp never gets about 160 degrees Fahrenheit, you probably have a bad thermostat...
 
Hello,

It’s really nice of you to take your time to answer my questions.
I bought this truck new and lent it to a friend for 5 years. He returned it to me in deplorable condition. my big wish would be to get it rolling again.

I replaced the knock sensors, all the hoses, the brake calipers, all the seals, the hydraulic pump. the water pump, the thermostat (I tested it before replacing it it opens at 199 degrees Fahrenheit).

I will run the engine as you advise with the cap open and I will make a video for you.

There is a word that I can't translate: blown head gasket. where is this joint located.

I'm away until Monday. I will take care of it when I return and I will contact you again.

I would really like this truck to run, because I have a lot of small problems such as on-board computer and electrical loss.

I will put a thermometer in the tank to see exactly the temperature

The coolant was drained and I added DEXCOOL mixed at 50% with clean water.
In the tank the water is clear
I definitely have to buy some to get the level up and here it’s very expensive. 50 USD per gallon
 
Typically speaking* the head gasket is the seal between the "Cylinder head" with valves\overhead cam whatever (where fuel\air is ignited & the exhaust gases vented out) & the engine block where the pistons move up & down in connected to the crankshaft.

*Apologies to any engineers out there I'm speaking as a layman with regard to Overhead Cam\Overhead Valve arrangements.
 

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To test HEad Gasket you would perform a COMPRESSION TEST.

Where you remove spark plugs and then insert specialized pressure gage into 1 spark plug hole and it woud seal off.
Then turn engine over a couple of times until pressure reaches max for that cylinder.
Record pressure anf cylinder number.
Repeat for the rest.

Compare results.
160PSI (11.0 bar) Is very good and almost new.
140PSI (9.66Bar) is about as low as you want to go for anyone cylinder.

IF 2 right next to each other are low then head gasket could have failed but the engine tends to run very rough and does not like to idle.


Compression tester example:

Your local mechanic should be able to do thi.
 
I would check on that thermostat since, while there are some that are designed to open at higher or lower temperatures, the stock temperature for opening should be 185 degrees F and the final operating temperature should be around 195 degrees F under normal driving conditions.

At the normal 195 degrees F, your dash gauge should read slightly to the left of the straight up position.

On my trucks, this indicates 195 degrees F when checked against scanner live data.

The 199 degrees F opening of the thermostat seems to be too high and your reading you are reporting of 160 degrees F is no where near this.

Perhaps a faulty engine coolant temperature sensor is giving a bad reading and if so, with a 199 degree F opening thermostat, your engine is actually running too hot, but your dash gauge is reading too low.

An engine that is allowed to run overheated can possibly cause other problems like blown head gaskets.

I am interested in seeing what the actual coolant temperature is when you test it later.

A digital infrared thermometer can also be used to check the temperature at many locations on the engine, such as the thermostat housing, the radiator and hoses and the actual coolant inside the tank through the open top.

A digital infrared thermometer can be fairly inexpensive and can be a handy tool to have on hand.

It is also possible that the dash gauge is not reading properly as these have been known to fail.

If you have access to a scanner that can read "live data", you can see when the temperature reading being given from the engine coolant sensor is and compare that to the reading you see on the dash gauge.

Some other things to consider would be a clogged up radiator that is going to allow the coolant temperature to get too high.

Radiators can be clogged internally or externally.

A clogged heater core can also contribute to overly high coolant temperatures.

When the engine is fully warmed up, how well does the heater inside the truck's cab perform?

How hot do both of the heater core hoses get as they enter and exit the firewall?

This should give you several things to look at.

Let us know what you find.
 
The fact you mention you have other electrical problems leads me even more to an issue with a faulty gauge, module or sensor like @EXT4ME suggests. I think you are on the right track to check the actual temperature when you experience the issue.
 
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