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Discussion Starter #1
Earlier this weekend I was driving through town when next thing I know the temperature starts climbing up. I am not far from home at the point where the reduced power comes on so I coast back home. I let it cool down and pop the hood and find the upper radiator hose had popped off and coolant was all over the place. I check the coolant reservoir and there is still some in there ( not a lot, but still showed min level). So, first thing I do is buy a new clamp and radiator cap, refill with coolant. Start it up, no problems. Drive around for maybe five minutes normally and all the sudden the temperature starts to rise again quite rapidly. I pull over, pop the hood and no leaks. Coolant level did not seem to move much which I would have suspected it would from refilling the system. Fans are blowing quite loud. Also I am not sure if it was just my eyes but at one point the temperature started to go down slightly before it started rising. I also got the service oil light ( p0523 code) not sure how that would factor in. There are no symptoms for bad gaskets, so I have ruled it down to thermostat or water pump. There are not any threads I have found about this specific problem so I decided to post. If thermostat I could replace it myself but if water pump I would have to take it to the shop. Thanks for any input
 

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The upper radiator hose could have popped off due to a buildup of excess pressure, weak clamp or some owners have experienced issues with it staying attached to the radiator neck. Is the replacement radiator cap a genuine AcDelco part? Does the heater get hot? Oftentimes, the temperature gauge will run close to hot and remain there briefly before returning to normal operating temperature after coolant, thermostat, or water pump replacement. An air pocket(s) in the cooling system not allowing the coolant to circulate could cause it to overheat as well.
 

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Aside from an air pocket, the heater not blowing hot air would be an indication of a bad water pump. But water pumps don't just stop (unless you lose the drive belt), the failure mode is usually a seal leak. A new tstat is a cheap easy fix, so I would start there.
 

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Discussion Starter #4
Update on the situation. After buying a new thermostat today and installing it, the problem persisted. Heater was not hot which got me worrying about the water pump but there was no leaks. Well I then try a few techniques I read on the board for getting rid of air pockets. Take it for a test drive and all is well. I took it through town and on the highway as well and it was working fine. Also the heater started working after that. Still not entirely sure what the initial cause was, but I am assuming it was a combination of bad tstat, cap and/or clamps. The service oil light is still on , does this come from the computer assuming the engine got to hot and broke down the oil?
 

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Are both the replacement radiator cap and thermostat genuine AcDelco parts? The service oil light could be a built in precaution since the engine overheated. Bear in mind, you'd have to get it pretty hot and keep it there for "awhile" to have a significant impact on the oil. Can check the engine oil life monitor through the driver information center. Check... 1. Press and hold the left thumb wheel on the steering wheel. 2. While holding, place the key in the ignition and turn to on i.e. accessory. 3. Release the thumb wheel after turning the key forward. 4. The driver information center should now be in engineering mode. 5. Scroll through the options until engine oil life appears. Reset... 1. Turn the ignition to on with the engine off. 2. Fully press and depress the accelerate pedal three times within thirty seconds. Can check the engine oil life before and after the reset for comparison.

 

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Generally, the upper hose pops off in these because the plastic barb was gone. They sometimes break off and then they fall out once the hose comes off (on the road somewhere along the way). If your radiator connector up top was smooth with no change in OD, then you need a new radiator; that clamp will eventually fail.

PONYMAN suggested that the Check Oil is a precaution; it is. I looked it up when I had the hose blow off and confirmed that the oil service light goes on because overheating can cause oil fouling. I honestly just changed the oil as a precaution, though I likely didn't need to do so.

When you refill next time (assuming you do more checking), take a look at that hose connection and then refill with the block bleed tube disconnected (run a temporary tube to a drain bucket to prevent spilling). Fill it up slowly until it comes out of that tube. That guarantees a full block. Then when you work the bubbles out of the hose you can repeat until it's full. Then replace the bleed hose and top off once more.

Make sure you fill the overflow a little bit to the cold level just in case it needs more coolant, and check the level there periodically.

Personally, I would be concerned about that upper radiator connection since it's already blown off once. It may not be intact.
 

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Discussion Starter #7
I don't think they were AcDelco, but they said they met OE standards and seemed good quality. I plan on changing the oil soon, I would rather be safe than sorry. I have been keeping an eye on everything and nothing abnormal so far but I might have the shop check on it when I take it in.
 

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I had a similar problem with my red G8 Base. I flushed the cooling system and changed the clamps and t-stat. I used Evans Waterless Coolant instead of antifreeze. Now the gauge comes up to the normal point and never a bit higher, even in heavy Pittsburgh summer traffic. The engine runs quieter, and seems to have a little more pep as well. It was a bit of a process, but it was worth it.
 

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Evans is Propylene Glycol. It's going to run hotter, and it is going to cool less effectively.

I layman's terms, means water itself absorbs more heat and leaves behind less. PG absorbs less and leaves behind more. It doesn't run hotter because it's cooling better. It's running hotter because it is absorbing less heat!

Not sure how they can talk about better cooling with a hotter motor.
 

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Evans is Propylene Glycol. It's going to run hotter, and it is going to cool less effectively.

I layman's terms, means water itself absorbs more heat and leaves behind less. PG absorbs less and leaves behind more. It doesn't run hotter because it's cooling better. It's running hotter because it is absorbing less heat!

Not sure how they can talk about better cooling with a hotter motor.
Not sure either, but maybe the higher combustion chamber temperature burns helps the fuel burn more completely? Temp gauge reads exactly as it did with Dexron. I guess I'll fire up the other Base that still has Dexron in it and take some temperature readings in various places between the two. Might be interesting.
 

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You did replace the thermostat, so it's entirely possible that your former was sticking open a little causing it to fall below the range. That said, the Base has a 180F thermostat in it, and that usually means 190-200 temp range give or take for actual ECT readings.

It might be a good idea to get yourself an OBDLink MX or something similar. You can check actual temperature readings. It takes some fidgeting to get some of the formulas right for oil temp, trans temp and such, but it's a neat little tool. I've got the oil and trans formula on my tablet.

Then you can see what your ECT is actually reporting, and check oil temperatures. A hot motor will be indicated by a higher oil temperature, at least it should.

Get a pH test kit too (one that you'd use on a pool). It is preferable for the Glycol to be above 8. That's just based on my experience with Glycols from Commercial HVAC. Where my experience doesn't lie is in the metallurgy department. I don't know what the maximum pH allowable given the metals in the block. Aluminum is finicky.

Not saying you need to get the PG out of there, but I would want some peace of mind at least. :)
 

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After bringing both cars to operating temperature, I checked several points on each engine, including exhaust manifolds, water pumps, heads, sides of blocks, radiators, hoses. The temperatures were within 5 degrees at any given point from one to the other. We've already closed the pool, so that stuff is buried in the cellar. I'll need to dig it out, or call Evans. They're pretty good about answering questions. From previous conversations, there are additives in their coolant, so it's not just PG. They advertise that it's non-corrosive with all base metals, so I'd have to think the Ph is acceptable. I have a couple friends that are chemists and car people. They've looked into Evans after I tried it and found it to be pretty good stuff. I've had it in my G8 for three years. It seems to support the advertised claims. I've also got it in our '96 F-250 4x4 and our '02 Grand Cherokee 4.0L with good results.
 

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It's not really about corrosion as much as it is about hotter engine components. That's my biggest gripe about the stuff. PG results in worse heat transfer outcomes next to 50/50 PG and 50/50 PG outcomes are worst than 50/50 EG solution outcomes.

The pH of a properly inhibited glycol (which Evans Coolant will be) should not decline quickly, but it will likely decline at an advanced rate next to 50/50. Without water to act as a suspension fluid, the inhibitors can precipitate out of the glycol where it is not being pumped (i.e. the overflow reservoir).

Like I said, I'm not really trying to convince you to immediately take the stuff out, but I'd at least want to monitor the pH level. It should be somewhere around 8-8.5, and once under 7 needs to be replaced.

They warrant the stuff for 2 years, so that should be an indicator.
 

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Discussion Starter #14
Re-Update on this situation. Today the hose came off again when I shut the car off . Found the lip of the rad connection broke off about 6 inches down the hose. I have a peace of mind knowing the real cause now , although was hoping it would have been easier.
 
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