Yea, use the GM coolant leak tabs and nothing else. They work. The others are a 50/50 crap shoot.
2005 Tahoe Slow Coolant Loss
- Thread starter Matahoe
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Alright. So I will add the tabs and some UV indicator. Will report back findings.
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Ginger. Yeah. Now I'm thinking sushi. Hey it's only $4.
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I put the UV dye in coolant reservoir and didn't add the tabs yet because now I am not sure the coolant is going down now. Just something I noticed. Will keep an eye on it.
It would help to know what, "Just something I noticed". is.
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Sure. I went out to the truck the other day and checked the reservoir to add the tab/coolant mixture and the level in the reservoir was normal when engine was cold. When the engine is hot/warm the coolant level in the reservoir is down a few inches. Normal ops? I'm not sure.
Just that one day or over a few days?
The surge tank coolant level in my '04 has always gone up (increased) when hot. After a cold soak the level is down maybe 1/2" from the highest level hot. Right at the tank seam when cold.
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No this has been something I have noticed consistently over past years. Coolant level is always an inch or two below the full level mark on the side of the reservoir after engine is fully hot. Temperature on dash is always just below 210 (looks good) but we all know it's not going by the coolant temp sensor exclusively. At least that's what I have gathered in prior posts and searches here.
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That's what I would expect as well due to coolant expansion...hence the need for reservoir. It's almost like an air pocket appears only when engine heats up which seems very odd. The coolant gods are playing a trick on me. Hehe.
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I don't know maybe I am dyslexic and things seem backwards in my eyes. I will keep an eye on it. Just really scratching my head for the past however many years.
Marky Dissod
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Burp it again.
mikez71
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I have the same issue with coolant dropping very slowly.. (2012 5.3)
Usually after several months, I look at it, and it's down 3/4" from the full line..
I had rented a coolant tester, pressurized it.. Nothing.
Checked for combustion gasses in coolant, nothing.
I replaced the entire cooling system, minus one little hose and the vent ports..
(I have new hose and gaskets, just need to get around to it)
For now, I'm NOT filling it up to the line. Am going to see if it drops further..
Usually after several months, I look at it, and it's down 3/4" from the full line..
I had rented a coolant tester, pressurized it.. Nothing.
Checked for combustion gasses in coolant, nothing.
I replaced the entire cooling system, minus one little hose and the vent ports..
(I have new hose and gaskets, just need to get around to it)
For now, I'm NOT filling it up to the line. Am going to see if it drops further..
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Coolant UV dye additive and a black light....
I think what is not being considered, like in @mikez71 case, "usually after several months" can be water evaporation. You have a 50/50 mixture and it is not uncommon for some water to evaporate.
mikez71
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But, shouldn't it evaporate into the sealed cooling system and re-condense?
As slow as my leak is, I'm thinking it's a tiny steam leak..
I'm leaning towards one of those steam vent connectors or plugs.
You can't really see the rear vents, but for my '12 model I heard they put a rivet in the hole.
I have some plugs I will put over the rivet with an oring seal... someday when I pull the intake..
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Yes I will check it out now that the uv dye is in. Evaporation? Not likely since the cap will not let pressure out unless overpressure from steam. And there is no steam with coolant unless the cap is removed to lower vapor pressure. It's basically a sealed system.
I watched a few videos. The crossover tube that goes through the throttle body and connects to each head might turn out to be something. There are block offs on the back side of the intake as well so can check. Will get back as soon as I find out more from the black light test.
I checked the reservoir an hour after a 300 mile round trip drive from Detroit to Grand Rapids. The reservoir showed full. But yeah it should be higher. Will check in the morning.
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From what I have gathered here in the forum there really is no need. The system is designed to allow air from the top of the radiator which is the highest point to escape through the hose that goes over the MAF and go directly to the reservoir. Now if you mean to run the engine for a bit while the cap is off? I guess I can do that but not when it's fully hot. I'll check my repair docs and see what the official GM procedure is. Might be a TSB in there or something odd that needs to be done.
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