Hey ya'll so there's multiple threads of coolant leaks and high temp issues on here, read a lot of them but want to get input on my situation. To make it as short as possible, its an late 86 model so L98 w aluminum heads. Randomly started to see a slow drip of coolant creating a puddle on the passenger side right from under the radiator. Specifically dripping from the hole in the plastic housing the radiator sits in. By the way this radiator was previously swapped out and "upgraded" by previous owner and now uses orange (dex-cool) rather than the green stuff. In the pictures you can see where it is dripping from. I used my endoscope to try finding the source and I only see coolant sitting at the the rubber bottom mount. Don't see coolant dripping down the plastic tank, neither at trans cooler line nor at drain valve. T-stat and hoses were swapped with the radiator. Reservoir tank is not leaking either. Lastly, I first noticed temps were rising faster than normal at idle. Would climb from cold to 200+ quick. So I assumed there was air in the system. I tried burping it (correctly), the bubbles wouldn't stop and temps dropped to 150 then slowly climbed back to over 220 and then the coolant was vaporizing. So I shut it down. I also put a laser temp gun to the coolant temp sensor bw cylinders 6 and 8 and reading was somewhat close to the gauge inside. I think that's it but any input before I pull the radiator is appreciated.
thanks in advance guys

 

I guess the good news is that, with it coming from the radiator shroud, you know it's at least isolated to that area. The things I would check are:

1 - How old are the radiator hoses going to and from the radiator?
2 - Are these hoses clamped down properly, or could they be a little lose and thus leaking?
3 - Have you checked the overflow hose that attaches just below the radiator cap? The early hoses GM used for this were non-pressure hoses and usually had a seam which can fail after decades and will have a slow leak.
4 - There is a valve at the bottom of the radiator called a "petcock" which is used to drain the coolant in the whole system without having to remove the hose. This can sometimes work itself lose and leak a little. On this, depending on whether your radiator is stock or aftermarket, opening and closing this valve may be different. For some, unscrewed all the way is closed and screwed in all the way is open... depending on whether it's stock or aftermarket.

Worst case, you have a leaky radiator.


As for the Dexcool... he probably used that because when you go to places like "AutoZone" it'll say "Older North American Cars" and it's the orange stuff. The "green stuff" is labelled as being for "Vintage Asian Vehicles." Which is kind of stupid, but it's only because they used it longer than us. You can absolutely use the one that's labelled for "Vintage Asian Vehicles" as long as it's the green one.

The colors designate the type of coolant. There's a chart you can look for online... but the reason why it never shows 80s American cars is because... well... 80s cars are insanely old now... even though it doesn't feel like it. And these charts are all written by Millennials which view cars from the early 2000s as "vintage." The green coolant is known as Inorganic Additive Technology, which has a lot of additives in it that were normal for older cars with less modern components. Like brass freeze plugs, or OEM coolant sensors and stuff. There are newer coolants that you can use that are "universal," but I prefer to use the older stuff, just because.

If you were to completely restore your car and replaced everything with modern components... as in, newer freeze plugs, newer OEM replacement sensors, modern hoses, etc... it would matter much less.