Spitting coolant from the reservoir could just mean that it’s too full.
Coolant at the back of the pax side could be a HG but it could also be from the intake manifold. If the leak is very small it isn’t an emergency to repair it immediately.

 

Yes, to remove the spitting coolant issue, slip a hose over the overflow tube and run it up under the windshield wiper so you can watch it.

 

Looks like something is bubbling up in the blue stuff, so where are those bubbles coming from? Maybe get a good inspection mirror to see precisely where the leak starts in the back. As Harv says, could be a couple different spots.

The main coolant passage through the head is back there, and a known leak point, especially if coolant changes have not been kept on schedule. In theory, it is possible to leak out there and not leak into Cyl 8 (or 7). Maybe throw in some GM stop leak tablets, if you like. I know some folks don't like that approach, but it has worked for me.

 

I have used stop leak for coolant leaks and it does work. The big downside is that it also closes the passages in the radiator and heater matrix. If you put in the tablets I think you should be expecting to replace the radiator later when you actually fix the leak.

 

The bubbling through the blue stuff is the leak detection thing. In theory, if combustion gases are getting into the coolant, then the blue liquid detects it and changes color. The clear tube base a hose that plugs into a vacuum source to pull from the coolant reservoir. Its a really cool thing actually, but didnt show a positive result.

My leak at the back of that head has been regular but minor. With no signs of anything in the closest cyl. But it does seem to be the head, cant see it coming from anything above that.

 

The bottle is one of the stainless ones from Carrs 4x4. I’m only ever filling to the line on the sight glass. But the level has been doing some crazy things lately. After I run the car for a while I can have either an empty bottle, or it’s way above full, and spitting out the top. I figured that could only be combustion gases playing with the coolant.

Hoses don't get rock hard, when I’ve resealed the coolant system.

Vision is limited but, it doesn’t look like anything is coming from above the HG.

 

So, seems it's not leaking to a cylinder, just out the back. Maybe pressurize the coolant system to see it coming out. Or drain down until level is below the heads, then pressurize, then spray with soap solution to see if any air bubbles, since air leaks out easier than coolant.

 

This. The coolant passage at the rear of one of the heads was leaking externally. Pressurizing the system made it quite obvious. Coolant dripped out the back and down the bell housing. Add some detection dye to make it even more obvious.

 

I have a similar coolant drip, but not overheating. I've already purchased all the items necessary to do the head gasket job, but I'm procrastinating until absolutely necessary.

 

So, it looks like this was exactly my case.

I just got the car back from British Auto Works, Bronx, NY.

Had HGs done and everything else associated. Resealed weeping water pump.

I was half tempted to tackle it myself. But with winter close I didn’t fancy a situation where I screwed it up.

$3300 if anyone is interested. It hurts, but maybe, just maybe hurts less than staring at the job again in December when I’m pulling the heads off for a second time.

And at 142k the job was definitely due.