I burped the radiator for over 30min on a steep incline with a long hose. I let it cool and topped off the radiator.

Went for my drive down the highway and and back and got waterfall at 1500rpm again.

The new cap seems to work fine letting fluid flow both directions on heat and cooling cycles.

This is frustrating. There is still stop leak copper in there so if there were any small leak, it should fix it, but the pressure test held 3 times so what the heck?

I burped the radiator for over 30min on a steep incline with a long hose. I let it cool and topped off the radiator.

Went for my drive down the highway and and back and got waterfall at 1500rpm again.

The new cap seems to work fine letting fluid flow both directions on heat and cooling cycles.

This is frustrating. There is still stop leak copper in there so if there were any small leak, it should fix it, but the pressure test held 3 times so what the heck? When it cools again I'll see if the stop leak clogged the release valve. Might have to flush the system if that's the case.

Ok car cooled and didn't suck the coolant back in. There is a slight area of stop leak on the rubber gasket.

I cleaned it up and moved the coolant from the overflow to the radiator. I am still skeptical that the neck of the radiator is misshapen from the factory where it had dings and initially didn't seal at all. I guarantee I still will have a waterfall sound on startup tomorrow

Interesting...

I decided to get a second can of stop leak now that I have a correct radiator cap. Just for giggles, I unplugged the drivers rear coil pack to reduce pressure {as that was the offending cylinder at 150k miles)

When idling up to temp, I noticed right away the lower hose had pressure now, which is interesting. Prior even when fully warm, I could squeeze the lower pretty easily.

Does this mean the new sealant will take hold? I dunno. Maybe long enough until I have a shop to do a proper repair. I'm doing two full warm cold cycles from idle tonight then my drive up the highway tomorrow.

Before my ride this morning, I tried to burp out the air from the heater core, but didn't quite get it. No more bubbles were coming out so that seems like progress.

My ride down the mountain to town results in still 1500rpm waterfall, same as back up the 3 or 4 mile steep grade. At the bottom, after a round of golf, I used my antifreeze tester to scoop about 4 bulbs of coolant from the tank into the radiator.

I'm back idling now with the middle cylinder coil pack unplugged to see if that might get it.

Hmmf.

Cooled down and didn't suck coolant back into the radiator. Was about 10 bulbs worth to move from the reservoir back to the radiator. About 1/4 to 1/2 cup.
I'm not losing coolant out the tailpipe or anywhere. No smell. I'm baffled.

Back to thinking the neck of the radiator isn't sealing the cap properly so as it cools it's bringing air in. I might try some flexible caulk I have all around the cap temporary on my next drive to see if that isolates the issue.

Ok bear with me here.

I'm going to run into town again and get a stupid combustion gas test kit, but also some new hose for the reservoir.

The syphon hose I noticed has gotten swollen, so despite having a small clamp on the inside to hold it, the volume of the tube is way bigger, so theoretically, it may be having trouble bringing the fluid up.

Good news.

The combustion test kit with fluid is a rental at O'Reilly. I also added new smaller diameter hoses to the overflow and the siphon.

Here are images from 2 tests over the course of 5 minutes. Doesn't look like it changed at all, which is consistent with the pressure test holding 15psi 3 times.

I'm going bonkers here.

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Returned the tester in town today down the mountain.
I haven't burped the recent air out in a few days, but I'm ok with waterfall as long as the radiator pushes and pulls coolant on heat cycles.

Checked the level after coming back up the mountain this morning and fluid didn't push out half an inch or more into the reservoir like it has been, so there's a SLIGHT chance it was the overflow hoses being old. I go go a longer drive tomorrow while pulling my camper, so that'll be the real test.

• New thermostat
• Newer hoses
• 3 new radiator caps
• Newer radiator
• Toyota coolant
• New plugs
• New transmission cooler
• New overflow hoses
• NOT overheating
• Blue combustion test stays blue
• Compression on each cylinder 120psi
• No coolant leaking
• No coolant in oil
• No coolant smell from exhaust
• Newer fan clutch
• New waterpump

Yet it still is making air in the system. I'll be back in Ohio where I have a garage to work and might just have to do the HG and machine the heads this time. That was a mistake not to.

I picked up a bigger, more expensive stop leak earlier today with a different chemistry.

It was more of a gel as it poured into the radiator. I idled it up to temp for 30 minutes or so and got both hoses warmed and flowing.

A few minutes after cooling off, the hoses actually were pliable. Prior to this application, the hoses held air pressure after cooling a bit, but still warm, thus not pulling coolant back.

I know it seemed like a HG the whole time, and I sorta expected it either right away when I put the new HG on at 150k miles or they'd hold. At least if this holds, I know I can fix it for $30 until I want to bust my knuckles.

Ive seen a lot of people use Blue Devil (not the pour and go version) with success on these 4.0s. I had a bottle ready to go but ended up just replacing my HGs at around 140k. My head were also warped. Had them resurfaced and so far so good.

Blue Devil Head Gasket Sealer: 1 Year Later - YouTube

Yep. I feel the problem with these failing is it's between 2 cylinders on the driver side and the pressure is too big there for it to take well and have a lot of surface to hold.

Hopefully it'll work long enough for my trip to my families garage to do the work. I'll be sure to get the machining this time.

Had a water type sound coming from my '05 Tacoma. Turned out to be water leaking into and under the dash/firewall area from a small rust hole over the windshield.

Yuck. Mines for sure the HG.
A few short trips and the air has circulated out and nearly 99% gone as the liquid fix is holding

In 2015 I had a leak in my 1991 Camry's heater core. Replacing it meant removing the dashboard and some of the equipment behind it. I gave up after a few hours, mostly because it was so old.

I put in some Bar's Leaks 1186 and the leak sealed itself and I got rid of the car in 2021 with no leaks. It's supposed to be the best of all the treatments for cooling system leaks. You might want to give that a try.

Amazon.com

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