Air Bubbles in Overflow Tank

[4Gears4Tires]

Don't forget oil temp sensors at every cylinder and in the pan, temp sensors at each brake rotor/drum, pitot tube for accurate speed reading, wideband sensors at each cylinder header, and replace the windshield with a giant LCD screen connected to 4 cameras facing forward.
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'87 Syncro
Ferric Oxyhydroxide Superleggera Edition

[smeeegheeead]

[Abscate]

[4Gears4Tires]

Actually I believe that was Mr. Hans Oetiker.
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'87 Syncro
Ferric Oxyhydroxide Superleggera Edition

[kaeferman]

I just had a similar event to the OP. Thought I d share. Sorry if it’s long ...
I hope it’s helpful for others
Mine is an 84 tin too with a 2.1 running on a 1.9 cools t system and stock digijet FI.
10-4 on the pressure check annually, others have posted about the razor thin margin for error ‘designed’..?! into the system. I have just diagnosed a bad pressure cap too and three used caps I had hoarded away in my parts Tun were also Scheisse.
I first noticed that my overflow was full while checking the oil and then i saw bubbling from the cap overflow or blowoff hose. Actually first I had noticed a whiff of roasted coolant smell coming from my corner vents as I ‘d walk around the bus after parking it. That was the last few weeks actually. I could t find the ‘leak’, i never saw a puddle. Slowly the dash gauge stick would start to creep up as it sat at a longer traffic light. The rad fan wouldn’t kick on so I d turn on my heater fans ( I have both rear seat and dash working with new cores in them). Initially the heaters would move the temp gauge stick back to its spot but over the courses of several hours of driving this stopped being as effective and I noticed the heaters quit blowing heat, first with the front dash one and then eventually the rear even. I had by now started driving with one eye glued to the stick and LEd which, finally reared its ugly red flashing eye on a good long climb and steam started out the corner vents. I was pulled over as fast as humanly possible and there wasn’t much boiling so or geysering going on, so I let it cool, added coolant ( I always roll with a gallon of 50/50!) and was able to roadside purge well enough to get it home with no more LED or stick getting hot.
Back at the shop the cap was unable to hold pressure . I use a plugged tank and shrader valve setup to test and it wouldn’t hold 5 lbs. Bentley says 13-17 lbs. so I was losing coolant while under way by blowing out a faulty pressure cap and overflowing the overflow tank and gradually lost coolant until the radiator sensor couldn’t detect temp since there was not enough coolant in the radiator, and eventually even drained the heater cores before it overheated. Glad my gauges work and my big ass nose found the coolant smell or I wouldn t have detected the problem or started watching things. Wake up and pay attention or you ll pay for sure .. b
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83 Westfalia wbx “Idaho”
84 Tintop “Vanamos”
formerly
71 Squareback sold
70 Westfalia lost to fire by new owner
71 Super Beetle rolled/scrapped