Does size matter?

I understand that it's more like a ratlle eliminator and failsafe helper if the thermostat got punctured. The thermostat would expand when punctured, to nearly fully open lenght. The spring might help it expand a little, by possibly helping the flaps get past any binding spots in their travel. (This is just my guess). In normal operation all it does is eliminate rattle.

Jan

Jan, I am putting together a John Connoly Mexilong block and including the flaps with the "new" brass thermostat. The old bellows type is no longer available. I got a spring from a donor engine. Do the "new" thermostats fail in the open position too? Don't want to waste my engine bucks due to failure. Eric 62 Ghia

68 bug

I am ashamed to admit that I don't know what the "new" type thermostat is or looks like. John would probably be the best person to tell us how they behave when they fail.

Jan

I have replaced it with the throttle return spring of a stock carb, without any problems. It is not a direct replacement, but the tension is allmost right and with minor modifications you can make it work. You might have to unwind one turn from the ends of the spring. The attaching point to the fan-shroud might also be worn by the previous spring and the vibrations of the engine. You can make a new attaching point with a wire loop attached to the lower oil cooler screw (dog house). Grease the sping's ends to avoid breaking from the vibrations.

Bill, '67 Bug.

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What is the correct size/length for the spring between the cooling flap linkage and dog house shroud pulling the cooling flaps towards open? The spring is listed as VW part number (113 119 279) in ETKA. Does the size matter or can I just put in whatever I like? Is the amount of tension crucial to correct operation of the the thermostat?

About a week ago, I was installing the airdam in the cylinder head in the middle (the one Squirrel was missing, and Bob Hoover helped him with story + pictures), and I noticed that my thermostat was almost entirely expanded. It was 10 degrees celsius outside, and I thought that it should not be expanded like that. How can I check if my thermostat is not punctured?

I read somewhere that there should be some liquid inside, is that true?

Greetings, Gerrelt.

I think you just did. If it's expanded when cold, it's done.

Max

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Take it out, clean it carefully, and then bring it in the kitchen with you. Dip it in boiling water, it should start expanding almost immediately. Don't leave it in there if it expands, you will then have received your answer. The movement will be clearly visible, keep an eye on it. Takes about 5 seconds?

Liquid inside: Yes. The thermostat has vacuum inside, plus a tiny amount of liquid that has a fairly low boiling point. The vacuum lowers the boiling point even further. As the thermostat warms up, teh liquid inside will start boiling, and it will then turn to gas and EXPAND, and create pressure. (Which is what liquids do when boiled). This pressure makes the thermostat extract.

When it cools down again, the boiling vapors condense back into liquid form and the pressure drops back to normal, allowing the thermostat to start collapsing. As the temps keep dropping, the pressure will soon be all gone, and the "micro climate" inside the thermostat will have vacuum again. This vacuum pulls teh thermostat together even harder.

Once teh thermostat bellows is puctured (about the only way they fail), the liquid inside and the vacuum are lost for good. Even if you patched up a punctured thermostat, it still wouldn't work.

How do I know? In addition to reading "the" books, some years ago I ran a series of tests with known good thermostats, boiled them, monitored temperature and punctured them intentionally, tried to bring them back to life, measured how far they'd expand under normal operating temperatures, when overheated, when punctured.. "they" say that a punctured thermostat will automatically expand to full lenght to allow maximum cooling, but I found out that this is not quite true. On average, they expand to 80% of their "fully expanded" lenght. There is no PRESSURE inside that would be forcing them to extract fully.

Jan

Jan and company...I bought a "new" brass thermostat kit with bracket and new rod. Rod didn't fit (used the old one) the bracket was twisted beyound bending back(used the old one after grinding top part off (the old cage part. How do the "new" thermostats hold up? Do they fail safe too. What is that external spring for? Eric 68 Bug vert 62 Ghia vert

Don't know. Doesn't sound familiar at all, Have Pictures?

Jan

Paste this in your browser and check it out. Its the thermostat kit Jan.. The pic of the brass thermostat is small but thats it? Anyone else have experience with this one? The old brass bellows type are NLA. Eric

Thanks Eric,

and wow! Never seen anything like that before.

Jan

That appers to be the same "thermostat" as the one on that Decklid I sold to Alan, out in Arizona or wherever it was.....................Anyone else seen that one?????

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