thermostat question

[sb001]

can the ambient (outside) temperature affect the thermostat's ability to fully retract (i.e. if it is hot summertime temps outdoors) even if the engine is cold?
I ask because my thermostat is only about 2/3 fully retracted even though I haven't driven the car in a couple days.
I do see that the operating temp of the thermostat is 65-70°, so if it's 90° outside (like it is right now in NW Ark) will the thermostat simply not fully retract? It makes sense relative to the operation of the thermostat system I suppose, since the engine wouldn't need as long to warm up...
_________________
I'm the humblest guy on this board.

1969 autostick sedan, family owned since new
1600 SP engine
Solex 30 PICT 3 carburetor
Bosch 113905205AE autostick distributor

[sb001]

And yes my thermostat/bracket setup is adjusted correctly...
_________________
I'm the humblest guy on this board.

1969 autostick sedan, family owned since new
1600 SP engine
Solex 30 PICT 3 carburetor
Bosch 113905205AE autostick distributor

[Tim Donahoe]

Steve, when testing mine with a hair dryer (while in the bracket), I had to get that thing pretty darn hot to get it to start opening. I don’t think 90 F would prevent full retraction.

During my test, the thermostat retracted fully within 30 seconds.

The operating travel seems to be about 5/8 inch, if I remember correctly. Assuming your unit is not going south, remove it and check to see if the interior of the accordion folds are gunked up with a mixture of oil and grit. I doubt this is the issue, however, as I suspect that something in the linkage is preventing full retraction. Either way, a test with the unit removed, using a hair dryer, will let you know if it’s the thermostat.

If the thermostat tests good, it’s got to be something ganging up in the flaps or linkage.

If the thermostat is good, you simply have a little more cooling air being allowed at start up.

Tim
_________________
Let's do the Time Warp again!

Richard O'Brien

[VW_Jimbo]

Yes it reacts to temperature of the air. On hot days it starts opening, as it is designed to.
_________________
Jimbo

There is never enough time to do it right the first time, but all the time necessary the second time!

[hanksjim1]

Just clarifying, the thermostat operating range temps are in Celsius; 65C = 149F

[sb001]

_________________
I'm the humblest guy on this board.

1969 autostick sedan, family owned since new
1600 SP engine
Solex 30 PICT 3 carburetor
Bosch 113905205AE autostick distributor

[sb001]

[Frodge]

The question is when do the flaps begin to open? What temp? I would think they would be partly open at @ 90 degrees.

[Tim Donahoe]

Frodge, 90 F won’t do squat. 149 F degrees (65 Celsius) starts the expansion. I just checked a good spare thermostat I have. The free space when cold in the bracket is closer to 1/2 inch than 5/8.

Tim
_________________
Let's do the Time Warp again!

Richard O'Brien

[sb001]

OK drove the car about 10 minutes a few hours ago over to a buddy's house, then just drove back home now.
Thermostat already fully expanded:

and (by extension) cable pulling air cleaner snorkel flap completely open:

I would think it would have taken longer for the thermostat to fully expand... unless the hot weather does indeed cause it to expand a bit without the car on.

I'm going to drive it to work tonight and park it indoors after sundown, see if it retracts fully back to normal.
_________________
I'm the humblest guy on this board.

1969 autostick sedan, family owned since new
1600 SP engine
Solex 30 PICT 3 carburetor
Bosch 113905205AE autostick distributor

[VW_Jimbo]

Do you have an IR temperature gun? It would let you know what temperature it opens at, you would just need to watch it.
_________________
Jimbo

There is never enough time to do it right the first time, but all the time necessary the second time!

[Tim Donahoe]

He’s concerned at what the temperature is when it’s in the fully closed position.

Tim
_________________
Let's do the Time Warp again!

Richard O'Brien

[sb001]

[VW_Jimbo]

Pull it out and stick it in the freezer. It should fully retract.
_________________
Jimbo

There is never enough time to do it right the first time, but all the time necessary the second time!

[Tim Donahoe]

I can only recount my experience with my latest bug. All other acvw’s I’ve owned never had a thermostat—except my first KG (but I didn’t know what a thermostat was back then).

When I install my thermostat, I loosen the thermostat bracket, then push up on the thermostat until the flaps are fully open. The bracket, being loose, automatically goes up into the fully open position of the flaps. Naturally, the top of the thermostat is in contact with the top of the bracket. At this point, I tighten the bracket and pull the thermostat down and screw in the bottom bolt.

When I pull the thermostat down, it does not partially open. It just pulls down easily, and I screw the bolt into the bottom. The thermostat is fully “retracted”.

If your thermostat is stretching (partially opening) when pulling it down during adjustment, something is wrong. It should just pull down fairly easily, despite the resistance of the return spring on the flaps.

Tim
_________________
Let's do the Time Warp again!

Richard O'Brien

[sb001]

[sb001]

More weirdness- I let the car sit overnight, to make sure the thermostat would fully retract. It did not. I removed it and put it in the fridge as sugggested to make sure it would fully retract. It still has not. Compare to another good t-stat I have:

Seems very coincidental that it was fully retracted when I installed it, but the first few hours of use it went completely bad! I suppose it's possible (as Tim suggested) that the pushrod ganged up on the cylinder head tin hole or something causing it to stay fully expanded, but it should have retractred once removed from the system unless it was permanently damaged in that scenario. Oh well- I guess it's toast. Hopefully the other one I have (shown in the picture above) is still good.
_________________
I'm the humblest guy on this board.

1969 autostick sedan, family owned since new
1600 SP engine
Solex 30 PICT 3 carburetor
Bosch 113905205AE autostick distributor

[Danwvw]

Yeah, the bellows thermostats are getting so old they just start doing that. Mine got where they would hardly move at all. Had to go to the new wax thermostat but they fail too. We need to monitor CHT.
_________________
1960 Beetle And 1679cc DP W-100 & Dual Zeniths!

[Eric&Barb]

Might be the thermostat folds are full of oil/dirt/sand built up. Could try cleaning it out...
_________________
In Stereo, Where Available!

[sb001]