911 SC: Thermo Valve Falls Apart

[silverlock]

TL;DR: Does anyone have a step-by-step for putting a thermo valve back together?

A few months ago I broke one of the hose barbs off the top of my thermo time valve (https://www.pelicanparts.com/More_Info/91160610603.htm?pn=911-606-106-03-OEM) when refreshing some vacuum hoses. No worries, I thought, chalking it up to old brittle plastic.

- I ordered a new thermo valve and when installing it, the top popped off, allowing the two metal plates, the heating element and the spring washer/o-ring to fall out. It failed to want to go back together and so I warrantied it (thanks, Stoddard!) and got a new one.
- Out of an abundance of caution, I used some light silicon sealant around the top of the replacement thermo valve, in order to keep the top from separating. That seemed to do the trick.
- Cue today: I was installing a new throttle spring and wanted to move a hose out of the way. Lightly bumped the thermo valve and the top just popped off. Great.

This may also be the culprit leading to some rough idle issues (https://forums.pelicanparts.com/porsche-911-technical-forum/1168470-78-sc-rough-idle-cold-temps.html) as the car warms up: probably leaking vacuum, and once warm (140F+) the leak no longer matters.

Since they're $180+ and/or a warranty is going to take a few days, and I want to drive my car tomorrow, I want to put it back together.

Any guides? Anyone else with fragile thermo valves?

[silverlock]

Photos:

[silverlock]

All the pieces. Struggling to find a diagram / photos of the order of the discs + heating element + ring.

[silverlock]

Based on the marks & (bad) contact cement, it looks like it goes together left to right. The thinner disc has a small ring mark on top that matches the top cap of the thermo valve.

Doesn’t sit “well” together though.

[pmax]

Originally Posted by silverlock

TL;DR: Does anyone have a step-by-step for putting a thermo valve back together?

A few months ago I broke one of the hose barbs off the top of my thermo time valve (https://www.pelicanparts.com/More_Info/91160610603.htm?pn=911-606-106-03-OEM) when refreshing some vacuum hoses. No worries, I thought, chalking it up to old brittle plastic.

- I ordered a new thermo valve and when installing it, the top popped off, allowing the two metal plates, the heating element and the spring washer/o-ring to fall out. It failed to want to go back together and so I warrantied it (thanks, Stoddard!) and got a new one.
- Out of an abundance of caution, I used some light silicon sealant around the top of the replacement thermo valve, in order to keep the top from separating. That seemed to do the trick.
- Cue today: I was installing a new throttle spring and wanted to move a hose out of the way. Lightly bumped the thermo valve and the top just popped off. Great.

This may also be the culprit leading to some rough idle issues (https://forums.pelicanparts.com/porsche-911-technical-forum/1168470-78-sc-rough-idle-cold-temps.html) as the car warms up: probably leaking vacuum, and once warm (140F+) the leak no longer matters.

Since they're $180+ and/or a warranty is going to take a few days, and I want to drive my car tomorrow, I want to put it back together.

Any guides? Anyone else with fragile thermo valves?

Originally Posted by silverlock

The new stuff isn't always better than the original German product.

If you bought one from our host instead of the other vendor, I believe there's a lifetime replacement warranty on it.

[silverlock]

Originally Posted by pmax

The new stuff isn't always better than the original German product.

If you bought one from our host instead of the other vendor, I believe there's a lifetime replacement warranty on it.

The part from Stoddard was genuine Porsche. Our host (at the time) didn’t have any in stock.

Less worried about the warranty at this point and more about taking a shot at putting it back together.

[pmax]

Originally Posted by silverlock

The part from Stoddard was genuine Porsche. Our host (at the time) didn’t have any in stock.

Less worried about the warranty at this point and more about taking a shot at putting it back together.

Says nothing about being genuine Porsche, so that usually means whatever is in the bin the supplier has.

Is there a logo on it ?

[911MANN]

Silverlock: I couldn't advise you as to reassembly, but I can confirm this may be part of your problem with the engine warming up.

My warm-up cycle was not functioning correctly a few months ago, and this valve was the culprit, even when the engine was warm but sitting for half an hour. The old valve would not hold the 35 second (or so?) delay the engine needed for enrichment, and it threw the engine into fully warm mode within 5 seconds. I replaced the original 1983 Thermo Valve with a new one from Porsche. I was a bit surprised to find it is made in Taiwan, but it works fine, and my warm-up cycles are now good. Good luck!

[PeteKz]

I haven't opened up one, as my original is still good, however, it should be obvious which way it goes back together. Look for "witness marks" that indicate what part went against another part. Maybe Tony will ring in with his experience.

However, if you want to go drive it now, just bypass the TV and extend that vacuum line directly to the WUR. You'll have to put up with rougher running for the first 30 seconds or so, but after that the TV would be open anyway.

[snbush67]

1 -plastic base with electrical connections
2- thick piece of coin like metal disk
3- shaped round metal piece
4- copper concave washer
5- hollow piece of metal that clicks when pressed
6- small rubber gasket
7- plastic top with vacuum line connections (one center and one outer)

[silverlock]

Originally Posted by snbush67

1 -plastic base with electrical connections
2- thick piece of coin like metal disk
3- shaped round metal piece
4- copper concave washer
5- hollow piece of metal that clicks when pressed
6- small rubber gasket
7- plastic top with vacuum line connections (one center and one outer)

Super helpful, thank you! I’m missing (it likely fell somewhere) the rubber o-ring.

However, neither TTV I had looks like that on the inside: both have a little heating element that is weakly adhered to the thick gold disc, and not the three disc setup shown - https://forums.pelicanparts.com/porsche-911-technical-forum/1169023-911-sc-thermo-valve-falls-apart.html#post12342185

@PMax - was told it was genuine. Wasn’t any cheaper. Markings as below. Made in Taiwan as per another poster’s.

[ammonman]

Had the same thing happen on my 78SC. Put a new one in as part of bringing the car back to life after the PO let it sit full of fuel for 12 years. Put less than 100 miles on the car before the top popped off the TVV just like yours. Sonnen (now Porsche Marin) replaced under warranty. I think Porsche must have got a bad batch from their supplier. No issues (yet) with the warranty replacement.

[silverlock]

Originally Posted by ammonman

Had the same thing happen on my 78SC. Put a new one in as part of bringing the car back to life after the PO let it sit full of fuel for 12 years. Put less than 100 miles on the car before the top popped off the TVV just like yours. Sonnen (now Porsche Marin) replaced under warranty. I think Porsche must have got a bad batch from their supplier. No issues (yet) with the warranty replacement.

I think this is what happened: both the one I bought and the warrantied replacement that fell apart just prior to me opening this thread were probably from the same batch.

The warranty replacement was still loose and the light smear of silicone sealant I used obviously didn’t last across a few months of heat cycling.

As a (slightly expensive) experiment I bought one from our host a couple of days ago. Same part number and markings as the others from Stoddard, but the top is definitely far more securely attached to the base. I applied a bit of glue for insurance but night and day difference in fit.

[pmax]

Don't know if it's just the batch but those do not look like they were made in the same factory.

The PP part is of much higher quality from the looks of it.