Thermo Time Switch

[gcw206]

I have a 1969 280SE Coupe W111, and the TTS has just gone bad.
If I place a jumper wire from the large terminal to ground, all works as it should.
I have tried to source another OE, but the cost is stratospheric.
I understand that I could use a Porsche TTS, but even those are $250.
Could I just run a ground line to the TTS all the time? 
Or maybe put a push button in the cabin to manually ground the system only when starting?
Or should I just bite the bullet, and R&R the old unit?

[wwheeler]

The TTS should be the same as the W113. Do a search and pretty sure there are posts about the alternatives. Some may require changing the terminal connections, but alternatives do exist. Here is just one example - https://www.budsbenz.com/catalog/230-250-280-sl/g-exhaust-intake/G207-013

[Nicolas Aristodemou]

I think your best bet would be to get the modern electronics type thermo time  switch from Bosch. Shop around and you will find it cheaper than $250. There are several Bosch types but all are marked 12V 35degC 8 seconds.

I did the same on my 280SL two years ago, runs perfect. You can find the in eBay searching for”Bosch thermo time switch”. They start from $160 to $175.

[FGN59]

I don’t see why a push button as you suggest wouldn’t work. Replacing ‘dumb’ electromechanical switch with ‘intelligent’ primate brain to perform the same function shouldn’t be too difficult 😉. Whether that is an efficient strategy is not the issue if you’re trying to save 250€, which is a perfectly respectable objective in my opinion. If it works, it works...

[Pawel66]

I think quite a lot of Members use the push button technique due to:
1. Expense related to have original TTS
2. It rarely works really good (seems not to be working properly during hot start, and it is needed at that moment too)
3. The modern one looks like a modern one under the hood (bonnet) and costs money.

The trick, I guess, may be to make this push button look acceptable or not be seen. You also need, obviously, to install a switch that is on only when you press it.

[wwheeler]

I have the CSV cabin switch on my W111 and is hidden under the dash. You can click while cranking but is honestly way better to do so just before cranking. That could be the cheapest way out. The only downside to me is that it becomes totally manual.

[Nicolas Aristodemou]

I have also installed a contact thermoswitch rated @ 45 deg C in series with the CSV power supply which prevents the CSV from operating even for a second or so when the temperature of the engine is above 45 deg C. This way the engine is not flooded with petrol resulting to rough running at start up when engine is hot.