930-78-3,3 thermo time switch ??

[jeos]

Hey where the engine sits thermo time switch.?? I can not find it.

regards John

[full quack]

On the engine block, in the back, below the fuel distributor, just to the left of the case seam.
Mark

[JFairman]

Top left corner of the left side chain case cover.

[JFairman]

Originally Posted by full quack

On the engine block, in the back, below the fuel distributor, just to the left of the case seam.
Mark

The one mentioned above is the emissions oriented thermovalve that blocks vacuum advance from making it to the vacuum advance pot on the distributor until engine heat migrates up to it, and then it opens if still working and lets vacuum advance start to work.

The purpose of that thermovalve is to block vacuum advance when it's cold so timing is retarded enough to raise exhaust temperature which heats up the catalytic converter faster and lowers emissions after a cold start.

I don't know if a euro car has one because they didn't have catalytic converters in the mid eightees.

[full quack]

Crap...I had my last project stuck in my mind...so sorry. JFairman is spot on!
Mark

[jeos]

I can only see this connector is it to?

[A930Rocket]

Look towards the back of the car, left of the crankshaft and on the far left side of the timing chain cover. Should have two wires connected to it.

Not my engine, but see attached picture:

[stevie 77 930]

Here's is were mine is....

[mark houghton]

Originally Posted by A930Rocket

Look towards the back of the car, left of the crankshaft and on the far left side of the timing chain cover. Should have two wires connected to it.

Not my engine, but see attached picture:

Glad that's not your engine! Looks like a boat anchor.

[jeos]

Thank you. for your great help.

Regards john

[Alan L]

Originally Posted by stevie 77 930

Here's is were mine is....

Nope. That is your throttle airplate safety switch - if I am seeing all your pic.
Airman is correct and gets the prize.
Alan

[stevie 77 930]

opps....wrong one. Here is the correct thermvalve for that connector

[jeos]

How do I measure the thermo time switch, to see if it is ok?

Regards John

[Ken911]

what is it's function anyway?

[Ronnie's.930]

Originally Posted by Ken911

what is it's function anyway?

It triggers the cold start injector . . .

[Alan L]

It cuts the Cold Start Valve off after a few seconds. They CSV fires extra fuel via injector straight down the intake throat below the throttle butterfly - so it goes to all cylinders.
You dont need this extra fuel after about 20 - 30 secs once the engine has fired up and the WUR takes over. The Thermo switch should cut the power to the CSV after that time. You can check it by hooking a multi meter over the terminals on a cold motor - you should have a intact circuit (Closed circuit - ohms), then it should cut off shortly after motor fires.
Alan

[Ken911]

oh ok

[bpu699]

Subscribed to this old thread. Rebuilt my 930 motor and cracked the thermotime switch.

Can I try to start the motor to break it in if this switch is bad, or need to replace switch first?

Will ohm test tommorrow

Thanks folks

Edit: found a cool way to test it:


The thermo/time switch grounds the injector relay for aprox 8 seconds when cold and less time as the temp increases.

The "simple" test is to connect the switch housing to ground, attach a test light to the terminal with the larger screw and to the + terminal of the battery. the starter connects to the small screw terminal. connect power to the testlight and the small termal at the same time. When cold the lamp should stay on for about 8 secs and drop off the time it ramains on as the temp increases to 35deg C.

Because this is an electro-mechanical switch the heating coil inside the switch has to cool for about 30 seconds between tests.

Also when installed in the car, the same holds true, The cold start injector will not operate a second time untill the heating element inside the switch has had time to cool