70 2.2S Engine questions

sdmcoupe · 07-17-2022, 02:57 PM

The previous owner removed the thermostat (for hot air) and replaced it with a block off plate. Any idea why he would have done that and what this does exactly?

Also, he cut the hose to what i think is part of the emissions system and plugged it with epoxy. Again, why and what would this do?

Thanks,
Rob

ed mayo · 07-17-2022, 04:54 PM

By using that blockoff plate the automatic mixture adjustment is eliminated. The mixture is now preset to be correct only at running temperature. That plugged vent hose is part of the gas tank vent system and included the charcoal cannister in the trunk.

sdmcoupe · 07-17-2022, 05:27 PM

Thanks Ed. I have a box of parts that includes the thermostat and charcoal canister which was removed from the f/trunk. Any opinions on if i should reconnect the thermostat?

Zuffenwerker · 07-17-2022, 06:26 PM

You should reinstall the thermostat. Clean the “cymbals” before reinstalling. Check and see if you still have the thin paper gasket that goes between pump and thermostat. Order the special hose that heats the thermostat. The hose connects at the left hand side engine tin.

If working properly the car will run much smoother on startup and throughout the warm up process.

Daniel

sdmcoupe · 07-18-2022, 08:59 AM

Thanks Daniel.

The one i have has metal gasket.

There are two hose on the thermostat. Does anything get connected to the one pointing to the back of the engine?

ed mayo · 07-18-2022, 09:10 AM

there are two hose NECKS on the thermostat, only the upward neck gets the hot air hose, the downward neck is just an outlet. You also need an outlet neck on the left heat exchanger, a VERY thick hose from the exchanger to the neck on the side engine tin, and an inner and outer hose from the side tin to the thermostat. Once you have all that the mixture settings will need to be redone to undo what was done.

sdmcoupe · 07-18-2022, 09:49 AM

thanks Ed...again. :-)

I'll likely leave it alone for now then. Im just trying to get the car started and running after a long period of not running.

targa72e · 07-18-2022, 10:57 AM

As others have said the warm up mixture adjustment is now manual. I did this on a 914-6 conversion as I was running headers and had no way to get heat to the thermostat. With the thermostat hooked up the car would lean out while sitting in traffic (thermostat gets hot) and then run rich while cruising (thermostat cools off). With the manual adjuster when adjusted so that things were good when hot then I could not get the car to start when cold. I had to adjust to start the car and then move adjuster back once warmed.

john

sdmcoupe · 07-18-2022, 01:44 PM

ok..maybe not. maybe its best i swap it back in. i have the external hose to the heat exchanger already connected. car will need to be tuned regardless once its back up and running.

Neven911 · Neven911's Garage

Also remember the heat exchanger to thermostat hose has an inner and outer, this is important to keep the thermostat at a constant temperature

cmcfaul · cmcfaul's Garage

If possible, put it back the way Porsche designed it, with a functioning thermostat. If you want to get it running best, no matter what you decide on the t-stat, get an AFR meter and adjust the mixture where you want it at the temp you want it.

Chris
73 911 E

stownsen914 · 07-19-2022, 01:41 PM

One reason to remove the thermostat is if the car has headers instead of heater boxes. The heat source for the thermostat is a small diameter hose that connects to the heater box. Aftermarket headers won't have this provision. Something to consider.

In case you have headers, it's still possible to have a warmup adjustment instead of the static adjustment like you currently have. It involves a lever/cable actuated adjuster that connects to that same spot on the pump, with the lever in the cockpit. I believe Supertec makes these?