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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: ChrisD on May 20, 2020, 05:11:12 PM

Title: What are these parts at the engine, and why two water temp sensors?
Post by: ChrisD on May 20, 2020, 05:11:12 PM

Hi,

while changing the power stering tubes and doing some other little things at and near the engine, I wondered
a. why the engine need two water temperature sensors?
https://www.directupload.net/file/d/5826/7mp2llqk_jpg.htm
https://www.directupload.net/file/d/5826/o8yc7np3_jpg.htm
Are they both needed, ore can I release one?

b. what are these things, I also have two of them?
https://www.directupload.net/file/d/5826/x9uwgaxa_jpg.htm
https://www.directupload.net/file/d/5826/alq92fid_jpg.htm
Are they leftovers of the old replaced engine?

Hope you can explain me that.

Regards
Chris

Title: Re: What are these parts at the engine, and why two water temp sensors?
Post by: JohnnyPopper on May 20, 2020, 08:35:20 PM

Chris,

the one at the side of the engine head is the main temp sensor that is most likely attached to your gauge.

The one in the thermostat housing is a sensor too, but may be part of the emissions system.

Both parts with the rubber boots are emissions switches. They open or close, allowing vacuum to be utilized in the control of emissions. Since they are capped off, they are not active and can be removed and plugged, unless the government requires emissions systems be working.

Title: Re: What are these parts at the engine, and why two water temp sensors?
Post by: ChrisD on May 21, 2020, 02:10:24 AM

Hi Johnny,

thank you, and again i‘m a bit smarter :)
I have to wait till the datasheet from the technical check authority arrives me,
then i can decide if i can release them or have to rebuild the emission system.
I don‘t hope so, because then i also have to find an original air filter assembly which fits to my
small carburetor.

Regards
Chris

Title: Re: What are these parts at the engine, and why two water temp sensors?
Post by: JohnnyPopper on May 21, 2020, 08:56:52 PM

Unless your government requires emission control, I wouldn't bother reinstalling any of it.

Back in the day when millions of these trucks were on the road, emissions were important.

There are so few now you won't need to feel any guilt if you have her running as efficiently as possible.