Manifold vice head temp sensor
Thread Starter
Melting Slicks
Joined: Mar 2004
Posts: 3,472
Likes: 18
From: Lake Ozark, MO
Manifold vice head temp sensor
Which is the most accurate for water temperature - sensor in the head or sensor in the manifold?
Does any one know of a sending unit that just give a full ground at a certain temperature ...say 190 or 200 degress so I can automatically turn my second electric fan on without using one of the radiator probes.
Does any one know of a sending unit that just give a full ground at a certain temperature ...say 190 or 200 degress so I can automatically turn my second electric fan on without using one of the radiator probes.
Melting Slicks
Joined: Aug 2003
Posts: 2,135
Likes: 2
From: Dayton Oh
I'm thinking that the head would be closer to actual than the manifold. For the temp sending unit, check out the sending unit originally installed on a 79 L82 that controls the aux. electric rad fan. You'll also want to use a relay with this sending unit. This sending unit was originally located in the passenger side head.
Le Mans Master
Joined: Aug 2003
Posts: 7,720
Likes: 12
From: Chattanooga TN
Originally Posted by Hvymtlc5
...Does any one know of a sending unit that just give a full ground at a certain temperature ...say 190 or 200 degress so I can automatically turn my second electric fan on without using one of the radiator probes.
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
The sensor in the head is there to monitor the hotestplace on the engine. Different places on the engine are different temps normal operation, so it depends on what you want to do be measuring temps. On my 81 there is a temp sensor on one head for the gauge and the other head turns on the aux fan. I wouldn't have put it there, but GM did. The purpose of the fan is to cool the water in the radiator, so if you can, put in a sensor in the thermostat housing, it will come on to cool the water based on the temps going into the radiator.
Race Director
Joined: Nov 1999
Posts: 10,643
Likes: 8
From: Foxfield CO 1970 Convertible
Another opinion:
The coolant temp in the heads is probably insignificantly different from that at the manifold outlet (once the car is heated up) since it just came from the heads a couple of inches away...I say "6 of one, half dozen of the other"...
The coolant temp in the heads is probably insignificantly different from that at the manifold outlet (once the car is heated up) since it just came from the heads a couple of inches away...I say "6 of one, half dozen of the other"...
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
thats pretty true, but there will be some difference since the coolant at the thermo outlet is a mix from all around the heads, the ends are several degrees cooler than the middle. But probly not a lot, be interesting to know
