I have a Mk1 Golf. The previous owner has put in the 3 GTi console gauges but didnt connect them.

I want to connect up the water temp gauge (which is the mechanical type with a heat sensing bulb) but still keep the original electric gauge working as well.

I was wondering if I could simply make a hole in the radiator hose and insert the bulb and seal it in.

Would having the bulb within the hose impede the coolant flow at all? Does anyone know another way of doing this?

(PS: diameter of hose is 30mm and length of bulb is about 25mm, and 8mm thick.

1 Answer 1


You don't want to put it in the hose as it would then destabilize the hose and it would never seal or be viable afterwards. You could possibly split the hose and put a housing in-line to house the sensor, but putting a temp sensor in a hose will not give you the correct engine temperature. It is not the coolant circulated throughout the engine, but bypassed coolant which is either going into the engine or coming out of it (making the side trip through a radiator of one sort or another).

What you need to do is find a place where you can tap into the coolant at the block. An easy way to do this is to find a "T" fitting which can house both the original temp sensor and allow for insertion of your mechanical sensor as well. This will show you the temperature which you'd expect as well.

  • I have placed thermocouples directly in the coolant stream by being extremely careful at the hose joint, but I don't recommend that for daily use. We did it on new test cars for summer hot weather test drives only.. Paulster is absolutely correct, you want a device held to a rigid part of the engine with coolant flow inside...
    – zipzit
    Apr 21, 2017 at 20:11

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