Pirrex

I desperately need som help asap, as i really need to drive 500km tomorrow. The thing is, i've had the engine out, so all coolant has been out. Now it's back together, but temp gauge shows only about 1mm up from the bottom when the engine runs at normal operating temperature. When i drove it earlier today, the gauge bounced up and down, but it will not stay above the first line.

It is probably just not vented properly, but i've tried for hours, but nothing. When i open the bleeder screw, only water/coolant comes out, but no air.
Could it be because i didn't pre-fill the radiator and block before pouring all the coolant in it? What would be the easiest way to go? I do have a pressure tester, but only for like 4 hours more from now.

Edit: Oh, and i do have hot air coming into the cabin. Another thing too, is this also related to the same thing; The same light is lit, as when the e-brake is on, but more dim. When the engine is at ambient temperature it's off, but quite soon, lights up more.

JohnKoaWood

Likely a poor sensor...

Air will cause it to overheat, not run cool!

Pirrex

I have considered that, but would be one heck of a coincidence, as it worked like it should before my rebuild, so my theory was that there would have been air close to the sensor, which would have caused a wrong read. Not saying it couldn't be the problem though.

Does the bulb on the red area of the gauge signal that it would be overheating, or what? It's also on, even though the needle shows it would be cool.

87944turbo

Double check the electrical connections at the sensor for the gauge?

Pirrex

I'm also a bit confused about the temp sensors, as i just drove the engine hot, gauge showing nothing, but the fan was on for a while when i came back. So, these don't go hand in hand? So what does the sensor do, which is under the pipe, that comes from the piece, where the bleeder screw is, and what does the one do in the Y-pipe, coming from the turbo?

Pirrex

I've checked the connectors too, but no difference.

Campbelljj

The gauge runs off the second sensor looking from the front of the engine. I am guessing it has failed. They are cheap. If not bled properly, air in the system will cause overheating and high temp gauge reading. Trust me, I know this. I drilled, tapped rear of head and have not had any more problems. Knock on WOOD!

JohnKoaWood

Sensor with 3 pin Bosche AMP style connector is the DME temp sensor, it tells the computer what the engine temp is.

Sensor with 2 spade connectors on it is the temp gauge sender, it ONLY sends the signal to the temperature gauge. (check the 2 wires going to this sensor, and replace the sensor itself)

Sensor in the Y pipe next to the turbo is the turbo temp sensor, it tells the coolant pump relay when to run to cycle coolant through the turbo center section.

Sensor in the radiator, with a 3 pin connector on in controls the low and high speed fans, signals the radiator fan relay when temperature thresholds are passed.

Pirrex

Allright, i'll drive the car and hope it won't blow up.
You mean the one which attaches to the turbo, right? What does the one in the radiator do?

JohnKoaWood

See highlighted text above...

Pirrex

Ah, i had forgotten about the sensor which information to the gauge, and thought the dme-sensor was that one. Got to check my connection to that sensor, as i remember i had some trouble with the connector.

Pirrex

Thanks alot guys, you were right. I disconnected, and connected the sensor again, and now it works great. I even completed the 500km drive right after my complete rebuild without any problems, and words can't describe how happy i am about that at the moment.

theiceman

its a 944, the moment wont last ...

theiceman

come on i was kidding ....