308 temperature gauge question

Are you referring to the coolant or the oil? You make referrences to both. I think you are referring to the coolant.

The coolant sender is on the radiator on the passenger side bottom. It's the same as a VW. Get a 165 degree sender of you live in a warm climate area. It is really easy to replace. You do need to drain the coolant however.

 

You may not have to drain the coolant if your really fast. I bet you are referring to the water temp and yes you have air in there. I bet it will swing up high and hang there for a minute or two then drop really fast. That's air. It's happened to me this way.

 

me too; thought it was an electrical or sending unit problem. I bled the system and had a bunch of air. since I'm still doing coolant maintenance, haven't checked whether that will solve the problem yet, but it sounds right.

 

That is the thermoswitch you are describing which turns on the fans. That does not send a signal to the water temp gauge.

 

the one by the oil filter is the oil pres sender and not the water temp. top of motor is the water sender temp. you may have to take of the plenem to get to it.

 

It does sound like a sender issue (which is located in the V of the engine under the plenum AFAIK). Could be you have an airlock issue though so I would check that first.

Also consider whether it could be a Thermostat problem. When they get old the spring gets weak & they don't close as fast as they should. Tends to manifest itself as the temp rising in traffic & then falling again once you get moving.

I.

 

This thread has taken off in many directions...many of which are wrong....Steve, you might want to check the archives for a more accurate description of where the water temp sensor is...but I do think that Ian is correct that it is under the intake plenum on a GTSi.

 

it is under the plenum i know i did replase my and is a 1980 308 gtsi same car with steve.

 

When you first start the car, the temp will be cold. As it warms up, the guage will rise with the temp. You will notice at some point that the guage will then go abruptly back down again, before it starts to rise again. This is the point when the thermostat opens and cold water from the radiator hits the engine. Once everything "settles" the temp guage should be relatively constant.

Birdman

 

Yes it is underneath the plenum toward the very middle in the cross over like mentioned above. Access it from the drivers side. Remove the oil filter and you can get to it. It is small and gold with black plastic on the rear where the electrical connector goes. Definitely drain the coolant otherwise you will get it all over your engine. It is tight in there and you will want to take your time so you don't cross thread it. It has one wire that goes to it that you will need to remove first. They part is only $15 or so. While you have the coolant drained I would recommend replacing the thermostat. It is doesn't cost much. Becareful when you loosen it as mine was very tight and I didn't want to chance damaging any of the threading etc.

 

I have a similar problem. I have replaced the sending unit (under the plenum) and the thermostat. Last summer the guage would rise dramatically if I tapped the gauge it would return to normal temp. Just last month the gauge was working great until it reaches just above 90C and then it drops to 0 and does not return, regardless of tapping. I am pretty sure it is the gauge, but since my car is a european model, do I need to buy a different sending unit for the C gauge?

 

You can probably just have it repaired at a speedometer shop, such as Palo Alto Speedometer (try a google search). Or buy a new one from Ferrari UK, they should have them in Celsius or F.