Hot Temps, guage, temp sender, bad water pump?

[Majin325]

The car heats up to the 3rd line or just a little above. I had replaced the radiator, water pump and everything else with a water pump job about 9 months ago(rebuilt water pump). Thought it was the t-stat cause the lower radiator hose does not warm up at all(stays cold to the touch). I changed it and still no difference in temp guage. Both fans do still come on, Coolant is still green as can be and oil is still clear so no sign of headgasket problems. Car dont smoke either.

The guage does jump up as I turn on more electrical things, heater, defoster, etc.
The temp rises to the 3rd mark within a couple miles from a cold start.
Temp sender... Where is it located and how hard is it to change.

[jackrussell]

Originally Posted by Majin325

The car heats up to the 3rd line or just a little above. I had replaced the radiator, water pump and everything else with a water pump job about 9 months ago(rebuilt water pump). Thought it was the t-stat cause the lower radiator hose does not warm up at all(stays cold to the touch). I changed it and still no difference in temp guage. Both fans do still come on, Coolant is still green as can be and oil is still clear so no sign of headgasket problems. Car dont smoke either.

The guage does jump up as I turn on more electrical things, heater, defoster, etc.
The temp rises to the 3rd mark within a couple miles from a cold start.
Temp sender... Where is it located and how hard is it to change.

I assume that the lower radiator hose now warms up since you changed the thermostat. The temp sender for the temperature gauge is located directly below the throttle valve inlet. You must remove the large J- boot to get to it. I think it's possible to change it without removing the inlet manifold. Before you change the sender, check the wire connectors.

[944Spec_bound]

sounds like you may have the common electrical ground issues. I'd suggest:

1) Borrow or buy a cheapo infared thermometer and see what the temp of the motor is when its showing hot on the gauge. If it's normal temp....

2)Contort into wierd postitions, pull your hair out chasing and cleaning all of the ground points and connections, changing sending unit, etc attempting to get the gauge working right. Or....

3) Buy an inexpensive 2" aftermarket gauge, install it in the clock hole of the console, install the matching sending unit using an in-hose adapter that goes into the top radiator hose and have yourself a complete stand-alone temp monitor.

I wish I had done #3 first, wasted alot of time chasing phantom temp issues for nothing. Never did get my factory gauge working right!

[Majin325]

Lower radiator hose still does not warm up after being driven for about 20-30min. It was cold after parking it in the garage. I saw on clarks garage how to check the water pump shaft if its slipping, prob gonna give that a shot and see what happens. The car has only had about 1300miles put on it since I changed everything.

[Majin325]

Pump shaft does not slip, Coolants seems to be flowing correctly. Temp stabilizes just below the 3rd mark while the car is running. I can shut the car off and turn the key to the on position and temp reads slightly above middle(black line in picture).

[many944s]

Depending on where you got the t-stat from.....

I recently had the same issue on 2 cars that came through the shop after I performed full front engine services on both. I finally ended up checking the t-stats in a pot of hot water on the stove, watching the temp for when the t-stat opened. Both of the stats were supposed to be OE 180 degree F stats, when in all actuality they were not opening til 200 degrees!

I ended up using aftermarket 180 degree stats from my FLAPS (Duralast), and both cars worked properly after the change.

Could be a bad lot out there!

-Nick

[944Spec_bound]

I'd say different readings with engine off and just key on says you got ground issues. Other than erratic gauge readings, I dont see the problem, thats within normal op range. If your up in the solid line area, problem.

If your just wanting it to run cooler, you can swap to a t-stat and thermofan switch from a VW rabbit, they are 160 degree units.

[SuperXRAY]

many944s, I have a Duralast as well in ours. It seems to be much more consistent than the OE that was installed. The only thing I wonder about is the pressure applied on the bypass port? The spring on the OE t-stat is MUCH strong than the spring on the Duralast for the bypass port...any feedback?

[jackrussell]

Originally Posted by SuperXRAY

many944s, I have a Duralast as well in ours. It seems to be much more consistent than the OE that was installed. The only thing I wonder about is the pressure applied on the bypass port? The spring on the OE t-stat is MUCH strong than the spring on the Duralast for the bypass port...any feedback?

When replacing the thermostat, be sure to check the inner seal that the thermostat bottoms out on when it opens. This seal is a PITA to change!

[SuperXRAY]

Originally Posted by jackrussell

When replacing the thermostat, be sure to check the inner seal that the thermostat bottoms out on when it opens. This seal is a PITA to change!

Was installed with new waterpump.