240z Temperature Always Over Half

[d240zx2]

Isn't anything south of red considered normal?

[Zed Head]

My car ran about medium-rare over the winter but since spring is here has been running medium. Coming up the Highway 26 hill the other day I let it rev in 3rd gear just to listen and see how things sounded. It started getting pretty close to done though show I shifted up before I really cooked it.

:laugh:

[yetterben]

. These gauges are the suck 30+ years old. If you where that hot you would here it boiling after you shut the car off.

[Arne]

Isn't anything south of red considered normal?

Normal is what ever your car is when things are right. If that changes, that's the time to get worried.

[Bonzi Lon]

During refurbishment the cooling system had been dry for years. Original rad, new cap, unknown thermostat. Added water and ran for 200 miles, temp needle at 'M' in temp, sometimes slightly higher into the 'P'. Drained, muddy looking, refilled with water, ran to 1k miles, still 'M to P', radiator sprung a leak 3 blocks from the driveway, rusty water all over the bay. :mad:

Took it to the shop, repaired leak, flushed out, pressure tested. He said it was full of mud, rust really. Put it back in with anti-freeze for 4k more miles and the needle is always on 'E' in temp. It got to the right of 'E' when driving hard. Drove it to a car show yesterday 150 miles round trip, never over the 'E'. There are several meat thermometers in the drawer, I'll find out for sure.

Bonzi Lon

[deadflo]

Get a meat thermometer. Put it in the top of the radiator. Start the car and let it idle until it gets full up to temperature. Check the temperature of the actual radiator fluid.

You will feel better. Trust me.

Good strategy Walter. My Temp gauge looks like yours in the pic when it gets over 75 Degrees outside.

Did you warm up the car with the cap off?

[lm71z]

We took the car for a drive today and the temp crept up almost to the P when idling. I don't understand how the car is getting that hot considering it has a brand new fan clutch, thermostat, and radiator. Any idea why the temp would have always been slightly under half before the engine was rebuilt (had an old radiator and a blown head gasket) ?

[lm71z]

I think I'll try changing that temp sending unit first. Right now we have the unit from motorsport. Does anyone have the part number for the Nissan one? I can't seem to find it in the FAST diagrams.

[Bonzi Lon]

I did the meat thermometer trick and found out I must have a 165* thermostat. When the guage reached where it normaly is at E, the thermometer was 165. The center of the guage, just to the right of M, would be 185*, just like Walter's photos.

Bonzi Lon

[Zforce]

How many miles are on the rebuilt engine ? Mine ran hot for about 300 miles during the break in process. Your temps will stabilize and power will go up slightly after the engine breaks in.

[lm71z]

How many miles are on the rebuilt engine ? Mine ran hot for about 300 miles during the break in process. Your temps will stabilize and power will go up slightly after the engine breaks in.

There are about 200 miles on the rebuilt engine. We've pretty much ruled out the main cause being the sensor, thermostat, missing fan shroud etc.. Within 1 mile of driving the temp goes up to 3/4 and the radiator is burning hot to the touch. And this is only in 75 degree weather. We're beginning to think it's something more serious (internal problem). Any idea of what a more serious cause could be? To avoid a big controversy on here, I'll avoid mentioning the person who worked on our car, but it seems that we received poor quality work for the amount money we payed to have the engine rebuilt.

[Gary in NJ]

When the engine heats up, grab the hoses. The top should be warmer then the bottom but if the bottom is cold, you have a stuck/frozen thermostat or a clog elsewhere in the system. If you suspect the thermostat, you can take the car for a drive without it to confirm it's not the pump or a clogged radiator.

You can also check the accuracy of the thermostat by placing it in cool water and bringing towards a boil. Put a thermometer in the water and take note at what temperature it fully opens.