OK so I know this is going to sound crazy. Most people have problems keeping their big block cool and I can't mine to warm up…

I have a 454 bored .100 over freshly rebuilt. The motor runs great and strong however It will not get over 140 degrees. I have a 180 degree thermostat in motor. electric water pump, 3 row ( brand new ) radiator with electric fans set to come on at 180 degrees.

I have driven the car for up to an hour and the temp still never gets above 140 degrees.

I have replaced the temp sensor, and thermostat twice just to make sure one or both were not the problem.

Any Ideas or help would be greatly appreciated .

 

If the t'stat is working properly it should let the temp raise. Make sure the t'stat is installed properly and that there no extra bypasses around it (most set ups have a small bypass around the t'stat so that it reacts faster to coolant temp change when engine is still cold). Could also be a bad temp gauge or a mismatch between the sender. Verify gauge by removing radiator cap and sticking an oven thermometer in coolant. Wait till t'stat opens and coolant flows, then see if the temp readings match.

 

And along with Pete's suggestions, use a temp gun and measure t/housing before and after t/stat opens.
Check t/stat in a pan of water on the stove ensuring it does open at temp stamped and fully open 10° above.

 

And if everything checks out, and it still wont get higher, try blocking part of the radiator temporarily with cardboard to see if the temp rises then. I've never had trouble getting a BBC to get warm enough!

 

ok so i did some more checking.. I opened the radiator cap and installed a meat thermometer , let the engine run for a few min at idle . I got a 200 degree reading inside the radiator, and i used a IR thermometer on the intake manifold ( on the aluminum outside next to the thermostat housing) an got a reading of 160 there.. I know the temp should be higher inside the manifold than it is inside the radiator. however Im guessing these readings are ok because the manifold temp was taken off the intake and not the actual water inside. Also the 180 degree thermostat opened and allowed water to flow through the radiator.

Could the teflon tape I installed on the water temp sensor be preventing the sensor from grounding properly?

Or do I need to move the sensor from its current location ( in the intake manifold next to the thermostat housing ) to a location on the head?

At this point its more of a indication problem ( sensor or gauge ).. whats got me confused is i also had a F.A.S.T Ez EFI system installed that has its own separate wiring harness, and temp sensor that reads out on a hand held display. That sensor also never got to 140 degrees. with that sensor installed in the same location on the manifold with teflon tape.

 

If the sensor has only one lead, then it relies on a ground path to complete the circuit. If this is the case, then the Teflon tape could be causing a high resistance to ground resulting in bad readings.

 

yes the sensor only has one wire on the top. Im going to pull the teflon tape off now and see what happens i will post the outcome.

 

Alum manifold is dissipating heat, thus the 160° reading.
Since rad is reading 200°, I would say t/stat is good, top hose should be hot to the touch.
OE temp sensor location is between the to inside exhaust ports, if OE heads are used.
Sensor body resistance to engine block/head should read less than 1 ohm.

 

Don't rely on the sending unit head location to give an accurate temperature of what the coolant temperature really is either, as the exhaust manifolds/headers makes that area of the heads physically hotter than the rest of the engine. Imo, the intake manifold location registers actual coolant temperature better than the head location does.

 

no change what so ever with the teflon tape removed .. I just ordered another temp sender ( won't be here till at least tomorrow) I am now going to move the sender from the intake to the head and see if that changes anything.