I have a 1984 f150 302: 86 302 roller motor, aluminum intake, fitech efi, bored .40 over.

outside temps 45-56 degrees

My temps gets to 180 and hangs around there

here is the kicker I have little to no coolant flow!

I have 2 temperature senders 1 reads at 180 and at idle it floats around 177-189 driving

The other temp sender floats around 172-176 (GM Type sender works with FItech EFI).

The coolant system is topped off and bled.

Once the the temp hits 180 trickles of coolant can be seen coming out of the tubes. It is slow, kick the RPMS up to 2,500 and it flows a little bit more but like a fast trickle (like a crappy coffee pot kinda trickle)

The coolant moves around, but its like watching coffee being stirred around with a skinny stir stick ever so slowly.

with the upper hose off and the temp at 180, the coolant pulses
(rises drops a little, rises drops a little until it starts running out)
once it starts flowing out the best way to describe the flow is, take a cup fill it and tilt it until its a constant stream of water (very small stream).

The motor never overheats that I know of but the coolant flow seems to slow.

This all started because I am trying to find out why the degrees between the two sensors seem to be 15 degrees off.

With the IR thermometer the temps at the thermostat housing are 178.6 +-.
At the radiator cap the temp floats around 102-112.

The digital temp sensor is on the rear passenger side, the efi sensor sits on the rear drivers side.

Stock fan clutch, and fan. The radiator was replace with one that has the plastic tanks and looks aluminum like.

blocking the radiator will not raise the temps at idle even at 2,500 rpm.

The 86 motor was from a mustang and had a reverse rotation pump, I put a standard rotation pump as I used my old belt system.

Questions:
How fast is the flow suppose to be?
Any reason the temp senders read different? (both have been replaced and give the same results)
why would the temperature not raise with the radiator blocked off?
Am i paranoid or what could be the issue.

Thanks

 

Update:

Removed the thermostat, started the truck and the coolant almost flew out of the radiator fill.

The thermostat 180.. was way to easy to push open up to a point.. then it got stiff and feels like it it catching on something.. once past that point, if you go to release it it catches and then snaps back closed.

Since I am running an aftermarket efi, and can only fit a heavy duty fan clutch, I opted to go with a 195 degree "premium" thermostat. It looks beefier, and looks like a better quality thermostat

I will update once I can get the block flushed and filled with new coolant. may be later in the week.

 

Since you're running EFI, you should be using a 192-195 thermostat anyway. The 180 opening would not allow the engine to reach the operating temperature that the EEC expects, so it will keep the A/F too rich.

Test the thermometer by heating it in a pot of water with a cooking thermometer, and watch it to see if it opens fully at the right temperature.

 

No two senders will ever read the same. Not to mention they're in different locations. That T Stat was doing exactly what it was supposed to do. To get it wide open, you'd have to work the engine hard to generate enough heat to keep it open. It'll never do that at idle sitting in the driveway. The rest of your cooling system is doing it's job obviously. Thank the man upstairs for that, that you picked the right combination of parts in the cooling system for that to happen.