Overheating

I started having a problem with my small block v8 overheating due to the fan not kicking in like it use to.  I was told that the sender may have lost it's ground, but I checked it and that is not the case.  I changed thermostats and that didn't help. I have a new sender and put in a manual switch.  The old sender is in the head, I was told to move the new one to the front of the intake and keep the sender wire away from the spark plug wires.  The car only has about 400 miles on the breakin.  My temperature gauge goes up to about 230 or 240 before the old sender kicks in the fan,  but no boiling over or over flow.  Can the gauge also be bad now? It is in the right head. I have a 180 deg thermostat and a 185 deg sender. Could the timing cause the reading to go that high?

I put in the new sender and the fan still dosen't work with it.  Also my manual switch does not bring the temperature down.  I don't think the coolant is circulating.  

Does your fan have relay? Is it working? Most fans use a relay with a constant hot and the line from the sender closes the switch.  

I asked the person who wired the car about the relay.  H said it is built into the Highway 22 american wiring harness at the fuse terminal.  

ok but is it working? You should hear it click in to activate the fan.  What is this engine in? Stock radiator? Mechanical fan or just electric? New water pump? Are the hoses from the engine to the radiator new? Is there a spring in the lower hose to prevent it from collapsing  

The fan is a 16 inch Spal electric fan.  The water pump is a new high flow.  The radiator is a Walker Z series coolmate.  All are new, this new crate engine only has about 500 local miles on it. I am not sure if the upper or lower hoses have springs in them, it doesen't feel like it, but I don't think the are collapsing.  

You should be able to pick out the relay. It looks like a small box about 1.5" and has wires running out. It should be close to the fan or near the fuse box.  

the sending unit in the head will give you a hotter reading. The sender should be in the manifold near the outlet to the radiator. The reading you are getting in the head is coolant that is hot due to it being near the exhaust valve area. But that is not the "true temp" of the motor . The coolant is hot there and is continuing to move up the motor to the radiator.  

Both the temp sender and the fan switch sender are in the heads.  It doesen't look like there is room to put them in the intake because the plugs are right below the alternator and the compressor. I will take the dash out today and look for a relay by the fuse box.  Right now it seems like I have a air lock somewhere.  

an air bubble in the system will make the motor get hot real fast. Best way to get the bubble out is to cycle the system.......that's getting the motor hot, then letting it cool down, and doing that for about 5-6 times should push that bubble up to the top and allow it to escape.  

what makes you think that you have an air bubble?  

I haven't worked on the car for about 2 weeks, but the last time I had it running in the garage the radiator and the hoses didn't seem to get hot after running for several minutes.  So I shut it down for then.  Will get back on it tomorrow and try it again.  I am trying to get a mechanic who works on cars on the side to come over  and check the timing and this problem.  Thanks for all the help, I don't get much help with the car and am learning as I go.  

if your hoses arent getting warm then coolant isnt circulating. I have seen thermostats malfunction and they can be installed upside down which would prevent them from working. take your thermostat out and put it in a pan of water on the stove, put a thermometer in the water and see what temp the thermostat opens.

what year is the engine? does it have the proper water pump on it? newer water pumps rotate assbackwards due to the serpentine belt system.  

Since everything is new, I would suggest that you place a handkerchief in front of the radiator when the fan is on and make sure that it sucking air in. On the outside side chance it blows out then you have the wrong fan directions.