I have a 1998 ford f150 with a 4.6 v8 it has about 170,000 miles on it. The truck seems to run hot when sitting still in park. I have replaced the radiator, the thermostat. I am lost at what could be causing this issue. when I am going the truck will cool down however if you ever let it get hot it takes longer to cool it down as opposed to getting in it and just going and not sitting before going.

 

Check out the fan clutch. If it is free-wheeling or near free-wheeling, cooling will be poor to bad when the truck is not moving, but OK at speed with air being rammed through the radiator.

 

The fan clutch had been replaced along with the radiator. If you are sitting it immediately runs hot but if you rev it up it cools down. While going if it starts to run hot; if you out it in a lower gear and let the truck rev way up it will cool down some but then shoots back up.

 

sounds like the water pump is shot.

 

Water pump. Probably an eroded impeller.

 

What are normal operating temps for these engines? 4.6 and 5.4 2v? Running a 190 thermostat

 

Usually around 195-210 F.

 

Ok replaced the water pump you all were correct about it being eroded. But now the manual temp gauge that I had to install (which is installed in the passenger side sensor hole) pegs out at 250 for seconds then drops all the way down to 170 where it ends up staying at 190 I have replaced the thermostat with a new one (again) but still am confused about why it pegs out at 250. Any ideas?

 

Air bubble.

 

That's right, you need to purge the air from the cooling system. This can be done by starting the engine from cold with the rad cap off, then while wearing safety glasses carefully squeeze the upper radiator hose with the engine running. While squeezing the upper rad hose, watch for bubbles, they will start to rise up through the radiator. Do this while the engine is warming and be very careful not to touch or get your fingers in the way of the cooling fan. They will be injured severally and you might break the fan blades as well. Add more coolant as the bubbles come out and the water level drops until all the air is out. Put rad cap back on and drive for a day or two, then (with a cold engine) check the rad. For proper coolant level, add more as needed until the level stops falling. Keep an eye on the temp gauge making sure it doesn't jump around anymore. Then you should be done.

 

We have done the suggested to et the air out of the cooling system but the truck is still pegging out and then cooling down. When it pegs out you have to hold the gas down and it will cool off far which point it will them run correctly. I have replaced the water pump, radiator, and several other little parts; but my heater core is "stopped up" would that have anything to do with it? Also in replacing all these parts my water is "muddy" looking maybe from the heater core? I had to put in a aftermarket temp gage because the original one does not work it acts as if there is a problem in the steering collum when you go from drive to park etc. it goes from hot to cold also does this when you turn on the blinker and things? I really like the truck but it's a little fusterating.

 

You must make sure the engine is really getting hotter than normal. There is a problem TSB with the wiring harness inside the steering columns with tilt steering where the harness was installed too short. Upon tilting the steering wheel the wire pins pull out of the upper column connector and cause numerous electrical problems till fixed. You have to pull the steering column covers off and cut the zip ties holding it to the column so that slack can be pulled up from below. You then need to look inside the harness connector and see if any of the pins are pulled out, even slightly causing an intermittent
connection. These pins must be pushed/snapped back into the plastic connector housing and the connector re-connected. This may be your problem? I had to get a new plastic connector housing as my pins would not stay in place, picked one up at the junk yard and re-installed all the pins in correct order in the newer connector body. No problems since.

I would still verify that the engine is actually getting too hot. You may still have an air pocket in the system if the heater core is completely blocked. Replacing the heater core is a major job, since the dash must be pulled out. While in there replace the blend door, because if it hasn't failed/broken yet, it will and you'd have to pull the whole dash out again to fix that. My blend door broke and while I was in there, I decided to replace the heater core so I wouldn't have to do it latter as described above. It does take about 45 mins to properly bleed all the air out of the cooling system by continually squeezing the hose as I described.