Hello all,

I currently have a 92 f150 with the 300 4.9l inline 6 in it and it is a manual 5 speed.

About 6 months ago (around 6000 miles), I replaced my water pump and thermostat. I then flushed my cooling system again about 2 months ago. When I did this the coolant was muddy looking and I kind of just thought that it was left over sediment because after flushing it twice, it was clean.
Another point to make is since I have owned the truck it has always run cool according to the dash gauge (about a quarter to a third up on gauge) and I thought doing thermostat and water pump would fix this, but I did have problems and heater worked great so I didn't worry too much about it.

Fast forward to yesterday, I was sitting in traffic for about 30 to 45 minutes. Then I started to smell coolant and noticed the truck was starting to over heat. I pulled into a parking lot as fast as I could and the second I parked, the lower hose blew. The coolant that blew out was, again, very dirty.

Well after sometime I was able to replace the hose and fill it up to see if I could get anywhere. I drove about 2 miles before I once again stopped because it was getting hot (and my heater in the cab was not working). After cooling down I drove another two miles and the heater in the cab was not working again.
Then I am on my final leg to the house, and the truck starts getting hot once more, only this time, out of nowhere, the heater started to work and the gauge went to dead center. It stayed dead center until I got back to the house.

My question is, what am I dealing with here? Is this a corroded radiator? Everything seemed to be cycling but could it be the water pump as well even thought I have recently done that? Should I just go ahead and do radiator, water pump and thermostat?

I haven't looked too much into today and was to tired by the time I got home last night but I thought I would see what you all thought, that way I know what to look for and don't possibly waste money on parts I don't need.

Sorry if this is a common questing and any help is appreciated. Thank you.

 

It sounds like the impeller on your water pump is not circulating the coolant, actually circulating the coolant very intermittently. When the engine got hot if the coolant was circulating the heater should have put out extra heat assuming an adequate amount of coolant. Other possibility the serpentine belt is not turning the water pump, but that would likely show other symptoms.