I have a 1978 Ford F150 2WD with the 351 Modified. Unsure of mileage on truck as odometer and gauges have quit working. I got it from a guy that drove the truck maybe 2 times a year but I am driving it almost daily so I know a lot of things will start popping up with me as I am putting more mileage on it. This is my first Ford truck so I am learning as I go. This is a work truck but I travel everywhere in it so I need to make sure it is safe and operating normally.

Two days ago, my truck ran hot. Upon inspecting the truck with the engine running, I could see that no fluid was flowing through the radiator so my first thought was water pump. So I went ahead and got a water pump, put the water pump on, as well as new heater hoses, heater core hoses, aftermarket temp gauge,,fan clutch, new thermostat, and new heater control switch .Had just put in new radiator a couple months ago. Pressure tested it first with pressure tester before starting up vehicle, which you could hear a gurgle sound through the block as the pressure tester was pumped up which I figured was normal as you are forcing air into the block so it is building pressure which would make the antifreeze in the block gurgle. Put everything back together and it seemed to warm up very quickly but I know that older trucks warm up quicker than newer trucks due to cast iron blocks instead of aluminum blocks.

As I was putting everything back together, there is a hose on the passenger side valve cover at the rear that had been loose with nothing over it and just steadily blowing out hot steam for the past couple months I had it. Well a buddy put a filter over it as you can see in the pic to try to keep some of the smoke/steam from coming out so bad. Test drove the truck down the road and everything seemed fine. I let the truck sit there for a couple minutes and noticed the temp almost up to 220 on the gauge and got to looking around and heard no leaks, nor saw any leaks but looked up under the truck and see oil pouring out the rear of the vehicle between the motor and the transmission bell housing. I knew that meant the rear main seal was shot, which it had been leaking for about 2 months but I was able to just keep a check on the oil in it and add it as it needed it But I also noticed that when the radiator cap was taken off that the temp went back down to around 190/195 as it is a 195 thermostat.

So my question is Could putting that filter on the back side of the passenger side valve cover have caused the rear main seal to finally blow out trapping the extra pressure instead of being able to release it like it had been doing? Also what would cause the temp to go back down after removing the radiator cap? Also where is this hose on the passenger valve cover actually supposed to connect to? and based on the picture does anything else look out of place or not connected that should be?

Thank you in advance for any help that you are able to give me.

 

Replace the radiator cap.

On the driver's side valve cover, is that a PCV valve or just an open elbow? Where does the hose go to that's connected to it? You definitely have a crankcase breather issue of some sort. The way it's supposed to work, the crankcase takes in air from the clean side of the stock air cleaner into one valve cover, then the PCV valve on the other valve cover meters the outlet to manifold vacuum.

If that is in fact a PCV valve on the driver's side, it doesn't look right, and it looks like it has an open port that should not be open.

 

It looks like a PCV Valve. The bottom hose coming out of the pcv valve is going to the rear of the carb and the top one isnt connecting to anything. The passemger side valve cover expells hot steam.

 

Radiator cap was replaced couple months ago along with the radiator.

 

Is the PCV valve seated in the filler cap properly with no leaks? Does the PCV valve rattle if you remove it and shake it? Cap off that open port.