Hey guys.94 f150 5.0 E40D 4x4. I'm losing coolant and I don't know from where.I'm not losing it real fast but I am losing it. Last month I did a water pump,t stat, upper and lower rad hoses and heater hoses. I'm sure all the air is out of the system. I've been keeping an eye on the over flow bottle and have noticed that the level of coolant goes about three quarters of an inch below where it was by the end of the week. No leaks that I can see. No symptoms of a head gasket leak,nothing in the oil and no oil in the rad,not blowing smoke out exhaust,no overheating. So I don't know where to focus my attention at this point. Any options would be great. Thanks guys.

 

If you are sure it's not slowly leaking from the pump or front of motor anywhere... You probably have a slow head gasket leak that is burning the water off. I have the same problem on my 88 4.9L and have ignored it since it's a really slow leak. Put some extra coolant in the reserve tank and ignore it, or get a new head gasket and tear your top end down... Up to you...

 

My 1992 F350 w/5.8L engine loses a small amount of coolant just like the OP posted. I traced it down to a very small leak on the radiator tank. Very common issues with these aluminum/plastic radiators. It never leaks enough to leave any coolant on the floor, tends to lose it driving down the road.

 

Check your hose clamps.

I thought I had a bad head gasket for a while and it turned out my hose clamp was loose.

I went through a gallon a week for three weeks trying to figure it out.

Check the bolts on the pump too. It may sound stupid, but just do it to be safe.

 

Thanks for the ideas guys. I'm not convinced its a gasket yet either. I'm gonna keep checking for leaks like everyone suggested.