i have a 98 f150 an div see to be having problems with the coolant going low. if i start the truck and drive it cold the oil gauge slames up to high and about two seconds later the coolant guage goes hot throwing codes. and i loose an inch of antifreeze/ water in the tank. but if i let the truck run a while its fine all day no problems. any ideas?

 

I think you have an oil/coolant sensor issue first. Check that out and see if it has an effect on what the gages do.
On the coolant level, be sure the drop isn't normal between normal cold and hot engine conditions. 1" isn't very far unless you have to refill the level.
If yes, then it may be a headgasket or a leak causing the coolant loss.

 

Had a similar issue with my old car. I would disconnect the (-) Battery cable and the problem would stop for a few days. I ended up replacing the coolant temp sensor and that solved the issue.

 

"but i let the truck run a while and its o.k.....You may have a small pin hole in the head gasket.. a bottle of gasket/ block sealer can fix that.. I think what you might really have is a problem with your thermostat.. I had the small 1/16 inch weep hole in a thermostat plug when i used some block sealer.. With the hole plugged, you dont get the small weep of hot water thru the thermostat back to the radiator. If you idle the motor and try to let it warm up slow it works.. If you run down the road and the water pump builds up pressure behind the thermostat, it is harder for it to open and regulate since the pin hole is plugged.. You then get the jump in thermo gauge and quick drop after that. If you run 100 miles down the road and then park, is the water leve down the next day? When you start motor in the morning, does it buck and chug like you might have a spoon full of water laying on top of the piston??

 

this stuff is pretty good at fixing gasket problems. it can be added directly to the antifreeze unlike the older stuff that required draining and flush.. I have done this and had good luck ----- but it is possible to plug the small hole in the thermostat as i said.

Bar's Leaks Liquid Copper Block Sealer

 

Try the easy stuff first. A radiator cap is a good start. You may find your radiator hose is sucked flat because the cap is stuck closed. If it is a 4.2 you may have the dreaded intake manifold gasget failure. And like Steve mentioned a possible headgasget issue. I however never recommend stop leak. I have more issues with it than the leaks themselves. IMHO