I have a 92 f150 flareside which almost every day i have to keep adding antifreeze to the reservoir/holding tank and it just keeps disappearing. No dripping or smell of coolant. I check the Radiator and its full...is it most likely head gasket or manifold? all i know is it can't be good if my engine is burning off that much antifreeze...the temp. gauge is fine never overheats... my truck is confusing lol

 

Do you have white smoke coming from the exhaust? And I don't mean white smoke that happens on start up. This would be noticeable at all times and would indicate a head gasket issue.

 

Check your oil, smell the dipstick. It could be in there, it would look whiteish. X2 with the smoke, you would know if you were burning that much coolant. Also, check under the truck, it might be leaking out and being blown down the underside while you are driving.

 

well the other day i changed my oil and it was the same color and odor as usual, nothing different than before. and no my exhaust is fine, i looked under the truck for leaks and i haven't seen anything thats out of the ordinary. usually when i had leaks before my temp went way up and then i could smell the antifreeze coming through my vents but i have no indication of any type of leak other than it disappearing, even my buddy who's been a mechanic for 10 years said thats strange

 

Well, then I would just keep adding coolant and eventually the problem will reveal itself. Hopefully sooner rather than later. GL

 

i have the same deal. but i have a leak at like 140* haha just start the truck cold sit down on the ground in front of it and watch. youll problly have a little drip for a min or 2 then it worms up and seals the crack. mine has a tiny tiny tiny leak but never overheats. the exact situation as yours. word for word.
its the stupid plastic caps that ford decided was a good idea for out trucks on the sides of the rad. i only randomly noticed mine after a quik drive to get gas. damn 460. on my way back to the pump i glanced and saw a wet spot on my tie rod. it was coolent. but i havnt caught it since that day.

no advice there just trying to help you pin point it. gl!

 

I have a 1991 F150 5.8L that did the same thing last year. The antifreeze in the radiator dropped to a point and then stops. For a while the level remained up to the cap. After several months the antifreeze dropped a little more. I began hearing running water on the passenger side in the heater core. Finally the engine began to run at a high idle. I finally removed the intake to change intake and head gaskets thanking this would fix my problem. I took the heads to the machine shop and found I had a crack that ran almost from one end of the head to the other (Passenger side) below the exhaust ports. At that point I decided to pull the block and put rings and bearings in it. This is when I found three cracked pistons. A year later I have almost got it back together.

 

wow. i dont wana think about that... haha. please just say its a simple crack or hose not a messed up head. damn. well now im terrified!

 

hd. have any other symptoms? bogging? bad millage? or just loss of water? please explain more.

 

The loss of antifreeze in the reservoir was what I first noticed. Once and a while I would see a small drop or two of liquid on the drive. I was some how thinking that the reservoir was leaking. I replace the radiator cap (Cracked rubber seal on old one) I started noticing a little more of a leak on the drive once and a while I got a whiff of antifreeze but never could find a leak. I just kept a check on the level and watched the temp gauge. Not until I started noticing the truck running faster on the highway with out having to depress the gas pedal did I know more was up than just a leak. I had driven out of town and stopped for a while and restarted the engine. The engine would not idle down it seamed as it was idling around 3 to 3.5K. At that point I had to do something. This all took around eight months to play out. The high Idling came from a vacuum leak, Crack in the head when it finally reached an intake.

 

****!!!!!!

 

Did you replace it with the correct radiator cap? my 90 when I bought it had a 7psi cap on it and would let coolant out when hot... truck calls for a 13-14psi cap

 

Yes
13 PSI

 

Missing coolant is never good. Hopefully it is a leak in the plastic end tanks but with none showing on the groung chances are it is a cracked head. Try to find a buddy with a pressure tester to verify a crack in the head or pull the plugs and see if they are discolored, easy way to see if you are burning coolant. I had a ranger that drove perfectly fine and happy with a crack for many, many miles(2 years) Of course it was a beater truck and I didn't really care if it ate a set of rings. It also did not put out the sweet smell you assume it would with burning coolant. The heads were eventually pulled and it had a huge crack in it. Has the truck ever been overheated ?

 

Hi ncgnito25
Thanks for the input but I have finished with the engine rebuild and moving on to the paint and seat.