Some hot items to this are to clean the undercarriage of your vehicle. We all know that at times we forget step and tend to try and fix the problem and then we are done. In this case you also want to start your truck and see what kind of smoke is coming from your exhaust. More than likely, if you have some white smoke you may have a pretty bad coolant leak. Blue/white moke is usually oil burning off. Just clean underneath before you perform a dye test.

Motorhead26

 

Today I tightened hose clamps and all the water pump bolts I could find. Then I took the truck for a 30 minute drive with heater on. No smell inside the truck. Still a mild coolant smell under the hood. No noticable loss of coolant. Waited 15 minutes and then pressurized the system up to 30 PSI while engine was still hot. Water pump holes top and bottom bone dry, front intake to head dry, rear intake to head on driver's side dry, can't really see intake to head on passenger's side but it looks dry from underneath, thermastat housing dry, no wetness around any hoses that I could see. Did not see any coolant under the engine anywhere. After looking it over I did notice the pressure tester lost about 5 PSI over about 5-7 minutes. Pumped it back up to 30 PSI and stared at guage for a minute or two. It did not move while I was looking. Poked head inside truck around heater core no noises while pressurized. No leaking noises under the hood while pressurized either. With 30 PSI you can barely squeeze the hoses I can't believe I can't find this leak. I'll check under it in a few hours. In the past I have driven it, no fluid anywhere, then I look under it the next day and coolant is on the oil pan. But right not its completely dry. And I have been adding coolant regularly so I know its been leaking somewhere. I'll keep looking. Thanks for all the tips so far. Bill

 

what a head scratcher.

it sounds like you are doing everything right.

i am stumped just like you.

 

I'll probably have to drive it and let it cool down again since I removed the cap after the last run. I don't know if tightening hose clamps and water pump bolts made a difference or not. On a previous outting I could smell coolant, looked everywhere, nothing. Then the next day I saw coolant on the oil pan coming down from the passengers side after the truck sat all night. Starter wires clearly had green fluid on them, driver's side was dry. But on another occasion the passenger's side was bone dry and coolant was coming down the driver's side of the oil pan. Makes me believe something from the front is leaking, running down the oil pan rail, and then dripping down. Never enough to get on the ground though. About 8 months ago coolant was leaking out of the bypass hose where it hooks to the water pump but it was an obvious leak. Tightened clamp and still smelled coolant but I thought it was just burning off. So before today's run I tightened the bypass hose clamp going into the thermastat housing. Had to use a 5/16 box end wrench due to the orientation of the clamp. I only drive the truck about 1500-2000 miles a year and it sits in a garage when not in use. So if I can't figure this out eventually it will get worse then the mystery will be solved.

 

Update: I took the truck out today for the first time since I last posted. It was about 82 degrees today and I went to Walmart and back, about 20 minutes each way, hauled back 20 backs of mulch. Did not smell coolant and no coolant was found under the truck. My guess is the bypass hose was leaking down the back side of the water pump and tightening the clamp fixed it?? Or maybe tightening the water pump bolts did the trick, I don't know. Anyway, thanks for all the helpfull tips, Bill '95 F150 Super Cab 4x4

 

The next time you see coolant on pan, check the joints on the engine front cover gasket (timing chain cover). That's where I finally found my mystery leak a couple years ago. It will seep out an drun down the top of the pan gasket/surface and then show up at rear of engine somewhere. Good luck.

 

I just took it for another drive yesterday and its not leaking any longer.

 

I had a very small leak once in the lower rad hose, 350 Chevy. It was a b-tch to find. I had to get it hot, and move it with a stick till I found the bad spot. I had pulled my rad and took it to a shop to find out that there was no leak in it. The man at the rad shop told me about the stick trick. The fan would blow the leaking antifreez all over the place. And the smell he mentioned was there all the time.