Hello Everyone,

I have a 99 F350 7.3 diesel that is leaking coolant. It looks like the coolant is coming out of a bottom drain (there are two what look like drain lines) located underneath the ac compressor. I am unable to trace the bottom one to its origin. This started leaking on its first start after sitting a month after our winter storms. Do you all have any idea where this line leads too and what could be causing this leak? I have tried looking for schematics/diagrams with no success. I have only idled this and don't really want to drive it far until I understand more. Any help is appreciated!

Thanks

 

Welcome to the forums

This is the Super Duty threads. There is a Forum for 99-03 7.3 Diesels. The guys there may be able to help you more. There is no 'bottom' drain that I know of (I have my truck for over 15 years) for 'coolant'. There is a drain tube at the front of the engine and to the left (when standing in front and face the truck). This is the fuel bowl drain. if it had set for a while and was cold, the o-rings on the drain valve against the fuel bowl could allow a leak from the fuel bowl (diesel not coolant). Some of the leaking could go into the valley and some could go down the drain tube. If this is where your leak is (diesel) you could gently try to tighten the star screws on the drain valve. It is best to overhaul the drain valve and put new o-rings in/on it.

get parts at Fuel Bowl Parts and O-rings - 1999-2003 Ford 7.3L

 

Brother Les,

Thanks, Ill start looking into what your suggesting. My diesel fuel seems to have a slight green tint to it, (when draining into the snow and giving it a green color I thought it was coolant). I smelled it today and it does indeed smell like fuel. Still seems its running out the drain and not running down the outside the line. It is a Super Duty F350. I will try a o-ring kit for the fuel bowl first. Thanks for giving me a direction to start looking!

 

Diesel fuel does come in a few different tints of colors. Diluted lime green is one of the most common. Your leaks is the fuel drain valve. Do not buy a new valve, get the seals and overhaul it. There is a 'HOW TO' instruction paper on the 'Diesel O-Rings web sits for this. When pressure is built up in the fuel bowl, your will have a slight leak. When the pressure is reduced in the fuel bowl, the leak will stop. As for draining down the drain tube (metal), the short black tube does not seem to fit really tight on the fuel drain valve and metal tube. At that point a little fuel will leak around the black tube and end up in the 'Valley'. When you have a bunch of fuel 'laying' in the 'Valley', after a time, this build up will drain out of a hole that is at the back of the 'Valley' and it will 'seem' as if you have a 'oil' leak.... but it fuel. Fix the water/fuel drain valve and this will help so much in have 'fuel' leak up the front and back of the engine. Get up on the engine and look into the 'valley' and see if there is a lot of Diesel fuel there. It will look like oil, so you will have to do a finger/smell test to find out which it is. It should be cleaned up at some point, so you know you will have stopped the leak.