I have a 89 7.3 with a lot of coolant loss behind motor but can’t see where leak is I’m assuming heater core could it be anything else?

 

Without a picture, it would be hard to help out. Places where the coolant could be near the rear of the engine:

• heater core (but that usually coincides with a sweet smell in the cab and layer of vaporized coolant on the underside of the windshield),
• head gasket,
• warped head,
• coolant plug,
• oil cooler rear header,
• loose or cracked heater hose

IIRC, i think the E4OD has some kind of coolant hose tee that goes back to the tranny, but I honestly can't remember. I only know about the C6.

 

usually a heater core leak will end up on the passenger side floor in cab, not on ground behind engine. unless there is no passenger side floor boards.
i would be looking at block to heater core lines, or freeze out plugs.

 

Before going too far and not having a clue, get some radiator dye and a UV/blacklight flashlight. Pour the dye in the radiator, drive it a bit to circulate, and leaks will glow bright green under the UV light.

Also, I've had a couple of IDIs like to weep at the rear corners of the head gaskets when they got overheated one time too many. If so, it means the head gaskets are due for replacement soon.

 

Ok thanks the waters been continuous leaking for 3 days with out driving the dye thing sounds good I’ll give that a try never heard of that before

 

You could also rent a coolant/radiator pressure tester from a local auto parts store and add some pressure to the rad and try to find it with the engine off and cold

 

Not really. It's a common problem on IDI's plus some other diesels, the majority of the time simply retorqueing the heads corrects the problem. Happens on engines that have never been overheated. In fact when IDI's were new it was the practice at some Ford dealerships to retorque heads at about 30,000 miles.

 

x2

I know I've read about folks retorquing head gaskets. I guess the IDIs like to weep at the back of the head gaskets.

Use a clean piece of cardboard under the truck when you return home from a drive. Remove it the next morning and I bet you will have oil/coolant drips at the back of the head. I did this with my 6.9l IDI in my 86 f250 and it just confirmed that the head gaskets are loose. I still drive it around town though. I just add oil and coolant from time to time. Eventually I need to add head studs since I have a turbo to put on it.

 

It's common on more than IDI's. If you ever tilted the hood on a truck with a 855 NTC Cummins (Google it) for minor engine work you always looked for seepage around the 3 heads and retorqued.

 

Well it’s either a cracked block or freeze plug behind the motor when I crawled under the truck today it looks like the tranny is leaking water so I’m 99% sure it’s freeze plugs

 

If I remember right, there's two small freeze plugs hidden by the bellhousing.