Hi, I'm working on my buddies' 1973 240 2 door. It has a 1990 motor under the hood. It's been leaking coolant lately and it appears to be coming from the back of the motor. I thought it might be coming from the coolant line that crossed over behind the motor and goes to the heater core, but it checked out good. I did notice a brass water fitting on the left side (if you face the engine bay from the grill) towards the bottom of the block near the rear. Nothing was hooked up to it and it had a drop of coolant sitting inside of it, getting ready to drop. He has a Clymers manual for the car, but I could not find a picture or any description of what that fitting might be for. I wasn't sure if it's supposed to be plugged or if there is a hose that's supposed to connect it to another fitting somewhere that I haven't located yet. In the meantime I put some clear, flexible, water hose on the fitting with about 3 feet of length and zip tied it to a support bracket in the left corner of the engine bay near the shock mount. He drove to and from work and told me that it's not smoking anymore, doesn't appear to be losing coolant, and that there is coolant now sitting in the water line that I hooked up to the fitting. A couple of questions. What is that fitting? What should I do with it? Plug it? Or does it need to go somewhere and mate up with another fitting?

I really appreciate any help that anyone can give me. I can get a photo of it if that would help anyone.

 

Also, I could not get it to leak from anywhere when trying to find the leak with the motor running. I'm sure it would have started leaking the second I turned my back on it though.

 

Is this the fitting you are talking about:

 

Check under the intake towards the back of the motor. One of the heater hoses go there and are pretty common to leak.

 

I don't think that's the one. But the car is going to be here later today and I will get a photo of it then.

 

I know just the hose you're talking about. That's the other heater core hose and it's high and dry. The leak seems to be coming from the exhaust side of the motor.

 

Then maybe it is the headgasket leaking somewhat common on the newer year models.

 

Whoops. I got the date wrong. It's a 1979 240 with a 1990 motor.

 

The 90 and up motors were common for the Head gasket leaks usually more up front but I have seen them leak in the back as well.

 

The FITTING is the block drain plug, and it sounds like it is the leak based on what you said. Just tighten it and it should be ok. It is a two part fitting, the base screws into the block, another part, the top, screws into the base, and when you loosen it, the coolant drains out.

 

Ohhhh. That makes a lot of sense. I got to take a look at it yesterday, but didn't get to take a photo of it. The tube I hooked up to it is collecting some coolant. I'll see if I can tighten that thing down. If not, I'll just put a plug in that tube I have hooked up to it. Thanks everyone for the help!

 

It is a brass fitting, i.e. soft metal, so don't overtighten it, I can't tell you the sizes... Actually, it is made just for that hose to put on so you can drain the block when changing the coolant. There is identical one on the other side of the block, but good luck getting to that one...

 

I'll see what I can do with getting it tight. Is it common for them to loosen up like this? If I can't get it to stop leaking by tightening it down I'll get some sort of heat resistant hose, safety wire it down to the fitting and put a plug in it. It may not be pretty, but it should work.

 

I don't think mine has ever done this. You could probably put a cap over it.