My '88 FC has developed a coolant leak from somewhere near the firewall. It appears to be coming from somewhere under the fuel injector housing. Before I go digging into this thing, I'm wondering if anyone can tell me what I am looking for here. Thanks.

 

Most common place of coolant leak is from a coolant nipple on the Rear Iron closer to the passenger side of engine. There is a small molded coolant hose that goes from this nipple to the throttle body for cold start fast idle. Often time it's small leak because that nipple on top of rear iron becomes corroded and the hose connected to this metal nipple expands and looses its dry tight seal. I've also seen this hose bulge and leak close to the nipple too. If your car is turbo then there is another area coolant could be leaking from. Let us know

 

Well, you are correct. The nipple has rusted through and has broken off. Am I screwed? Or can a new nipple be somehow sweated into the hole?

Obviously, someone ran this engine for quite a while without anti freeze for this to happen. The Previous Owner syndrome has popped up.

 

I wonder if I could tap this out and insert a brass nipple from the hardware store? Any thoughts?

 

I would try and salvage what is left of the nipple there. If not you can choose to eliminate that Coolant port. It is really not necessary for the engine to run. It just aids in the cold start fast idle like Chris Said.

 

I'd go more along the lines of someone hasn't changed the coolant as often as they should, and didn't use distilled water

I'm not sure what you can do, if you aren't that worried about coolant going into the thermowax (thus losing cold start high RPMs) you could drill it out and tap it and put a bolt in it with thread sealer, have to be super careful being its cast iron so it doesn't crack

Or do the exact same thing with a threaded nipple and hook your hose back up

 

OK. So why does the cold start high idle exist? Is it an emissions thing, or something for cold weather. Since I live in Florida, eliminating either of these is really no problem.

I am inclined to eliminate it, as I expect that hose is gonna be impossible to find.

There is no part of the nipple to salvage. It is broken off clean at the housing.

 

My experiences with these leaks there has always been some material to work with on the lower undamaged portion of the nipple, which i just cut off the damage part (top) and smooth out the rest of it with wire brush or sand paper. Make sure not to get debris down inside the nipple. And in order to access and repair this the upper intake plenum will need to be removed. Worse case is that the nipple broke off so close to the block that there isn't enough material to attach hose to, in this case you would need to extract the remainder nipple and tap new nipple or just block off entirely by tapping and tread in plug. But like i said usually your able to salvage that nipple. Either way the intake will need to come off to see up close how much material you have to work with so you know which strategy you'll be using to repair the leak.

 

The hose is cheap (<$15), readily available and frankly, the least of your worries.
Your big problem is how to deal with the hole in the iron.

Regardless of whether you decide to thread or plug, the first thing that must happen is the removal of the remaining steel bung. Originally it was just a simple tube press fit into a hole and the shell that remains in the hole has to go.

A simple method to try involves a tap.
Find the tap that feels like it will thread in...not too hard, not too easy.
Sometimes just the act of threading it in will grab the remaining tube and you can spin it out. If not, go in deep as you can and then try to pull the tap out, which hopefully will drag the remains with it.
In either case, slathering some wheel bearing grease on the tap will grab most of the minimal chipping that may occur.

When I deleted my thermowax (which has proved hassle free even here in CO, so I agree you should be fine) my bung was intact and I grabbed it with some pliers and twisted/pulled it out manually, so it's not a monster fit.
Corrosion will probably be an issue, so soak the area down with some DeepCreep or PB Blaster to maximise your chances.

 

being that putting a plug in the iron takes as much work as putting in a new nipple, i'd say you should keep the accelerated warmup system.

it's more of a hassle on the turbo cars, those who are complaining about it on a non turbo car, you're a pansy.