Okay, finally got the 3/8 NPT tap I've been waiting for today. I tapped out the hole where the 3100 heater pipe used to be for the CTS (to get it out of the way of my new heater hoses), and put a 3/8 NPT plug in the intake where the CTS USED to be. Now, in the hole to the driver's side (looking at the engine from the pulley end) of the thermostat, there is a 1/2 NPT to 12AN fitting in it, which runs into a 12AN 180* hose end coupler, to which I have the inlet side of the heater core attached.

I've got a leak where the 180* bend in the 12AN coupler meets the nut that attaches it to the NPT adapter. I've tightened the crap out of this union and it's still leaking. Luckily, it's only water at this point, until the coolant mixes (yes, there is a gallon of straight antifreeze already in the block and another in the radiator with water in the middle), but I know this leak is going to get worse under pressure.

This was a (not-so-)cheapo fitting from eBay. Should I try to get another?

 

I'm just curious why you chose to route the heater core line that way. With my 3500 LIM the heater pipe exits very close to the heater core and only requires a short hose.

 

Check there's no debris stuck in the mating surfaces, otherwise you might have to replace one or the other or both fittings.

 

I chose to route the heater lines the way I did because the original plan was to have the engine in the 87 and use the A/C heater assembly. Which meant that I was going to retain the stock heater pipe with heater control valve. Therefore, the heater pipe that was in the intake manifold was useless. It was either remove the 3100 heater core pipe and plug that hole and utilize the heater hose connection by the thermostat housing (which points in the wrong direction) or find another way to connect the HCV to the intake. I decided that I would be using the 4th gen dash and heater assembly LONG after the intake heater pipe was removed and so twisted that it couldn't be reused. My only option was to use the NPT to AN fitting and the 180* bend and plug the hole where the heater core pipe was. Once I ran the stainless hoses to the AN fittings in the intake, it became apparent that I was going to need to move the CTS to where the heater pipe was (too close to the heater hose for comfort) and plug the hole where the CTS used to be.

I'll check the area where the fittings join for debris, but I'm pretty sure they're already clean. I think it's just a case of a cheapo fitting...

 

is this an -12 hose end or a -12 to hose barb adapter?

if its a hose end is it leaking on the thread side or the hose side


sometimes a lil antisieze on the threads of the npt to an adapter will cure a leak on that side , though u shouldnt need it

9 out of 10 times the braided hose isnt properly installed into the hose end causing a leak as well

 

I'm not using a braided hose. I took the end fitting off of the hose end of the 180* coupler and have a full stainless hose complete with its own clamp attached to where a braided hose would go (like any other heater/radiator hose). The leak isn't from the hose end, it's at the fitting where the 180* coupler goes into the NPT adapter.

I took the fitting back apart and it seems as though there should be an o-ring between the AN nut and the 180* pipe, but there isn't, so there isn't any seal. Both the NPT adapter and the end of the 180* pipe are clean, but the fitting is still leaking at the nut.

I'll have to try to get a pic, I suppose. But I think I'm going to need to replace the 180* hose coupler from the looks of things.

 

Pic, with notes:

I should add that the blue nut on the 180* coupler is VERY loose, which makes me think there isn't any o-ring in the joint like, I would tend to think, there should be. This is compared to the side where the hose connects, which I can feel has an o-ring seal.

 

an fittings dont use orings , unbolt the 180* fitting and make sure u can pull the nut away from it and look inside and see if it looks sealed up on the inside

if the nut isnt sliding all thway down were it should be it will leak on the backside of the nut which i think from the picture u are saying its leaking

had the same issue with one of my fragola fittings as it binded a lil bit took it off slid the nut down ( was caught on a burr) and it sealed right up

 

Um, if the fitting isn't supposed to use o-rings, then why does Jegs say that their fitting has a "triple seal, double-o-ring design"?

http://www.jegs.com/i/JEGS-Performan...oductId=830891

Can't move the nut... It's pinned in place and I can't get the pin out even though it's pretty loose in the bore. I have no way to access the back of the pipe where the nut is or the inside of the nut. If I could, I'd put an o-ring on there and this wouldn't be a problem any more.