Here's the story:

I did the full heater core replacement on my 98 F150. About a month after the replacement I started smelling antifreeze. One of the hoses had not fully "clicked" onto the metal tube flange in the engine compartment. This must have sprayed antifreeze all over the place with it being under pressure.

I checked the fitting at the end of the hose, slipped it over the metal tube flange and pushed hard enough to make sure it had "clicked" and was seated. It stopped any leaking in the engine compartment.

Here's the bad part. It's been a few weeks and I still get a smell of antifreeze when I change the temp from cool to warm (opening up the heater box flap). After a minute or so the smell goes away, but it always comes back the next time I run the truck and open the heater box.

Question is: could I have pushed on the hose connection hard enough to cause a leak inside the heater box, or is this more than likely residual antifreeze from when the hose was loose and sprayed antifreeze everywhere? There was a small opening between the metal tube and it's opening in the foam going through the firewall.

Let me know your thoughts, and if there is any way to test this out. I had thought about removing the hoses and blowing air into the heater core to see if I "hear" any air leaks inside of the heater box. I sure don't want to have to tear that whole thing apart again if I just screwed up my new heater core installation!

 

I would think that if you had a constant link, the smell wouldnt go away after a minute or so.

 

Well, here's an update. The whole thing (heater core) took a dumper today.

I was driving home and smelled antifreeze. Stopped to get my son from school and there was fluid pouring out from under the truck.

Got home, parked it to cool. I tried to get the "click-connect" fittings off, but that didn't work out. I followed one of the hoses to the back of the block. The other hose has a clamp that comes off the side of the manifold area. I unclamped the hose from the manifold metal pipe and cleaned the end of the tube up (some deposits on it).

Next, I cut the other hose off just back from the click fitting at the heater core. I did a "heater core bypass" and connected the hose end to the metal tube near the manifold, and put the hose clamp on. Everything works, runs, doesn't leak ... but I will have no heat.

I am resigned that I will have to tear the dash apart ... again ... and do the heater core all over again. Not sure how soon I want to take that on ... again ... but I'm sure the first cold snap we get will be inspiration enough for me.

My advise to anyone else that does this replacement is to make sure you get new hose fittings for the quick-connects, and have someone help hold the heater core in place inside while you make the connections to the tubes.

 

If you attempt to fix your heater core again could you take pictures of the process of what and what not to watch for? I havent searched for this yet but found this and figured I would post about it. It sounds like it might be a tough process?

 

I had the same problem on my 98. Was a complete days worth of work, only to have the replacement core leak within a few months. Dont know if the replacement core was just junk or if I messed it up pushing it through the firewall, as the tubes did not line up with the holes. The tube seemed to swivel with no problems but I always wondered if it didnt cause a leak. I will never know, dont have the truck anymore.

 

I did the replacement. I did not feel I had the time to photo-documentation of the replacment, so I apologize for that.

However, I do have one other question to ask. I still get a rush of water going into the heater core when I start the engine. Is there some sort of process I should use to get the cooling system fully "bled" of air, or will this still be an issue? Anyone else get this sound. I usually park the truck nose down backed into my driveway, which does have a pretty good incline.

Let me know what you know.

 

Latest Update - Third Heater Core replacement!!!

The first time took 16 hours. The second time took 12. The third time I did the entire replacement in 5-1/2 hours. This is not something that I want to get really good at, but I did learn something that I need to pass on to everyone here in the forum.

Look at the tube connections for the replacement heater core that you purchase. The first and second heater cores that I purchased were from O'Reilly's. They use a design of a gasketed flange that is inserted into an aluminum cup and crimped over. The second heater core failure was at this flange. I have followed other forum posts and TSB's that mention putting a pressure reducer in the feed line to the heater core. I tried the fix of putting a ball valve in-line when I started smelling antifreeze again, but it did nothing but restrict the flow of antifreeze and allow steam to rise up from the defroster vents.

The latest heater core I purchased was from AutoZone and it has welded tube connections. This should be a much stronger core and hopefully will not have any issues due to pressure within the system. The price was basically the same between these two types of heater cores.

I kept the ball valve in the hose for the feed side of the heater core. I may consider turning it down some to assist in reducing the pressure leading in to the core.