96 F150 - heater core leak(??)

Hello all,

Driving older vehicles (by choice, mo$tly) I keep a close eye out for signs of leaks. My 90 Sentra has long had seeping oil leaks, so intermittent drips of old crud don't scare me; if it becomes common, I take notice, clear oil on the ground is a call to battle stations.

I have had the car since it was new, but the truck I bought just over a year ago. In that time, it has barely made a mark on its part of the driveway. I find this odd because it has some signs of minor leaks, but I can live with it :)

Today, I started to leave for an errand and noted a fairly large wet area under where it had been sitting; fortunately, I did not pass it off as rain water. It was from the right side, and felt a little oily. I hate to admit it, but my first reaction was "it's not coolant." A flashlight from the top didn't reveal much. A little oily patch here or there, but nothing scary, all consistent with the engine's normal condition, and nothing that would explain the "spill."

I didn't see much from below, until what I now think was coolant dripped on my arm, and I noticed the trickle leading back up to what I am assuming is the heater core. The hoses inside the engine compartment look fine. So far, I do not see any signs of coolant inside the cab; is that something that I should expect to find, or does the cover arrange for it to fall (forgive the ravings of a green mechanic) between the cab and the wheel well, or something like that? Please feel free to correct my anatomical references as appropriate.

The only other thing that comes to mind is that it _could_ be some dyed fluid from the AC system. I doubt it, but I will mention it. The AC was working fine recently, though I had no use for it today. I do not know whether it has dye in it.

It appears not to leak very much when the engine is not running. Does that tell you anything?

Assuming it is the core:

Haynes says to disconnect the negative battery cable. I'm happy to do it, but am wondering why that would be necessary. There is also mention in both Haynes and the Ford shop manual about vacuum connections. It might make sense when I get into it, but any pointers to what is going on would be appreciated. Partly curiosity, and partly wondering what I am getting into.

Since the core seems a likely offender and apparently costs all of $22, I am off to get one before it sells, and to have it on hand for when I tear into it (probably tomorrow). With that said, is there anything else you would consider as a source of the leak? My plan is to remove the glove box and then put a pressure tester on it to hopefully prove the core is the problem. Is there any problem with that approach? Does removing the glove box ask for trouble with the battery connected? Any other risk?

Haynes also says to drain the coolant. Again, no problem, but is it really necessary? The heater hoses are high in the system, and can be covered and supported high enough to prevent lots of coolant loss. The coolant looks fairly clean after my relatively recent water pump and radiator adventures, so I am inclined to avoid creating a lot of waste just yet. It seems that I should be able to get away with losing only what spills before I get control of the hoses and a little more installing the new core. Please let me know if I am missing something.

Is there anything else I should be asking? You might recall advising me on replacing the shocks, thermostat, water pump, and radiator. Translation: I know just enough to be dangerous :) Cautions and hints will be gladly accepted.

Thanks,

Bill

Reply to
Bill Schwab
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It's a CYA thing the OEMs do. Sometimes it's well advised to do it, other times, there is absolutely no point. Common sense dictates whether you should, if there is a chance of shorting something out while working, by all means, disconnect the battery.

Should become obvious once you get under the dash.

Good idea. Whatever is dripping, you can put a little on your tongue and taste it to see if it's antifreeze or not. Yellow GO-5 coolant (if that's what's in it) is tougher to see compared to orange or green.

No problem here.

Again, more CYA procedure... Take the hoses loose and either plug them or pinch them off.

Being a 96, this shouldn't be too hard of a job, labor time is under 2 hours. 97 and newer, labor time is 7.0 hours and requires removal of the dashboard.

Reply to
aarcuda69062

Got it.

After a couple of "now it's leaking over there..." cycles, I was getting tired of making waste coolant, so I used the cheapest green stuff I could find :) The drops collecting at the low spots on the truck are obviously green; all bets are off when it hits the ground, perhaps because it is not a very big leak. As indicated, it could be something else.

Yikes! Is the change of any benefit to the owner, or it simply Ford getting cheap on us?

Thanks!

Bill

Reply to
Bill Schwab

On Sat, 05 Jan 2008 09:43:32 -0500, Bill Schwab rearranged some electrons to say:

Uh, Bill, the 97 is a different design truck than the 96.

Reply to
david

Uh, David, my question is whether that difference is a good thing in general that happens to result in complicating a particular repair, or a questionable design change that reduces up-front costs for Ford at the later expense of the owner? Uh, is that, uh, clear enough?

Bill

Reply to
Bill Schwab

On Sat, 05 Jan 2008 12:32:30 -0500, Bill Schwab rearranged some electrons to say:

It's a totally different truck for cripes sakes. Haven't you noticed the differences between your 96 and the newer ones on the road today?

Reply to
david

Of course. That is not the question. If you just want to snipe, I have better things to do with my time.

Sincerely,

Bill

Reply to
Bill Schwab

Gang,

I _think_ I made sense of a few things.

It *is* a coolant leak (but I'll stick to green tea or Peach Snapple), and it is starting to look like it is intermittent, and very likely coming from one of the heater hoses. I can make it leak a little by playing with one of the hoses, but it seems to hold pressure, which is weird given how much coolant appeared to hit the ground at one time. Maybe it pooled over a while and then spilled when I backed up??

The leak _could_ be coming from the core, running along the bottom of the tubing and trickling down the wheel well, but a leaky hose is probably the problem. The apparent absence of coolant inside the cab AFAIK also points to leak elsewhere.

As an aside, my Sentra did something very similar, with weird timing. I did NONE of the work in that case, ok :) The AC compressor quit after "only" 14 years, so I had the pros I trust with the car replace it and convert it for the new refrigerant. A coincidental coolant leak ended up looking a lot like an AC system leak (dyed oil), and it flat fooled us. It took a couple of attempts, but they told me they tightened a clamp on one of the radiator hoses, and I must say the leaks stopped, and the AC has worked fine all along. Skeptical? You would not be if you knew these guys. It was actually a little more complicated than that, but that's the general idea of it. The real point being that coolant was able to leak enough to make a small mess, but there was no steaming or other signs of a "real" leak.

Back to the truck, one of the things that bothered me a few months ago when I was changing the heater hoses was that the core moved as I pushed on the hoses. It now looks as though the heater cover is missing a couple of screws at the top. I can't move the hoses and see the cover at the same time, but my guess is that a couple of extra screws would hold the core steady and make it easier to install the hoses.

I have noticed other trucks with LOTS of silicon or some other kind of sealant where the heater hoses meet the core. Is that needed to prevent leaks like this?

For now, I am torn between beefing up the connection and watching it for a while, and just changing the core while I'm there. It's cheap, I really should mess around with the cover to add the missing screws (any idea whether they are all the same length?), and I need the practice ;) I would add that the core is ancient, but I am suddenly not sure about that. The missing screws might suggest that it has been changed; hopefully it left the factory with them. There are also some small rust stains on the cover, which might mean the core leaked and was changed.

A couple of hours ago, I was fairly confused about what was heater cover and what was stuff I might not want to disturb. The illustrations I found made the cover appear flat; it seems to be more of a rounded rectangular bubble on a flat back, or there abouts. There is an "extra box" that appears to be the RABS module mentioned in the shop manual. They say to move it out of the way. It appears to be held in place with two hex/star head screws, and has an impressive electrical connector on the right side. My thought would be to simply remove/disconnect it and replace it later. Is there any reason to leave it connected vs. remove/replace?

There is some wiring that looks like it is intended to run along the bottom of the dash, and should probably be happy to have the core pass behind and below it. Any reports of problems with that would be appreciated.

As always, please feel free to answer any questions I should be asking. Thanks!

Bill

Reply to
Bill Schwab

Hello all,

I replaced the heater core Sunday afternoon. After some struggling with identifying what I did not have to do, I had very little trouble. I also question whether or not I needed to replace it, but at the price, it is nice to know a new one lurks behind the dash. Also, I felt it was important to remove the cover to verify that I knew where the missing screws were going; they indeed helped when making the hose connections. After all that messing around with plastic parts, it seemed reasonable to replace it to avoid having to tear it all apart soon. The vacuum connections never got in my way - not sure why. The direction switch seems to work.

Somewhat by accident, I found that the Ford shop manual mentions back-flushing the heater core after a flush. Any opinions on it?

After another pressure test, and LOTS of jiggling of the offending hose (the leak turned out to be at the connection to the old core), I took the truck on the road a couple of times, and let it cool nose-up with plenty of coolant in the reservoir.

Any suggestions for knowing when a clamp is properly tightened? That and some struggling due to the missing screws seems to have been the problem the first time around.

Bill

Reply to
Bill Schwab

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