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Procedure: My Heater Core Experience (looong!)
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Posted by Noel [Email] (more from Noel) on Mon, 16 Aug 2010 09:31:56 Share Post by Email
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The core in the '95 CS was hemorrhaging like I owned a coolant factory, so it was finally heater core time. I printed out various procedures and braced myself. The job completed, I'm wondering why people say this is such a terrible job. Given the horror stories people post, I expected this to be truly awful, but on a scale of 1 to 10, with 10 being the worst thing imaginable, this was maybe a 4 --about the same as doing brakes.

I had it all apart a couple of hours. And that was figuring it out, working slowly, taking pictures to aid reassembly, and making sure not to break anything. No cut hands, not even any cussing. I actually didn't bother with the procedures I'd printed except for finding how a couple things were connected. In my opinion, they were either too brief, assumed too much, or didn't have what I needed. So here's mine:

In these instructions, all directions (unless noted otherwise) are from the front of the car, facing the engine compartment, so LEFT means to the passenger side, RIGHT means to the driver's side

There is no need to remove the hood as suggested by Fix My Saab. It's not in the way and removing it is just extra work.

Begin by removing the aquarium cover. Set it aside and remember where you put the screws.

Disconnect the battery ground. You'll see why in a minute.

Next, unbolt the false bulkhead (FB). There are two Torx head screws or 8mm bolts at the outer, upper corners. All the procedures available seem to be on pre-93 models, so if you have a '95 or later (or maybe even a '93 or later) leave it in place for the moment.

On my '95 (and later models) there is a big plastic fitting on the FB that houses a wiring loom that goes down behind the engine. The loom is in a flexible, corrugated plastic tube. It goes into the fitting on the FB, which is held closed by 5 torx head screws, None of the procedures I found mention this. I couldn't get the fitting on the back of the engine undone, so I undid the big clamp-type electrical connections at the other end, inside the FB. One is at a main power junction (gray on my car) and one goes to the ECU (black on my car). This is why you disconnect the battery!

In retrospect, you can actually do the job without taking all this apart, just setting the FB off to the side, but having it completely out of the way is a lot easier. Still, the process described here takes maybe 10 minutes, tops, and really opens up the work space. So if you decide to pull it apart, here's how:

On the inside of the fitting on the FB is another round fitting. (Note how this goes together so you'll remember when you put it back together later.) The inner round piece has a couple of little tabs that hold it in place. Squeeze these to release them. There is a soft, closed-cell foam rubber plug that pads the wires as they pass through the plastic fitting. Pull the plug out and work the power connectors (one at a time) out through the hole in the FB and it's done. Just leave the removable part of the fitting on the wire loom. You'll re-route all this when you put it all back together.

Making space to work:
Then I cheated--and you may be able to, too. The '95 hasn't had any R-134a in the a/c for a long time, so I disconnected the evaporator housing and removed it entirely. My indy tells me he does this on cars when the a/c is inop as it makes the job much easier, and he usually evacs the system so he can get the evap out of the way. He says it's much faster. It may be worth asking your indy if he can evac the A/C system for you and recharge it when you're done with the core. I'd probably do this if I had a good charge and didn't want to wrestle with the blower removal with the evap in place. Having the evap out of the way gives you much better access to the blower motor housing. You can also just lift the evap up and to the left (facing the car) and tie it out of the way, but that doesn't give you a whole lot more room. You can do the job with the evap housing in place, but it's harder and takes longer because you have a lot less maneuvering room to deal with the blower housing.

To remove the evaporator housing, undo the 10mm bolt that holds the aluminum tubes to the housing, the torx bolt in the center front, and at the left rear corner. Disconnect the two thin wires at the top that go to a squarish dohicky on top of the evap housing and the plug to the fan controller. Keep track of these, as they are a bit in the way as you work. Unclip the plastic fitting that holds the aluminum pipes and lift them out of the way --they don't have to move much. You have to wrestle a bit with the evaporator to get the angle needed to remove it, but it only takes a minute or so. This is a good place to cut your fingers, so be careful.

On to the blower housing.
On the right side of the blower housing is an electrical plug. Lift the tab on it and undo it. Facing the car, there is a stiff steel wire coming out of the firewall and connecting to a plastic arm on left side the blower housing. It may have a toothed metal clip on it. GENTLY work the clip off and put it where you won't lose it. (I have no idea where my clip went!). Pull the wire off the plastic arm --it should slip right off. This arm moves the flaps inside the blower that direct air. More on that in a moment.

Now look at the bottom corners of the blower housing, right by the firewall. There is a little tab with a hole in it that holds the housing in place. A little nub on the housing goes through the hole in the tab. The blower really just snaps into it. Pull back gently on the tabs while pulling the blower toward the front of the car. Do this by holding the blower underneath and pulling/lifting slightly. The blower should come free easily. You will have to angle and pull to get it the rest of the way out but it is a very simple, easy motion, basically up and to the front of the car.

(As an aside, my indy told me about having a former dealer tech working in his shop who was wrestling and cussing, trying to get the blower out. My indy asked him what was wrong, then just lifted and pulled and it slipped right out. And that's just how it should be.) A caveat. The tab on the driver's side may be hard to get at, or so it is claimed. People say you need a long screwdriver to release it. I don't remember exactly what I did, but it wasn't hard. I may have just undone the one on the passenger side and then pulled and turned the blower to get it out. No biggie. And it just snaps back in, too.

With the FB and blower out of the way you can see the core it all its leaking glory. You have good access to the heater hoses from the engine and the clamps where they join with the ones from the heater core (HC). I know you want to get that core out of there, but wait a sec.

Before you go after the hoses, put a drain pan or two under the car. My coolant tank was almost empty and I still drained over a gallon from the core and the heater hoses.

The heater core sits in a little box in the firewall. There are two hoses coming out of the right side of the HC. The top one goes to the shorter of the two heater hoses from the engine and the bottom one to the longer hose. They are joined inside the aquarium with short connector pipes and hose clamps. The clamps will be either worm drive screw clamps or the spring type. Undo them and work the hoses off the connector pipes and let the coolant drain. I used a long funnel to help direct the flow down to the drain pans. You can put it under the aquarium drain and it works fine. If you aren't going to put in new heater hoses, you can plug them with wine corks to eliminate drips while you do the rest of the job.

The (now drained) HC comes out with a pull straight toward the front of the car. Mine came out easily, perhaps lubricated by all the coolant in the HC box, but you may need to assist yours with some side leverage from a screwdriver. Once it is out you can see where is was leaking. Mine seemed to be leaking all over, and there was about a quarter cup of coolant just sitting in the bottom of the HC box. Yikes!

Now look at the aquarium area. It will likely have some coolant and assorted debris. Wipe the liquids up with a rag. I also cleaned mine with Simple Green and rags, let it dry, then vacuumed up the solid stuff like bit of leaves and general dirt. Time and the leaking coolant had eroded the fabric tape on the various wiring that runs across the bottom of the aquarium. I like wires to be protected, so I pulled off the old tape, got some new friction tape and re-wrapped the wiring. If you do this, note that there are three plastic wire ties that are attached to the bottom of the aquarium. There is a tab on these that you can lift so the tie can be released from the wires. Very convenient!

I didn't have to replace the blower motor, as it was done five years ago, not long before we got the car. But I still took it apart to clean out the coolant that had gotten in there. There are four U-shaped plastic clips on the wide parts of the center "rib" that just snap off, and a screw more or less in the center of the housing that holds it all together. There's also a grid that snaps off and some flaps that help direct the air. These are controlled by that plastic arm we talked about earlier; the one you pulled the steel wire off of. Take some pix if you need to remember how it goes together. I cleaned the flaps (which had a lot of coolant on them) with Simple Green and dried them in the sun. It's important to pay particular attention to how these flaps work. Take some pix or shoot a little video with your digicam so you can see how they work. It's only obvious if you think about it. And if you're like me, with the spatial skills of a large rock, it may take some thinking. But it really only works one way.

If you don't have the 4 plastic clips you can use duct tape or maybe find some other clip to do their job. I had all four, but maybe something like those springy metal binder clips like those used to clip paper together would do the trick. Hog clips (used for metal fencing) would also do the trick.

Clean all the housing parts up, remove any random strips of foam that may be attached, otherwise it will be coming out the air vents in the cabin. If any of the foam is soaked with coolant, just pull it all out. It's nice to have, but hey, this is a 13+ year-old car and you can live without it. Put the housing back together, flaps and all, and set it aside.

It's now Heater Core time.
If you got the full HC kit from eEuroparts, it will come with two hoses and four clamps. Attach the hoses to the outlet pipe ends from the core. Clamp 'em down. Next, plug the coupling/connector pipes into the other ends of the hoses. Water or saliva work fine as a lubricant to help the hoses slide onto the connectors. Use the supplied clamps on each one and tighten it down.

The kit also includes some cheap open-cell foam with removable backing that makes them self-adhesive strips. These actually work, but you do have to double layer the ones on the left side (facing the car) to get the HC to fit in snugly. Some folks have just cut a chunk of heater hose to fill the gap, but I found a double layer of the cheap foam works fine --at least for the moment. I put one strip on the back of the core, one on the driver's side, and two, side by side and double-layered on the passenger side. Plus, the foam makes for a more professional install.

Now slide the HC into place, It should be a little snug. The hoses go on the driver's side and will line up (more or less) with the heater hoses from the engine. The top one goes to the shorter of the two heater hoses and the bottom one to the longer hose. Put a clamp over the ends of the connector pipes or the heater hoses, then work the pipes into the heater hoses. Fit the clamps over the heater hoses and tighten.

For your next magical trick, you'll put the blower motor back in place.
This is just the opposite of removal. The opening on the blower motor --flaps and all-- lines up with the HC. Think about it for a minute and it's pretty obvious how it should go. The blower housing pivots down and the corner nubs go into the tabs. DO NOT FORCE ANYTHING! It should really just slip into place without much force. Reconnect the power plug and be sure that the hose for your windshield washers will be there when you need it to connect to the nipple on the bottom of the aquarium cover.

If you pulled the a/c condenser housing, now is when you get to put it back in place. It takes some twisting but is just a tad awkward. Be sure to get the rubber gusset that helps connect the evap housing to the blower housing wrapped around the flange on the blower housing. They sort of plug together, but you just have to futz with it to make sure it's connected. BTW, putting the evap unit back in is the only place where I cut my fingers in this job.

You're most of the way there.
Tighten the bolts and screws that hold the evap unit and the aluminum tubes in place. Reconnect the power to the fan controller and the two small wires to the squarish dohicky on top of the evap housing.

This next part is much easier to do than describe. This deals with the fixed plastic fitting on the false bulkhead (FB), the one the big wiring loom fits through. Look at the pix you took for reference.

Run the wires with the two big connector plugs through the hole in the FB. Put the removable center piece, wires and all, through the one fixed to the FB. Now, this center piece LOOKS like it just goes to the notches in the fitting on inside of the FB. But no. It goes ALL THE WAY in, with its clip ends over the TOP of the fixed fitting on the back side of the FB. The front (engine compartment) side should be oriented so the end where the wire loom in the flexible plastic cover is pointing downwards and generally toward the passenger side. Now put the cover on the front side and clamp it down with the 5 Torx head screws. Take the black foam plug, wrap it around the wire loom, and stick it into the fitting on the inside. Put the FB in place and secure it with the screws in the upper corners.

OK. You're getting real close. But DO NOT put the aquarium cover on yet, though.
Reconnect the battery.
Reconnect the MAP sensor--both the electrical plug and the vac hose to the manifold.
Put about a gallon of coolant in the expansion tank, or until it is full, and leave the cap off.

Start the car and let it idle.
Use a flashlight to check down inside the aquarium cover for leaks at all the hoses you've touched. The ones at the HC, the connections at to the heater hoses, the ones on the head and block if you changed the heater hoses, too. No leaks!? The world is a good place! Ya done good!

Check the coolant level and add some. It probably needs it as the water pump does its thing.

Let it idle while you put the aquarium cover back on. Be sure to connect the washer hoses! Top up coolant as necessary.

Put your tools away and go have a well-earned beer. Good job!

From opening the hood to cracking open a beer after you put your tools away, this is a 2-4 hour job. I spent more than that, but I took a bunch of pictures, re-wrapped wires with friction tape, did the heater hoses, and groped around figuring stuff out because the other procedures I found left me guessing. If I went back in on another car, I could do it in about 3 hours, maybe less. My indy says they do it in about 2 hours, with the core out in about 45 minutes.

Good luck.

->Posting last edited on Tue, 25 Sep 2012 07:10:07.

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