Heater core leak suspected, opinions please!

[juze]

I started off with the "coolant dump" thread but from my further research and observations, it is looking more like a heater core leak to me now so I'm starting a new thread distinct from the coolant bypass valve topic from the original thread.

BTW, i tried to post this same message in the Saabcentral forum (just discovered these forums a week ago, I'm new to this) just now but I keep getting the "awaiting moderation" message, that's 3 out of 4 posts I put there. Can't be sure that my message will get aired at all over there so copying and pasting here, hoping to get more attention here.

Do bear with me for being long winded for most people's attention span but I want to be clear about it:

---

It's a long story that started with a coolant leak that got progressively worse to the point where the coolant literally drains.

I looked around on the internet and decided that the coolant/heater bypass valve was the culprit and replaced it, that was last weekend. No more coolant leaking from the bulk head but this did not solve my coolant dump problem.

I looked around on the internet some more and am inclined to think that the problem comes from either the heater core leaking or the o-rings connections to the heater core leaking. As I find no conclusive and definitive problem/how to solution on this on the internet, I thought I'd get your opinion on this before dismantling the center console to look for leaks. Here are the symptoms I have right now after the CBV fix and have had since December:

1. When I pour coolant down the expansion tank, a fair amount of it comes straight out through the drain holes in the undercarriage, mostly on the passenger side (RH), some from the LHS. I see no leaks or drips coming from the bulkhead.
2. As I drive, the coolant continues to leak severely through those same drain holes, once again, mostly from passenger side. (I barely drive it now except to run errands in town, with little or no coolant, engine does not overheat from the short 5 min drives, temp gauge stays at 9 o'clock).
3. I get of course the "Fill coolant" message on the SID every time.
4. The one time I put real coolant in after the CBV fix last week, the whole gallon of it leaked out within minutes, the next time (yesterday) I put water in instead, knowing it would drain, my windshield fogs up, not immediately but after the engine has warmed up, to the point where you can't see out of it without constant wiping. I've had this fogging since December. (Don't worry I don't drive around with a fogged windshield, I barely drove it since and lately with no coolant so the windshield won't fog up)
5. I did smell something as I was driving, since there is residue of a bit of antifreeze with mostly water in the system, it doesn't smell too bad but you know that there's something there.
6. Yesterday when I drove the car, I noticed that there was no heat coming out from the vents, just the fan blowing. It is possible that the hoses to the right hand side of the CBV were mixed up when I put them back but I doubt as I marked them before undoing them.

So these are the symptoms. From what I've read, it could well be the o-rings that have failed and not the heater core itself, though frankly I don't fully understand it as I haven't found anything visual that I can look at in my research. The way the coolant drains while the car is stationery and cold indicates to me that it's likely to be a hose/seal/o-ring type of leak.


If anyone has a similar experience or has worked with fixing heater core/heating problems, you would know if I am on track or not with the diagnosis, which is no more than an "educated" guess on my part. Would love to hear what you have to say.


Oh, a couple more questions if I may:

1. I've found no instructions so far on how to replace the heater core except for this one here from Giovanni Cirillo that everyone quotes (Heat core removal). But it's for a 900 and it has no pictures. Does it also work on a 9-5? if you've come across any other instructions, would appreciate a link.
2. I saw that someone is selling a new heater core on eBay for $80 shipping included, made in Estonia with parts from Italy. Seller says it's an upgrade from the original and works better. I would go for that if I have to replace the heater core. Sounds good enough and it's the best price I've seen so far. What do you think of that?

Thanks v. much in advance.

It's not just that it costs more to have a mechanic fix your car, I don't want to be totally at the mercy of mechanics and be blissfully clueless. I want to know what's going on with my car and I have a healthy distrust and skepticism of certain so called "professionals".

[nordwulf]

Here are the instructions for the heat exchanger from the WIS: Saab 9-5 heat exchanger - WIS.pdf

[Mike Brennan]

I am thinking that if this is you problem the coolant would drain onto the floor of you car rather than thru the evaporator drain holes. I think the heat exchanger is below the collection plate for the concensation and the embedded drains. If you box has failed you pretty much have to toss the car. I coulod be wrong about this as I am just applying logic as I have been where frank is sending you and those pipes are inside the vehicle.

What do you think Frank?

[juze]

Thanks Frank for posting the instructions. I'll take a look and see. I had no idea where the heat exchanger was until I read the instructions. And Mike, my gut feeling is that there is a leak or crack somewhere, I don't think it's anything too drastic or unfixable, other than the coolant draining, the car seems to run fine. Of course I can't really drive it until this is fixed.

[MI-Roger]

I PM'ed you on your earlier posting, sorry I haven't visited this site in over a week. My suspicion is the same as yours, and you should immediately buy that heater core you saw advertised!, after verifying the inside of the heater box is wet with coolant. I seem to recall that particular part has been back-ordered for months.

The other information included in your posting above, foggy windows, coolant smell in car, etc., support my suspicion.

[juze]

I PM'ed you on your earlier posting, sorry I haven't visited this site in over a week. My suspicion is the same as yours, and you should immediately buy that heater core you saw advertised!, after verifying the inside of the heater box is wet with coolant. I seem to recall that particular part has been back-ordered for months.

The other information included in your posting above, foggy windows, coolant smell in car, etc., support my suspicion.

I'm glad you told me to order the heater core. As it happened, it was the only one they had and the auction was ending in a few hours. Will get it in a couple of days and will open up the console and heater box and take a good look then. If it turns out that it's not the heater core, I can always sell it. I have a feeling that it is though.

i didn't order any o-rings for the heater core, obviously it would make sense to put new ones in at the same time. Do I have to have the Saab o-rings or can I just use o-rings that are the same size?

I replaced all my vacuum hoses today with 4mm silicone hoses and checked my coolant bypass valve job again. As it happened, I noticed that the PCV grommet was torn off from the engine. It must have just happened or else I would have got some serious fault warning on the SID. The reason why I mentioned that is because I immediately went and got a replacement generic grommet of the same size from O'Reilly's. That's why I was wondering whether any same dimension o-ring would do for the heater core.

[juze]

Sure enough, it was the heater core!

I poured in some water to the expansion tank yesterday after having opened the access panel to take a look at the heater core. There was water leaking from the heater core there and some of it dripped through the drain holes in the undercarriage. It did not all drained out like it did after I installed the CBV. (incidentally I didn't do such a good job with the CBV installation as I forgot to hook up 2 of the vacuum lines but I rectified that right away). That's already somewhat of an improvement.

I got a new heater core today and went ahead and replaced it (simple job by the way, even for a novice "mechanic" like me, thanks for Frank's instructions). When I took the old heater core out, the bottom half, esp the spongy insulation, was drenched. I did the test in my kitchen sink to see where it was leaking and i could see two nasty cracks at the U bends at the end of the core. The old o-rings look fine and since I don't have new ones to hand, I decided to leave them where they are. My kitchen sink "post mortem" of the old heater core confirms that that was the cause of the coolant "dump", as water leaked out at the exact same rate and pattern as it did through the drain holes the day before.

It was getting dark so i'll have to put the rest of it back together, fill up with coolant and then take it out for a drive tomorrow. Fingers crossed. Hopefully with a new heater core and CBV-2 parts that are know to have broken, that should take care of the coolant leak.

As for the PCV hose grommet issue that I mentioned, I read about the PCV upgrade since. I have a feeling that I do have a sludge issue.The PCV upgrade will be the next job on the list.

[juze]

I am thinking that if this is you problem the coolant would drain onto the floor of you car rather than thru the evaporator drain holes. I think the heat exchanger is below the collection plate for the concensation and the embedded drains. If you box has failed you pretty much have to toss the car. I coulod be wrong about this as I am just applying logic as I have been where frank is sending you and those pipes are inside the vehicle.

What do you think Frank?

Now that I have actually accessed the heater core and replaced it, I can confirm that it is above the collection plate for drips, which totally explains why the leak came out of the drain holes. I have to admit that until I did that, the whole thing was a complete "black box" mystery to me, I had no idea where the heater parts and drip trays were.

[juze]

All's well! No more leaks, no more foggy windows, no more "Fill coolant" messages, heater works great! Thank you very much for all your help.