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NG900 & OG9-3 Workshop NG900 (1994 to 1998) & OG9-3 (1999-2002) & '03 Convertible Technical Forum

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  #1  
Old 29th November 2006
Sha_kri Sha_kri is offline
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Default coolant flow to the heater core?

Anyone know what might stop this? My mechanic ran a hose through the heater core to make sure it was not blocked up. Then he changed the thermostat, still coolant wont go to the heater core.

Now he wants to check the control rod in the dash, which evidently takes some time to get to. Does this control coolant flow to the heater core?
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  #2  
Old 29th November 2006
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hmm interesting we have indentical cars with indentical problems! I had the dealer do a "back-flush" where they disconnect the hoses and run high heat and pressurized fluid through the hose that returns to the engine block (disconnected of course) and that solved any and all problems it was quite cheap as well.
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  #3  
Old 29th November 2006
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Quote:
Originally Posted by koniq
hmm interesting we have indentical cars with indentical problems! I had the dealer do a "back-flush" where they disconnect the hoses and run high heat and pressurized fluid through the hose that returns to the engine block (disconnected of course) and that solved any and all problems it was quite cheap as well.
This seems to be the answer - a backflush..Maybe some PO used a stop-leak long ago ???

Does your mechanic know of this procedure ? Does he use the WIS CD , even the Haynes manual ??

The heater temperature knob controls the operation of the hot air door, NOT the coolant - this is a much newer design that the old Saab 900s and 96s where a coolant valve was used...
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  #4  
Old 29th November 2006
Sha_kri Sha_kri is offline
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Quote:
Originally Posted by koniq
hmm interesting we have indentical cars with indentical problems! I had the dealer do a "back-flush" where they disconnect the hoses and run high heat and pressurized fluid through the hose that returns to the engine block (disconnected of course) and that solved any and all problems it was quite cheap as well.
how did that solve the problem? Was the hose clogged or something?

My mechanic says that besides the hot air door, there is something else that controls the flow of coolant there.
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Old 29th November 2006
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Quote:
Originally Posted by Sha_kri
how did that solve the problem? Was the hose clogged or something?

My mechanic says that besides the hot air door, there is something else that controls the flow of coolant there.

"hot air door"? what is that? if the driver's side of the car is the only part where it's getting warm then one of the hoses is plugged or worse the heater core it self... do you hear gurgling noises? or smell antifreeze? if so then the heater core or hoses have a problem..... ie a hole in them.
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Old 29th November 2006
Sha_kri Sha_kri is offline
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Quote:
Originally Posted by koniq
"hot air door"? what is that? if the driver's side of the car is the only part where it's getting warm then one of the hoses is plugged or worse the heater core it self... do you hear gurgling noises? or smell antifreeze? if so then the heater core or hoses have a problem..... ie a hole in them.
I believe what they mean by the hot air door is the door that the air temperature control knob controls. Adjusting the mix of warm/cold air to the cabin. No I do not hear gurgling noises or smell anti-freeze.

What I am asking is what exactly did the "backflush" fix?

I must say that this Saab is a high maintanence car. Not so much with having problems with it, than as trying to figure what is causing the problem when it happens.
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Old 29th November 2006
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Does the water pump have anything to do with the circulation of the coolant?
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Old 29th November 2006
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Originally Posted by dtsirlis
Does the water pump have anything to do with the circulation of the coolant?
of course!



as for the "back flush" I had a plugged up heater core hose so that cleaned it
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Old 29th November 2006
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Quote:
Originally Posted by koniq
of course!



as for the "back flush" I had a plugged up heater core hose so that cleaned it
haha I know I am still learing this stuff.... well then maybe his water pump is not functioning properly..
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Old 29th November 2006
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The coolant flows around the engines perfectly. The water pump on my 900s is also brand new.

I will give the dealer a car ~friday. Right now I am prepared to drop a grand just to find out what is causing the problem.
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  #11  
Old 1st December 2006
Sha_kri Sha_kri is offline
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Called the dealer and talked to a technician. He said that the 1994 990s v6 does not have a fluid control unit (valve) inside the heater core area, but they started putting them in from 1995 onwards. He said it sounds like my mechanic put the hoses on the wrong way.

Anyone know if this is true? Are the heater hoses only designed to flow one way? Sounds kind of odd.
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Old 1st December 2006
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Quote:
Originally Posted by Sha_kri

Anyone know if this is true? Are the heater hoses only designed to flow one way? Sounds kind of odd.
Hmm, that does sound odd - especially if there's no valve to control the fluid. I don't think that reversing the hoses would matter that much - maybe some theoretical loss in efficiency, but hot water is hot water, no matter which direction it is flowin in.

It also sounds like you don't have the problem that koniq did, mainly because they were able to make water go through yours.

I think it's worth investingating the hot air door theory more. I don't think I've ever seen a diagram, but if you can remove the passenger side kick panel you'll see a cable that moves with the heater control knob. I assume this moves the heater door people mention. Check to see if the parts you can see are working and that might tell you a lot.
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Old 1st December 2006
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Quote:
Originally Posted by JMarkert
Hmm, that does sound odd - especially if there's no valve to control the fluid. I don't think that reversing the hoses would matter that much - maybe some theoretical loss in efficiency, but hot water is hot water, no matter which direction it is flowin in.

It also sounds like you don't have the problem that koniq did, mainly because they were able to make water go through yours.

I think it's worth investingating the hot air door theory more. I don't think I've ever seen a diagram, but if you can remove the passenger side kick panel you'll see a cable that moves with the heater control knob. I assume this moves the heater door people mention. Check to see if the parts you can see are working and that might tell you a lot.
I looked into this hot air door if that is truly the problem you are looking at a potentially expensive fix.... see the air door is operated by a cable and if that cable has snapped.... then you have to take half the dash apart and replace the component that is attached to the door.... the parts required for this can be found at www.eeuroparts.com
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Old 2nd December 2006
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Quote:
Originally Posted by Sha_kri
Called the dealer and talked to a technician. He said that the 1994 990s v6 does not have a fluid control unit (valve) inside the heater core area, but they started putting them in from 1995 onwards. He said it sounds like my mechanic put the hoses on the wrong way.

Anyone know if this is true? Are the heater hoses only designed to flow one way? Sounds kind of odd.
The heater hoses are clear, but the replacements come as a set..Why, I do not know ??
So, there could be a possibility that the heater hoses are mal-connected...

Sha-kri, I think you should do the same thing Konig did - I suspect that you are not recieving any proper coolant circulation at the heater..

It may be possible to mis-route the heater and coolant hoses..
I did this with the '79 Saab 900, the end result looks good, but the heat exchanger did not work well at all..
This depends a lot on the heater core design; I think with most cars this does make a difference......this is a very hard thing to find out- one way or the other...
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Old 9th December 2006
Sha_kri Sha_kri is offline
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I took my car to my mechanic this morning. He said he cannot look at it today (i was going to wait for it) because he needs to take the dash apart to look in the heater core area and check that alledged "heater coolant control valve." We agreed I would drop it off on a weekday.

I then drove to the dealer. Skipping to what matters, they looked at it and told me the heater coolant hoses were not connected up correctly. So....164USD to hook up the hoses correctly (probably a 10 minute task).
They did wash my car and I got 4-5 cups of free Starbucks coffee while they did the task though. Heater works great now.

Here's the thing though. He put in another engine last spring. coolant was flowing to the heater core before he did that. He told me after he put in the new engine that coolant was not flowing to the heater core. I told him it worked before he put in the engine. He said, "well I do not know that." And that there is probably a clog in the heater core.

This fall, while it was being inspected, he ran a water hose thru the core and that showed it was not clogged. He then put in a new thermostat ($40 bucks for the stat), 140USD labor, and then he charged me $57.07 for the manifold gaskets he ripped while he was getting to the thermostat. He said he does not feel he should pay for the gaskets even though he broke/ripped them.

Anyone have experience with sort of thing. Should I be responsible for all these charges. He did not cut me any kind of breaks money wise to put in the engine. I paid like up to $3000 for that in all.
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Old 9th December 2006
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Sha_kri, these very similar things occured to my '79 as well - BUT in this case I was the mechanic..

I misrouted the hose to the heater, the job end result looked good, but did not work well. I also discovered that the thermo-stat was missing - perhaps a PO was too foolish to repair the car correctly...
And this was the real Saab, the 900 - so easy to work on that a blind man could be successful..

One problem is communications; your 'mechanic" does not know the vehicle he is working on, any more that I did back in the middle 80s - I was too cheap to buy the correct manual...and this great site did not exist back then

Another is greed
$124 to correctly rout the heater hoses ?
Your "mechanic" should pay this !
This greed may be the undoing of our nation !

As much as the dealer overcharges, he is still less expensive and more effective that an incompetent mechanic...
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  #17  
Old 15th December 2006
Sha_kri Sha_kri is offline
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So apparently even though there is no control unit to control coolant to the heater core, the hoses some how matter how they are hooked up. I mean the "intake" hose apparently cannot be switched with the "outtake" hose.

Talked to the mechanic this morning and after some reluctance, he agreed to pay the 164USD this evening.
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  #18  
Old 15th December 2006
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Quote:
Originally Posted by Sha_kri
So apparently even though there is no control unit to control coolant to the heater core, the hoses some how matter how they are hooked up. I mean the "intake" hose apparently cannot be switched with the "outtake" hose.


Talked to the mechanic this morning and after some reluctance, he agreed to pay the 164USD this evening.
Nicely done! glad to hear you got your problem solved! financially and literally
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  #19  
Old 16th December 2006
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The heater hose hookup has to do with thermodynamics. Try messing around with the engine cooling hoses - connect them backwards as I did one day in the early 70s with the '60 Saab V4 - the result is near instant overheating..
The trouble with some cars is that one cannot tell which heater core nipple is which as they are on the same level, apparently..
So, I am very pleasantly surprised that the man admitted to his mistake and is willing to pay the $164.
It takes a real man to do this ....
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Old 16th December 2006
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Quote:
Originally Posted by Sha_kri
I
I then drove to the dealer. Skipping to what matters, they looked at it and told me the heater coolant hoses were not connected up correctly. So....164USD to hook up the hoses correctly (probably a 10 minute task).
They did wash my car and I got 4-5 cups of free Starbucks coffee while they did the task though. Heater works great now.
I'm glad you got the hoses fixed, although I'm surprised to learn the order makes a difference. I'll keep that in mind if/when I replace mine.

One thing though, you really are getting reamed by this meachanic. Switching the hoses around the right way IS a ten minute job on a lift.

And forty bucks for a thermostat is serious rippage. I'm pretty sure that even one right from the dealer comes to less than twenty. I guess maybe the V6 could be more expensive, but I doubt it.
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