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  1. #1
    Saab Enthusiast
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    19 Oct 2012
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    UK
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    Saab(s)
    9000CSE, 9-3 Aero Convertible, 9-5 HOT Aero
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    Coolant tank bubble fiasco....!!!

    Recently replaced the radiator (new) on my 9-5 Aero and noticed that the temp would go up without the cooling fans kicking in....and coolant expansion tank starts bubbling and keeps bubbling after switch off as well ........settles after a while. Haven't driven it for a few weeks so just wondering if there is an air-lock somewhere in the system and whether I carried out the coolant bleeding correctly....should I have also changed the thermostat and the temp sensor at the same time?

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  2. #2
    Dave
    Saab Enthusiast
    Join Date
    25 Oct 2014
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    Nottinghamshire, England
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    Saab(s)
    2001 93 2.0Ltr HOT Aero coupe & 2011 1.9TTiD Aero saloon
    Thumbs Up:   3
    Hi
    Although my knowledge is mainly based around a 2001 93 Hot Aero with the B205R engine.
    What year 95 is it and do you know the engine model.
    Did you replace the radiator due to the overheating problem, or due to it leaking?
    Did the new radiator have bungs in the end of the inlet and outlet ports?
    Are the fan blades moving freely by hand?
    Have you checked the fan motor connecter plug is on correctly?

    Dave 2 93s

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  3. #3
    Saab Enthusiast
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    19 Oct 2012
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    UK
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    Saab(s)
    9000CSE, 9-3 Aero Convertible, 9-5 HOT Aero
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    It is a 2.3 Hot Aero Auto, 2003 model.....rad was replaced because original had rusty core and was leaking, it had plastic caps at the oil cooler pipe connection holes.....as for inlet/outlet hose connections, don't remember any bungs as such(?)........please clarify.
    Fan blades are moving fine by hand and fan motor connector is in place.

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  4. #4
    Dave
    Saab Enthusiast
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    25 Oct 2014
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    Nottinghamshire, England
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    Saab(s)
    2001 93 2.0Ltr HOT Aero coupe & 2011 1.9TTiD Aero saloon
    Thumbs Up:   3
    Hi
    Just done some googling, 2003 Saab 95 2.3 engine. It appears your engine is a B235R , which looks very much like your 93 engine with the exception of the engine mount on the left hand side. If that's correct then any links or info I try to post you wont be a million miles away and it wont make me look too much like a noodle. I only mentioned caps or bungs because over looking something like that would be the sort of thing I would do, then find out later after some sort of major strip down.
    Anyway
    Found this that might be of some help. Will post more shortly, but need to attend to a crossed legged dog.


    http://saabworld.net/showthread.php?...cooling+system

    Dave 2 93s

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  5. #5
    Dave
    Saab Enthusiast
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    25 Oct 2014
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    Nottinghamshire, England
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    Saab(s)
    2001 93 2.0Ltr HOT Aero coupe & 2011 1.9TTiD Aero saloon
    Thumbs Up:   3
    Hi

    After quite a while of over thinking things, such as temp sensor resistances, checking the water pump, thermostat and re-reading the link I left in my previous post, and also reading the link here.
    http://saabworld.net/showthread.php?t=2691
    I decided to tell you what I would do, and I'll try not to waffle on..
    On average the amount of coolant in the system is between 7 and 8 litres. When you drain the system about 2 litres remain in the system, usually in the heater matrix and pipework. So assuming you used roughly 5 or 6 litres to refill the system, we are heading in the right direction.
    To check for trapped air.
    With the engine off, cold and the expansion tank cap off , I would first squeeze the top radiator pipe. you should be able to feel some resistance of water inside.

    But to double check this I would.
    Slacken off the top hose on the radiator just enough for it to start weeping.
    Then a quick squeeze of the bottom radiator hose, should force the water through the radiator enough to make the top hose weep more. Confirming you have the radiator full of water.

    Then squeeze the top hose till it weeps more. Keeping pressure on the top hose at that point, tighten up the top hose connection. If you don't maintain the pressure on the top hose, air could be drawn back in as the hose reforms its shape.

    Next start the engine and turn the cabin heater to max heat. And let the engine warm up.
    Initially all the coolant is just circulated around the engine and not the radiator. So the top radiator hose may feel cold or cooler until the thermostat heats up and opens.

    Once the temp gauge on the dash is around the half way mark the thermostat should begin to open, diverting the hot water through the radiator and the top hose will begin to get increasingly hotter.

    After this point all should be fine, you may need to top up the expansion tank a little . Replace the expansion cap and check the cabin heater is blowing hot.

    Hope this helps

    Dave 2 93s

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  6. #6
    Saab Enthusiast
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    19 Oct 2012
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    Saab(s)
    9000CSE, 9-3 Aero Convertible, 9-5 HOT Aero
    Thumbs Up:   1
    Thanks for the very informative comments, Dave, will give it a go to see if it sorts the bubbling coolant.....

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  7. #7
    Derek

    Join Date
    04 Dec 2019
    Location
    Nanaimo, BC, Canada
    Posts
    4
    Saab(s)
    '97 900S; 2004 9-3 Vector; 2001 Viggen
    Thumbs Up:   0
    Quote Originally Posted by T4hir View Post
    Recently replaced the radiator (new) on my 9-5 Aero and noticed that the temp would go up without the cooling fans kicking in....and coolant expansion tank starts bubbling and keeps bubbling after switch off as well ........settles after a while. Haven't driven it for a few weeks so just wondering if there is an air-lock somewhere in the system
    It's fairly easy to check the temperature sensor's resistance. If it was working prior, may not be an issue but I'd replace it if taking too long for the fan to run. (after checking that the fan actually works.)

    I agree that you should first ensure all air is expelled as outlined in another post by Dave 2 93S. I'd replace the thermostat if the motor has been running too cool. (Never saw one that stuck closed.) I check my thermostats in boiling hot water and use a thermometer to verify correct opening temperature so I'm not having to go back again.

    To ensure the cooling fan is working, try pulling the relays and use a jumper to check that the fan works on both LS and HS. If not, then remove the complete fan assembly and check the LS ballast resistor an wiring.

    Note - If the resistor is shot (as may be expected if the LS doesn't work), you can try locating a replacement resistor. I managed to reuse the ceramic core and wrapped a short length of 0.024" SS lock wire around it to make a replacement for the Viggen. This is the same setup as the 9-5. You can test this out on a battery prior to installing. This was sealed up in epoxy steel and reinstalled in its original position. This is also a good time to repair any wiring insulation to the fan as it's located precariously close to the exhaust manifold and turbo. (Thankfully, my 9-3 doesn't have these issues as the exhaust manifold is on the opposite side from the rad and cooling fan.)

    Hope this helps or anybody else having similar issues.
    Derek

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  8. #8
    Saab Enthusiast
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    9000CSE, 9-3 Aero Convertible, 9-5 HOT Aero
    Thumbs Up:   1
    ..... Thanks for the informative tips......replaced with new thermostat and temp sensor.......carried out coolant refill/bleed process......both fans kicking in fine, temp gauge climbs as normal and remains dead steady at halfway on gauge.....heating works fine.......after drive turn off engine and bubbling still occurs in expansion tank and coolant still seeps out.

    Plan B ....... what's the view here on adding a good quality Head Gasket Sealer to the coolant? Would it work as symptoms point to a possible HG failure?
    And......is the cylinder head bolt re-torque procedure applicable to this model....would that be worth a check if they are loose?

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  9. #9
    Derek

    Join Date
    04 Dec 2019
    Location
    Nanaimo, BC, Canada
    Posts
    4
    Saab(s)
    '97 900S; 2004 9-3 Vector; 2001 Viggen
    Thumbs Up:   0
    Quote Originally Posted by T4hir View Post
    ..... Thanks for the informative tips......replaced with new thermostat and temp sensor.......carried out coolant refill/bleed process......both fans kicking in fine, temp gauge climbs as normal and remains dead steady at halfway on gauge.....heating works fine.......after drive turn off engine and bubbling still occurs in expansion tank and coolant still seeps out.

    Plan B ....... what's the view here on adding a good quality Head Gasket Sealer to the coolant? Would it work as symptoms point to a possible HG failure?
    And......is the cylinder head bolt re-torque procedure applicable to this model....would that be worth a check if they are loose?
    that
    Rislone Head Gasket Repair may work or at least buy some time. If you are lucky, may get several years. (Had a cooling system that kept building up pressure and this has solved it, at least temporarily.) It allows one to plan for the repair if wants to plan other mtc at the same time.

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  10. #10
    Saab Nut
    Join Date
    10 Apr 2017
    Location
    Denham, England
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    362
    Saab(s)
    2011 2.0 9-5 Aero
    Thumbs Up:   55
    Before you even consider the cylinder head, replace the pressure cap on the coolant expansion bottle. If the coolant isn't under pressure it will boil.

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