Saab 9-5 issues x 2 coolant overheating ~ gear change issue

[thelicencee]

Hi,
Can anyone help?

My wife's 2004, 54 plate, 9-5L 2.0lt auto has a couple of issues,

1) it keeps 'boiling' the water, so the level drops, when i top it up it starts to purge the air but then just bubbles up.
The 'top hose' does not seem to have any water in it as when you squeeze it nothing happens.
I think this hose goes to the thermostat housing.
This makes me think that the thermostat is not opening so stopping the water getting around the engine which means that the water that is in the engine block just gets very hot and the 'bubbles' out of the header tank when the cap is left off.

can anyone advise if this is correct and would be cured by changing the thermostat or does anyone have any other information that would help.

2) the car runs fine while driving it normally and the gear changes are smooth, it also drives well when using the 'flappy paddles' on the steering wheel, however if you are driving 'normally' and then you come up behind, lets say a tractor, and you put your foot down , the 'kick down' activates but then the car struggles to 'change up and accelerate' and you have to come off the accelerator to let the car change up gear. This has only started recently, i have checked the auto box fluid, engine running - go through the gears - drive, neutral and reverse - then hand brake on, car in drive and then check the gearbox fluid level. It was a little low so I topped it up but has not made a difference.
Obviously this is not really acceptable, I don't think it will cause any serious issues or problems, but really needs to be sorted so we can enjoy the full benefits of our Saab.

I look forward to receiving any information, please keep any details as simple to understand as I am not a mechanic, also if I need to check any parts etc please try and give me as much simple instructions to locate where the part is and how to access it and what to look for and how to repair/rectify any issues.

Many thanks in advance

Paul

[Digger]

A new thermostat could resolve both of your issues as the gear box, I assume automatic as you mentioned flappy paddles and drive, cools its fluid through the radiator and it has an expected operating temp range.

Am a bit curious about the bubble up on top off. It could be my American understanding of English English, or you could be describing a head gasket symptom. So check your water pump by turning the heat and fan to high, check that both heater hoses get hot. If you have hot water moving through the heater, changing the thermostat should get the job done and what has me curious is nothing more than our English language barrier.

[nordwulf]

Definitely start with replacing the thermostat as Digger mentioned. It is not very difficult to replace but it sounds like you're not into car repair and a car repair place may only need an hour to replace. More details here: http://saabworld.net/showthread.php?t=1019

Here is a Saab TSB with fault diagnosis information for the automatic transmission for MY02-04:
http://saabworld.net/showthread.php?t=33163

Not sure if any of those solutions apply to your situations. Your best bet is to take it to a Saab specialist and have it checked out. Another thing that comes to mind is the solenoid valves in the automatic as they are common to stick or fail when they are getting older. But I don't know if this is causing the problem as I am not very familiar with it. But maybe something you want to research more.

[GeoffR]

If the coolant is boiling the only realistic cause is that it isn't getting to the radiator, either because the thermostat isn't opening or because the pump isn't circulating. The thermostat isn't difficult to change, though why Saab decided to bolt a bracket on the top of the housing is another matter. You will need a good ratchet spanner (wrench, but being from Nuneaton you don't need that). Halfords do very good ones at a reasonable price.

The water pump is less accessible but you would normally have other indications if that had failed.

[DanielZ]

also, doesn't the thermostat go to full open when it fails as not to risk overheating and instead run cooler than optimal?

[GeoffR]

also, doesn't the thermostat go to full open when it fails as not to risk overheating and instead run cooler than optimal?

A thermostat isn't that clever. Essentially it is a wax filled capsule, when the wax gets hot it expands and in doing so moves a disc to open the valve. Unfortunately they can fail closed open or anywhere in between.