Saab: minor coolant leak?

John B wrote: 

You don't need to drain down completely, but you do need to
drain at least 3-4 litres if you don't want any spillage.

Personally I wouldn't bother - I'd just put a tray under the
front and undo the hose.

If the coolant is more than a year old drain it down and replace
while you're doing this - it makes sense.

--
Grunff

On Sun, 14 Dec 2003 00:31:24 +0000, Grunff <com> wrote: 

I think the coolant is more than a year old, so I guess I should just drain it.
Is it necessary to flush the system also, or is simply draining it usually ok?

Also, what else should I do while I have it drained? Should I replace rusted
clamps or old hoses, even if they're not leaking? I was also considering
putting in a cooler thermostat as suggested on the townsendimports site, since
my c900 displays the symptoms of getting very hot after highway driving.

Speaking of that- is the replacement thermostat really necessary, or would it
be sufficient to replace the fan temp sensor and/or rewire to make both fans
come on when the AC is off? I've been thinking of doing something like this for
awhile, because it really does get quite hot when sitting in traffic (esp.
after highway driving) when the AC is off.

Also, since this is an epic post anyway: My heater works very well when I'm
driving around, but when the car isn't moving only cold air comes out. What
gives?

Thanks,

John

John B wrote:
 

Well, it all depends on how much you like doing routine
maintenance! I would flush both the radiator and block with a
hose whenevr I drain down. Is it necessary? Depends on the
condition of your cooling system.

 

I don't normally replace hoses unless they need it. Check the
hose for any signs of cracking. The radiator top and bottom
hoses are the most likely failures. If there are any signs of
surface cracks, then replace.

 

Good idea - but how hot is very hot? You may have another fault
causing the overheating.

 

The thermostat and the fan stat do totally different things. The
thermostat controls the engine's temperature by controlling
coolant flow through the radiator.

The fan helps the radiator lose heat when there is insufficient
air flow through it.

At speeds greater than say 40mph, you already have all the
airflow you'll ever need. If your car never travelled slower
than 40mph, you wouldn't need a fan at all. Doing anything to
the fan stat, or wiring in a second fan won't help you if you're
overheating at speed.

 

Sitting in traffic is different. Get a lower temp fan stat.

 

Does this coincide with the engine temperature being really
high? It's supposed to work this way. When the engine is really
hot, all coolant is pushed through the radiator, to achieve the
greatest temperature drop.

--
Grunff

On Sun, 14 Dec 2003 19:20:00 +0000, Grunff <com> wrote: 

Ok. Having never done this before, I must ask: how do I dispose of all that
used coolant? Dumping it in the street doesn't seem like a good idea.
 

It get just short of the red, but it has never actually overheated. The fan
kicks in at that point, and it gradually cools down to normal. Then the fan
goes off, the temperature slowly creeps back up, and the cycle repeats. Turning
on the AC (and thus the other fan) keeps it at normal temperature consistently.
 

Ok, sounds like that would indeed fix things. Do I need to drain the coolant
for that, or can I do it seperately?
 

Ah, good point. That might explain it. I'll see if there's a correlation.


John

John B wrote:
 


Some enviro types won't agree with the following - As an
ex-chemist, I have a realistic understanding of the dangers of
ethylene glycol. Discharging a small amount to your sewer won't
do any harm. If you're worried about it contact your local
authority and check with them.

 

Is this while travelling at speed? Either way, your fan is
kicking in too late. New fan stat.

 

You'll need to drain about 2-3 litres to do the thermostat. Do
it at the same time, it makes sense.

--
Grunff

Of course, maybe I should be less concerned with my cooling system and more
concerned with my exhaust, seeing as my muffler just rusted off tonight...

Although honstly I think the car sounds much better without it

John

On Sun, 14 Dec 2003 20:35:08 +0000, Grunff <com> wrote: 

Nope, only when sitting in traffic.
 

I was really asking about the fan stat, not the thermostat...


John

John B wrote:
 

Ok, definitely fan stat.

 

A bit more than the thermostat, because it's slightly lower down.

--
Grunff