A couple of tips about thermostats and hot running engine

[fura]

Hope somebody will find these tips usefull 8)

1. OEM Saab thermostats are manufactured by Motorad. So if Motorad thermostats are available at your local autoparts shop, it's should be possible to get OEM quality thermostat at lower price (of course thermostats from Saab are not very expensive too :wink: ).

2. If engine temperature gauge starts behaving strangely and indicates hot running engine it doesn't necesserily mean that you've got cooling problem (like thermostat failure).
Check how the temperature gauge reacts to electric load - if it jumps when turning on/off the lights, ventilation fan or rear window defroster, then you've got electric gremlin
Check temperature sensor connectors at thermostat housing for corosion and clean them by pluging/unpluging a few times. Also check ground points in engine bay for corosion and lose ends. This should fix your "hot" engine :wink:

[DrSquirley]

are they the same same 3 way style thermostats? i replaced my thermostat two weeks ago but only with a 2 way is this accepetable or should i go right to a 3 way saab one? :-??

[900 spg]

I remember reading that one should ONLY use the 3 way kind. I think it was on townsends site or somewhere else. by the way, thermostats are not that expensive even when you get them from an official saab parts supplier. besides the small hole on the body, which should be aligned to be on the highest point was put there on saab thermostats to enable to let air out of the system. very important. you do not want hot spots of air in the head, do you?
best regards
dusan

[fura]

Well, I don't think that making two lines of thermostats for the same car (one as OEM and another for aftermarket) makes any sense.

BTW I don't understand how can the hole on the thermostat body be aligned to be on the highest point, as thermostat housing and it's body are horisontal and have no highest points I simply installed new thermostat in the same position as the old one and let the engine run for a few minutes with coolant tank cap off. I saw lots of air bubbles escaping through thin hose connecting radiator to coolant tank.

[DrSquirley]

Originally Posted by 900 spg

I remember reading that one should ONLY use the 3 way kind. I think it was on townsends site or somewhere else. by the way, thermostats are not that expensive even when you get them from an official saab parts supplier. besides the small hole on the body, which should be aligned to be on the highest point was put there on saab thermostats to enable to let air out of the system. very important. you do not want hot spots of air in the head, do you?
best regards
dusan

i just talked to my "mechanic", good friend of mine that works at saab garage and he says as long as its funtioning, that the 2/3 way doesnt matter.

[MSOEMiller]

Originally Posted by fura

BTW I don't understand how can the hole on the thermostat body be aligned to be on the highest point, as thermostat housing and it's body are horisontal and have no highest points

Align the thermostat's air-hole with the bleeder valve.

[fura]

Originally Posted by MSOEMiller

Align the thermostat's air-hole with the bleeder valve.

I did that unintentionaly, as the old thermostat was aligned and I put the new thermostat in the same position

[Matthew]

Originally Posted by fura

BTW I don't understand how can the hole on the thermostat body be aligned to be on the highest point, as thermostat housing and it's body are horisontal and have no highest points

This is the case for 8v engines. However, the thermostat on a 16v engine is vertical.

Originally Posted by DrSquirley

i just talked to my "mechanic", good friend of mine that works at saab garage and he says as long as its funtioning, that the 2/3 way doesnt matter.

I just cannot agree with that. If your temperature gauge shows 2/3rds when cruising at average speeds in moderate ambient temperature, then IMO that is around 1/3rd too high and further investigation is required (blocked radiator or sticking thermostat would be the first places to start).

Be aware that many 900s are still fitted with their original radiators, and many will have had their cooling systems refilled with tap water. This causes a lot of scale build up inside the engine's waterways (same as you'll find inside your kettle) (this is one of the causes of headgasket failure). Much of this junk ends up in the radiator (better there then in the engine) but over time it'll cause a loss in cooling efficiency.

[Jezzadee]

Originally Posted by Matthew

I just cannot agree with that. If your temperature gauge shows 2/3rds when cruising at average speeds in moderate ambient temperature, then IMO that is around 1/3rd too high and further investigation is required (blocked radiator or sticking thermostat would be the first places to start)."

I think by 2/3 way he means 2 or 3 way thermostat, not two thirds of the way on the gauge. I think.

You're absolutely right about limescale.The water here is foul - we get rocks growing out of the tap - so I use Brita filtered water. Seems to keep the kettle clean, so I hope my radiator is gleaming inside.

[DrSquirley]

Originally Posted by Jezzadee

I think by 2/3 way he means 2 or 3 way thermostat, not two thirds of the way on the gauge. I think.

yeah, 2 or 3 way thermostat

[Jezzadee]

While I doubt the 2 way one would do much harm, the heater never seems to get hot with them, only warm. Also they seem to have more of a reputation for sticking, for some reason.

[gorper]

I have read -- on internet, so maybe it's complete BS -- that the three-way stat does, in fact, have a real purpose: it shuts off coolant to the heater when the car gets hot, apparently because sending it through the radiator is the better way to remove heat.

[900 spg]

talking about "stones in the water". has anyone done any descaling of the cooling system and with what? I am afraid that my car has in the past been run with regular tap water for quite a while as the liquid looks pretty muddy.

any suggestions?

thanks.
dusan
p.s. I have had to get a new radiator recently as the old one was pretty much clogged up.

[uberfast]

As for the heater... if you turn your heater on the core will help cool down the engine. Muddy water is rusty water that just needs to be flushed out. Good old fashined cooling system maintenance is the cure. Since I live in the middle of a desert I just use water in the radiator. Antifreeze isn't as good of a heat conductor. I heard something about a product called water wetter. Supposed to make water even more heat conductive. I don't really know.

[Matthew]

Originally Posted by gorper

I have read -- on internet, so maybe it's complete BS -- that the three-way stat does, in fact, have a real purpose: it shuts off coolant to the heater when the car gets hot, apparently because sending it through the radiator is the better way to remove heat.

More information here:
http://www.saabcentral.com/forums/vi...=150048#150048

Originally Posted by uberfast

I just use water in the radiator. Antifreeze isn't as good of a heat conductor.

You're right - antifreeze isn't a very good thermal conductor. However, you need to run antifreeze in your car otherwise the engine will rot from the inside out. The antifreeze is required for the corrosion inhibiters. Alternatively, find the raw inhibiting additive and add that to the water you put into the cooling system.

[gorper]

Originally Posted by Matthew

More information here:
http://www.saabcentral.com/forums/vi...=150048#150048

Thanks for the link...

[Matthew]

Originally Posted by uberfast

I heard something about a product called water wetter. Supposed to make water even more heat conductive. I don't really know.

Came across a post about Water Wetter this afternoon which might be of interest to you:
http://www.saabcentral.com/forums/vi...?p=18832#18832