Engine running hot- thermostat?

[sbn]

My engine is running a little hot during stop and go traffic, but just fine on the highway. My best guess is I need a new thermostat. Anything else I should look at instead?

[soneway]

Hi,

I thought the same a couple of times too. Unfortunately it's almost always the radiator. How many miles on your car?

You can do a thermostat change since it's easier but be prepared for doing a radiator.

[sbn]

I have 133,000 now. I sure hope it is not the radiator, that knocks a good weekend down for me.

[soneway]

been thinking on this some more. the only other thing I can think of is if the fans aren't coming on. You should be able to hear them before you get into the hot zone. If they aren't working you have a variety of things to check.

[StephenA]

It depends on the age of the 9000. The older models had a "real" temp gauge that moved up and down a lot. My MY92 sits at 9 oclock during normal running but gets up past 10 in start/stop.

Do the fans run after you switch off if the engine is still showing hot?

Steve

[sbn]

Yes, the fans turn on when I shut the engine off, but they do not seem to turn on while I am driving.

I guess I should add that the auto is a 94 9000 CDE

[soneway]

Hi again. I have three 1992 9000CDT's all auto! Ok, only two really run, the third is a parts car.

Anywho, the fans running after you shut off is a good sign. It means the circuit recognized it's still hot and needs cooling. Try this to further test. When you get home, don't turn the car off, instead cover the intake area between the headlights with a blanket or large towel. Basically we are trying to get the car to heat up and force the fans to come on. If they don't that circuit has a problem, If they do then we are back to what is the condition of the radiator?

You guys have had some funny weather lately, lots of snow, then warming up and melting it all! My wife's family lives all over the Minneapolis area, she was there last week.

let us know how this turns out.

http://www.saabphotos.com/gallery/Everyday-Saabs

[mark e]

Whereabouts does the needle sit in each case Sean?

[sbn]

When driving in the country the needle sits half way between bottom and the end of the white/ start of red line. When I hit stop and go traffic it will creep up to 3/4th to the red line at a stop. But once I start moving it goes back down to half way.

As for the weather, my first thought was maybe I had a winter thermostat in. Some cars here use winter/summer thermostats because of the extreme temps. Often the thermostat will not heat a car efficiantly in the winter, which is not fun in below freezing temps because that also means no heat for the car.

[mark e]

That doesn't sound anything to be too worried about. Your year of car has the "real" temp gauge, and so wide variations are quite normal.

If anything I would try changing the block temp sensor first- it's cheap and easier than the stat.

There are two temp stats available- 89 deg C is the nonormal fit, and 82 for very hot climates (or those running loadsa mods).

[deebel]

Make sure that it is a Saab thermostat as I believe it reacts slightly differently to a normal third party thermo.

[StephenA]

Originally posted by deebel:
[qb]Make sure that it is a Saab thermostat as I believe it reacts slightly differently to a normal third party thermo. [/qb][/b]

I had been told that the Saab thermostat was a 2 stage which partially opens at a slightly lower temp.

Steve

[soneway]

The saab thermostat has a small "bypass" which I believe keeps you from frying in the event of a total thermostat failure. I had one stick and almost fried the engine, but didn't... The waxstat doesn't have the feature. A local (in the US) shop put a Waxstat in one of my 900's before I started doing them myself. It's on the shelf now...

[mark e]

It's the implementation of the stat in the block that special to Saab as well as the little hole in it (which should always be mounted uppermost BTW). Under extreme coolant temps, with the stat open fully, it tends to close off the flow to the heater matrix, meaning that more goes to the the raditor, the reason being that the radiator is a much more efficient heater exchanger than the matrix.