[prm]

I noticed when I got home from work last night that the oil cooler was stone cold, and I mean as cold as it was when I set off. I know there will be a thermostat but, from memory on other vehicles, they usually open at about 80 deg C. I’m certain the oil would have reached this temp after a 90mph run up the A3 and 30 mins driving around town. Anyone any experience of this?

Thanks, Paul

 

[adrian]

Yeah 80degC thermostats for oil coolers is pretty standard. Never checked the cooler on my old Carly or latest 2.3T. However, my 900T8v + T16S have the aux gauges fitted - the gearbox sump oil very rarely gets above 55degC, only in the summer caining it up the M62 do things start to move.
Now imagine fully loaded car, full throttle for an hour or so on the autobahn in high summer - thats what the cooler and gearbox oil system will be designed for so maybe not so surprising that in 'normal' 90mph use the cooler isnt needed

 

[prm]

Originally posted by Adrian:
[qb]....thats what the cooler and gearbox oil system will be designed for so maybe not so surprising that in 'normal' 90mph use the cooler isnt needed [/qb][/b]

but it's an engine oil cooler???

 

[mark e]

Originally posted by Paul M:
[qb]   QUOTE

Originally posted by Adrian:
[qb] ....thats what the cooler and gearbox oil system will be designed for so maybe not so surprising that in 'normal' 90mph use the cooler isnt needed [/qb][/b]

but it's an engine oil cooler??? [/qb][/b][/quote]... and equally there's no flow through the regular coolant radiator until required... don't forget that the sump provides quite an effective heatsink/cooler with all that air flowing over it at high speed. At a steady 90mph the load imposed on the engine is quite low.

 

[prm]

Originally posted by Mark E:
[qb]and equally there's no flow through the regular coolant radiator until required... don't forget that the sump provides quite an effective heatsink/cooler with all that air flowing over it at high speed. At a steady 90mph the load imposed on the engine is quite low. [/qb][/b]

Agreed, and I can believe it at 90 mph but my 30 mins around town is about 5 miles and coolant fan cuts in several times. Would have thought there can be relatively little oil cooling at near zero speeds and oil temp would be fairly close to water temp. Suppose I could stick a thermocouple into the sump and check.

I'm NOT saying I don't believe you, just surprised, and if stone cold coolers is the experience of others then I'll forget about it.

 

[Mark B]

From my experience, the oil on turbo Saabs seems to get warm pretty quickly compared to other cars that I know, which I always assumed to be because of the oil flow through the turbo.

However, engine oil only gets really hot when it has some serious cooling to do. The main item cooled by the oil is the underside of the piston crowns, the turbo being mainly water cooled. The pistons only get seriously hot when you are burning loads of fuel. As Mark E said, a constant 90 mph does not really put that high a load on the engine (i.e. require that much power), and toodling around town certainly does not.

I would expect the oil cooler to be hot immediately after a hard run, but in our climate the oil will cool quickly and the thermostat will soon close.

From memory, I've only noticed my oil cooler being hot a few times. The thermostat temperature may be hotter than you think (I can't remember what it is, but a Mark 1 Golf GTi had a 110C stat).

The important thing, of course, is that it does open when you work it hard, but this may have to be harder than you imagine, and in warmer weather.

 

[adrian]

Opps, I'll read the question next time!

 

[adrian]

Not even sure if there is a thermostat that controls oil flow to the cooler - would have expected one but never come across it

 

[glib]

You can remove the trans cooler t-stat and replace it with a hose kit from Saab. A good alt. for someone with leaks. This will not effect the function or reliability of your trans.

 

[billj]

The thermostat opens at 80°C (176°F).

 

[Mark B]

The Haynes book of disinformation gives the following oil thermostat opening temperatures:

B202 90C
B234 upto 1993 75C
B204 & B234 from 1994 107C

So if the latter is correct, you'll have to give it some to get it that hot. But you'll enjoy trying.

 

[sgould]

I wonder if it's ever opened in its life? Could be stuck shut after nine years just sitting there

 

[wrighar]

Could be stuck shut after nine years just sitting there[/b]

Should be well lubricated so shouldn't be

 

[adrian]

Must be getting dumb (er) in my old age. The aux gauges measure oil sump temp - and it rarely gets above 60degC.

Went to the Steam an Spares over the weekend. Stopping in Nottingham on the Friday night, as soon as I got there I checked the oil cooler - cold.