Can we discuss oil Temps; cause and effect...

[kruat]

So lately I've noticed my RS oil temps barely hover over 160-170. Now, it has been on the cold side here, but what struck me as odd is today the wife and I went for a cruise out in the Colombia Gorge, (hwy 14) and a couple times my coolant needle dropped back off the halfway tick. It was around 30 degrees out, but I wasn't really taking it easy on the beast. Several bursts up too 100mph. My oil temp stayed about 160-170. And, of course this is all based on the guage in the cluster. I should of brought my VAGCOM and logged actually temps.

I almost suspecting I'm having a thermostat issue. But isn't there a couple thermostats on these 4.2s? My car doesn't even have the bellypan mod, and at this point, I don't see the need. So should I be alarmed? I bought my RS in Aug, so don't have enough experience with it in the summer.

What are everyone's thoughts?

[hahnmgh63]

I think your right about Vagcom. You really need to see the data right from the ECU.

[4everRS]

I think the t stat is going. There's only 1. It's behind you're t belt covers. A real pain to change. You'll likely want to do the t belt service if it's anywhere close.

There is a coolant sensor behind the drivers cylinder head. Maybe that's what you're thinking in regard to multiple t stats?

[RS8]

If this oil sensor in the oil pan is broken or disconnected, will it then affect how the engine is running?
or is the only thing that happens is that you get warnings on the dashboard?

[kruat]

I think the t stat is going. There's only 1. It's behind you're t belt covers. A real pain to change. You'll likely want to do the t belt service if it's anywhere close.

There is a coolant sensor behind the drivers cylinder head. Maybe that's what you're thinking in regard to multiple t stats?

Ya, I don't know what I was thinking. I know on the chain driven 4.2s, there's a small check valve that if it goes bad it'll start causing a code of, system cooling performance, (or something along those lines) and your first guess is thermostat. I help a buddy change his on his S4, only to have the code come back because we didn't know about this check valve off one of the aux radiators.

Well I picked up a slight idler pulley noise as well, so doing a timing belt service is in my near future. Although, it was done less then 10k ago, but about 3 years ago also. So I might as well do thermostat as well.

Does it hurt to drive with it stuck open? My wife drives it, and she rarely puts the hammer down, and she's real good about letting it warm up.

[RSoverAll]

If this oil sensor in the oil pan is broken or disconnected, will it then affect how the engine is running?
or is the only thing that happens is that you get warnings on the dashboard?

No the engine will run fine without it. Light on instrument panel should remain illuminated.

[4everRS]

It could run a bit rich if anything. When the engine is cold, the ecu tells the fuel system to inject more. Eventually, you'll need to get it fixed, but I wouldn't call it critical.