Erratic Oil Temp gauge (continued)
10-18-2005, 03:23 PM
#1
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Erratic Oil Temp gauge (continued)
I logged the oil temp (yellow), coolant temp (white), and engine RPMs (green) for about 5 minutes after warm-up, at idle in my driveway.
Check out the oil temp graph (yellow)...
<img src="http://pictureposter.audiworld.com/13357/oil-coolant-revs.jpg">
Now, the first half of that graph, the gauge needle was pretty steady and never strayed from 250 by +/- 25. At the halfway point, the gauge went up to 300 and never strayed by more than about +/- 10 for the remainder of the log.
At first I thought that the gauge may not have that great a refresh rate...so the brief blimps on the graph wouldn't be portrayed in the gauge. But then, I turned off the ignition and the needle dropped; turn the ignition back on an it shoots right up to where it was pre ignition cutout.
I ordered a new sender for $20, and found out where the lil bugger hides...
<img src="http://pictureposter.audiworld.com/13357/oil_temp_sender.jpg">
...but if it has no effect, I think it's safe to say something else is awry. But, I'm not gonna jump the gun; one step at a time.
Check out the oil temp graph (yellow)...
<img src="http://pictureposter.audiworld.com/13357/oil-coolant-revs.jpg">
Now, the first half of that graph, the gauge needle was pretty steady and never strayed from 250 by +/- 25. At the halfway point, the gauge went up to 300 and never strayed by more than about +/- 10 for the remainder of the log.
At first I thought that the gauge may not have that great a refresh rate...so the brief blimps on the graph wouldn't be portrayed in the gauge. But then, I turned off the ignition and the needle dropped; turn the ignition back on an it shoots right up to where it was pre ignition cutout.
I ordered a new sender for $20, and found out where the lil bugger hides...
<img src="http://pictureposter.audiworld.com/13357/oil_temp_sender.jpg">
...but if it has no effect, I think it's safe to say something else is awry. But, I'm not gonna jump the gun; one step at a time.
10-18-2005, 04:23 PM
#2
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by the graph, it looks like the oil temperatures are normal.
the oil warms up, thermostat opens (graph goes flat, then down) then the thermostat closes and the oil warms back up (the graph goes up). I'd estimate that the sensor for the gauge is bad.
10-18-2005, 04:54 PM
#3
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Err, are thier multiple oil temp sensors?..are you thinking the coolant temp?...
...because the coolant is the white flatline, no fluctuations at all. I'd imagine the fluctuation of the t-stat would affect the coolant moreso than the oil(??).
10-18-2005, 06:33 PM
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there should also be a thermostat for the oil cooler
once warmed up, the thermostat for the coolant should pretty much stay open, especially while idling. The viscous fan keeps coolant temps pretty steady.
10-19-2005, 01:26 AM
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Re: Erratic Oil Temp gauge (continued)
That seems high though, even if the gauge is working fine. My 2.7T has never gone past 240 or so, even if it's 100+ degrees out and running fast and hard.
10-19-2005, 06:42 AM
#7
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That's something I forgot to mention; it seems to be running hot.
Average temps I saw in the hot hot summer while driving around town were 275-300, now it's more like 250-275...or course, that's when it isn't darting all over the place. :P
Welp, hopefully the sender will cure the problem...otherwise searching the harness for knicks might be the next course of action. Lastly would be a dash, which wouldn't be too bad since the center display is toast. Ha, it never ends. :P
Welp, hopefully the sender will cure the problem...otherwise searching the harness for knicks might be the next course of action. Lastly would be a dash, which wouldn't be too bad since the center display is toast. Ha, it never ends. :P
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