# Why is oil temp suddenly sky rocketing? (87' Golf Mk2 GTI 16v)



## Golfbear (Aug 2, 2009)

Guys, 

Need some help with this. Since a few days ago (car is not daily driven, but at least weekly) I've discovered the oil temp on my digital gauge (the one between the clocks on the panel) has kept unusual high figures. 

Today I drove my wife to the airport in it, tackling morning traffic and quite a few traffic lights etc. Pace was rather slow. The gauge showed 127 degrees Celsius (!!).

I have an external meter as well, picking the temp from inside the oil pan - it showed roughly 100 degrees.

When traffic eased and I got on to the freeway, running about 70-80 km/h with almost zero load on the engine, I noticed the digital gauge still showed about 116 degrees, not really decreasing. Reaching the suburban area and close to my work, level dropped to 110-111 degrees and seemingly stuck there till I stopped. Analogue meter (oil pan) showed about 95 degrees, cooling the oil from wind under the car while driving.

At the time I noticed 127 degrees on the oil, water temp gauge was slightly leaning to the right, indicating slightly more than 90 degrees. My analogue gauge for water showed approx 95 degrees.

On my way home today I was never in heavy traffic, but digital gauge showed 110-115 degrees in the oil regardless of speed/load. These figures are higher than I am used to.

The engine is tuned and producing around 180-190 bhp and runs like a dream. I've owned it for over 5 years and it has run, and still does, very well. When I run it on a track, or just fooling around the streets, I'm used to oil temps around 100-110 degrees. Todays figures were abnormal. Strange thing is, the oil temp sensor looks new. I've checked it visually.

I performed an oil (and filter) change in May/June. I use Mahle filters, but this season I wasn't able to get one by the time of change, so it runs a Champion filter now - if that has any importance. I've used the same brand 5W40 oil every year, and change springtime. During winter the car is garaged. 

Can you help and advise me please, what would cause this sudden temp problem?

Sorry for long post. Any help appreciated.

/Gb


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## afawal2012 (Jan 9, 2013)

Do you have a separate engine oil cooler?

Some rads have a built in cooler for the engine as well as the tranny. Check your radiator and see if you can trace the metal lines back going in and out.

Have you done a coolant flush recently? If your engine is running hotter because the coolant is not efficiently drawing the heat away, then your engine oil will be hotter as well. Maybe the coolant needs to be changed.

Just some ideas for places to start diagnosing the issue.


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## Golfbear (Aug 2, 2009)

Many thanks for your comments and ideas afawal2012.

I do not have a separate oil cooler.
I am running a "colder" thermostat for the coolant fluid, something that is maybe good for track use but since I am mostly on street I am considering a VW original thermostat. By changing that, I will flush the system and refill with new coolant fluid. What I can say is that this fluid is not keeping a high temp, generally I am running too cool.

Today I have discovered the oli temp sensor behind the top of the engine, a brass-metal looking thing with a white marking on. I have aquired a new one. One idea is to change that but I also do see the cable running to this sensor is taped and must've been fixed some time ago. Maybe there is incorrect resistance in the cable? Sensors, or rather the MFA, is relying on correct resistance to present the correct temp on the MFA digital display. Maybe my problem is here?

On my way home from my VW garage I yanked the cable "shoe" to the sensor and cleaned it a bit. I was running typical highway speeds and noticed oil temp was nut up to more than 110 degrees. My analogue instrument (picking up the temp from the oil pan) showed slightly above 100 degrees. 

We'll see how this proceeds, maybe a new thermostat, new coolant fluid, new oil and new filter + checking the cable to the temp sensor will do the trick.

Gb.


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## ps2375 (Aug 13, 2003)

My guess is that the reason for the change is electrical. Anything from increased resistance in wiring or at a connection or a change in voltage , possibly by the dash's voltage stabilizer.


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