Engine oil temp issue

[captainredeye 0]

I have had concerns about my engine oil temp getting too high, today it nudged 120c so I pulled over and turned the engine off and checked the temp without the engine running and it read 20c lower, start the engine up and it would read 20c higher, I did notice temps below 80 read only 10c lower.

any ideas on the possible fault or correct temp and how I could find out the correct temp without the Mfa.

 

Cheers Ben

[seanl82 23]

Have you changed anything to try and diagnose it?

I remember someone else here had similar, but when going through the MFA options and back to oil temp, it would be 20 degrees lower iirc. Have a search via google and you may locate the thread. Can't remember how it was solved in the end, sorry........

[fla 9]

Might be a ground issue with the temp sensor. Take it out clean and refit. Might cure the issue. Also clean and lube the spade connector.

Those high figures on the gauge can be unnerving!

[captainredeye 0]

Not really played with it as of yet, I can tell you driving it was like running on fumes and times it by 20, May order some brown pants just for Corrado driving.

I will have a play over the weekend and maybe change the sensor after cleaning the connectors, I remember someone else having a similar problem but unfortunately all my googling powers couldn't unearth anything.

 

If some one gets a chance could they test their Corrado go for a drive and see if the oil temp is the same with the engine running and then off?

[VAG-hag 0]

I have a known good sensor that I just removed if you want to switchk?

[Harrier 1]

Hi Ben :) What temp does your water run when the oil reads 120 ?

[Rustynuts 0]

Swap the oil temp sensor, they can go wrong - I had similar issues on my G60 which was fixed by popping and sensor in.

[captainredeye 0]

The water temp runs between 90-100 and no higher than that but has dropped to just above 80 when going at a nice pace. The oil temp does move up and down with the water temp.

[captainredeye 0]

Thank you mr vag hag , I went and ordered one from vw heritage as they were apparently on sale at 50% off so we will see how I get on

[VAG-hag 0]

50% off you say..... May have a peek

[captainredeye 0]

Was only £5, I have just found this from a 12 year old thread, still not quite sure what to make of it????

 

Quote Originally Posted by bad2vbone

Hi.

 

I'm a bit concerned about the temperature my VR6 is running at. However I noticed if i read say 124, turn off the engine, then immediately turn the ignition back on, it will read randomly between 10-20 degrees lower. Is my sensor nackered?

 

I'm a newun to this forum and VR's by the way!

 

Quote by guest user

If you mean that the reading is different when the engine isn't running, I'll give you a clue - the alternator stops charging when the engine stops, what do you think happens to the voltage across the battery terminals?

 

Another freebie : a high post count around here doesn't necessarily indicate an expert, especially with VR6s.

[Harrier 1]

From that post it might suggest the alternator is overcharging ??

Worth a check, shouldn't be much higher than 14.5 v

Could be a fault in the instrument panel , do you have access to another you could try?

[captainredeye 0]

I will do a volt check on the alternator although I'm sure it was a 120 amp unit but I had put a larger pulley on it so would of thought it would not produce quite so much power, the display had burnt out wiring due to some dodgy electrical works but was fixed last year, I will have a look at that although I don't think I can get my hands on a spare display that easily.

[dr_mat 0]

Actually it's more likely the dash is presenting a rolling average over a short period of time to prevent it swinging about too rapidly. When you turn the ignition off and back on it has no historical data any more so it shows the live value.

 

I've seen 115 degrees or so on the oil in summer on motorway runs too. Ease off the speed and it should come down a little.

[Jim Bowen 1]

I've had two different looms and the wire to the oil temp sensor corroded on both on them which made the oil temp very erratic until one day it just stops reading. Worth checking the wire out

[Kezbo 0]

If some one gets a chance could they test their Corrado go for a drive and see if the oil temp is the same with the engine running and then off?

 

Saw this thread earlier so tested this on my drive home. While driving the oil temp read 106. When I stopped, turned engine off and then turned ignition back on straight away the oil temp reading had dropped to 98.

[captainredeye 0]

Hmmmmm that's roughly 10c difference, my mechanic has stated that there tends to be a 10c variance or tolerance with these sensors any way and that they are not 100% accurate, I will do some tests tomorrow as I have a day off and hopefully the rain holds off and the new sensor arrives.

[dr_mat 0]

And you do know that oil flows from cool parts to hot parts and vice versa. Turn your back for ten seconds and you get a slug of cooler oil on the sensor. I just don't see this as a real problem.

 

The sensors themselves use standard temp sensor modules that will be accurate to within a degree or so, and more to the point they will be consistently inaccurate rather than randomly wrong (unless they are faulty). Secondly, look at a newer car and the oil temp values fluctuate much more rapidly than those reported by the VR6 - the reality is it's heavily smoothing this data before you see it.

Edited May 10, 2016 by dr_mat

[Dox 22]

 

Quote by guest user

If you mean that the reading is different when the engine isn't running, I'll give you a clue - the alternator stops charging when the engine stops, what do you think happens to the voltage across the battery terminals?

 

Another freebie : a high post count around here doesn't necessarily indicate an expert, especially with VR6s.

 

If that was the case the fuel gauge and temp gauge would also jump around?

 

Dashes have a voltage regulator fitted to prevent the voltage differential from battery / alternator charging rates affecting readouts.

 

MK2s had a 3 prong 9V regulator fitted to the rear of the clock for this reason.

[g0ldf1ng3r 13]

get yourself one of those cheap hand held laser temperature devices - they work a treat

 

Vince at stealth did a test on my VR when it was there where he laser registered the temp of an oil temp sensor so as to compare again the MFA reading.

it consistently showed 6 degrees BELOW the temperature reported by the MFA on the dash. FYI this was with a brand new oil temp sensor fitted

[dr_mat 0]

If that was the case the fuel gauge and temp gauge would also jump around?

 

Dashes have a voltage regulator fitted to prevent the voltage differential from battery / alternator charging rates affecting readouts.

 

MK2s had a 3 prong 9V regulator fitted to the rear of the clock for this reason.

Correct, regulators everywhere. Car circuits are very well aware they have to tolerate the world's muckiest spikiest and noisiest power supply.

 

It's not this, otherwise you'd see the gauge drop when you start the car too.

[Dox 22]

And virtually every 240v appliance has a regulated power supply inside too.

[Dox 22]

Quote by guest user

If you mean that the reading is different when the engine isn't running, I'll give you a clue - the alternator stops charging when the engine stops, what do you think happens to the voltage across the battery terminals?

 

Another freebie : a high post count around here doesn't necessarily indicate an expert, especially with VR6s.

 

Would you like to provide a link to where this was taken from? Any idea who the guest user (deleted account presumably?) was?

[captainredeye 0]

http://the-corrado.net/showthread.php?8325-VR6-Oil-Temp-Sensor

 

Here you go.

[captainredeye 0]

Ok alternator charge is 14.3 volts, I have now replaced the sensor and checked the wire all seem OK. Going for a long drive now so we will se how it goes