Very high oil temps (VR6) + drastic reduction on switching off

[Stonejag 10]

Been having some trouble with my oil temperatures recently. My fans haven't worked on stages 1 and 2 since I've owned the car (over the last 18 months I've changed all the senders, thermostat, housing, hoses, aux pump, fan controller - basically everything but the harness and heater matrix!) so maybe it's just because the weather's been a bit warmer. Anyway, I haven't noticed any difference in driving, it's just been looking like it's getting a bit toasty on the MFA. It's regularly 15 degrees over the water temperature now, where previously it used to track it very closely.

 

It's only a 20 mile drive to work, but even driving really gently I've still been getting over 108 on the display. Previously the same drive would only have got it up to 96 or so. After getting stuck in traffic it gets really warm, in the 120s. Had a couple of worrying moments when it just starts clicking up and up, an extra 2 degrees every 5 seconds or so. It still seems to be working plausibly - getting out of the jams and driving a bit faster, coasting down hills or driving very gently all reduce it as the water temperature comes down but it's still heating up faster than the cooling system seems to be able to get rid of it.

 

Here's the weird thing - when it's heated right up, turning the ignition off and then on again will instantly cut loads off the reading. I had to pull over on the M3 at the weekend with a reading of 140 - after stopping the engine and then turning the ignition back on it was reading 98! Obviously that's not sensible, but I don't know if it's likely to be reading distressingly high but actually be fine, or if it's reading wrong after switching off but is actually getting that hot. It seems to be consuming a bit of oil but it's not been really low or anything.

 

I'd prefer not to drive it until I know what's going on but it's my daily :( Planning to get it booked in for a new (stock) oil cooler at the weekend, any ideas I can try before that? Not sure if I can get to the sender beforehand, maybe it's just electrical but it's still worrying!

 

Thanks in advance,

 

Stone

[Billzeebub 1]

My VR is currently at Tutts of Dorking with a very similar ailment. They have investigated and are replacing the temp sender, oil pressure switches and breather pipe before road testing and then maybe looking at Oil Cooler etc. I had to be recovered by AA from Leicester Forest Services Southbound the other night because of oil temp up to 140!..water temp was ok..I await the result of their investigations this week with some trepidation. It was my first day of ownership of new car too, driving back from picking it up! Still hoping to make it to the National Day next month. Good luck with getting yours sorted, I will post up results of Tutts testing

[VW_OwneR_85 1]

maybe replace the oil temp sender, it might be telling you porky pies

[Jim Bowen 1]

I had funny oil temps once, was all over the place and turned out to be the wire to the top of the oil filter housing had perished where it meets the sensor.

[Kevin Bacon 5]

Does sound like a fibbing oil sender. Oil doesn't lose 42 degrees in 10 seconds :) Being on the front of the engine, the connection is exposed to crud and water.

 

You really want to get those fans sorted out Mr Stonejag! You're quite lucky we've not had summer yet :) I used to run a switch from the dash to the black sender for emergency use.

[fla 9]

if the oil was at 120C you would really notice a heat blast from the bonnet when opened - I had a similar issue a while back, scared the socks off me, but replaced the sender and refitted a new spade plus cleaned the contacts on the clocks and it was all back to normal. So I wouldn't worry but as Bacon has said get those fans fixed!

[Stonejag 10]

You really want to get those fans sorted out Mr Stonejag! You're quite lucky we've not had summer yet :) I used to run a switch from the dash to the black sender for emergency use.

It's on the list ;) I've hacked a rear-windscreen-demist button to include the gubbins from a second button so I can use the blank space, just need to find time to wire it into the harness...

 

Rang the garage to organise swapping the oil cooler but they told me not to bother unless all my oil(coolant) was full of coolant(oil) or it was visibly ****ing out somewhere. Which is reassuring! No sign of anything untoward in either so I agree the sensor's probably just gone a bit senile. Next job is to figure out which it is, apparently there are lots of different ones all superseded by different part numbers and vagcat's down again :bonk:

 

Stone

[J.C 10]

Hi Stone,

My VR6 Golf only worked on full fan speed,

turned out to be the resistor inside the fan motor itself,

I just wired in an external large resistor(25W+) of (I think) .33/.64 ohms, between the high and low speed supplies to the fan,

I'm sure given your talents, that'll be easy

 

Keep a look out for a MK3 golf VR6 with a shiney gold block of metal behing the grill!!!

Edited June 12, 2013 by J.C

[Stonejag 10]

I should have added - the fans were replaced after they seized and caught fire(!) and manually bridging the pins of the radiator thermoswitch connector runs it on speeds 1 and 2 correctly. I think that rules out the fan controller and harness, but then again thermoswitch is new as well...

 

Not sure if I've tried the same test with the engine running though - could be the wrong live feed was used in a harness repair somewhere? Will be a hell of a job to trace through the birds-nest if so. Beyond that I've drawn a blank, which is why I've left it for so long ;) A dodgy pin or two in the circular engine harness connector, perhaps? :shrug:

 

Ordered a new oil temp sender earlier so I'll give it a swap at the weekend and see if it helps :)

 

Stone

[Kevin Bacon 5]

That low speed not working was a Golf thing anyway. Still happens on MK4s and MK5s today. What is it with VW and their useless bloody fans?!?! :) Golfs with A/C run the fans on low speed every time the A/C is switched on, so the resistors burn out prematurely. You can get fixes for that but Corrados had the most over-engineered fans of all!! I've never heard of low speeds burning out personally it's so rare. Practically every MK4 V6 on the roads has a burned out low speed resistors. Did VW do a recall? Nope!

[J.C 10]

Gives me something else to think about, when I do my MK4 climatronic with AC install:scratch:

That low speed not working was a Golf thing anyway. Still happens on MK4s and MK5s today. What is it with VW and their useless bloody fans?!?! :) Golfs with A/C run the fans on low speed every time the A/C is switched on, so the resistors burn out prematurely. You can get fixes for that but Corrados had the most over-engineered fans of all!! I've never heard of low speeds burning out personally it's so rare. Practically every MK4 V6 on the roads has a burned out low speed resistors. Did VW do a recall? Nope!

[Kevin Bacon 5]

Gives me something else to think about, when I do my MK4 climatronic with AC install:scratch:

 

Into a MK4 or Corrado?

 

This might help - http://www.users.on.net/~graeme86/images/R32fanschema.jpg

 

And this is the easiest fix for the low speed not working - http://www.nime.co.uk/content.php?fsc1

 

You can run external 1ohm resistors but they get pretty hot and ideally need mounting onto a heatsink, plus they get exposed to water etc, so I used the Nime solution instead, which works well.

[J.C 10]

Into a MK4 or Corrado?

 

This might help - http://www.users.on.net/~graeme86/images/R32fanschema.jpg

 

And this is the easiest fix for the low speed not working - http://www.nime.co.uk/content.php?fsc1

 

You can run external 1ohm resistors but they get pretty hot and ideally need mounting onto a heatsink, plus they get exposed to water etc, so I used the Nime solution instead, which works well.

 

Into my Corrado,

I sorted out my fan with an external resistor mounted in front of the rad. didn't have any issues, granted not as good as a PWM box but a lot cheaper, £2 if I remember correctly

[Kevin Bacon 5]

Where did you get a 1 ohm 50W resistor from for £2?

[J.C 10]

RS components

I worked it out that 100W would be best,

http://uk.rs-online.com/web/p/panel-mount-fixed-resistors/0158301/

I think I got 2 of these wired in parralell to give me 0.5 Ohm

and I got another one of these

http://uk.rs-online.com/web/p/panel-mount-fixed-resistors/0188087/ but can't remember the value, I ended up using the single 100w resistor

 

http://uk.rs-online.com/web/c/passive-components/fixed-resistors/panel-mount-fixed-resistors/?sort-by=default&sort-order=default&applied-dimensions=4294465990,%204294444411,%204294466729,%204294449197,%204294448990,%204294461356,%204294455932,%204294466730,4294875272,4294867536,4294877730&lastAttributeSelectedBlock=4294956957

[Kevin Bacon 5]

Bargain! Cheers for that. Some chap on the R32OC was selling 2 of those on an ally plate with some wires for 40 quid!

[Dox 23]

Bargain! Cheers for that. Some chap on the R32OC was selling 2 of those on an ally plate with some wires for 40 quid!

 

 

Bigals fan fix has been around for ages

 

http://website.lineone.net/~alan.james.lorely/fan%20mod/Repair.html

[CazzaVR 0]

Stone, did you get anywhere with this? Mine does the same. Got up to 134 on the track at Castle Combe yesterday. Turned engine off then ignition back on again and it was just over 100. Also goes up by around 10 when I use the lights :lol: I know the oil temp is probably fine, especially as I have a Mocal, but I want to sort it. I guess it's almost certainly the oil temp sender.

[CazzaVR 0]

using the interior fan and the heated seats also makes the oil temp jump. Obviously something to do with increased load on the battery. Bad earth?

[J.C 10]

FYI basic temperature circuits use a voltage devider circuit, it shouldn't change with load UNLESS the supply and the voltmeter(gauge) have different supplies(+ and/or -)

http://www.facstaff.bucknell.edu/mastascu/elessonsHTML/Resist/Resist3.html#Temperature%20Measurement

I'd be checking G1/5 is earthed to cylinder head,

[Stonejag 10]

Stone, did you get anywhere with this? Mine does the same. Got up to 134 on the track at Castle Combe yesterday. Turned engine off then ignition back on again and it was just over 100. Also goes up by around 10 when I use the lights :lol: I know the oil temp is probably fine, especially as I have a Mocal, but I want to sort it. I guess it's almost certainly the oil temp sender.

Yeah, I bought a new fan controller at Inters. Turned out to be the wrong fitment but I stuffed a load of WD40 down the plugs when I refitted the original and now my fans work :D Bizarre as I'm 100% sure I'd tried that before, but..!

 

Still seeing a 15ºC drop when switching off, but it seems to just be a Corrado thing. Much happier with my oil/water temperatures now though, might not need to fit the Mocal after all!

 

Stone