Engine too hot?

[GreasyWeasel 0]

My engine recently went supernova and needed a new radiator, and when it went in the garage said there was also an electrical fault in that the engine fan was only coming on after the engine was turned off. I got to thinking and couldn't think of a time it had come on recently so thought nothing more of it and so they went ahead with repairs.

 

Now I'd never had any problems with engine overheating before so now I find myself clock watching, and the fan still seems only to be coming on after I turn off the engine and seems to still be running a bit hot to me. It's frequently getting up to 110 degrees when stopped in traffic and no signs of the fan coming on, but otherwise seems fine.

 

So am I now just worrying for no reason? How hot should the engine be running when not being thrashed and at what temp should the fan kick in?

 

Weasel

[blackthorn 0]

hmm my engine always runs at 110' dude... fan kicks in at 113' so its the normal running temp for mine ive been told :eek: so i wouldnt worries to much apart from the fan not working!

[Supercharged 2]

^ No it's NOT!!! - all VW's should sit mid gauge when warm at around 90 degrees

 

If it's going up to 110c then it's likely that the fan is only running at the higher temp range

 

Probably due to a faulty thermoswitch on the radiator.

[boost monkey 0]

Yeah as Supercharged said. The rad fan overrun switch (makes fan come on if engine's still hot after engine is switched off) is completely seperate to the thermoswitch in the bottom of the radiator.

 

110 degrees is NOT a normal operating temperature for coolant!

[GreasyWeasel 0]

Cheers chaps.

 

.....

[blackthorn 0]

hmm shows my knowing of the rado so far is crap haha

 

so basiclly i should order a new thermo switch yeah?

[bigjamesk 0]

Sorry to jump on the thread but I am a bit confused / worried / concerned / have lost the instruction manual (another one ordered on fleabay though, )and have no idea about mechanics...

 

I've had my VR6 (totally standard) for about four months now and the temps seem to be running higher than when I bought it. I haven't seen / heard the fans working either after I've stopped or when driving - and the engine does seem to be very hot under the bonnet. I have viewed the forum and can't seem to get any definitive answers. Basically the coolant temp seems fine, and whereas the oil rarely got over 100 it now seems to on a regular basis. I have the following questions for anyone who can help...

 

1. What are "normal" running temperatures i.e. when should I start worrying (oil and coolant).

 

2. At what temperature should the fan come on? Is it based on oil or coolant temp?

 

3. I have read about the fan working at low and high temps, what is this all about - can someone please explain.

 

Of course it could just be that I haven't got the thing hot enough - and the answer may just be I need a heavier right foot!

 

Any answers most appreciated!

[davidwort 0]

This is the behaviour I'd expect:

Run a car up to temperature (mid way on the water temp gauge, and over 80 deg oil) and let it idle. Then let the radiator and hoses both get hot if it's a cold day and the thermostat has partly shut off the radiator.

Leave it idling, the temp gauge should move slightly over the mid point and then the low speed fan will come on. IRO 95 deg water temp.

The low speed fan switch is usually around 95 degrees, switch on point, and will switch off a couple of degrees below that.

As the gauge settles back to mid-way the slow speed fan should switch off, so the needle should not undershoot.

Oil temps can be a little higher when idling, particularly after a good run as the heat tends to build up in the head (where the sensor is) when there's no airflow from driving.

The only time the high speed fan should come on is after a hard drive when you pull up or reduce speed to a crawl, if the airflow when driving is not sufficient to cool the engine then no fan is going to spin fast enough to aid the cooling.

At normal driving speeds I'd expect a cold engine to come up to temp in about 10-15 minutes and 5-10 miles driving, if the car still has the water/oil heat exchanger (and not replaced by just an oil/air cooler) then water and oil temps should be fairly well balanced and run with each other, oil lagging behind in the warm up phase a little until fully up to temp, at which point the water will cool the oil, so water temp may lag oil temp rises.

Again, in normal, or even hard road driving conditions, water and oil temps will stay fairly well balanced with the oil temp rising furthest, dragging up the water temp a little from time to time, but generally the water temp will stay between mid and 3/4, some cars hardly move above the mid mark.

If the water temp needle makes it up to the top of the scale and the LED flashes then you either have a duff water temp sensor, a broken or disconnected wire or connector to the fan (or bust fan motor), a stuck shut stat, or a more serious failure of the engine or cooling system.

I'm also pretty convinced that elderly wiring and dash units can give some strange behaviour, sometimes affected by ambient temperature as resistances increase and decrease.

God, that was a ramble :roll:

[bigjamesk 0]

Thanks for the reply, most helpful. Much clearer now but still a little confused...3 more dumb rse questions!

 

Which is the low speed and which is the high speed fan? The only one I can know about (and as, I said earlier I don't look under the bonnet that often) is the big twin fan in front of the radiator?

 

And to be clear if the water temp doesn't get up to above 95 (ish) then I shouldn't expect anything to happen?

 

And if the oil is getting significantly hotter than the oil then I have probably have an issue with a sensor somewhere?

 

Cheers, and sorry for the stupid questions...

[Henny 0]

low speed and high speed are both the same fan (fans in the VR6 case)... the low speed simply spins them slower, the fast speed runs them flat out... ;)

[davidwort 0]

oh, and you've got the added complication of a secondary electric water pump on a VR, which I think is mainly to circulate water after the engine is switched off?? - perhaps someone else can confirm.

[Toad 0]

oh, and you've got the added complication of a secondary electric water pump on a VR, which I think is mainly to circulate water after the engine is switched off?? - perhaps someone else can confirm.

 

Depends on the age of the VR.... Hehehehe.

 

On early VRs the secondary water pump pumps water while the ignition is switched on and for 10 minutes after it is switched off.

 

On late VRs, the secondary water pump pumps water while the ignition is switched on and if the coolant temperature is above a certain level for 10 minutes after the ignition is switched off.

 

The late VRs have a fan/pump control unit next to the header tank with 3 fuses, rather than 1. These units can also overheat and the components inside can unsolder from the pcb. Take it off and see if it rattles for proof.

[Kevin Bacon 5]

I've had my VR6 (totally standard) for about four months now and the temps seem to be running higher than when I bought it. I have viewed the forum and can't seem to get any definitive answers.

 

I'm sure a member called Dinkus started a VR6 cooling thread? Not sure what happened to it as I remember it being stickied. Oh well.

 

Right then....(for the 1000th time :D )

 

Fan speed 1 - 90 - 95 deg switch on temp. Permanent live to battery. Signal source - 3 pole sender in radiator - Thick red/white wire.

 

Fan speed 2 - 100-110 switch on temp. Ignition only. Signal source - 3 pole sender in radiator - Thin red/black wire.

 

Fan speed 3 - 115-120 switch on temp. Ignition only. Signal source - 2 pole sender (black) in thermostat housing.

 

Yellow 4 pole sender in thermostat housing; Left half = dash water temp gauge, right half = auxillary water pump.

 

Big black box with heavy gauge wire bolted to nearside turret = Fan relay / fuse box and aux pump after run timer.

 

The Fan speeds have between 5-10 degs of hysteresis (lag) to stop the fans coming on and off constantly at a precise temperature, hence the 100-110 comments.

 

Now, armed with that information, it's pretty obvious what you need to do in order to test the fans.

 

Common culprit is the sender in the radiator.

Next common culprit is the yellow sender (lazy water gauge and aux fan on permanently with the ignition)

Next common is the fan fuse / relay box.

 

After that, anyone's guess....

 

Do yourselves a favour, bin the whole damn crappy lot and fit 2 slimline 11" fans (hooked up to speed 1) and never worry about overheating again.

[GreasyWeasel 0]

Good acid test was performed yesturday.... 'stuck in rush hour' and 'hooning down motorway'.

 

My engine sits perfectly on 90 when in motion and when cruising at 80mph in 5th oil temp is 116 which is about the same as before. However when stuck in traffic I'm getting no fan action at 95 degrees at all as Mr Pianowire states should be happening, and a mental 15 second burst at 105 degrees which then cuts out. The engine doesn't get any hotter than 105 but being a concerned parent I timed the fan and it was 15 seconds every time with a couple of minutes between blasts, if that's significant?

 

So is this likely to be a loose/disconnected wire, as the fan is clearly still being triggered by coolant temperature? The old girl needs to go in to get the bearings replaced and I want to get this issue sorted, and I intend to go in with as much info for the grease monkeys to work off as possible.

[G-Lad 0]

My engine recently went supernova and needed a new radiator, and when it went in the garage said there was also an electrical fault in that the engine fan was only coming on after the engine was turned off. I got to thinking and couldn't think of a time it had come on recently so thought nothing more of it and so they went ahead with repairs.

 

Now I'd never had any problems with engine overheating before so now I find myself clock watching, and the fan still seems only to be coming on after I turn off the engine and seems to still be running a bit hot to me. It's frequently getting up to 110 degrees when stopped in traffic and no signs of the fan coming on, but otherwise seems fine.

 

So am I now just worrying for no reason? How hot should the engine be running when not being thrashed and at what temp should the fan kick in?

 

Weasel

 

My engine is also running very hot indeed, though i have managed to avoid a rad blowout or anthing as messy. I have had the little heater matrix helping out and all the windows and sunroof open, just to maintain 110degrees on the coolant and 122-130 on the oil - not good!! :gag:

 

I noticed the same thing, whereby I know the water temp gauge says 100+ degrees, but the fans only start when the ignition is off, and vice versa; the fan stops if I turn the engine over.

 

I thought this was odd, however when I called my mechanic brother, he asked me if the radiator was actually getting hot, or is the heater matrix the only active radiator. ie, is the thermostat knackered and keeping the main rad out of the circuit.

 

My answer was no, the rad is still cold at 95 degrees on the coolant needle.

 

it sounds like my thermostat is shot! Anyone got a pic handy, so I know what to replace? I'm new to VR6s :confused4:

 

Weasel, what was the verdict on your "fan only runs when ignition off" issue?

[Leonard 0]

My engine recently went supernova and needed a new radiator, and when it went in the garage said there was also an electrical fault in that the engine fan was only coming on after the engine was turned off. I got to thinking and couldn't think of a time it had come on recently so thought nothing more of it and so they went ahead with repairs.

 

Now I'd never had any problems with engine overheating before so now I find myself clock watching, and the fan still seems only to be coming on after I turn off the engine and seems to still be running a bit hot to me. It's frequently getting up to 110 degrees when stopped in traffic and no signs of the fan coming on, but otherwise seems fine.

 

So am I now just worrying for no reason? How hot should the engine be running when not being thrashed and at what temp should the fan kick in?

 

Weasel

 

My engine is also running very hot indeed, though i have managed to avoid a rad blowout or anthing as messy. I have had the little heater matrix helping out and all the windows and sunroof open, just to maintain 110degrees on the coolant and 122-130 on the oil - not good!! :gag:

 

I noticed the same thing, whereby I know the water temp gauge says 100+ degrees, but the fans only start when the ignition is off, and vice versa; the fan stops if I turn the engine over.

 

I thought this was odd, however when I called my mechanic brother, he asked me if the radiator was actually getting hot, or is the heater matrix the only active radiator. ie, is the thermostat knackered and keeping the main rad out of the circuit.

 

My answer was no, the rad is still cold at 95 degrees on the coolant needle.

 

it sounds like my thermostat is shot! Anyone got a pic handy, so I know what to replace? I'm new to VR6s :confused4:

 

Weasel, what was the verdict on your "fan only runs when ignition off" issue?

 

When mine did the same I had a water pump on the way out and also my Thermostat housing had cracked as well.

 

Matt

[dr_mat 0]

FWIW in 7 years of driving in all weathers and even stuck in stationary traffic idling for three hours, I have NEVER had the high speed fans come on on my VR. I don't even know if it works! If your normal fan speed isn't coming on, it's faulty, and you need to get it fixed asap.

Plus, my water temp has NEVER gone over 100 degrees, not even slightly.

[G-Lad 0]

FWIW in 7 years of driving in all weathers and even stuck in stationary traffic idling for three hours, I have NEVER had the high speed fans come on on my VR. I don't even know if it works! If your normal fan speed isn't coming on, it's faulty, and you need to get it fixed asap.

Plus, my water temp has NEVER gone over 100 degrees, not even slightly.

 

I'd definately say the same of my Mk2 16v Golf - cooling has always been perfect :(

[G-Lad 0]

 

When mine did the same I had a water pump on the way out and also my Thermostat housing had cracked as well.

 

Matt

 

Oh dear! If it gets to that I'm definately going to ask for a refund and return...

[Leonard 0]

 

When mine did the same I had a water pump on the way out and also my Thermostat housing had cracked as well.

 

Matt

 

Oh dear! If it gets to that I'm definately going to ask for a refund and return...

 

Its not silly money, probably £250 max so you could always ask for this back if they are willing. These things do go on the Corrado. So if they have not been done on a car then they would need doing at some point...

[G-Lad 0]

Fair comment, it just feels a bit rough to be "investing" in the car so early in my ownership!!

 

It's taken the shine off my new toy a bit to be honest. It's not that I'm afraid to spend money on it, in fact that was the plan when I bought a cheaper one from a genuine enthusiast Vs a random off the internet (who would tell me to f off once I'd handed over the cash!). I have other things I wanted to improve first, rather than paying extra money to make it road worthy :gag:

 

I'll see what my mechanic suggests... more news later ;)

[fla 9]

Its nothing major tbh. If you are happy with the engine and bodywork then dont worry. These things are striaghtforward and 'relatively' inexpensive. were i to have been in your postion, i would have allowed at least a grand to fix the small things like thermostat housing, crack pipes, heater matrix etc. all these are old plastics now and no amount of care will presvent them from becoming brittle. If the chains and clutch have been done, thats the major cost done with. Water pump is not too costly and not too hard to change either. You'll get to the stage when you've sorted it mechanically and are just trying to sort out all the rattles and squeaks - or maybe i'm just paranoid!

[G-Lad 0]

Finally sorted today - thermostat was definately at fault, also needed a new housing (old one cracked, bought & fitted genuine, pattern one was leaky), plus various seals etc, plus a couple of senders while it was off = £109 parts and £40 labour (very reasonable labour charge I thought!).

 

All works A OK now, coolant no more than 90, usually 80. Oil is still running up to 106 but I'm less worried as it seems to come down again courtesy of the effective coolant. I guess the oil is getting so warm as I'm very used to keeping the rev needle at 12 o'clock or more (I blame 16v Golf ownership for my revvy ways!!).

 

Someone please shout if they think I should be worried about the oil running at 106 degrees, but otherwise I'll assume its now sorted :clap:

[fla 9]

106 oil is absolutely fine. Up to about 114-116 is Ok for most oils. You have to worry when it gets to 130, but under any normal condirions that wont happen. I have aircon and in trffic see up to a max of 114 with the aircon on, but then again i also have a mocal fitted. This drops down quickly to about 100 when i'm on the move again.

[G-Lad 0]

cheers for the reassurance :)