Cooling a 2.0 16v - rad fan (new switch fitted..)

[Jim 2]

grey body and thin metal washer attached

 

This makes me think i've got the wrong one on mine as the one I have fitted has a black plastic body and never came with the metal sealing washer - I had to buy the MK2 Golf fiber washer seperately.

 

Time for a trip back to VW! Or maybe I should just go to GSF, as it sounds like they've got the right ones. Any chance of the part number you got David? :)

[davidwort 0]

I think the washer business depends on the manufacturer of the sender, some seem to have a slightly sloping section to the end of the thread on the body of the sender and the metal washer then compresses partly at an angle rather than a flat to flat mating surface, some senders come with the washers on, others not.

Unfortunately Bally has the GSF receipt, you could pm him, but to be honest the easiest way is just to get them to find a sender in their parts bin that has the right connection, thread, 3 pins, and has the appropriate temperatures stamped on the side.

The stamped temps can be a bit confusing as some senders will have both switch on and switch off temps for each of the two speeds, others only have the switch on temp stamped.

Generally your looking for the two speed temps as around 95 deg and 103 deg IIRC, but they vary slightly. It's not that critical and I'm sure they will only be approximate values anyway, what you need is the first speed to come on at approaching 100 degrees the second at 5 or so degrees higher and it'll do the job just fine.

 

looking on etka the on/off temps are listed as

speed 1 ON 95 deg

speed 1 OFF 84 deg

speed 2 ON 102 deg

speed 2 OFF 91 deg

 

so the pattern one may just have something like 1=95, 2=102 stamped on the side

[Jim 2]

Awesome. Thanks for that mate. This is a pretty definitive 'my rad fan switch is shagged' discussion thread! :)

[boost monkey 0]

Time for a trip back to VW! Or maybe I should just go to GSF, as it sounds like they've got the right ones. Any chance of the part number you got David? :)

 

Non-genuine parts being purchased by a Mod?! Sacrilege!! :wink:

[Jim 2]

Non-genuine parts being purchased by a Mod?! Sacrilege!!

 

Yeah - because the genuine part did its job SO well! ;)

[boost monkey 0]

Yesss, come over to the dark side... *breathes through hands* :lol:

 

Seriously though, I hope you get it fixed soon. If you find that it's the fan motor on the blink I may have one kicking about in teh shed of delight.

[Jim 2]

Nice one. Will let you know if a new rad fan switch doesn't cure it!

[davidwort 0]

Jim, easy enough to test the switch, heat the end of it over a flame, I used the gas hob!

the circuits 1 and 2 will switch over as the sender heats up, use a multi-meter to check the circuits switch.

you can actually hear them click as they switch, but you'll still need to check continuity just to be sure.

[Jim 2]

If I actually knew how to use a multimeter, I would do that David! Unfortumately i'm a bit too crap at electrical stuff! :( Not only that but i've got a crap halogen hob in my place, and not a gas one so a bit of a PITA.

 

Just been to VW (wimped out!) and spoke to my parts guy. Turns out whatever fan switch i've got probably isn't the right one as when we checked chassis numbers and temps and found the RIGHT part, discovered that one of those hasn't been ordered in some time.. so not entirely sure how we ended up with the wrong one. Replacement is on order!

[Jim 2]

Hm. So I got my new rad fan switch (genuine VAG) and some G12+ and fitted it today. Once all done back up and the system refilled I started it up and let it idle and at the correct temperature (on the coolant temp gauge), fan speed one came on as it should. Excellent! Problem solved I thought. Took it out for a drive and got back to put the car away and despite the temp being at well up to and then over 100 centigrade on the dash instruments the fan wasn't on. So how the hell does that work, that it WAS working, and now its not?

 

I'm starting to wonder if, for some reason the temp of the coolant where it hits the temp gauge sender in the side of the block is radically different to the temp as it reads it for the fan switch down at the bottom of the rad? I can't account for it in any other way given that this is the second VAG fan switch AND i've seen it come on at the correct speed just...

 

Anyone?

 

Confused, Leamington.

[boost monkey 0]

I would think perhaps investigating the fan motor next, or have we already done that? :scratch:

 

That is very odd that it's differing so much, there' can't be much piping between the head sensor and the rad switch I would have thought.

[Jim 2]

That is very odd that it's differing so much, there' can't be much piping between the head sensor and the rad switch I would have thought.

 

Well i'm not saying its definately that - just something that occurred.. probably wrong! Not looked at the fan motor yet - not sure how to diagnose it or anything as i'm just not that good at this sort of stuff :(

[Toad 0]

Hm. So I got my new rad fan switch (genuine VAG) and some G12+ and fitted it today. Once all done back up and the system refilled I started it up and let it idle and at the correct temperature (on the coolant temp gauge), fan speed one came on as it should. Excellent! Problem solved I thought. Took it out for a drive and got back to put the car away and despite the temp being at well up to and then over 100 centigrade on the dash instruments the fan wasn't on. So how the hell does that work, that it WAS working, and now its not?

 

I'm starting to wonder if, for some reason the temp of the coolant where it hits the temp gauge sender in the side of the block is radically different to the temp as it reads it for the fan switch down at the bottom of the rad? I can't account for it in any other way given that this is the second VAG fan switch AND i've seen it come on at the correct speed just...

 

Anyone?

 

Confused, Leamington.

 

Your gauge/temp sender to the gauge are playing up??

[Jim 2]

I dunno mate. It was fitted two years ago and was, again, genuine VAG. I suppose its quite possible though? I'm really not sure where to go next - think I need to speak to Eric about his infa-red thermometer thing to try and confirm what the temps are.

[Toad 0]

I fitted a genuine VAG one to my VR and it was even further out than my 15 year old wonky arsed unit I replaced.

 

If your car isn't boiling over, the fans come on when it gets hot etc then I wouldn't get too worried just yet, but I understand that it would be nice to have a properly working gauge.

[Bally 0]

Blimey Jim, I wasnt aware you were having cooling issues etc til I read this.. Dave knows his stuff, big thanks to him for al his help with my corrado...

 

what sort of temps you getting from yrs on a run on the motorway etc?? myn for some reason is starting to creap upto the 120mark & then cools down after being parked up.. water temps stays just above the middle though, is that abt right?

 

like yrs, replaced everything.. rad (pattern part), oil cooler, vag thermostat, water pump, fan switch, oil pumps been done too...

[Jim 2]

Hiya mate... mine is a bit different - fine on a run (water temps go way down, oil about 102-106 centigrade) but just water goes right up to 110 and oil to about 114/116 degrees if I park up before the fans actually come on. I figured it was the fan switch to blame (only working on stage 2) and earlier today I assumed it was happy as when I started it up for the first time after changing the switch and coolant (AGAIN!!) the fan came on exactly when I expected it to according to the temp gauge on the instrument cluster.

 

Since i've had the car (just over 2 years) its had just about new everything for the cooling system. I guess new fan or the relays that control it for me next..?!

[Bally 0]

Hiya mate... mine is a bit different - fine on a run (water temps go way down, oil about 102-106 centigrade) but just water goes right up to 110 and oil to about 114/116 degrees if I park up before the fans actually come on. I figured it was the fan switch to blame (only working on stage 2) and earlier today I assumed it was happy as when I started it up for the first time after changing the switch and coolant (AGAIN!!) the fan came on exactly when I expected it to according to the temp gauge on the instrument cluster.

 

Since i've had the car (just over 2 years) its had just about new everything for the cooling system. I guess new fan or the relays that control it for me next..?!

 

Its so annoying when you have to change coolant.. Ive done it so many times in the last year!!

 

Im in a simlair boat when it comes to replacing bits...but most of them have been orignal parts which was abit shocking!! myns on 198k & rising..

 

see im not to famliar with the 2.0L but with the age these cars & miles etc things are gona give & breakdown.. only bummer is trying to pinpoint the cause of the intial problem.. especially when you replace everything!!

[davidwort 0]

Jim, the coolant temp sender for the gauge is deliberately at the hottest location, right where the coolant exits the head, so you know how hot the top of the engine/valvegear is. The fan switch is at the bottom of the radiator where the cooled water will be, the reason for that is if the radiator is failing to cool the water sufficiently for entering back into the engine (i.e. not enough airflow - stuck in traffic etc) then the fans are needed to draw air through the radiator and help the radiator work as a better heat sink.

My golf is mad, tiny 1.6 engine, huge radiator because of the aircon ,so it rarely needs the fans at all and the water exiting the rad bottom hose can feel quite cool compared to the top hose, it just cools the water really well even with no airflow.

 

Now i'm not saying you haven't got any partial blockages or odd electrical gremlins but you will get different behaviour depending on how the car has just been run or whether it's been idling from cold, similar things happen with oil temps on some cars, turn the engine off and the coolant stops circulating, wait for a few mins and so much heat builds up in the head that your oil temp readings can actually be higher than before you turned the car off when you run it again. Pretty much why the VR's have an electrical pump to continue to circulate water after the engine has stopped running.

 

We'll have to compare similar cars side to side with temperature probes like you suggested I think, to try and work out if you really have hot spots or intermittent problems.

[renson 0]

Just wondering if anyone could shed some light on a new issue that i have, Last week i had a oil leak around the oil cooler, changed the seal and all was sorted for a few days then it started leaking again (had no issues with overheating first time seal was changed). Have sorted the oil leak and refilled the coolant and thought all was fine till the car started to overheat in traffic. Checked the coolant when i got home and the there was next to nothing in it. Refilled it and didn't have any coolant leaking out so let it run to get any air out, re fitted the cap and then after a bit water was shooting out of the side of the coolant tank. Found this was down to the cap seal and sorted that, but my fan is not cutting in at all. Checked the levels today and all is fine, when i got to work the top hose to the rad was hot and the bottom was cold which is what i would expect in the 2 mile trip, yesterday both hoses were hot so i'm sure the thermostat is working. I think the overheating is down to the fan not cutting in, could the low coolant levels have caused the rad switch to die? and would this also cause the fan not to turn on like it used to when i parked up after the ignition is switched off? I have checked the fuse by the way and don't have the relay thing by the header tank on my 9a?

 

Any ideas would be greatly appreciated. :help:

[davidwort 0]

no reason for rad switch to die if coolant gets low, if you've lost water through the engine/oil then the oil cooler could be leaking, but you generally get oil in the water and water in the oil if that happens.

You need to check for air locks in the system and check the fan motor is OK, rad fan switch can be tested off the car by connecting a multimeter/test light t othe circuits and heating it over a low flame (hob etc)

[renson 0]

No water leaking now, that was the seal on the lid causing water to escape from the overflow on the header tank. Oil cooler is fine, i had oil leaking out of the old seal where it bolts to the bracket so no oil/water mix. I'm going to short the fan in a bit to see if its still working. I know the fan switch controls the two speeds of the fan but does it control the fan after the ignition has been turned off or is that someting else?

[davidwort 0]

I'm pretty sure the fan run on is controlled by a little switch on the left front of the cam cover under the fuel lines, it's there to make sure the fuel in the pipes doesn't over-heat and vapourise causing starting problems.

It may be different on the later cars with the fan relay pack by the battery.

[boost monkey 0]

I'm pretty sure the fan run on is controlled by a little switch on the left front of the cam cover under the fuel lines, it's there to make sure the fuel in the pipes doesn't over-heat and vapourise causing starting problems.

It may be different on the later cars with the fan relay pack by the battery.

 

Early 16vs deffo have this switch. Frotn left corner of rocker cover underneath the kink in the injector lines :salute:

[renson 0]

think i may be somewhere near solving this. Just went and picked up a new thermostat and fan sensor during my lunch, also tried to short out the fan but couldn't get anything to happen. Once i got back, felt the top and bottom hose which were both hot, and the radiator which felt hot all over including at the sensor. Tried shorting the over run but nothing happened there either. After a quick scan around the bay noticed a broken earth terminal to the battery, quickly connected it up and the fan started working :D Going to redo the battery terminal after work a hopefully all should be well. Thanks for the help, feel a bit of a stupid for not noticing it in the first place but this past week the car has been nothing but problems.