Engine running temp

[red_baron 0]

I posted a thread a few weeks ago about my 1994 VR6's lumpy idle and tendency to overheat. I was losing a fair bit of water from the reservoir and the engine temp (taken from the gauge) was hitting 110 degrees plus in traffic. After I saw steam billowing from under the bonnet on a drive home from work, I quickly sussed that the radiator was knackered and hoped that's what all the fuss was about.

 

So... new radiator installed... drive belt between fans refitted (I found it in the bottom of the engine bay, not connecting the two fans together where it should have been!)... new expansion bottle cap fitted (a blue one this time).

 

Since all this (about 3 weeks ago) I haven't lost any water, but I'm a bit concerned about the engine temp. Out and about it reads a virtually constant 85 degrees, but once I get into traffic it very quickly gets up to just over 100 degrees (it doesn't get as hot as 110 since having the rad changed). The fans kick in for a minute or so to cool things down to about the 100 mark and do so every couple of minutes or so until I set off again where things quite quickly get back to sub-90 degrees. Can anyone say if this is normal, or does anyone think I've got other "issues" with my cooling system?

 

I've had it VAG-COMmed (cheers reggit for all your help) and the only error flagged up was for the front left ABS sensor...

 

Idle is still lumpy and I think its a bit down on power (it cut out at a pedestrian crossing a couple of weeks ago - engine temp less than 90). Plugs have been changed with the proper NGK ones and I've checked all the leads to make sure they're all connected properly - a couple of them "clicked" into place when I used the proper tool but it's not made any difference to the lumpyness... any thoughts anyone?

 

Sorry for the mass of info. Hope someone can help.

Cheers, Ian

[dr_mat 0]

The temperature ranges you're seeing there aren't too bad now. The VR runs hot - you need either the fans on or constant speed > 30mph to keep the thing from building heat under the bonnet - fact of life.

The thing that's wrong here is that your fans don't seem to kick in till you're over 100. There's a multi-stage fan system and you should have low-speed fans on from around 94 degrees. These are controlled by the thermoswitch that you forgot to refit to the new radiator from the old one .. ;) Well. ok, maybe it's just faulty. It's mounted in the near side of the radiator, facing into the engine bay about 2/3rds the way down the plastic housings.

 

Not sure about the idle lumpiness - does it use a lot of oil?

[bigbluec 0]

Sorry to jump on your thread Red-Baron but i'm in the same situation as you and have been advised to change the fan switch and thermostat.

 

Problem is with all the different posts when you search "overheating" it seems to get a bit confused (maybe it's just me!)

But looking at diagrams on the Vw tech site the 3rd plug furthest right after ecu and gauge is supposed to be for a/c yet i have this (black 2pin) no a/c in my C and according to My stealer this is the fan switch i need to replace? and they think there is no switch in the rad which there is! as you say dr matt.

Please can someone help me and clarify exactly:

 

1. what the switch in the rad is for and its colour no. of pins?

2. what the third position switch (above thermostat in the row of three) is for if not a/c

 

Many thanks in advance Will

 

my C is a 94 VR6

[red_baron 0]

I'll have a look at the thermoswitch when I get a chance later this week or at the weekend.

 

As for oil... the only stuff it seems to lose is the stuff it drips over my drive/work's drive/ my parents drive :oops: from the underside of the engine (sneaking suspision it's a crank case oil seal cos I've already replaced the sump gasket :( ) It doesn't seem to burn any at all...

[dr_mat 0]

Switch in the rad is the control switch for the first two speeds of fan operation (i.e. the one that's not working in the above story). I think it's three pins but couldn't confirm that..

Go to GSF and ask for the in-rad thermo switch for a VR6 and you'll get the right bit.

[red_baron 0]

no probs bigbluec... I know what you mean. I get confused really easily so I thought it'd be easier to set up a new thread!

 

dr_mat - is the thermoswitch expensive?

[red_baron 0]

Had a quick look after driving home from work this evening. When I got home the engine temp was just below 90 degrees. At just above 95 the fans kick in for about 30 seconds and then go off. They continue to kick in every now and again whilst the engine temp rises. As soon as it gets to 100 (or even just slightly over) it stops rising, but the fan action seems to be exactly the same (i.e. same speed, same off/on duration).

 

From this it definately sounds like the thermoswith not kicking the fans in sooner at a lower speed... one problem - looking down at the radiator from the front of the car I can't see any kind of switch on the RHS of the rad... the battery & cover obscures everything. Is it mounted below the battery and easy to see from underneath?

[dr_mat 0]

Erm .. kicking in at ~95 sounds about normal, actually.

The thermoswitch is on the *rear* of the radiator.

[red_baron 0]

Well... 95... 100...110...115...BANG! :cry:

 

Stuck in traffic this evening it happened... The engine got so hot the pressure ruptured a pipe running along the bottom of the engine (not had a proper look yet, but the man from the AA told me that's what had happened).

 

So now the Rado is dead (well... maybe just poorly for a bit) parked in my parents' garage awaiting my next move. I think the plan is to get it to a garage (somehow :| )and get the whole cooling system checked out and get it sniffed too in case the head gasket's gone.

 

Off to have a few beers now though to help ease the pain (well I was originally off there when things went tits up).

 

p.s. thanks to the Police (both the Omega and the Range Rover) for getting me off Princes Road from "a very dangerous position"

[gaz1000 0]

red_baron

 

IM HAVING A SIMILAR SORT OF PROBLEM WITH MY 2.0L 16V BLACK BABY. IN TRAFFIC IT SHOOTS UP2 100oc IN BOUT TEN MINUTES HAD THE HEADGASKET CHANGED RECENTLY (NOT CHEAP) AND ALL BELTS AND EVERYTHING ELSE. STAT WAS CHANGED RECENTLY 2.ITS GETTING RATHER ANNOYING AND LIKE red_barons ITS LUMPY SUM1 TOLD ME IT MITE B AN AIRLEAK.

 

IT WAS OVERHEATING A WHILE AGO BUT I CHANGED THE RAD FAN SWITCH COST BOUT 20QUID.

 

NE IDEAS????????

[dr_mat 0]

Thermostat got stuck closed, I would say. Should never hit 110 deg!! (You didn't think to turn the engine off maybe??)

This would also explain your previous issue with fans not coming on. (If the rad isn't hot, the fans won't come on ...)

[red_baron 0]

Unfortunately I was stuck on one of the main A roads into Manchester in traffic doing about 4 miles an hour with no hard-shoulder so the idea was to attempt to crawl to the nearest lay-by (100 yards away - the one the Police towed me too eventually). Once I saw steam from the coolant reservoir I cut the ignition and that's when the system exploded.

 

Not sure what the next move is to be... its going to be a hassle whatever.

 

It is quite strange that none of the hoses etc or the reservoir itself gave up before the pipe or whatever it is that has gone. I'll have a quick look tonight.

[Supercharged 2]

Yeah - agree with Mat but also check the electric water pump is working...

[dr_mat 0]

Worth checking the leccie one, but the main water pump should be adequate on it's own.

The expansion cap lid is supposed to release excess pressure in fact. Possibly yours is faulty.. Get a new one, they're only a few quid.

[red_baron 0]

New radiator (3 weeks old) and new expansion cap lid (fitted at same time). It was venting last night but I think the pressure was so high something else had to give. Worse thing is I'm off on holiday next week - I was thinking of leaving it with a garage whilst I'm away (there's a couple I can trust not to fleece me, I think) and see what they come up with.

[dr_mat 0]

Yeah, most likely the cap was venting, but as you say, if the temps continued to climb, so did the pressure. Definitely sounds like a thermostat problem.

[red_baron 0]

Had a look this evening and took some photos of the pipe that broke yesterday (this went suddenly - the second I killed the ignition because of steam coming from the expansion tank).

 

Sorry to bore you all with it, but I'm wondering if this sheds any more light on the problem or just confirms its the thermostat (got told independently again this evening it most probably is).

 

The photos show the position of the pipe/pipes that's broken (around half way down the engine) and also more detailed photos showing the pipe(s) and what happens when water is poured into the expansion tank (it just runs out where the break is. I've also put a picture on showing the large-bore pipe as it reaches the RHS of the block.

 

The pressure must have been really high to cause this to go as it look like a metal t-joint that's broken apart. Anyone know how serious this is and how much/easy to replace? As the moment I can't put any water in the car to run it anywhere as it just runs straight out again!

 

Just anpther thought... could it be the main water pump that has seized somehow and caused a blockage and a massive amount of pressure to build up causing this joint to fracture?

[red_baron 0]

Well... picked her up from the garage last Friday afternoon after being 'fixed'. Got to the the traffic lights to get onto the M60 when they were on red... and it overheated again! Luckily as it got just over 110 degrees the lights changed to green and the engine temperature very soon got back down to sub-90 degrees once I was moving again.

 

The garage replaced the pipe that broke and put a new thermostat on (I have the old one that they took off), but it seemed to have done nothing to the running temperature.

 

Got the car home and had a quick look under the bonnet. Everything looks ok... disconnected the thermoswitch on the radiator and shorted out the connections on the plug to see if the fan spins (that department seemed quite silent on the drive home!). Shorting any combination of two pins didn't do anything. Then I noticed the wiring on the fan motor loom... looked a bit dodgy. Messed with this a bit whilst shorting the plug and hey-presto the fan springs into life.

 

With a temporary fix on the fan motor wiring (courtesy of my brilliant father and his chocolate box connectors!), when shorting out two of the connections the fan comes on (I think at high speed), when shorting out the other two connections all that happens is a relay clicks... any ideas? My Dad's looking over the wiring thoroughly today so may have some answers... he asked me to ask if anyone has a wiring diagram for the VR6.

 

"Has anyone got a wiring diagram for the VR6?"

 

Hopefully once all this is sorted out the overheating problems will be a dim and distant memory... can't wait to give it a try!

[bcstudent 0]

Try this...page 7. Not the best diagram, and I'm not even 100% sure it's for a VR6, but it's a start!

[bcstudent 0]

With a temporary fix on the fan motor wiring (courtesy of my brilliant father and his chocolate box connectors!), when shorting out two of the connections the fan comes on (I think at high speed), when shorting out the other two connections all that happens is a relay clicks... any ideas?

It'd be a lot easier to offer a suggestion if you told us what cable colours you were shorting out :)

[Kevin Bacon 5]

On the rad temp switch, black/red is Speed 2 and red is speed 1. The horizontal spade is the common connection and the two others are your speeds.

 

It's usual for one of the 2 speeds to go and replacing the sender is the cure.

 

The black sender in the thermostat housing is speed 3 (120 deg trigger) and I would always recommend VR owners bridge this connection to a dash mounted over-ride switch as a backup in case speeds 1 and 2 fail.

 

You won't believe how fast Speed 3 cools the engine! :-)

[red_baron 0]

Right... just been on the hotline to HQ (as I'm stuck at work and my Dad's retired and got all the time in the world... plus he wants the car off his drive ASAP!).

 

First update... I now have a new thermoswitch. Hopefully this'll be fitted by the time I get home!

 

Secondly... the wire colours. Red & green(?) is at 12v all the time. Connect this to the red & white wire and the fan spins. Connect red & green to red & black and the relay just clicks...

 

Hope this helps

[red_baron 0]

Cheers for the diagrams bc... I'm sure I'll be able to figure out what's going on... looks to have everything I may need!

[Colley 0]

Stick with it my man, i had a problem with the cooling on my VR was so fustrating but your get to the bottom of the problem eventually its a lot of trial and error i found though