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Unsolveable problem
dubstar_04 - 6/10/08 at 04:39 PM

I was wondering if anyone can offer any advice?

I Have a mk3 golf 2.0 gti engine code 2E. I have been having overheating issues with it.

I have changed:

Water pump
Thermostat
All sensors switches
Expansion cap
Head Gasket
All seals

The problem remains unsolved...

I have recently realised that the problem started not long after the AA changed the coil...

What are the chances that it could be the coil causing the engine to overheat?

Failing that do you have any other suggestions?

Any help much appreciated.

Cheers,

Dubstar_04

Paul TigerB6 - 6/10/08 at 04:42 PM

Have you considered the condition of the radiator at all?? How old is it?? Could be that the core is knackered (to use the proper technical term)

russbost - 6/10/08 at 04:47 PM

If it remains ok when idling, ie comes up to temp fan cuts in & then later out again, but overheats as soon as under significant power on a run then it sounds like a blocked rad core - I have also seen the situation where a blocked heater rad core screws up flow within the rest of the system & causes overheating.

dubstar_04 - 6/10/08 at 04:48 PM

I have flushed the complete system and water passes through everything freely. also it overheats so quickly the thermostat doesn't have chance to open!!

I have tried 3 different thermostats...

How can something so simple be so complicated?

Danozeman - 6/10/08 at 04:51 PM

Cool powering the spark wrong? Too hotter plugs? If it over heats that quick could be this.


Does the rad get hot all over or are there cold spots?

dubstar_04 - 6/10/08 at 04:52 PM

quote:
Originally posted by russbost
If it remains ok when idling, ie comes up to temp fan cuts in & then later out again, but overheats as soon as under significant power on a run then it sounds like a blocked rad core - I have also seen the situation where a blocked heater rad core screws up flow within the rest of the system & causes overheating.


I have concidered the heater matrix as a while ago it seemed to have an air lock and never blew hot air; however after a good flush it seemed to be ok, i have also made a by pass piece for the matrix and when used it seems to make little difference!!

dubstar_04 - 6/10/08 at 04:56 PM

quote:
Originally posted by Danozeman
Cool powering the spark wrong? Too hotter plugs? If it over heats that quick could be this.


Does the rad get hot all over or are there cold spots?


I changed the plugs for some that GSF recommended, might be worth trying some more!!

I have never felt the rad because the fan cowling cover it. Also the thermostat does't open until the temp goes all the way off the gauge!!

omega 24 v6 - 6/10/08 at 04:58 PM

Is it overheating though??? Or is the gauge/sender just telling you that it is??
It could be a faulty gauge or sender.

Also check for damaged/chaffed wiring especially around the coil area it could be that the AA man has done some damage

dubstar_04 - 6/10/08 at 05:02 PM

quote:
Originally posted by omega 24 v6
Is it overheating though??? Or is the gauge/sender just telling you that it is??
It could be a faulty gauge or sender.

Also check for damaged/chaffed wiring especially around the coil area it could be that the AA man has done some damage


I have changed the sender unit, and I just assumed that the clocks / temp gauge would be ok!!

I am hoping to get a replacement coil this weekend and I will examine the wiring whilst changing it.

Its such a strange problem. Normally cooling issues are really obvious!!

Howlor - 6/10/08 at 05:10 PM

I had a Sierra once that pressurised the system really badly. Cracked head was the cause.

Steve

dubstar_04 - 6/10/08 at 05:26 PM

quote:
Originally posted by Howlor
I had a Sierra once that pressurised the system really badly. Cracked head was the cause.

Steve


I checked the head before i has it skimmed. It was in very good condition.

One thing I did notice was the exhaust valves were white suggesting that it is running lean?

Litemoth - 6/10/08 at 05:31 PM

The electrics causing significant heating problems just doesn't stand up. The differences it would cause would be subtle and should be easily accomodated by the cooling system. Timing used to be a possible cause in days of yore but not with electroinic management.
My bet would be radiator (run the car without a thermostat and see if it still runs hot) or an air lock (some cars have a right involved procedure for sorting this) or, and you don't want to hear it, a cracked head which causes hot spots and short circuiting. The cracks are usually in the galleries and only open under pressure i'm afraid. There are rigs for testing this but the cost of a replacement may be less than the set up costs.
Is it boiling or losing water?
What happened to make Mr AA change coils and things?

[Edited on 6/10/08 by Litemoth]

[Edited on 6/10/08 by Litemoth]

dubstar_04 - 6/10/08 at 06:06 PM

The coil was changed because we went through a puddle and the car cut out, then a few weeks later it just wouldn't start.

I have just been out in it and run it up to temperature and the thermostat just isn't opening. also it sounds like there is air coming from one of the hoses which won't help.

There is no water loss and it doesn't seem to boil. I ran the car for a few days with no thermostat in and it seemed ok however I was only doing short runs to work and back.

rusty nuts - 6/10/08 at 06:25 PM

Prbably a silly question but is the thermostat in the right way round? It sounds very much like an air lock , try bleeding the system by removing the highest sensor or hose while filling . Some VWs have a problem with the water pump impeller coming loose and not pumping . Might be worth getting head gasket tested with a block tester kit and maybe getting the rad flow tested

dubstar_04 - 6/10/08 at 06:32 PM

quote:
Originally posted by rusty nuts
Prbably a silly question but is the thermostat in the right way round? It sounds very much like an air lock , try bleeding the system by removing the highest sensor or hose while filling . Some VWs have a problem with the water pump impeller coming loose and not pumping . Might be worth getting head gasket tested with a block tester kit and maybe getting the rad flow tested


The thermostat will only go in one way due to a plastic elbow on the bottom of the pump.

The pump and head gasket are new so shouldn't be any probs there.

Mk3 golfs have a bleed jobbie in the top water inlet / outlet which i used and I gave all the pipes a good squeeze so it shouldn't have an air lock.

At least when I find the problem everything will be new so I won't have to do any more work on the car!!

TOO BADD - 6/10/08 at 07:48 PM

Blocked rad here too. You may still have circulation but unless you take it out and get it tested at a rad specialist you will never know !

maartenromijn - 6/10/08 at 08:40 PM

Check the thermostat in a pot of boiling water.

omega 24 v6 - 6/10/08 at 09:48 PM

Erm how big a puddle did you go through??? any change of water induction and subsequent hydraulicing of the engine??
This could cause a split in the cylinder

dubstar_04 - 15/11/08 at 01:28 PM

After all the fuss I took the car to vw for a electronics check and the report said either a faulty temp sensor or an ecu fault!!

They said they could replace both items for only £900...

my mate breaks vws and sold me an ecu for £20 and a new thermostat from gsf is £8.99

Thats still not solved the problem!!

I have been driving it now for 3 weeks and its not spontaneously burst into flames so i will just keep driving it and hopefully get another 6 months out of it...

Rob Lane - 15/11/08 at 06:52 PM

Two common faults :-

1. Temp sensor faulty

2. Fan(s) not working. (VW won't admit they are inherently faulty.)

Fans are expensive from dealers !!

owelly - 15/11/08 at 09:50 PM

The OBD would show faults on the temp sender and ECU because you've been fiddling with them!! The dealer should have noted the faults and then cleared them. Then checked for reoccurence.

If you could give us a tedious but accurate timeline of events for the car, starting from when and why the headgasket was changed, when the AA poked around and when the overheating started, we could perhap, have a better guess?

It will be something elementary. But well hidden!

martyn_16v - 16/11/08 at 10:27 PM

quote:
Originally posted by dubstar_04
my mate breaks vws and sold me an ecu for £20 and a new thermostat from gsf is £8.99


This may just be a typo but just to be sure, a thermostat is not the same thing as the temp sender.

There's a couple of temp senders (or possibly three, been a while since I last poked around a 2E) on the engine. If I remember right the one the ECU uses is the blue one. They're all the same though, just make sure you change the right one.