over heating mk 3 golf

[craig101]

Hi everyone. Im new to these forums, but have read much of your threads. Im working on my brothers mk3 golf. Its overheating, and the radiator is cold which suggests the thermostat. I would just like to know if the thermostat comes away from the water pump without removing it?:confused:

[kenney]

Yes (2) 6mm bolts hold the housing to the pump

[Crasher]

It depends on what engine it is; the 1.4 can suffer problems with the thermostat cover inner reaction point breaking off.

[manc]

Hi,

My Mk3 1.4 is overheating, regularly running between 95 to 97.

I've put in a new stat and radiator fan sensor switch, and flushed the system to no avail.

But what's this about the thermostat cover inner reaction point breaking of ???, has anyone got a picture of a broken one?

The car has been running OK otherwise, desperately don't want to change the head gasket if there's no need.

Thanks,
Manc

[Crasher]

has anyone got a picture of a broken one?

http://i222.photobucket.com/albums/dd20/Crasher1964/coverwitharrow.jpg

[manc]

Hi crasher thanks for the picture.

I should have said, mine's a 1994 1.4 Golf Match (single point injection) with the thermostat housing on right hand side of the engine, looking from the front. which takes a conventional looking thermostat with a metal bridge on the hose side.

So I'm not sure we're on the same hymn sheet with the shown part, as I don't remember seeing anything like that when I put the new stat in? but wish there should be.

Last chance saloon. Going to try running it without a stat tomorrow, and I'm already re-living Angle-tightening head bolts, which gives me the heebie jeebies!

PS Should one of the thermostat housing outlet pipes have a valve in it??

[Crasher]

In that case the reaction point issue does not apply to your engine. 95 to 97 degrees is about where the fan kicks in, does the fan come on and does the bottom hose get hot? What do you mean about valves in the pipes, like on the Mk2 recall?

[manc]

I am getting some circulation through the small pipe into the header tank before the thermostat opens, but it seems like a circulation problem, as what appears to be happening is that the fan is only trimming the heat in the radiator whilst the main heat is staying in the engine?

Could you then please tell me if this engine does have a history of impeller problems?

I am getting some pressurization of the system, but then I am opening the cap slowly with the engine hot, to see if it needs topping up. But the car is now running at 95 to 97 and 100 on short journeys which it didn't do before.

So I'm now staring down the barrel of a new head gasket, pump, timing belt and outer belt tensioner etc. even though I'm getting no steam in the exhaust or water in the oil?, yet maybe tellingly I have had a tiny, tiny misfire when the engine is under load for some years which I could never trace but thought might be due to an aging head gasket?

Re the valve: I was looking for an image of my thermostat housing on the net and probably saw one for another model below which has got something shiny in the top right of the three smaller outlets.

14296

[Crasher]

I think you should pop the water pump off and take a look at it. If the impeller is tight, suspect the head gasket.

[manc]

UPDATE

Before pricing up the said parts, I took the new thermostat out to see how the engine ran without it.

Took the car for a spin, pulled up outside my house and let it idle, and after a while the fan cut in at 91 on the gauge, and out again at about 85, so I waited and watched it do it again, which it did, exactly the same!?

Mulling this over I went in put the kettle on and decided to test the new thermostat, and on submersing it in boiling water it didn't open a smidgen. *@~@

No wonder it wasn't any better!!!!!!!! a duff part from BGAutomotive!

So hopefully I can now just worry about why it wouldn't start for about two hours after I back flushed the radiator, but I could have got some water on the muti connector in front of the gearbox which I dried out with a hair drier, the symptoms were like it was getting no petrol, which it has done before, and it decided to start again after I checked all the relays, the fuses and the fuse block connectors!

So at the moment I'm on a reprieve, but have you any insight on finikey non starting issues?

Thanks for the responses

[Crasher]

have you any insight on finikey non starting issues?

Nope.

P.S. DON'T FIT **** PARTS!

[manc]

Yes, it's a lesson I don't want to repeat, and I'm usually very good and go straight to VW.

I've still got my fingers crossed for fitting the VAG thermostat tomorrow, and feel I could go on University Challenge now reading German Temperature Gauges.

Finally, is there a brand of antifreeze you would recommend?

[Crasher]

You don’t have to go to VW for everything, you need to be selective about what make of aftermarket parts you fit but that is something which comes with experience, one like you are having now, it is how I had to learn, the hard way. I must admit through that I only tend to buy genuine thermostats after experiencing many problems with alternatives. I would use genuine VW G12++ coolant.

[manc]

Cheers Crasher.

[manc]

Oh Dear,

As said previously, when running without a thermostat my engine was if anything running too cool at about 60-65c at 50mph, and if idled the temperature would gradually climb until the fan cut in at 91c and out at about 85c on the gauge, perfectly.

With a new VAG thermostat fitted the engine is back to running in the 90c zone, the fan cuts in at 91c but does not cool the engine by as much, taking it just below 90c, and with a shorter time between heat cycles.

So I started the engine from cold today, took the cap off the expansion tank and disconnected the small pipe from the top of the tank to see how good the flow is from this pipe, and can only describe it as a small trickle about 2mm in diameter, and (in full experimental mode) when I lifted this pipe a bit higher nothing came out of it?

I then stuck the pipe back on the tank and with the engine still running waited for the bottom hose to become hot, which it didn't until about 90c, and waited a bit longer until the fan cut in but couldn't feel much of a temperature drop between the top and bottom hose, and the top was hot, hot!

So I'm back to thinking it's a case of poor circulation, and the impeller of my water pump has a problem (as on other cars, I've seen condensation on the fins of a radiator dry almost instantly when the thermostat opens)...

...and that my engine is struggling to get by on thermal flow alone, which a working thermostat impedes enough to cause problems, and no reduction in temperature from air passing through the radiator core when the car is moving at speed.

The water pump on my engine also tensions the timing belt so it's not something I want to take off for fun, so would like to know how good the flow should be through the small pipe into the expansion tank first?

Manc

[Crasher]

Yes, you should not run it without a thermostat as it will over cool which will confuse the ECU and make it put more fuel in which shuts down the lambda sensor and eventually damages the cat. At idle to bypass pipes flow is very slight, it should increase significantly with some revs.

[manc]

I've just tried the car and the flow into the header tank doesn't increase significantly with more revs, I also think the ABD engine shares a water pump with some Polo's which have a plastic impeller as shown.

So reluctantly, I'm thinking of having a look next week.

Manc
14323

[Crasher]

From what you are saying I would have the pump out. The ABD is very simple to do, just think yourself lucky it is not a 140PS twin cam PD TDI Golf 5.

[manc]

A 140PS twin cam PD TDI Golf 5? Surely not as bad as a Fiat Coupe cambelt change in situe, or an old Mini bypass hose, now they were a nightmare!

[Crasher]

True but I was talking VAG family and as far as I know the Fiat Coupe timing belt is impossible wit the engine in. Mind you, nothing quite compares to a T5 2.5 water pump, I avoid these like the plague.

[manc]

Yes VAG family, but Coupe timing belt possible with post-fitting therapy.

[manc]

I stripped it down the other day. Oh! the shame of a poor diagnosis.

It was a circulation, problem but instead of being the water pump it was the waterway apertures in the headgasket, which had become all-but blocked with the passage of time, plus the gasket was borderline on a couple of cylinders.

Manc

[Crasher]

I haven’t seen that for a while.

[manc]

IT'S GETTING PERSONAL NOW.

After fitting a new head gasket, pump, and belts it's still climbing to 95 on the gauge, and when I got back from a run with the gauge in the 90's the bottom hose was still cold, which means the stat hadn't opened yet!!!!!!!!!

And I have two stats at the moment, a motor factor job and a VAG one (which came in a bag!?) but neither of have 84 stamped on them, so I now think that both stats are wrong, and open at a higher temperature.

I'm pretty sure I'm fitting the stats right, the side with the springs etc. into the housing and then the O ring and elbow cover.

I has to be the wrong stats now surely!!!! but I'm open to any suggestions as this problem is driving me nuts.

Manc

[Crasher]

Have you run it with the stat out and seen when the fan kicks in?

[manc]

Not yet as I've literally just done the head gasket, and did try it without a stat before the HG job and when the engine was idled the fan came in and out perfectly at the right temps? I also have a new rad sender unit.

I'm racking my brain, and also wondering if a fault has developed with the thermostat housing which is affecting the opening of the stats????

Like maybe the internal tube in the housing has come lose or something, and I had the housing off today to fit a new O ring and never REALLY inspected it?

Manc

[manc]

The engine never never ran at these temps before, and the fan worked perfectly, so what the hell has happened???

I am taking this personally, as I never give up on a problem until I find the cause, and can point a finger at it.

[kenney]

(Quote) It was a circulation, problem but instead of being the water pump it was the waterway apertures in the headgasket, which had become all-but blocked with the passage of time,
I'am wondering if the problem is with a blocked radiator,

[manc]

Hi Kenney,

I fitted a new radiator since then!

The problem is bit better with a new head gasket, as turning the heater on will now take the temperature down to under 90, which it wouldn't do before.

But I'm starting to lose sleep over this problem, which seems to be a lack of circulation of hot water round the thermostat, as even a thermostat of a higher opening range should be open at 90-95, which mine isn't, so I'm going to study the pipework again, to try and work out what could be going on.

Added to this, I had a struggle getting the bottom hose to seal on the new radiator, VW's spring clips are just hard work in this location, so I'm going to replace it with a jubilee.

[kenney]

Might be an idea to remove one of the core plugs to check the condition of the inside of the block.

[manc]

I just don't think it's the block as I seem to be getting a good flow through the heater, and believe the flow from the heater is:

into the tube at the back of the block and through the pump

around the block and head and into the thermostat housing

and then back into the heater.

But the thermostat housing is quite complex and has a diagonal slot feed from one of the rear facing outlets, so and I'm going to check to see if this slot is blocked from the pipe side.

[manc]

What's the opinion on testing thermostats with boiling water???

[Crasher]

What tells you that it is overheating?

[manc]

I'm now using the word "overheating" loosely, as it seems all I need to do is get hold of a thermostat that opens at the right temperature, which you wouldn't was that hard to do?...

..but I currently have a VAG stat (stamped 84 degrees), an BGA stat (with no number), and a Wahler stat (stamped 84 degrees) which I pulled out of the car originally, and which has a bit of gland seal coming out round the central rod.

So using a jam thermometer I got a pan of water to exactly 84 degrees and popped the original Wahler stat in and it started to open, I then put the other two stats in and by slowly raising the temperature I found that the VAG stat didn't start to open until 86 and the BGA didn't start to open until 92, and this was the stat I had in last !, as I lost track of what I had in.

And at 92-93 I was panicking and turning the heater on to cool things down, thinking my new head gasket was going to fry, I'm also now using G12 plus, plus antifreeze.

This is my story so far!?

[kenney]

with a temperature reading of 95 degrees does not mean the engine is overheating,and i have seen it often,without any logical explaination were the temperature reading starts to read higher

[manc]

OK, so I put the VAG stat in and the car is now running nicely at 83-84 degrees out on the road, and if idled the fan will eventually come in and out as once before, HALLELUIAH !!!!!!! so my post head gasket job concerns were caused by the non OEM stat opening late.

I also replaced the spring hose-clip on the bottom hose (radiator end) as I just couldn't take fighting it any more.

Thinking of giving it a treat now, oil change?, ht leads?

Thanks for all the suggestions,

Manc

[Crasher]

Imagine if that non genuine stat had been fitted to an Audi V6 2.5 TDI. It is a major strip down to get at it, about a days work. This is why I only fit genuine VAG thermostats.

[manc]

I see what you mean Crasher

The next job looks like my sister in laws 2005 Golf FSi which suddenly wouldn't start, and sounds like it's firing into the exhaust when my brother tried to start it, as if the ignition timing or something worse has slipped.

He had it towed into VW, and all they could find in two hours was the compression is down on one cylinder and the engine requires further investigation, with estimates sounding like the Greek debt?

He might then snatch it back from VW and I could be cracking the head bolts on that next!

[tochter1926]

Crasher, regarding the reaction point breaking off, whats the issue ? i.e. what occurs if you reinstall a housing with a broken point and new thermostat ?
The housing I have has the outside sealed end broken off(looking from the outside inwards) the inner (retaining, or locating hole is intact) centre hole is ok.

regards,

[Crasher]

http://i222.photobucket.com/albums/dd20/Crasher1964/coverwitharrow.jpg

[tochter1926]

Hi crusher, my question was what are the symptoms that will occur if I install a new thermostat with the centre of the housing being as described below ?

My golf is a mk iv 1.4 16v 1999.
The picture from the inside looking out is slightly different and the centre hole is intact, only the backing of the centre has fallen away, i.e. when you look from the outside looking inward, you can see through the centre hole which is still completely circular.

[Crasher]

You should not be able to see through the centre, it should be closed off. If it is open, the thermostat pin will slide through the hole and the thermostat will not open so it will overheat.

[tochter1926]

Ok Crasher, I get the principle , thank you very much for taking the time to answer. Looks as if I need a Thermostat cover also then. Once again, many thanks.