Heater Not working / Temp Gauge going into Red

[woody97uk]

Hi Newbie here (ish) after some advice / help from the experts

Wondered if anyone could point me in the right direction here..

My missus got home last night and her temp gauge had gone into the red and her heaters were blowing cold all the 12 miles home.. Shes got a MKII GTI 2.0 8V

We had the head gasket done 11 months ago, head skimmed properly etc and its been fine since until yesterday... checked the oil cap for any gunk and that was fine too..

I checked the coolant levels and they seemed to be low so topped it up with about a pint of water, and ran it for 10 mins, and it was running fine, temp gauge hovering half way and there was a definate if only very slight improvment on the heater, still cold but definate increase in temperature. Then all of a sudden the temp gauge started to go right accross into the red so i called it a day and thought i'd check again today as the snow was coming down heavily. Been today and bought some G12 coolant and was going to drain it a bit and top it up to ensure there was plenty in and just bought a thermostat too as it'd been suggested it could be that.

Any suggestions on the cause if i've not already covered it?
and also how easy is it to fit the thermostat? I've not got a haines for it and although i'm fairly good with my hands i know very little about Seats and due to having a company car for the past 10 years i'm a little bit out of touch with where they are thesedays and how to go about doing it.

Many thanks in advance for any advice / help you can offer

Woody

 

[Gav_F]

when you change coolant etc just make sure to get as much air out as possible! an air lock can create problems but it does sound like the thermostat tbh

 

[woody97uk]

when you change coolant etc just make sure to get as much air out as possible! an air lock can create problems but it does sound like the thermostat tbh

Hi

Cheers for the reply Gav.. anyone tell me where abouts the thermostat housing is please?

 

[Caffienated]

Haven't got my own car with me or any diagrams etc, and the thermostat is one thing I've never even needed to look for, so can't say if this is correct.

Did a bit of googling and found this which might be your answer: http://www.********************/index.php?topic=146310.0

I'm assuming your GF's 8v is the AGG like mine, and not the earlier 2E engine. Think they changed over around 96/97?

Air bleeds for the coolant are little screws (like bike tyre caps) on a 1" or so dia hose coming out of the bulkhead at the top near the middle. As you stand in front of the engine, just to the right of the inlet manifold/throttle assembly. The Idea is: get the car up to temp so the thermostat should be open, run the heater on hot with the engine running on idle, and open the bleed screws. Have a bucket/jug of ready mixed antifreeze handy (should be 50/50 I think) and keep topping up the expansion bottle until you have a nice steady stream of coolant coming out of the bleeds. Then whack the caps back on them quick as you can without letting teh level get too far down...

Other things that could be a problem are; internally collapsed hoses, internally collapsed or blocked radiator, generally high levels of gunk in system.

You'd only get the mayonnaise in teh oil if the head gasket had gone again... Think yourself lucky!

You can get a good idea of whether pipes are likely to be causing problems by giving them a good squeeze when they're cold. They should be quite stiff. If they're very soft you may have found your problem or possibly next weeks' problem...

I've heard a few horror stories about mk 2 ibiza radiators. Mine was replaced about 3 years ago...

 

[Caffienated]

Okay. Not sure why that link got censored. Here it is again. Doesn't like being quoted in one line? Take out the '_' characters. golf gti forum is all one word...

 

[woody97uk]

many thanks for your reply mate, I'm not 100% sure that is causing the problem as i've had some conflicting advice as to what exactly could be causing it since i first posted, so i've decided to let our usual mechanic take a look at it monday.

Thanks again for all your googling etc, really appreciate you taking the time to do so

 

[Caffienated]

Fair enough!

In a nutshell, though there aren't that many possibilities really.

If the needle's in the red and the heater's blowing cold, you don't have water circulating properly, which means you either have a blockage or no pump to circulate it with. Given enough time, assuming engine wasn't cooked first, the heater would begin to warm up even without water circulation simply due to heat conduction through the system.

Airlocks, stuck thermostats, blocked radiators/heater matrix, silted waterways and collapsed pipes (in no particular order) are your 'blockage' options. Broken pump vanes or lack of drive are your 'no pump' options. - All assuming you have the right amount of coolant in there - and if you have an airlock you certainly don't. There are more catastrophic options for too little water given the weather, like blown core plugs/cracked blocks etc, but all only apply if insufficient antifreeeze in there.

Bleeding the coolant shouldn't take 15 minutes and may fix you without paying your mechanic. Might be worth a go first!

 

[woody97uk]

Fair enough!

In a nutshell, though there aren't that many possibilities really.

If the needle's in the red and the heater's blowing cold, you don't have water circulating properly, which means you either have a blockage or no pump to circulate it with. Given enough time, assuming engine wasn't cooked first, the heater would begin to warm up even without water circulation simply due to heat conduction through the system.

Airlocks, stuck thermostats, blocked radiators/heater matrix, silted waterways and collapsed pipes (in no particular order) are your 'blockage' options. Broken pump vanes or lack of drive are your 'no pump' options. - All assuming you have the right amount of coolant in there - and if you have an airlock you certainly don't. There are more catastrophic options for too little water given the weather, like blown core plugs/cracked blocks etc, but all only apply if insufficient antifreeeze in there.

Bleeding the coolant shouldn't take 15 minutes and may fix you without paying your mechanic. Might be worth a go first!

You seem to know your onions more than the other people ive had advice off had mate so will give that a go tomorrow weather permitting. Many thanks again

 

[SKOPARTS]

Check both top and bottom rad hoses and those going to the heater matrix, see if any are cold this would point to a circulation problem, also whilst running is there a trickle from the top small pipe leading back to the header could be jammed thermo or packed in water pump

 

[woody97uk]

Also meant to mention. After topping up coolant today, I ran it again for 10 mins or so to see if there was any difference. On idle heaters were cold, temp gauge stayed around the middle. When I started revving the engine a bit the heaters got warmer but seemed to go cold again when I left it back idling. Not sure if that confirms or negates what you posted earlier. Thanks again mate

 

[SKOPARTS]

Sounds pump or air lock related to me

 

[Caffienated]

10 minutes is more than plenty to get up to temp even at idle.

Not really sure why revving should give a temporary boost to warmth. I suppose it's not something silly like voltage for the heater blower motor? You don't have headlights that get (really) noticeably brighter when revving do you?

How much fluid did you manage to add?

 

[woody97uk]

10 minutes is more than plenty to get up to temp even at idle.

Not really sure why revving should give a temporary boost to warmth. I suppose it's not something silly like voltage for the heater blower motor? You don't have headlights that get (really) noticeably brighter when revving do you?

How much fluid did you manage to add?

About a pint I'd say..Including the water I topped it up with last night.. Not noticeable on the headlight thing btw

Cheers for the other replies too btw

 

[Caffienated]

It is possible for an air lock to clear itself eventually, usually when it happens the needle suddenly goes into the red because the water level in the system has just dropped so far. Being in the red for a bit isn't great but it's not the end of the world. Suddenly reading no temperature after being in the red isn't good.

I admit I am thinking in terms of slipping pump drive though.

Still, it's silly predicting major disaster if we don't know the air's all out yet!

 

[SKOPARTS]

have you 100% bled the system? i.e by the screws and running it for 5/10 with the header cap off?

 

[Caffienated]

Didn't really expect it to be voltage related, silly suggestion really.

It could be the drive to the water-pump. That's better than pump vanes. Both cost a pump, but drive doesn't chuck bits of broken impeller all over the inside of your engine.

It could easily just be air in the system though. Honestly, I'd bleed it and see if you still have a problem. Happy thoughts!

 

[woody97uk]

Check both top and bottom rad hoses and those going to the heater matrix, see if any are cold this would point to a circulation problem, also whilst running is there a trickle from the top small pipe leading back to the header could be jammed thermo or packed in water pump

All the hoses seemed to be warm and pressurised once the engine had warmed up. I did for a second think there was a bit of steam emitting from the rad but I think it was a bit of snow evaporating tbh, didn't seem to notice it after a couple of mins.

 

[woody97uk]

Didn't really expect it to be voltage related, silly suggestion really.

It could be the drive to the water-pump. That's better than pump vanes. Both cost a pump, but drive doesn't chuck bits of broken impeller all over the inside of your engine.

It could easily just be air in the system though. Honestly, I'd bleed it and see if you still have a problem. Happy thoughts!

Will give it a whirl tomorrow guys, better than paying the mechanic!! Many many thanks for all the advice.. My missus doesnt have much luck with cars in winter. 4th year running somethings gone wrong with various cars over the Xmas period

 

[SKOPARTS]

hmmm have a look in the top of the header to see if theres a stream coming down the return pipe...if both matrix pipes are warm should negate it being a blocked matrix, if you were local id say nip it into my work and id have a quick 15 round it for ya

 

[Caffienated]

Well if the top and bottom hoses are warm, you probably have a working thermostat.

Thinking about it, if the system as a whole is warmed up (all the water pipes that is) your water pump probably isn't too shabby either.

I think you'll be doing the happy dance tomorrow if you bleed it right...