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General => The garage => Topic started by: Sykopaf on 11 April 2009, 13:29

Title: Mk2 GTI 8v - Overheating when idle
Post by: Sykopaf on 11 April 2009, 13:29
Hi, I'm new here and have a problem I'm hoping you can help with.

It's on my 91 GTI 8v, it boils the water in the radiator when idle, steam just comes gushing out once the engines warmed up. It's blown the head gasket twice (and the heads been skimmed twice) so once more and that's all she wrote.

I've replaced the water pump, thermostat, radiator fan and one of the water pipes so far.

I've got a quote for getting my engine reconditioned and a mate has also offered me his VR6 engine for free when he transplants an R32 engine in his but I have a feeling this is something really simple that I'm totally missing.

It's a great little engine and I don't want to write it off just yet - it's been stood for 18 months or so in the cold and wet, untouched. Yesterday I charged the battery and she fired first time. Inflated the tyres and drove around the village like I'd been using it every day. You've gotta love that!

Any help would be appreciated.

Cheers
Title: Re: Mk2 GTI 8v - Overheating when idle
Post by: Tom mk2 on 11 April 2009, 13:56
is the fan definately kicking in? and have you bled the coolant system, could be an airlock?
Title: Re: Mk2 GTI 8v - Overheating when idle
Post by: Sykopaf on 11 April 2009, 18:11
The garage were supposed to have drained the coolant system when they changed the water pump, but I've lost faith in that garage since my other car went in for it's MOT a couple of weeks ago and came out on the back of a flatbed because they'd been ragging the tits off it (I can't prove it but it's the only logical explanation).

So I think I'll try that myself.

Cheers
Title: Re: Mk2 GTI 8v - Overheating when idle
Post by: T_J_G on 11 April 2009, 18:17
Hi, I'm new here and have a problem I'm hoping you can help with.

It's on my 91 GTI 8v, it boils the water in the radiator when idle, steam just comes gushing out once the engines warmed up. It's blown the head gasket twice (and the heads been skimmed twice) so once more and that's all she wrote.

I've replaced the water pump, thermostat, radiator fan and one of the water pipes so far.

I've got a quote for getting my engine reconditioned and a mate has also offered me his VR6 engine for free when he transplants an R32 engine in his but I have a feeling this is something really simple that I'm totally missing.

It's a great little engine and I don't want to write it off just yet - it's been stood for 18 months or so in the cold and wet, untouched. Yesterday I charged the battery and she fired first time. Inflated the tyres and drove around the village like I'd been using it every day. You've gotta love that!

Any help would be appreciated.

Cheers

Expansion tank cap?
Title: Re: Mk2 GTI 8v - Overheating when idle
Post by: Sykopaf on 11 April 2009, 20:45
Expansion tank cap?

Thats where the coolant and steam pour out of. I have replaced the cap as well, in fact I think I replaced the tank itself a couple of years ago.

Given what I've already replaced what else is there I should try?

Radiator, pipes, anything else?
Title: Re: Mk2 GTI 8v - Overheating when idle
Post by: Ben Lessani on 11 April 2009, 20:52
Screams water pump / stuck thermostat.
Title: Re: Mk2 GTI 8v - Overheating when idle
Post by: Sykopaf on 12 April 2009, 01:04
Screams water pump / stuck thermostat.

Thanks for that.
Title: Re: Mk2 GTI 8v - Overheating when idle
Post by: rubjonny on 13 April 2009, 08:56
have you checked it over as per the coolant faq?
Title: Re: Mk2 GTI 8v - Overheating when idle
Post by: Sykopaf on 13 April 2009, 10:28
have you checked it over as per the coolant faq?

Yeah, I just did that yesterday. I have the blue cap the FAQ refers to. Thermostat and water pump seem OK. It starts to boil over when the temp gauge gets half way, before the fan should kick in according to the FAQ. Didn't want to leave it running after that to see if the fan does kick in at 3/4. I'm going to check the fan operation as per the FAQ this morning but it looks like it's not reading the temperature properly.

The thermostat seems to be behaving as it should according to the FAQ, the lower pipe out of the radiator stays cold until the temp gauge reaches almost halfway then heats up, but if the temp gauge is not accurate that would throw everything out right?

Cheers
Title: Re: Mk2 GTI 8v - Overheating when idle
Post by: Sykopaf on 13 April 2009, 10:45
have you checked it over as per the coolant faq?

Yep, bridged the pins on the fan and it spins straight away. Temp sender is knackered.

Thanks jonny, really appreciated!
Title: Re: Mk2 GTI 8v - Overheating when idle
Post by: rubjonny on 13 April 2009, 13:08
what does the oil temp say?
Title: Re: Mk2 GTI 8v - Overheating when idle
Post by: Sykopaf on 13 April 2009, 13:17
That's another problem needs sorting. The computer isn't working, so I can't see the oil temp  :undecided:
Title: Re: Mk2 GTI 8v - Overheating when idle
Post by: rubjonny on 14 April 2009, 10:07
ah, its nice to get a 'second oppinion' when you're diagnosing coolant faults  :sad:
Title: Re: Mk2 GTI 8v - Overheating when idle
Post by: Sykopaf on 14 April 2009, 15:53
A new temp sender is only like £5.50 and I can fit that myself (being a complete simpleton and relying entirely on my Haynes manual!), but I wouldn't know where to start on the computer!

Cheers for the help
Title: Re: Mk2 GTI 8v - Overheating when idle
Post by: Sykopaf on 18 April 2009, 10:00
A little help?  :huh:

I'm trying to replace the temp sender, only when I take the part out as instructed in the Haynes manual, it doesn't appear to be what it's supposed to be.

I've removed both plugs as below, it's supposed to be the front of the two:

(http://c2.ac-images.myspacecdn.com/images02/94/l_082f09a94a7443d0b8bce5e23f29767d.jpg)

These are the plugs I've removed:

(http://c3.ac-images.myspacecdn.com/images02/71/l_9e9aa841b389487c8b45d864cbf14cfa.jpg)

And this is the new temp sender:

(http://c2.ac-images.myspacecdn.com/images02/78/l_e17f445e0756492bb97b821326fcd831.jpg)

I feel like a kid where you've got to put the shaped bricks in the correct holes. The cube won't go in the round hole! :undecided:

I'm a complete novice as you can tell so if someone could point out my stupidity and give me a nudge in the right direction?

Cheers
Title: Re: Mk2 GTI 8v - Overheating when idle
Post by: rubjonny on 18 April 2009, 10:17
that is an early 8v and 16v sensor, so no good to you :(
blue one is for the ECU and you want from VAG:
025 906 041 A - 13.33+VAT

black one a gsf or scrappy one would be ok as the gauge isnt so important to be spot on, but if you want a vag one its:
251 919 501 D - 19.95+VAT
Title: Re: Mk2 GTI 8v - Overheating when idle
Post by: Sykopaf on 18 April 2009, 11:16
Legend, cheers jonny.

Was scratching my head cos the sender I bought matches the one in the Haynes manual for 1.8 fuel injected. Hadn't occurred to me there'd be a different one on mine.  :embarassed:
Title: Re: Mk2 GTI 8v - Overheating when idle
Post by: Khare on 18 April 2009, 12:44
judging by the colour of the water id flush the system, unless that is the colour of the coolant...
Title: Re: Mk2 GTI 8v - Overheating when idle
Post by: Sykopaf on 18 April 2009, 16:42
judging by the colour of the water id flush the system, unless that is the colour of the coolant...

It's Halfords brand 'colour of piss after ten pints and a curry' coolant  :wink:
Title: Re: Mk2 GTI 8v - Overheating when idle
Post by: Sykopaf on 25 April 2009, 15:50
 :sad: I've put the new temp sender in, still overheating. It's boiling over way before it should. Any other ideas?

Cheers
Title: Re: Mk2 GTI 8v - Overheating when idle
Post by: rubjonny on 27 April 2009, 08:13
is it still boiling just after half way?  what does the rad feel like, is it hot at both ends?