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Cooling system, am I going mad? 
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Joined: Mon Aug 18, 2014 6:07 pm
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Post Cooling system, am I going mad?
I bought my Libra last year, it has been nicely built and has very low miles. The head gasket, pump, bolts and belts were all replaced just before I got the car. However, it has had an overheating problem which shows itself when the speed/revs drop, rather than chancing it boiling over during the MOT I've tucked it away until I have chance to look at it.

My understanding is that the 'hot' water comes out of the top of the engine and is piped down the right (as you sit in the car) side of the tunnel. It should then enter the bottom of the radiator with the 'cool' water exiting the top of the radiator before it is piped back up the left side of the tunnel and back to the thermostat.

In that case, this might explain a few things..

https://drive.google.com/file/d/155i_ricl3bebdjHvUvduKLycXQLeI3Al/view?usp=sharing

Please excuse the poor quality of the picture, my phone camera has taken a beating.


Sat Sep 15, 2018 5:18 pm
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Post Re: Cooling system, am I going mad?
Mine was plumbed the same way:
Attachment:
WP_20151204_09_30_07_Pro.jpg
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Mine did overheat a bit in slow traffic and substantially on my first track day with the Metro rad. My cure was to go down the passat radiator upgrade that many others have done before before me - look out for Paul Drawmer's write up on his conversion as that is what I followed. I still routed the left hand pipe to the rad top (as did mr Drawmer):
Attachment:
pipelayout.jpg
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Worked a treat for me and no hint of overheating since, even on half hour track sessions. The oil overheats but not the water!!!

The passat rad you need is only about £50 new so would be a shame not to when you are already partly stripped down.


Sat Sep 15, 2018 8:08 pm
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Post Re: Cooling system, am I going mad?
The hot water should go to the top of the rad which appears to be what you’ve got?

Agree with Sanz though, stick a Passat rad in in.


Sat Sep 15, 2018 8:42 pm
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Post Re: Cooling system, am I going mad?
Interesting, thank you. Is it any particular Passat radiator?


Sat Sep 15, 2018 8:53 pm
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Post Re: Cooling system, am I going mad?
If you read through the 'radiator change' thread (below) all the info you need is there including an excellent how to guide by Paul D.

I've recently done mine and it was a doddle.

radiator-change-t3207.html?hilit=passat


Sun Sep 16, 2018 9:43 am
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Post Re: Cooling system, am I going mad?
Hot water rises cold water sinks, suction goes to the engine.

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Tue Sep 18, 2018 10:46 am
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Post Re: Cooling system, am I going mad?
Bottom hose to the engine i mean.

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Tue Sep 18, 2018 10:50 am
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Post Re: Cooling system, am I going mad?
Strictly speaking both hoses go to the engine 8)

In a radiator the hottest water is at the top and coolest at the bottom, so you want the bottom hose to be connected to the rear (inlet) of the engine (where the pump is) and the top of the rad connected to the front (outlet) side of the engine.

If you're getting overheat on idle that's almost certainly air in the system restricting the flow. On a factory setup the coolant flows round the (separate) heater circuit constantly so soon as the coolant is warmed up you should get hot air out the vents. If you aren't getting heat from the vents (esp at idle) then likely you have air in the heater matrix and it needs bleeding.

Also (IMO) the overflow take off (that goes to the expansion tank) at the rad is in a poor position given it is lower than the top of the rad so it's possible for air to get trapped at the top of the rad.

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Tue Sep 18, 2018 1:55 pm
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Post Re: Cooling system, am I going mad?
Hi all
I think some ended up with the plumbing wrong as I see it because of the original drawing which I will attempt to show here.
I crossed the pipes over at the engine end when I built mine as as others have said hot water should go to top of rad. I wondered if the confusion arose because the then usual donor car (Metro) had a Cross-Pipe by the rad.


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GTM Libra Water pipes.pdf [115.32 KiB]
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Wed Sep 19, 2018 2:52 pm
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Post Re: Cooling system, am I going mad?
A few mods to that sketch and it's much clearer.

Attachment:
Coolant pipes.png
Coolant pipes.png [ 105.15 KiB | Viewed 1487 times ]

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Wed Sep 19, 2018 3:12 pm
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Post Re: Cooling system, am I going mad?
Hi
Yes clearer for how it should be. But note Peter Beck's marking of TOP FEED at the Engine end going to the Bottom of the Rad and BOTTOM FEED to top of Rad, that is the confusion I was trying to convey.
Regards
Howard W


Wed Sep 19, 2018 5:11 pm
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Post Re: Cooling system, am I going mad?
Somewhat ambiguous yes. I think that's supposed to refer to top and bottom of the engine, rather than which bit of the rad it goes to.

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Wed Sep 19, 2018 6:32 pm
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Post Re: Cooling system, am I going mad?
Thank you all, I was clearly going mad!

I'm going to go with the Passat radiator and use the opportunity to reduce some of the restrictions in the system (some of the rubber elbows are almost flat across the bend). At the same time I can relocate the expansion tank take off to the highest point of the piping.


Mon Sep 24, 2018 11:20 pm
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Post Re: Cooling system, am I going mad?
Consider fitting a Pressure Relief Remote Thermostat too.

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Tue Sep 25, 2018 9:52 am
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Joined: Mon Aug 18, 2014 6:07 pm
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Post Re: Cooling system, am I going mad?
sidewinder wrote:
Consider fitting a Pressure Relief Remote Thermostat too.


It's certainly an option for the future, I fitted one to my K3 a few years back.


Tue Sep 25, 2018 9:09 pm
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