AGU Coolant lines re-route

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SUB-LIME
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AGU Coolant lines re-route

Post by SUB-LIME »

Hi All,

busy working out the coolant route for the AGU 20vT in my Polo Playa.
I have done a lot of reading and came up with this.

My diagram is on the left; does this look correct?

What i am confused about is the loop; taken from the ref link below " when the t-stat reaches temp, it opens up allowing coolant to flow through the radiator part of the system"
Does the thermostat open mechanically? Does it open a valve switching between A and B (my diagram)?


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Ref used: http://forums.vwvortex.com/showthread.p ... ing-System
Polo Playa 1.8 20vT, FMIC, K03s, Hi-flow manifold, TIP, 80DP/76FF, PP XMS5B, Custom FFZ.
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Re: AGU Coolant lines re-route

Post by SUB-LIME »

Also want to know which is the inlet and outlet of the heater matrix that comes from the firewall on the polo playa 1.6i (2002) ?
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Re: AGU Coolant lines re-route

Post by Torker »

The thermostat got two disks covering the two outlets, they are mechanically linked together. When the thermostat opens the smaller disk closes the 2nd outlet thus diverting the water through the radiator.
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Re: AGU Coolant lines re-route

Post by SUB-LIME »

@Torker thanks. Okat I see. But if the thermostat closes the one inlet then where does the return from the heater matrix go?

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Re: AGU Coolant lines re-route

Post by SUB-LIME »

Id assume that "B" is opem first to allow the water to heat up quicker for cold start and from what I have read a bypass loop for low rpm... if that inlet closes ?

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Re: AGU Coolant lines re-route

Post by Torker »

SUB-LIME wrote:@Torker thanks. Okat I see. But if the thermostat closes the one inlet then where does the return from the heater matrix go?

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That's the part that I don't understand, if the heater valve is closed you will get no circulation through B, in the 8/16V motors B goes to the water port on the front of the head (to allow the water to circulate in the motor when the thermostat is closed)

Edit to add: I had a look at the diagram again and when the thermostat is closed the water will circulate from B through the oil cooler to the port on the side of the head, allowing circulation through the motor...
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Re: AGU Coolant lines re-route

Post by Viper »

Torker the AGU has a single stage thermostat so no second disc. It got a internal water pump.
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Re: AGU Coolant lines re-route

Post by SUB-LIME »

@Viper so how does it work? Will the diagram i posted work correctly?
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Re: AGU Coolant lines re-route

Post by SUB-LIME »

So does only "A" close and when the tstat reaches temp it opens "A" as well?
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Re: AGU Coolant lines re-route

Post by SUB-LIME »

So i have done more reading and figuring out the loop. What @viper said would make sense if it does indeed use a single valve on the thermostat.
The reason the heater return,oil cooler return flow and the turbo return ("B") into the block inlet is to warm the car up faster then once the thermostat reaches temp it opens "A". B never closes even though it is a hot water return going into a cold feed from the radiator it gets balanced out. Id assume that the heater matrix and oil cooler really dont have a big heat effect on the inlet water temp; howeber this is based on these cars being built for coolder temps (Europe) and we rarely see -2*c +. So my plan is to re route the turbo outlet to the hot side of the radiator. this should 1) lower the inlet temp going into the block 2) supply a cooler water flow to the turbo.

* I hade to turn my oil cooler frontwards as the pipes for the AC were interfering with it. In the diagram to the right you can see the oil cooler faces the right.

I have done research on using the stock Polo radiator. the difference is around 200ml as both radiators are 2 core.
Audi A3 1.8t 8l Stock Radiator: 652 x 404 x 24
Polo Playa 2001 1.6i Radiator: 628 378 x 34 (Double check your car as some come with a 400 x .. x .. radiator and that is far too small.)

I have phyically measured both and spoken to Silvertons; since they are both 2 core you can actually use a volume calculator to work out the dimensions and get a measurable difference between the two in ml. The other concern was pipe diameter as you can have a larger radiator but if flow is restricted then you have issues; luckily both radiator/main pipes are 32mm diameter.

To compensate for the slight loss of volume between radiatiors i will increase the coolant mixture. if that doesnt hold up i will have a small pre-radiator built and use it after the main radiator outlet but before the block inlet. this will give better cooling and give more water volume. this is really a last resort. (small custom full ally rad with 32mm ports from Silvertons are around R2-2.5K)

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Re: AGU Coolant lines re-route

Post by missioner »

I have read through this thread and I hope that I can help in some way.

I will ignore the diagram as I believe it's confusing matters and has some errors.

The main pipes should flow like this, water pump through the block to the top pipe of the radiator, bottom pipe to thermostat and back to the water pump.

The 8v engine has the dual action thermostat in the water pump housing and that is where the bypass circuits come in, therefore for the AGU they can be ignored, as it's thermostat is in the block iirc. Then to get back to the expansion bottle which I assume you would like to use for the OEM looking engine bay, on the 8v MP9 motor it has a bleed pipe that runs via the throttle body that is usually attached to the highest poin in the cooling system that is on the main radiator circuit. This is simply to allow air to escape to the bottle and bleed the systems and avoid airlock, which is lethal to engines. The lower pipe on the bottle is not vital as to where it is connected as long as it's reasonably low down to fill the cooling system and force air to the bleed pipe.

The heater and the oil heat exchanger, I've noticed, run together on a bypass circuit. This line will run parallel to the main circuit and should circumnavigate the thermostat.

Torker if you can post the link you gave CCBB about the function of the heat exchanger. I think it will help our friend here.

Sub-lime what car did you source your engine from? The diagram you have is for the A4 and I think that may be a source of some of the confusion regarding the polo install as the A4 is longitudinally mounted vs transverse.
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Re: AGU Coolant lines re-route

Post by SUB-LIME »

@Missioner,

Cheers for reply.

The Engine came from my A3 1.8T.
The bottom diagram is from transverse motor; the diagram came from Alldata :)

Where have i gone wrong with my diagram?

1) The expansion bottle bottom feed is going to the lowest part of the feed into the motor and the bleed pipe going to the top pipe of the radiator.
2) From what i have seen #9 is a Gearbox oil cooler which is only on auto gearboxes. - http://workshop-manuals.com/volkswagen/ ... u_aqa_arz/

Regrdless if the motor is longitudinal or transverse both motors waters lines run the same direction through the block and have to supply and return the exact same parts (oil cooler, turbo, heater and oil).
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Re: AGU Coolant lines re-route

Post by missioner »

First the radiator is in backwards I relation to the motor if memory serves me, and it seemed that something was off.

Personally I wouldn't go to so much trouble for this. It has been done before and as long as you have at least 80% of what's in the Audi engine bay you should be fine.

What I mean is if you scavenge a large part of the plumbing from the donor car and it very well might be a plug and play thing, or at least be close enough to only require minor modifications in order to work. A little mixing and matching with what comes out and you could have a very OEM looking install, without any ugly joins or goonies to get it to fit.
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Re: AGU Coolant lines re-route

Post by missioner »

Sorry I only saw the second diagram now.

no way will I disrespect them again.

I am a more hands on guy and it's harder for me to visualise what's going on without a car being present
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Re: AGU Coolant lines re-route

Post by SUB-LIME »

Haha they say you're fogiven . Thanks for the input. Yeah the diagrams give me a headache..

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Re: AGU Coolant lines re-route

Post by missioner »

Then why do them?

It's not like the build will be done in a weekend. There will be quite a few hurdles to overcome to finish the job.

I understand that preparation will help avoid a number of issues, but nobody can foresee every possible problem ahead of time.

If I can give a small tip
Check if the transplant motor is a short or long block, it has to do with the engine mounting. Short block mount is taller than the long block one and if you have the wrong one the engine tilts up on the drivers side.

I use tapatalk and can't see signatures, post a link to the build thread
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Re: AGU Coolant lines re-route

Post by SUB-LIME »

@missioner, the motor is mounted already. Gearbox fitted and turbo and most wiring done already. Control arms, cv's and all have been done and fitted poly bushes. Its water pipes, fit exhaust and tune. Thats all thats left

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Re: AGU Coolant lines re-route

Post by SUB-LIME »

Polo Playa 1.8 20vT, FMIC, K03s, Hi-flow manifold, TIP, 80DP/76FF, PP XMS5B, Custom FFZ.
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Re: AGU Coolant lines re-route

Post by missioner »

Thanks heading there to subscribe
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