Twin Fan Set-up...

[bacardincoke 42 1 Cars]

Before you roll your eyes, I'm just looking confirmation that my understanding is correct before reinstalling my set-up.

 

There's a lot of useful write-ups on the forum, but I'm obviously relying on what has been said is still current and correct.

 

When I got my '89 1.9 GTI last year I later discovered it already had the twin fans / heavier radiator and cowl from a TD fitted. The install seems to have been an old one from the 1990's and the radiators age meant it had sprung a small leak.

 

I now realise the twin fan set up is generally considered a pointless upgrade for normal UK driving but as it was already there I stuck with it.

 

I also now know it was only a partial upgrade as the original GTI fan wiring, including the resistor was still being used and had not been replaced with the TD's additional box of relays. Only one fan was being powered!

 

I've since added that extra box / removed the resistor etc. which probably wasn't working anyway, as it was crumbling apart.

 

I've marked out where I believe the various connectors go on some of the images below, it's mainly the 2 pin brown one from the TD relay box to the GTI shunt box that I'm unsure about. There's only one remaining free slot so I'm perhaps wrongly assuming it's the correct one?

 

The brown test connector... Am I correct in saying it's just a case of bridging one or other of the two outer pins to the center pin to check each fans in turn? I already know they're working fine having connected them directly to a battery, but if they need checked in the future when back in the car it'd be useful.

 

The leads with the grey 2 pin connectors from the fans themselves... their counterparts within the TD relay box - one has three wires coming from it, the other two. Is it immaterial which connects to which?

 

I'm guessing which ever way round you do it will determine which of the two fans is powered on and when, but that's presumably of no consequence?

 

The thermoswitch... the TD relay box came with one that has the range 92.5 - 97.5 stamped on, it's a purple banded one.

 

As it's an unknown and secondhand I have a new Valeo 819747 with the ranges 97/92 and 101/96 stamped on... are one / other or both suitable?

 

I've identified the previously unused 2 pin red connector in the car, which goes into the TD relay box... all's OK there.

 

The yellow earth block from the TD relay box... I believe it goes to the earthing block behind the nearside head light.

 

Thanks in advance...

 

 

[welshpug 1,621]

looks all in order yes, make sure it has an 83 degree thermostat installed not an 89 degree one.

 

with a single fan I'd be using the lower TD fan switch but as its a twin fan arrangement you'll be fine on the slightly higher gti temp, probably rarely switch to the higher speed!

[bacardincoke 42 1 Cars]

Thanks, looking good then... at the risk of looking foolish, I'm new to the mechanical side of things and it's taking time picking up stuff!

 

When you say thermostat, do you mean the cap on the expansion tank?

 

If so I got one recently here - https://www.ebay.co.uk/itm/Genuine-OE-Quality-First-Line-Radiator-Expansion-Tank-Pressure-Cap-FRC67/352082186956?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649#vi-ilComp

 

I've tried ringing the seller and maker but they're seem to be closed because of the virus.

 

There's nothing on their sites, the cap or packaging that mentions temp. only bar and psi... I didn't even know they had different ranges.

 

The old cap may well be the original its that well used but it too doesn't have any obvious temp. info. on it.

 

They do all show it's for my '89 1.9, but then the radiator isn't standard.

 

 

[welshpug 1,621]

no, that's the expansion tank cap (as is evident from the description ,

 

thermostat is a valve in the system that allows coolant to flow from the thermostat housing on the end of the cylinder head through the top hose into the radiator.  

 

2x 13mm hex nuts hold the cap down, underneath will be the thermostat and a rubber lip seal, or two flat seals either side depending on the type fitted.

 

they are rated in degrees that they open at, the original temperature for the gti engine was 89, there is an 83 degree thermostat which physically sits in the same hole.

[bacardincoke 42 1 Cars]

That's spot on, cheers... this is probably small stuff to most but a school day for me so appreciated...

 

Have the thermostat out (Made in France, Dauphinoise Thompson, 89 degrees)  and it's dated 04/96. The rubber seals were rigid and the valve itself was an effort to move so likely not been out for quite a while, nor performing at it's best.

 

Did the hot water test and in fairness it still works, plus smoothly at that, but it didn't seem to fully open to around 96 degrees.

 

Getting there!

 

 

 

 

 

[bacardincoke 42 1 Cars]

On 4/24/2020 at 11:48 AM, welshpug said:

looks all in order yes, make sure it has an 83 degree thermostat installed not an 89 degree one.

 

with a single fan I'd be using the lower TD fan switch but as its a twin fan arrangement you'll be fine on the slightly higher gti temp, probably rarely switch to the higher speed!

Finally got an 83 degree thermostat (with both the seals needed, oddly most seem to only come with one for some reason)... Ordering small items like this online isn't as straightforward as you'd want it to be, for every seller you approach there's a different answer as to what's suitable.

 

Having read another recent post... is the 83 degree thermostat recommended so that there's compatibility with the 97/92 - 101/96 thermoswitch - I'm trying to build up my knowledge and knowing why is useful.

[petert 549]

No, if I was fitting the 97/92 - 101/96 thermoswitch, I'd fit an 88 or 92 thermostat. An 83 thermostat is too cold, even for Australia.

[welshpug 1,621]

gti6 runs 83 standard without issue, later alloy engines use 83 also.

[bacardincoke 42 1 Cars]

As it stands this is my set up -

 

Twin fans running through the correct TD relay box / larger, new TD radiator (Ordonez) / 83 degree thermostat and 97/92 - 101/96 thermoswitch.

 

The car's a standard non-cat. 1.9 GTI, Oct 1989 phase 1.5, 118K, good history and seems to have been well maintained all it's life... It's a hobby car, so will not be doing more than 3000 easy summer miles per year under normal UK driving conditions.

 

Will this combination cause any issues, no matter how small?

 

For the price of another switch and /or thermostat I'd prefer to have the optimum set-up and as the cooling systems out of the car now it'd be the handiest time to do it... Cheers.

[pug_ham 240 3 Cars]

 

 

On 4/30/2020 at 10:52 AM, bacardincoke said:

Finally got an 83 degree thermostat (with both the seals needed, oddly most seem to only come with one for some reason).

Later thermostats use a single thicker over seal that fits over the thermostat rather than the earlier type that sit either side.

 

On 4/30/2020 at 1:04 PM, bacardincoke said:

As it stands this is my set up -

 

Twin fans running through the correct TD relay box / larger, new TD radiator (Ordonez) / 83 degree thermostat and 97/92 - 101/96 thermoswitch.

 

The car's a standard non-cat. 1.9 GTI, Oct 1989 phase 1.5, 118K, good history and seems to have been well maintained all it's life... It's a hobby car, so will not be doing more than 3000 easy summer miles per year under normal UK driving conditions.

 

Will this combination cause any issues, no matter how small?

 

For the price of another switch and /or thermostat I'd prefer to have the optimum set-up and as the cooling systems out of the car now it'd be the handiest time to do it... Cheers.

That should be fine, I doubt you'll have any problems with that set up imo.  Swapping the thermostat is easy enough if you decide it's running a bit cool but the 83' thermostat is very widely fitted to the XU petrol engine range in the UK so I wouldn't expect you'll find it needs changing for a higher temp one.

 

For the use you state, a normal GTI rad with single fan should be more than sufficient, especially running the TD fan relay system over the standard set up.

 

I don't think the twin fan set-up is necessary on a GTI, all it does is cool the system down quicker but with the TD thicker rad & additional coolant in the system, I doubt they'll ever reach the second stage of the switch.

 

I used to run the original system wiring & resistor on a single fan & standard GTI radiator on mine which used to do trackdays without any issues.

 

g

[bacardincoke 42 1 Cars]

Cheers for that... I only realised the twin fan set up wasn't standard when a new radiator was needed and all sorts of complications arose when trying to order different bits.

 

On reflection, as a mechanical novice, it would probably have been less complicated to have gone back to the standard set up at that point, but I'm committed now... hopefully this is it sorted out!

 

Hasn't dulled me wanting to learn more, really enjoying getting into learning how stuff works and the satisfaction of fixing in preference to replacing.

 

 

[bacardincoke 42 1 Cars]

The car's not been able to be started for longer than hoped due to being let down by a part supplier.

 

Anyhow, got most of what was needed this week and it's all fitted.

 

The brown test plug has turned out to be useful and this is what it's showing -

 

One of the two test connections operates just one fan at high speed, while the other fan is idle.

 

The other test connection will operate both fans simultaneously, but each is at low speed.

 

Is this what I should expect, indicating things are working as they should be?

 

 

 

 

[bacardincoke 42 1 Cars]

Let her sit idling for 10 - 15 minutes and the temperature gauge went up to just short of the mid position and stayed there. 

 

Both fans then eventually kicked in at low speed for less than a minute then off again, and repeated that cycle, so everyting seems to be spot on... finally!