Reinstating cooling/thermostat system

[Zcat7]

This has been something I've considered for some time, more so since building my 1776 motor and as it's been a bit of a topic on here recently it's prompted me to think about it again.

I have none of the thermostat system in place that I can see and wondered what the best way to reinstate it would be. So far as I can tell there are no flaps, thermostat bracket or anything so what should I do; try to buy new or look for a 2nd hand shroud complete with the flaps and linkage?

Are new thermostats reliable or am I looking for (N)OS? Do old ones die after a while like water cooled equivalents? Also, as the engine is now 1776 should I consider a different rated stat, if there is such a thing?

 

[Trikky2]

Standard stat will be fine in a 1776 (or even a 2.3).

The stock stat is a type of brass alloy made on the principal of an accordion. They have inside them a small amount of a type of alcohol. When they warm up the alcohol becomes a gas and allows the unit to expand. This means if the thermostat ever cracks or leaks it will spring open. Eg. the thermostats "at rest" position is open (extended). It's a fail safe system.

If you buy a second hand stat then, if its in its closed (or compressed) state then its in working order. For this reason it doesent need testing.

If however you would still like to test it then only ever test it while its mounted in its bracket. If it is allowed to expand while not in its bracket it will over extend and this will cause cracks due to metal fatigue.

Being made of a brass alloy it can suffer from corrosion over a long period, especially from salt. Hence to protect it, its wise to keep it oily ( or alternatively a coat of internal cavity wax will also work). Paint will not work since its not flexible enough.

Sets of flaps and the associated linkage do come up for sale second hand or, as you say, so do complete fan housings.

I did see some Nos for sale a while back on the net but they were pricy.

 

[Zcat7]

Thanks Trikky

So all I need are the flaps, the stat, bracket and a pushrod? Are there any bushings in the fan shroud that I'd need to find if I found a set of flaps?

The stock stat is a type of brass alloy made on the principal of an accordion. They have inside them a small amount of a type of alcohol. When they warm up the alcohol becomes a gas and allows the unit to expand. This means if the thermostat ever cracks or leaks it will spring open. Eg. the thermostats "at rest" position is open (extended). It's a fail safe system.

Clever chaps those VW engineers...

 

[sparkywig]

The flaps are secured with 8 (4 each side) machine head screws as the picture. If your fanhousing has these holes then the flap mechanism with bolt straight in.

 

[Zcat7]

Thanks for the picture Sparkywig, very helpful. Yep, looks like those holes are there. I managed to find a full set of flaps, rods, springs, stat etc in the For Sale section so hopefully this will be going in place soon!

Neil

 

[sparkywig]

You know it makes sense.

 

[Trikky2]

Good news

Nice find especially with the rods and spring included.

When you get round to fitting it just make sure the rod down to the thermostat is not catching because they are not straight but rather easy to bend by accident.

A workshop manual will tell you how to adjust the thermostat when you fit it or there's also info on the net if needed.

 

[Zcat7]

You know it makes sense.

I know it

Will take a look in my Bentley manual when it comes to hooking it all up, hadn't even realised the thermostat needs adjusting!

The guy I got the bits from has a bit of a job lot going and has apparently sold 3 sets of flaps already. Seems like thermostats are cool again, if you'll pardon the pun...

Thanks guys

 

[Zcat7]

OK so the flaps are in place. Its a pretty hot day here so I thought it would be good test conditions. After refitting the engine I ran her up and just watched the stat to see if I could spot the bellows opening. This is quite hard to do as your eyes start to play tricks on you and the process is quite slow! Actually what I noticed more than anything was the draught start to blow from the lower sled tins. I was quite surprised at how long it took for the stat to open at all, which just goes to show that even on a warm day like today the bus would have been over-cooling without the flaps! However with that said, the only indication I have now with regards to the engine temperature is the oil temp gauge. Back in January, on the longest run I managed, this went up to about 130 (it starts at 120...) today it rose to 180 after a touch of brisk driving (accelerating up hills) and cruising at about 50. Is this too hot? How can I check if the flaps are opening fully and/or the stat is expanding enough?

 

[Trikky2]

180F is fine. Start worrying if it goes to 240F (115C).

When fully open the thermostat contacts the top of its mounting bracket.

 

[Zcat7]

Thanks Trikky. I'll check for that. Its good to know that when I tune the carbs I will have a "fully warm" baseline to work from!

 

[dannyboy]

May I ask who you got the flaps & bits & bobs from? I'd like to reinstate mine...

 

[Zcat7]

Got the bits from this guy

http://forum.earlybay.com/viewtopic.php?f=27&t=54349

 

[dannyboy]

Got the bits from this guy

http://forum.earlybay.com/viewtopic.php?f=27&t=54349

Cheers