wbx twin thermostat puzzle

[itchyfeet]

To help Atoomer23 who has an early and a late thermostat housing on the same engine with a mixture of early and late pipes I'm trying to work out if it's a problem of it whoever did it thought about it and it's ok.


I have both early and late parts diagrams
I have the late flow diagram in the wiki, but I need an early diagram, anybody have one?
it looks to me like the main flow through the water jackets is in and out on the same side on the early system anybody confirm this? (Late is in one side out the other)

Also can anybody confirm if the early thermostat housing above the stat has two seperate paths or are all ports joined?

[CJH]

Here's an early system schematic, from Bentley



I have a spare of the early thermostat housing - I'll dig it out and let you know about the internals.

[itchyfeet]

Excellent thanks, never thought of Bentley, I was right main flow is back out same side, so as there is a metal pipe from rhs exit back to housing with lhs exit it's important to know whats happening in the stat housing as his return to rad from there is capped off.

[CJH]

Can you see what you need to in this photo? That capped off outlet (the topmost outlet in your engine bay photo) is directly connected to the stubby hose that goes to the left hand head, and to the circular hole (next to the triangular hole) in your photo of the housing. And it's the same chamber that the temperature sender sits in.

[CJH]

Rewriting that in terms of inlets/outlets:

That capped off outlet (the return to the radiator) is directly connected to the inlet from the left hand head, and to the inlet from the right hand head. And it's the same chamber that the temperature sender sits in.

Until the thermostat is fully open, such that the end of it blocks the circular hole in the middle of the housing, the triangular hole (the flow to the pump I think) is also connected to this main chamber.

[silverbullet]

"Circular hole in the middle" is the bypass port that allows coolant to circulate around the engine block and heater but not the radiator before the thermostat opens

[itchyfeet]

Ok so I think I have got it
the confusing thing is that on a late the bypass hose shown on the diagram must reverse direction of flow to cool the left hard side whereas the bypass pipes on an early stay the same flow direction

Now with a capped off out to rad on this setup the bypass pipes no longer carry coolant when thermostat opens but then the late cooling system path through the other side of the water jackets kicks in.

I think even if one stat opens before the other it still works, going to draw it.....

I wonder if having two bypass circuits when cold is an issue, probably not

[silverbullet]

The cooling system can't possibly work properly with two stats on the same engine.
At least one cylinder is going to be starved of coolant flow, it doesn't take much to get a head cracked from local overheating.
I would stick with the system that suits the age if the van, unless its more economical to sell any good early parts and go late...

[CJH]

I may me a bit late with these if you've already figured out the flow.

Here's a shot with the thermostat in place:


Here's one which I've annotated to show the interior connectivity:


And here's another annotated one showing a different angle:

The cooling system can't possibly work properly with two stats on the same engine.

Is it possible that one of the housings doesn't actually have a thermostat inside it? Maybe the early housing has been retained purely for connectivity reasons, and actually there's no thermostat inside?

[itchyfeet]

Thanks CJH & Silverbullet for the pics and explanation, assuming I understand right the thermostat closes off the bypass route when open and rad route when shut.

So I have seen Atoomer's this van this morning ( new to him) and had a good look, the rad gets hot and fan kicks in, temp guage sits right ( it did register too hot once with a genuine coolant loss fault). The cooling system appears to work.

So I drew out the stats closed and stats open flow diagrams and I think it works, not sure by luck or judgement but it looks like it works to me.
You would have to have two stats for this to work or the bypass route does not get closed, when you think about it it would not seal without a stat in place, the old housing has one as he has seen it, new housing we don't know yet but I think it will have.


Having said all that my advice to Atoomer23 was change to to the correct late system, you can never be sure it will perform well, I hope he takes my advice but let me know if you agree with my diagrams and it will buy him some time.

I can help with a list of parts some of you lot may have some of them.

Original post
https://club8090.co.uk/forum/viewtopic.php?f=39&t=138748" onclick="window.open(this.href);return false;

[itchyfeet]

Parts list, worth shopping around but also worth buying quality not rubbish.
Also worth asking breakers on here or wanted section

left hand head to bleed rail hose
http://www.brickwerks.co.uk/index.php/t ... -rail.html" onclick="window.open(this.href);return false;

Header tank to bleed rail hose
http://www.brickwerks.co.uk/index.php/t ... -rail.html" onclick="window.open(this.href);return false;


rh head flange to bleed rail
http://www.brickwerks.co.uk/index.php/t ... -2806.html" onclick="window.open(this.href);return false;

Large metal pipe to late pump (out of stock but they will get it in)
http://www.brickwerks.co.uk/index.php/t ... ystem.html" onclick="window.open(this.href);return false;


Header tank to carb and large metal pipe ouch look for second hand
http://www.brickwerks.co.uk/index.php/t ... choke.html" onclick="window.open(this.href);return false;
http://www.ebay.co.uk/itm/VW-T3-1-9-WBX ... 3a84f4a1b6" onclick="window.open(this.href);return false;

Late header tank
http://www.brickwerks.co.uk/index.php/t ... 86-on.html" onclick="window.open(this.href);return false;


Late tank cap ( genuine)
http://www.brickwerks.co.uk/index.php/t ... nuine.html" onclick="window.open(this.href);return false;


Need a late pump but you have one

need the late header tank support, second hand I think 025121409D

[andygriffiths]

I know this is an old post, but did this get resolved, I have two thermostat housings and not surprisingly some cooling issues, which I think I have nearly worked out.

Just interested..

[itchyfeet]

I know this is an old post, but did this get resolved, I have two thermostat housings and not surprisingly some cooling issues, which I think I have nearly worked out.

Just interested..

No idea, another one of those people that were happy to come around my house take my help then never heard from them again.

Post up some pics of yours and we can help.

You can add pics here and copy BB code link then paste in you post on here
https://www.techpowerup.org/upload" onclick="window.open(this.href);return false;

[937carrera]

He already has in his own thread............ and is using the search function

https://club8090.co.uk/forum/viewtopic.php?f=37&t=168482

See you over there