No thermostat and no vents flaps

[Adam1970bay]

Hi our bay has both. The trekker has neither, the dog house has the air block offs as does not use the heat exchanger. Both engines are 1641 twin port

What are the pros and cons to having no vents flaps and no thermostat?
Or would you source getting them and fitting them?

 

[neilswheels]

So, the thermostat and vents allow the engine to warm up when its cold, blocking air to the barrels/heads until the stat expands and the flaps open, allowing air to pass over the heads and barrels, as I suspect you already know.
Personally, I kept them all in our buggy engine, mainly because at the time (early 90's) I thought it was necessary, however, the tinware for the bus engine i'm putting in, i've deleted the lot. My thinking is that they were originally fitted to allow the engine to come up to temp in the winter, my bus wont see winter use, not proper cold use anyway, so I left them out. That and hearing that the 'new' thermostats fail in the closed position, allowing no air flow at all, made me think this is also the better option for an occasional use car.
Just my opinion, I'm sure their will be others that think they are extremely necassary.

 

[Clem]

The general argument is that VW would never have fitted them from factory if they hadn't been required.

The thermostat allows progressive cooling on start up so the engine warms up efficiently and doesn't get full bore cooling when its cold, so it prevents premature engine wear. The flaps direct the air so the hottest parts of the engine get priority cooling, and make the heating system most effective.

All that said, our VW's are now in general, low mileage hobby cars that are modified and subjected to fairly regular maintenance, so I think the effects mentioned above will be minimal. If you have the parts and they are in good order, then fit them and use them, but I really wouldn't worry about not having them.

 

[static]

Here in California it was common to remove the thermostat, flaps, levers, etc., as they were thought to either be unnecessary in our temperate climate or because folks were worried that the thermostat would fail (and that would fry the engine).

In essence, my Hippie forefathers were convinced that they knew more than multi-generational teams of German engineers.

My ‘71’s engine has no thermostat. The levers are long gone and the flaps are welded in the “open” position.

Now, (1.) it takes about 30 minutes to come up to proper operating temperature where it runs its best, and (2.) my heater never really heats, even though my mechanics have repeatedly assured me that everything is correct underneath (heat exchangers, insulated covers, cables et al).

I live in the desert now. For most of the year, a heater is not needed, but right now it is, damn it!

 

[matty74]

I managed to source some and fitted them last year when changing to twin webers.
As others have said they don’t fully open in colder weather, allowing the engine to be controlled at a nice operating temperature.

I noticed this on our last trip of the year last December and was slightly concerned because the flaps weren’t fully open after a long run, but then realised it was perhaps because of the fact it was Baltic outside.
The van ran a nice steady temp on the gauge throughout all of this and the dipstick was cool to the touch.

My basic understanding is that the flaps regulate the temperature rather than being either open or closed. I’m happy to have them mine’s a 1970 1641 S/P

 

[Adam1970bay]

Thanks
Basically if I can find some before engine goes back together get them and fit them, guessing there is s a size difference between twin and single port ones.

 

[K@rlos]

On stock, 100% original spec engine builds we fit the thermostat & flaps, On anything breathed on however we do not.

 

[matty74]

Thanks
Basically if I can find some before engine goes back together get them and fit them, guessing there is s a size difference between twin and single port ones.

I’m not 100% sure about the flaps themselves being different, but the actuator bar at the back differs between single and twin because of the doghouse cooler.

Hopefully someone will post to clarify that.

Return springs are readily available, as are the retaining clips that secure the actuator bar at the back.

Thermostat and brackets are a bit hit and miss, but they do pop up on eBay. You’ll need the actuator rod too.

I ended up buying a couple of shrouds that had some but not all of parts, then cobbled it all together and sold the bare shrouds on.

They’re out there, it’s just finding them.

Here’s a pic from Bentley manual


Good luck

 

[pierrox]

You can get new ones, and if they were to fail, it would be like the og ones (ie in "open" position, not in "closed" like the Brazilians).
But they have to be shipped across the pond:
https://www.awesomepowdercoat.com/vw-thermostats

 

[static]

You can get new ones, and if they were to fail, it would be like the og ones (ie in "open" position, not in "closed" like the Brazilians).
But they have to be shipped across the pond:
https://www.awesomepowdercoat.com/vw-thermostats

Yep. That’s where I bought mine. Luckily (for once!) I live on the same side of the pond.

 

[Clem]

Test them by using hot water, don’t be tempted to use a blowtorch

 

[sparkywig]

Test them in the bracket with hot water or they will rapidly stop working.

 

[Stuartk]

Hi guys I'm just fitting the flaps etc to mine as I've been running with out them for a couple years on my 1776cc. The engine never warmed up and rarely got the oil above 80 degrees. I even removed the external oil cooler. The replacement doghouse ( fan shroud) didn't come with drilled holes and cutouts to handle the flaps so having to drill them myself. I have a waxstat instead of a bellows type. Hopefully it may help. I don't have heat exchangers as I have a gas under floor heater connected to the original heating pipes of the van.

 

[Stuartk]

The wax stat.
Test fit of the flap assembly

 

[matty74]

I’ve been really pleased since fitting them a while back .

 

[Stuartk]

Having trouble getting the thermostat rod between the cylinders on my 1776cc . The lower air shielding is in the way. Not sure how to progress right now

 

[scull]

Thanks
Basically if I can find some before engine goes back together get them and fit them, guessing there is s a size difference between twin and single port ones.

Hi all. When I blew up my old stock 1600 twin port engine and replaced it with a 1915, my garage (specialist air cooled) had suggested I leave the thermostat and flaps out as in their opinion they were more trouble than they are worth. So I took their advice and I have got to say I have had no troubles since. That was around 10 years ago! However, my bus takes around 20 mins to warm up to around 85C sump oil temp, so on short trips the sump oil temp barely reaches 80C. On longer runs averaging around 3500 rpm my sump oil never gets warmer than 92C. I have a secondary external oil filter and oil cooler fitted. My oil temp thermostat opens at 85C so sends the oil through the cooler only when its above that temperature. I have a nicely located flashing LED on me dash to let me know when the oil thermostat is open. I guess (like most of us on here), I have fitted additional 'worry gauges'. Mine are for oil temp and cylinder head temp plus others fitted to keep me alert during longer drives. For me, the more important parameter for sufficient air cooling is CHT (No 3) rather than sump oil temp which has had some cooling on its way down to the sump after doing its work around the engine where the oil temps will be much warmer locally. My main concern with my engine with no thermostat fitted was the potential for excessive water condensation oil contamination forming sludge due to my oil not getting past 100C but I have not seen evidence of that when examining my oil and inside of filler cap plus my catch can for mayo deposits after my oil changes (yes I know what your thinking, very very sad). However, lets face it, if you are changing your oil at least every 3000 miles then I would think you would be draining any excessive sludge out during the oil change. Sorry to go on a bit.......... Scull.

 

[ozziedog]

Yet another on my ‘To Do’ list. I’ve got a fan housing in my garage but not the correct one for the van, but it’s got a full set of flaps in it. It’s the rounded one with no place for the oil cooler. Does anybody know for certain if these flaps as a unit might fit my regular fan housing? Ive also got a thermostat somewhere and bits and bobs. This has always been on my list of the next time that motors out!!! And usually, fixing it , and getting it back in, usually over rides the long list of ‘To Do s’ while the noisey cupboards empty. I like the idea of the motor warming up quicker, and having a fully working heater in the winter really really should take precedence over a lovely hot heater on the hottest days in the summer. Mrs Ozziedog comments every year on how cold it is in the van in the winter when ever it’s baking hot outside and the heat is scorchio on the screen and we’re opening the little windows trying to blow the heat out. The condense issue is also there in the back of your mind and secretly we all would like our motors warmed up to temp quicker especially in the winter without resorting to charging up the local big hill to gain a few degrees.

Ozziedog,,,,,,,,,,Mrs O might like the heater working great too in winter

 

[Stuartk]

Well if it helps ive just moved the flaps from the original dog house to a round one .

 

[YellowBay69]

Flaps connected as is the bowden cable to control on the air filter.