Thermostat opinions

[CornishSilver]

Just wondering on peoples thoughts to thermostats. I have a brand new engine with the old thermostat flaps welded open, is this advisable or would you say get a brand new one from the engine supplier? Paranoia of a thermostat failing and killing the engine was my initial reason for leaving the old unit on and welded open, however I'm now thinking that if I want maximum longevity out of the new investment that I'm probably better with one. Thoughts please

 

[Raggles]

Just wondering on peoples thoughts to thermostats. I have a brand new engine with the old thermostat flaps welded open, is this advisable or would you say get a brand new one from the engine supplier? Paranoia of a thermostat failing and killing the engine was my initial reason for leaving the old unit on and welded open, however I'm now thinking that if I want maximum longevity out of the new investment that I'm probably better with one. Thoughts please

The original Bellows thermostats fail open ...ie safe, I believe that the Mexican ones don't. If you can get hold of one ... go that way. I picked mine up from V W Evolution who had some in - so they are around. also see..

http://vwparts.aircooled.net/Thermostat-Type-1-65-70C-111-119-159A-p/111-119-159a.htm

My understanding is that the engine will not run correctly without the flaps operational and the thermostat in place. It also helps if you have an original fan shroud too.

 

[Webbaldo]

Age old question, like coke vs pepsi

On standard engines - General consensus is run them
On high performance - Don't bother but keep the flaps

The forum police on thesamba basically say if you don't fit them, you are committing treason.
Geneberg states without one your engine will wear roughly 18% quicker.

The 'local garage' man who says you don't need them is considered b*llocks these days.

However (and the major however), thousands of people run them in our climate without them fitted without much negativity.
I've had beetles etc without them. Just let them warm up and don't drive hard when their cold.

Never heard of an engine failing due to NOT having a thermostat, some may wear out quicker, but if your doing 3000miles a year I doubt you would find out.

Some people debate having the flaps is more important as they direct air around the heads which is needed. You have that so personally I wouldn't worry.

If its a summer driver personally I wouldn't bother, if its all year round or you have all the parts already maybe fit them?

As mentioned, original german bellows type, don't buy the Mexican spring crap.

Bellows can be easily tested with a heatgun

 

[chad]

If the flaps are welded open then the thermostat will have nothing to move.

You'll need new flaps and the associated bars etc along with a thermostat

 

[Zcat7]

I sourced and fitted flaps to my 1776 build. Seems a no-brainer really as fundamentally they don't stop the engine getting cooler, it just warms up quicker (especially with the failsafe vacuum/olcohol filled thermostat bellows). It's accepted wisdom that most engine wear occurs when cold around startup.

Air diversion to the head and around the pistons to avoid hot-spots is the next benefit and an 18% quicker wear rate (quoted in Webbaldo's post) is almost 1/5th of the engines lifespan so is considerable enough for me.

Can't comment specifically on hi performance (big bore) builds but surely the core principles are the same? I would only imagine that airflow around the larger bores might be different as you can't use standard tinware above 90mm pistons (might be worng on that?). I'm lead to believe that VW spent an eye watering amount on developing the cooling flow so that will naturally be changed if the piston bore and tinware is altered significantly.

 

[speedwell68]

There is no good reason to not have one.

 

[sparkywig]

Can't comment specifically on hi performance (big bore) builds but surely the core principles are the same? I would only imagine that airflow around the larger bores might be different as you can't use standard tinware above 90mm pistons (might be worng on that?). I'm lead to believe that VW spent an eye watering amount on developing the cooling flow so that will naturally be changed if the piston bore and tinware is altered significantly.

I'm running thermostat, flaps, standard tin and fan housing with 94mm barrels on my stroker engine.
You shouldn't need to adapt any tinware when running a stroker, as they're the same dimensions as a stock motor externally.

 

[Zcat7]

I'm running thermostat, flaps, standard tin and fan housing with 94mm barrels on my stroker engine.
You shouldn't need to adapt any tinware when running a stroker, as they're the same dimensions as a stock motor externally.

Thanks for clarifying!

 

[CornishSilver]

Thanks for some great input/views guy's. Had a chat with my air cooled guy who put the engine in today and turns out I had gotten a little confused, the flaps are not welded and are operational, it just the thermostat I don't have. His take on it and he's always had bugs and vans without and built quite a few engines, is not to worry about it as buses generally heat fairly quickly anyway. He reckons theres not a massive difference and that if its warmed up sensibly it would equate to 10% premature wear. The other thing as Webaldo pointed out at 3k a year I'm likely to not find out anyhow. I have just read that if you just have a hole there and no Stat that exhaust fumes can get sucked up into the heating system and into the cabin? If this is the case then think I will reinstate it, if not I'm not sure I will bother.

Another thing that I just thought of, am I right in thinking that when VW designed the engine that the oil recommended was a straight 30. If this is so then if I'm using 15-40 ,which I am, then would that make a significant difference to Genebergs 15-18% wear calculation, must do surely?

 

[Zcat7]

I have just read that if you just have a hole there and no Stat that exhaust fumes can get sucked up into the heating system and into the cabin? If this is the case then think I will reinstate it, if not I'm not sure I will bother.

Another thing that I just thought of, am I right in thinking that when VW designed the engine that the oil recommended was a straight 30. If this is so then if I'm using 15-40 ,which I am, then would that make a significant difference to Genebergs 15-18% wear calculation, must do surely?

The thermostat is on the "hot" side of the airflow and reacts to the temperature of the air blown over, and radiated from, the piston bores, so it's already done it's work and is on the way out and away from the bus. The thermostat doesn't even "plug" a hole, it just sits in the airflow. As the air that makes its way into the cabin gets sucked in at the back of the fan shroud (in the engine bay on the "cold" side of the airflow) I can't see how the absence of a thermostat could possibly result in exhaust fumes being collected as it's on the other side of the foam seal all together.

As for the oil question, I'm not brave enough to go near that one! :lol:

 

[CornishSilver]

[/quote]

The thermostat is on the "hot" side of the airflow and reacts to the temperature of the air blown over, and radiated from, the piston bores, so it's already done it's work and is on the way out and away from the bus. The thermostat doesn't even "plug" a hole, it just sits in the airflow. As the air that makes its way into the cabin gets sucked in at the back of the fan shroud (in the engine bay on the "cold" side of the airflow) I can't see how the absence of a thermostat could possibly result in exhaust fumes being collected as it's on the other side of the foam seal all together.

As for the oil question, I'm not brave enough to go near that one! :lol:
[/quote]


Thanks Z, make sense what you say

Im sure a scientist will come along and tell us at what temperature will the viscosity of a straight 30 be the same as a cold 15 :lol:

Cheers

 

[atafonso]

Never heard of an engine failing due to NOT having a thermostat, some may wear out quicker, but if your doing 3000miles a year I doubt you would find out.

That's where the problem is; if driving only short distances the engine will almost never get up to temp properly and it will wear considerably faster than if it had the thermostat.
Vw would NOT install them in the buses if they didn't think was necessary. Imagine how much money they could have saved?
If you want your engine to last, use the thermostat.
Just my £0.01
Abel

 

[speedwell68]

For a while my Bus didn't have a stat. When I finally fitted one the difference was immediately apparent. The stat is not there to help cool the engine, it is there to maintain a constant temperature. My engine ran at more or less the same temp around town and on the motorway. Also, VW have never solely recommended 30 grade for these engines.

 

[Zcat7]

Im sure a scientist will come along and tell us at what temperature will the viscosity of a straight 30 be the same as a cold 15 :lol:

I'll be honest I'm terrified of getting involved in the oil debate, though would love a definitive, undebateable answer to arise from somewhere!
I just try to apply logic to the problem but the thing is my head tells me a modern oil (at least a Fully Synthetic) should be better than an old mltigrade mineral oil from a "technical" point of view and yet our engines were designed to run on just such an oil. Then there's the whole operating temperature of an aircooled etc etc. Hence I default to Mineral and use the Halfords Classic stuff, changing it regularly.

Thinking about it - I used to race cars and religiously used Millers in my Caterham 7 racecar. My engine builder (assigned by the championships I used to run in) always said that my engines came apart clean and usually without hotspots of carbonated oil around the bearings, especially compared to other engines he worked on from within the championship. He attributed that to the quality of Millers Oils. Maybe I'll contact Millers and see if I can get a view from them..?

 

[CornishSilver]

Ok I ve decided a stat is a good idea, thanks for swaying me that way people it does make sense. What are your views on this though - As my engine is fitted already and I don't want the aggro of having the engine out, is it viable to leave the flap as they are and fit one of these as I'm full flow ??

 

[sparkywig]

That's an oil thermostat which goes inline with an oil cooler. It stops the oil from being cooled continuously and only opens when the oil reaches 80 degrees.
Totally unconnected with the cooling thermostat and flaps conversation.

 

[CornishSilver]

That's an oil thermostat which goes inline with an oil cooler. It stops the oil from being cooled continuously and only opens when the oil reaches 80 degrees.
Totally unconnected with the cooling thermostat and flaps conversation.

:lol: I just realised that and was about to edit my post so I didn't look like a knob :lol: too late now haha. The guy I spoke to on the phone suggested it and I have since cancelled the order, nice chap and a good salesman!!

 

[CornishSilver]

Double post deleted

 

[CornishSilver]

Can anyone point me in the direction of finding a nos bellows stat?

 

[sparkywig]

I might have a thermostat and mounting bracket in the lock up.