engine thermostats

[johnr]

My engine ('71) has no thermostat.  Is anyone else running w/o one?  I've had no problems except she seems to take quite a bit longer to warm up in the winter.   

[Bookwus]

Hiya John,

Yep, without a thermostat your engine will tend to run cool and take longer to warm up.  That can pose a bit of problematical situation in that your engine wants to warm up quickly.  That, in turn warms up the oil and thins it out allowing it to get where it needs to go to protect surfaces.  When the oil stays cooler at start-up the engine is going to be seeing more wear during start-up.  So, it is a good idea to run with a thermostat.

It's been argued by those in warm climates (sorry, Oregon does not qualify) that they do not need to run thermostats.  I could think of situations in which this MIGHT be true.  But when I consider that VW specifies thermostats to be run in EVERY climate I tend to think it just might be a good idea to have that thermostat in there.

By the way, do you have the cooling flaps in the fanshroud?

[singlecab61]

Hello there!

I am speaking from OPINION ONLY here so please don't jump down my throat!!!

I have run thermostats on several VW's in the past and seemed to have nothing but problems with them. They all seemed to fail and they would fail closed preventing air from getting to the engine, causing overheat damage.

I have always believed that a cold engine, is a happy engine, especially air cooled ones. Cooler engine temps allows for better performance. I take every provision necessary to keep a VW engine cool. From replacing the engine compartment seals to large oil sumps and pumps to extra fan cooled coolers to adding hood stand offs in the summer. If an aircooled engine reaches anything more than 200*F (93*C for all you metric folks), it is overheating IMHO!!!! 

I am, however, a firm believer in the flaps though! If you decide to not run a thermostat at least keep the flaps installed but wire them open. The flaps better distribute the airflow over the engine allowing for better cooling. 

I agree that oil works best when warm because it is thinned out and can flow better. The drawback to thinned out warm oil, however, pressure drops. Oil volume will decrease but not as dramatically. I have several engines still running quite happily with over 200,000 miles on them that I have built, none of them have a Thermostat on them.

Pressure is a resistance to flow, we all agree on that point. The engine parts are only cooled when the oil that is in them is pushed out by fresh cool clean oil. You can have tons of volume, but you still need pressure to create that volume. The hotter it gets=the less oil pressure=the less cool clean oil is pushed through the engine parts=the more chances for overheat damage to occur.

Rule of thumb: 10PSI of oil/1000RPM
     EXAMPLE: @4000RPM, there should be no less than 40PSI oil pressure in the engine at any temperature

The VW engines that I have run thermostats in all have run hot, even when the thermostats are operating correctly. The average temp is 195*F or hotter. Too hot IMHO. I do not have a thermostat in my Auto-Stick mostly because I do not trust them, but also because when my engine is colder, It gets better fuel mileage and better performance.

I also run a split grade oil in my engines, and also change the grade depending on the season. Winter time I use 15w-40, in the summer, I run 20w-50.

One other thing to think about: VW does say to use a thermostat all the time, but that does not mean that it is practical in the real world despite there testing. I work for BMW as a service technician. I have another friend that is a service technician for VW and another that is a service technician for FORD. We have all figured out that the engineers don't know what is best for their vehicles even though they designed them to operate that way. I think one should do their own testing to find what works best for them.

If you find that your testing proves a Thermostat is best for you, then by all means install one. All of my testing revealed Thermostats in air cooled engines are a waste and should not be installed.

I have much more information on this this topic but already have posted a novel. Will post more as the thread continues.

-Evan.

[Bookwus]

Hiya Evan,

I'm not jumping down your throat, but I'm not agreeing with you either.  

A couple of your statements left me scratching my head.  Perhaps you could explain?

....They (thermostats) all seemed to fail and they would fail closed preventing air from getting to the engine, causing overheat damage.

Would you please explain how that could happen?  Every VW person I have ever talked to concerning thermostats is of the opinion that the OEM style thermostat can only fail in an open position.  

.....One other thing to think about: VW does say to use a thermostat all the time, but that does not mean that it is practical in the real world despite there testing.

It doesn't mean that they aren't either.

....I work for BMW as a service technician. I have another friend that is a service technician for VW and another that is a service technician for FORD. We have all figured out that the engineers don't know what is best for their vehicles even though they designed them to operate that way.

With all deference to your position, I'm thinking that the engineering team that designed these engines knows considerably more than three service technicians, no matter how capable they might be.  After all, these engineering designs had to pass through many checks and failsafes before ever getting to the test track.  Modifications followed that.  And after all that VW would put their stamp on it.  And that does not include over thirty years of field reports on actual usage, repairs in the field and subsequent modifications.  The VW engineers got the big picture and honed the details.  VW put their deserved reputation for well engineered car on the line.  I gotta believe that thermostat is a necessary piece of eqiupment.  

[hercdriver]

I'd also add that if VW could save 5 bucks per vehicle by omitting the thermostat in warm climates, they would have. Every part and use of labor on the assembly had a direct impact on the bottom line of VW.

Good conversation BTW.

Dave

[johnr]

Flaps?  I really don't know!  I don't recall seeing anything in the shroud.

[Bookwus]

Hiya John,

It's pretty much all the stuff inside the circled area below............



The flapsets (#22 & #23) sit into the bottom of the fanshroud on either side of the fanshroud.  Here's a picture of them removed from the fanshroud............



And the rightside flapset installed with the thermostat connecting rod...........



Note that, in the picture directly above, the flaps are open.  Many folks who toss the thermostat also pull the flapsets.  Others who run without a thermostat may wire the flapsets open to insure airflow.  You might want to check for all that.

[singlecab61]

Hiya Evan,

I'm not jumping down your throat, but I'm not agreeing with you either.  

A couple of your statements left me scratching my head.  Perhaps you could explain?

....They (thermostats) all seemed to fail and they would fail closed preventing air from getting to the engine, causing overheat damage.

Would you please explain how that could happen?  Every VW person I have ever talked to concerning thermostats is of the opinion that the OEM style thermostat can only fail in an open position.  

.....One other thing to think about: VW does say to use a thermostat all the time, but that does not mean that it is practical in the real world despite there testing.

It doesn't mean that they aren't either.

....I work for BMW as a service technician. I have another friend that is a service technician for VW and another that is a service technician for FORD. We have all figured out that the engineers don't know what is best for their vehicles even though they designed them to operate that way.

With all deference to your position, I'm thinking that the engineering team that designed these engines knows considerably more than three service technicians, no matter how capable they might be.  After all, these engineering designs had to pass through many checks and failsafes before ever getting to the test track.  Modifications followed that.  And after all that VW would put their stamp on it.  And that does not include over thirty years of field reports on actual usage, repairs in the field and subsequent modifications.  The VW engineers got the big picture and honed the details.  VW put their deserved reputation for well engineered car on the line.  I gotta believe that thermostat is a necessary piece of eqiupment.  

The thermostat can fail either open or closed. All of the thermostats that failed that I have seen, have failed in the closed to mostly closed position. Don't ask me how, I would love to understand why, but they just did. I have inspected bad thermostats with the engine hot and the flaps are not open. I replaced the thermostat, with a known good used one, and it would open the flaps. I have never see one fail open. Doesn't mean they can't though.

VW has tested the unit, they say the thermostat is required.

I have tested the unit, I say they are a waste of money, no matter how cheap the cost.

My technician friends and I are not engineers, but we do know enough to understand that the engineers who design this stuff do not think some of these things though very well.

One other little piece of information to think about....The thermostat was phased in when engine emissions started to be monitored. The principal goal of a thermostat is to heat the engine up as fast as possible and keep it as hot as possible to decrease emissions output. At the same time, thermostats in water cooled engines started raising in temperature. It worked for the emissions, but it shortened the life of the engines as well. 

I say: TO EACH HIS OWN (or however that phrase is worded).

As I already mentioned, VW and others say it is a detrimental piece of equipment that the engine needs to properly operate and therefore should be installed.

My testing has proven to me a thermostat in an aircooled VW is not needed and therefore should not be installed.

I do agree that this is a good conversation!!!

[tmea]

Single cab:

I have to disagree with you on this one. Automatic theromstats began on the 25 hp engine's doghnut on the front side of the fan shroud well before anyone cared anything about emissions. Before that and to the first production vw engines there was a manually operated thermostat with a handle on the fan shroud.

I have never seen a properly adjusted thermostat fail in the closed position (admittedly I have only seen 3 or 4 fail over these years). My emphasis is on "properly adjsuted" which tensions it so that it can only fail in the open position.

Note that VW sold their cars both in Australia and S. Africa with thermostats. They even built them in Australia and still installed the thermostats there. Only slightly worse than running an engine too hot is running one too cold, even in Australia and S. Africa. If properly functioning and adjusted it will restrict air flow in a fully warmed up engine when tempratures are in the 70s/80s.

The missing part of this discussion is that there is a minimum desired temprature for a an engine running at speed. Too much of a good thing isn't good. Off hand I can't recall what the temp is but I will try to find it and post it. If my memory serves me it is in the 160-170 range for oil temp. Too cool and the differential between the head temp and the oil is too great.


There was great pressure on VW to save every penny possible. Thermostats never succumed to cost savings and in fact were further developed and improved over time. They were not stupid and until any of us can amass enough knowledge to refute their metoodology proven in solid research, I'd err on the side of leaving the cooling system OEM.

We seem to only value what we can observe in the immediate sense. Engine overheats and is destroyed quickly. Pretty starightforward. Engine runs too cool (no thermo) and it's life is shortened by 10,000 miles or so. Can't immediately observe or measure that so it isn't a factor. Trust me VW figured it out and put the thermo system in for that reason.

That's my 2 cents and yes this is a good disucssion!

Tom

[Rick]

I agree with ditching the thermostat.I have a 71 SB that sat for about 9 months in my garage. When I took it out this spring she overheated within one mile big time. The flaps RUSTED shut from being closed and the thermostat couldn't open them. I rebuilt the engine and placed the flaps in, but didn't connect the thermostat(wired the flaps open)- I don't want to cook another engine. As far as the mantra that everyone on this site follows " If installed by the VW Corporation, it must be good" is baloney. The overall AS setup designed by VW is a nightmare. Between the vacum lines, torque convertor setup, and electric switches I don't consider it a well engineered system. I also had a dealer installed VW A/C system which was a joke- it took up 1/2 the engine compartment and weighed about 40 lbs for the compressor- this was a VW option and a stupid one at that. VW is not infallable in their designs or setups. There is always a difference of opion, but I opted out of the thermostat. Im sure to stir the pot- but again you guys were great in helping me get Greta giong. thanks

Rick
Oakland, NJ

[singlecab61]

Single cab:

I have to disagree with you on this one. Automatic thermostats began on the 25 hp engine's doghnut on the front side of the fan shroud well before anyone cared anything about emissions. Before that and to the first production vw engines there was a manually operated thermostat with a handle on the fan shroud.

I personally have never seen one on that engine. I did however know about the manual Thermostats. Thanks for the info.

I still stand by my findings and my opinion on the subject though. NONE of my engines will have a thermostat installed on them. I prefer the engines to run cold, heat is the enemy!

I see Rick seems to be in agreement with me. Thanks Rick for helping me out here.

I am not trying to change anyone's views or practices. I just don't agree with using Thermostats in ACVW's

[johnr]

Nope,  I ain't got a flap to my name!   

[Bookwus]

Hiya John,

Should you decide to install a thermostat you will also need those flaps and miscellaneous other parts shown in the diagram above.

[kimbill]

[quote.......... I have a 71 SB that sat for about 9 months in my garage. When I took it out this spring she overheated within one mile big time. The flaps RUSTED shut from being closed and the thermostat couldn't open them.......

Rick
Oakland, NJ
[/quote]
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Now I'm concerned about frozen (rusted) dampers, since we store our car for six months each year.  Following engine start up, how can one check that the dampers are opening?  Are they visible?  If the thermostat can be observed expanding, does that mean the dampers are opening?  If not, how can I be sure the dampers are opening?  ....(Our old '57 Beetle had a pie-plated-like damper on the fan inlet, so you could feel back there to determine the damper was opening).

Bill