Modified Thermostat for higher MPG's...

aNUT

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...good luck with that. Replaced head, switched to G013 and 87C 50K ago. No more issues.

That's interesting.

I have more miles than that individually on two ALH's with no issues. I've also used Evans and a hotter thermostat on two 7.3PSD's with no issues.

I'd think you have another issue that caused the cracks or is was a bad head in the first place.

.
 

dremd

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Figured I'd add that my last UOA indicated coolant in my oil, but I'm thinking that it is actually the washer fluid I'm spraying as water/ methanol injection.
I turned that off and will update in 10,000 miles (aka 4-5 months) when I do next drain.
 

JohnWilder

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Well I read a lot about the coolant (and learned a lot) as to why we use water in our cooling systems for instance. Two reasons cheap and relatively abundantly available.
Now why do we have the system pressurized? The only reason is to raise the boiling point of the coolant/water mix, so this in itself told me this was a compromise in order to be able to use water in there.
I was extremely skeptical to this stuff first off, as I am to most "magical" auto chemicals :), but the more I read the more it made sense.
So for my personal application I wanted it due to these benefits:
"Evans Waterless Coolants have a boiling point above 375°F and will not vaporize, thus eliminating overheating, boil-over and after-boil."
Now the no pressure in the system is just an added plus if you ask me. Not that you should (need to) open your coolant system when it's hot but I can with this stuff at any time. I also personally believe (totally subjectively yes) that my coolant components might last longer as they don't have to operate under pressure at all times.
I ran across the info about it through Leno's Youtube channel first off:
http://youtu.be/t7PykrgzWPQ
http://youtu.be/KRLXKW2ph0w
Yes those are indeed as much commercials as they are anything else so take it that into account!
This is not quite true. Water has the highest specific heat of any liquid that is practical. It also has very low viscosity. You mix it with other things to prevent freezing and to prevent corrosion but in doing so you reduce the specific heat and increase somewhat the viscosity. Higher viscosity means a bit lower flow rate. Lower specific heat means a greater temperature increase of the coolant to carry a specific quantity of heat as compared to pure water. The pressurized system is to keep the water from boiling until a bit higher temperature. You don't want localized boiling to occur in the heads near the exhaust region. This causes a local gas (steam) layer which transfers heat poorly as compared to liquid water. This can result in localized hot spots. Not good for heads.
 

Kristofk

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So I have installed this hybrid thermostat, and as temperatures have "dropped" ever so slightly in California, it has been incredibly difficult to get it up to operating temp. Now, my dash gauge has been working fine before I switched, but now it keeps under the normal mark. Even going up a long hill 4-5 miles out, still wont reach normal temp.

I have slightly compressed the spring during install. Any issues resulting from this?
 

SD26

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The pressurized system is to keep the water from boiling until a bit higher temperature. You don't want localized boiling to occur in the heads near the exhaust region. This causes a local gas (steam) layer which transfers heat poorly as compared to liquid water. This can result in localized hot spots. Not good for heads.
This happens in engines today with increased boiling points of pressurized and additive based coolants. And that was the basis of how PG based coolants came about: to continue producing cooling in hot spots.
 

JohnWilder

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This happens in engines today with increased boiling points of pressurized and additive based coolants. And that was the basis of how PG based coolants came about: to continue producing cooling in hot spots.
Yes, I understand but my point is nothing cares as much heat as water--nothing. Anything else will result in a greater temperature rise in the coolant to carry the same amount of heat. This is the primary reason for water.
 

Riflesmith

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Yes, I understand but my point is nothing cares as much heat as water--nothing. Anything else will result in a greater temperature rise in the coolant to carry the same amount of heat. This is the primary reason for water.

Yes, water has a tremendous capacity to absorb heat. That is well understood. I have been running Evans Waterless coolant for four years now. Dodge Cummins that sees a good bit of towing duty as well as TDI cars. Overheating has never been an issue.

Another quality of water, this one not so shiny, is it tries to dissolve everything. It does it's very best to dissolve your engine through solvent and electrolytic corrosion. Evans does not have either of these issues.

In an earlier post, you mentioned film boiling unless the cooling system is under pressure. Water based coolants have this issue, not Evans. Evans does not boil at atmospheric pressure until 375 degrees F.
 

puntmeister

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..."can be used in high performance street vehicles with high flow cooling systems. NPG is NOT recommended for daily drivers or cold weather operation, and may require system modifications to ensure a successful conversion."

This statement makes it sound like a high-flow cooling system is necessary for proper performance of the Evans. Why? Is it the case the Evans doesn't absorb heat as efficiently as water, thus needs to flow faster?

In any event, the main benefits seem to be for use in situations where ethylene glycol is banned (race tracks and food service?), and, as claimed elsewhere, for better MPG, due to less on-time of radiator fan.

I'm skeptical of the radiator fan thing in general - but, with respect to TDI's - other than when running Air Con, I have only once ever heard the fan turn on (after driving for an hour, up a steep mountain, in first-third gear). And I live in the desert.
 

SD26

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..."can be used in high performance street vehicles with high flow cooling systems. NPG is NOT recommended for daily drivers or cold weather operation, and may require system modifications to ensure a successful conversion."

This statement makes it sound like a high-flow cooling system is necessary for proper performance of the Evans. Why? Is it the case the Evans doesn't absorb heat as efficiently as water, thus needs to flow faster?
NPG is thicker stuff. Yeah, it's different than an EG/water mix.

For road racing motorcycles, we used stock cooling systems. Yes, EG was banned because it makes a mess on track. Often, the thermostat body was removed, but the housing was retained as a restrictor for straight water applications. This allowed the water to move slow enough to shed heat out the radiator. With Evans NPG, the entire thermostat was removed as the unrestricted flow worked well.

Observation:

In our normal use of the race bike with water, after the race, the engine was way too hot to touch. The temperature gauge showed temperatures that we recognized as normal. After replacing with NPG, the temperature gauge would show a higher temperature, but the engine way noticeably cooler following a race.

Water is great. But there are many points in the engine that the water turns to steam, and those areas don't get cooled. That heat gets distributed through the metal of the engine. Yes, what heat the water can pick up is shed in the radiator. NPG never became steam, and the heat was moved into the cooling system. The heat wasn't shed so quickly, so there was a little more left in the coolant compared to water. It may have been the case that we could have left the thermostat housing in to restrict flow so that the NPG remained in the radiator a little longer to shed the heat.

In any event, the main benefits seem to be for use in situations where ethylene glycol is banned (race tracks and food service?)
A number of racing organizations don't allow PG as a coolant. It is easier to clean up than EG, but it is still harder to clean up than water.

Some time ago, NASCAR rejected its use because the radiator could be completely closed off because of its boiling point, and that allowed for an even faster aerodynamic package.

I use a upper and lower grille block on my TDI year round as a result of that opportunity.

NPG...

Honestly, that is their old tech. Used it in race bikes as early as 2001, in my 7.3PSD soon after, and in our Ford Focus after that. NPG+ is less viscus, but it now has a new name as we discussed some posts back. Works well in stock cooling systems.
 

nicklockard

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Isn't this Evans discussion besides the main thread point? Can you take it to its own thread?
 

Riflesmith

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Isn't this Evans discussion besides the main thread point? Can you take it to its own thread?
Running a 205 degree hybrid thermostat in these cars entails considerable risk of film boiling in the head and resulting damage. PG based waterless coolants eliminate this risk.

Sounds on topic to me.
 

nicklockard

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Running a 205 degree hybrid thermostat in these cars entails considerable risk of film boiling in the head and resulting damage. PG based waterless coolants eliminate this risk.
Sounds on topic to me.
I disagree on the physics and think some of you make waaaay too much of a non-issue (sub-nucleate boiling), but even if you're right, it's pretty distracting when you hijack the whole thread off of the main point.
 

compu_85

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Running a 205 degree hybrid thermostat in these cars entails considerable risk of film boiling in the head and resulting damage. PG based waterless coolants eliminate this risk.
Sounds on topic to me.
The new Passats have a ~200*f thermostat in them, and are set up to run hotter under load. Going up hills during a regen can make the temp go past 225*F. In normal driving the car runs 210*F. Still using G12++ coolant.

-J
 

Riflesmith

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The new Passats have a ~200*f thermostat in them, and are set up to run hotter under load. Going up hills during a regen can make the temp go past 225*F. In normal driving the car runs 210*F. Still using G12++ coolant.
-J
VW does not expect us to own these cars for fifteen years like many of us do.

I have spent my life in power plants and understand "departure from nucleate boiling" all too well. The effect is cumulative, not immediate.
 

G3TDI

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Just got back from the 2014 SEMA show and had a chance to chat with Mike Tourville who you can see in this video https://www.youtube.com/watch?v=KRLXKW2ph0w about the use of the Evans coolant in the TDI setup with this 205F thermostat, turns out he is an Audi owner and very interested to put me in touch with their engineers on this topic for further exchange of info! :)
 

SD26

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Isn't this Evans discussion besides the main thread point? Can you take it to its own thread?
Have you read all 50+ pages of this thread? Evans has been a regular discussion because of the risk reduction that the coolant provides. Yup, many use G12 based coolants, but that is developed for use under the original VW engineering. The 205*F Hybrid themostat is not part of the original VW engineering for this car. Evan is not the main point of the discussion, but it is relevant...and it comes up in questions.
 

nicklockard

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Have you read all 50+ pages of this thread? Evans has been a regular discussion because of the risk reduction that the coolant provides. Yup, many use G12 based coolants, but that is developed for use under the original VW engineering. The 205*F Hybrid themostat is not part of the original VW engineering for this car. Evan is not the main point of the discussion, but it is relevant...and it comes up in questions.
I may have skipped the last five or so because it seems like it's becoming an Evans infomercial. And I don't agree that it provides any meritable risk reduction.

I agree that it is related to the topic. It sounds like it can merit an "all things Evans/EG/PG coolant fluids" thread of its own.
 

G3TDI

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And I don't agree that it provides any meritable risk reduction.
I want to point out that I am a huge skeptic to most "miracle products" and I also felt the same about EVANS coolant when I first ran across it, I thought it basically was another snake oil product (as there are so many in the automotive chemical industry!) but having used it now I am a firm believer, and everything I have read and researched on it so far makes all the sense in the world. The fact that SEMI truck drivers are in general aware and often interested in it says something too if you ask me. But yes I am all for the idea that each one decides for themselves.



It sounds like it can merit an "all things Evans/EG/PG coolant fluids" thread of its own.
Well not really, because although Evan's does talk about fuel economy on their website (you have to dig for it though) it is NOT part of their main sales pitch, nor even mentioned as one of the main benefits. You could almost call it a "side effect" (although a positive one), see for yourself if you are allowed to? ;)

http://www.evanscooling.com/questions-and-answers/faqs/

P.S. A side note I learned from talking to EVANS, there was an old lawsuit between Evans and GM : http://caselaw.findlaw.com/us-federal-circuit/1372013.html and the only reason GM finally settled it was they HAD TO settle all pending lawsuits to get the bailout, so in return Evans got their lawsuit funds and was then able to proceed with the focus on the waterless coolant for the public. ;)
 
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frosz

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I ran Evans coolant & a Wahler 92C t-stat in my ALH a while back. Result was 12 cracks in the head in about 30K miles. Do not recommend. Replaced head, been running 87C & G012/13 coolant w/ zero issues for 50K.
Strange, so my head is about to crack? Been driving about 20 000 km with the Wahler 92c with g12/g13 coolant. Can't understand how 5 degree difference would result in a engine failure. I think the boiling point is about 175c (Could be wrong, was hard to find the correct data, the boiling point).

My VCDS readings is 92-93c, never seen anything higher. But then again Evans have a slightly less cooling ability, so that could be your culprit.

G13 Specs
 
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G3TDI

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Strange, so my head is about to crack? Been driving about 20 000 km with the Wahler 92c with g12/g13 coolant. Can't understand how 5 degree difference would result in a engine failure. I think the boiling point is about 175c (Could be wrong, was hard to find the correct data, the boiling point).

G13 Specs
I always feel it is somewhat silly to make comparisons like that (the ALH head & 92c thermostat) because obviously it didn't run this from NEW, and who knows what this engine/head went through before this change.

In order to make such a claim/comment you'd have to have apples vs apples i.e. two identical NEW cars with identical driving with different coolant and thermostats, but in reality that's very unlikely to happen. Even at that it might not be objective, as we know one car breaks down under warranty while the other doesn't...so...
 

frosz

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In order to make such a claim/comment you'd have to have apples vs apples i.e. two identical NEW cars with identical driving with different coolant and thermostats, but in reality that's very unlikely to happen. Even at that it might not be objective, as we know one car breaks down under warranty while the other doesn't...so...
Ah you want consistency. Do you mean aNut? It wasn't my statement, I just commented it. But even if there is allot of variables, we can still draw conclusions if it happens often.
 

G3TDI

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Ah you want consistency. Do you mean aNut? It wasn't my statement, I just commented it. But even if there is allot of variables, we can still draw conclusions if it happens often.
Well in order to compare things yes they should be comparable :)

Yeah I know it wasn't your statement :)

Oh yes definitely there would be some statistical value to it if you can locate a multitude of similar cases but I have still to find much negative feedback about Evans, and if you see my post above, I was VERY skeptical on it to begin with.
 

frosz

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Well I have nothing against Evans. But for me regular g12/13 is enough for 93c. I will report back if I have any problems but I guess not, feel quite confident with it.

If it can transport enough heat in a warm desert I guess it will be enough in my subartic climate even with a +5c increase. But I still don't get the none-corrosion properties but I don't see that as a issue.

But if I would buy a Formel 1 car I would most certainly consider Evans :)
 

G3TDI

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Well I have nothing against Evans. But for me regular g12/13 is enough for 93c. I will report back if I have any problems but I guess not, feel quite confident with it.

If it can transport enough heat in a warm desert I guess it will be enough in my subartic climate even with a +5c increase. But I still don't get the none-corrosion properties but I don't see that as a issue.

But if I would buy a Formel 1 car I would most certainly consider Evans :)
VW used the 92c thermostat in oder Diesel models themselves so :)

I'd dare to guess that the added accessories we now have on the cars is one of the reason they haven't been using it so much anymore, but if I am not wrong I actually think they are using it again in some models (not sure if it was gassers though) my 205F is around 96C I've seen around 110C on my Scagauge at times.
 

frosz

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Ah okey, I didn't know that. I contacted Wahler in Germany before I order it and they didn't think it would cause any problems.

Would be better to get a answer from VW R&D but I don't really have a way in there to ask and half of the engineers that developed the 1,9 TDI is most probably retired. :).

Well before winter thermostats were common on diesels also. I had a idea to build a digital controlled thermostat with a micro controller (Arduino). That was just to much work for almost nothing in return. :)
 

94cobra2615

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Has anyone had problems separating the top and bottom of the stant 195 thermostat.

I just tried to do this while using josh's youtube videos as a guide.

It looks to me like my thermostat is a solid piece down in the hole where the stainless washer is.
Josh shows using a 1/4-20 bolt to tap the two apart. When looking down in the hole on this one it appears to be solid after about 1/2 inch and in turn can't hammer against the main thermostat body to separate.

Did stant change the design of the 195
 

G3TDI

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Has anyone had problems separating the top and bottom of the stant 195 thermostat.

I just tried to do this while using josh's youtube videos as a guide.

It looks to me like my thermostat is a solid piece down in the hole where the stainless washer is.
Josh shows using a 1/4-20 bolt to tap the two apart. When looking down in the hole on this one it appears to be solid after about 1/2 inch and in turn can't hammer against the main thermostat body to separate.

Did stant change the design of the 195
I did this a year ago without any problems, have a picture of yours?

http://forums.tdiclub.com/showpost.php?p=4395536&postcount=180
 
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