Modified Thermostat for higher MPG's...

dieselfuel

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Josh,

Using Evans HD coolant and a 210F thermostat, and I'd bet you'd be fine. Maybe add a set of ARP studs.

I just read an article about the Evans HD Coolant. Jack Evans is recommending to use a thermostat 20F warmer than normal. Program the rad fan to activate at 235F and use the Evans HD Waterless Coolant. Jack says one could expect a 3-8% increase in MPG.

I found the article yesterday in a diesel trade paper at a truck stop in Kansas. If I can find a link, I'll post it later.

Edit: Forgot to say: I returned from Death Valley where it was 80F. I never removed my "winter front end" (pipe insulation to cover grill opening and clear tape to cover the VW emblem). The temp guage never moved off the "190" mark (center).

FWIW,
 
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josh8loop

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Shizzler,

Your right, I do need to get a Vag Com or Scan guage to get temp readings. I do have some calibrated temp probes at home, and a IR non-contact thermometer, but haven't had a second to do some measurements. Honestly I didn't think actuating the thermostat in the microwave while submersed in water could change the T-stat operating temperature, but it may be possible. I will check the temps the coolant system is getting to soon. Thanks for the input.
 

josh8loop

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Dieselfuel,

Thanks for that very interesting link about the waterless coolant and higher temp T-stat. Very interesting. Eventually I will be contacting Stant to see if they do custom temperature T-stats. It would be nice to get one for the temperature I desire without having to make it myself.
 

josh8loop

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Fuel mileage update:

Still going up in mileage, last tank was 44.7, and this one is 45.8 MPG(576 miles). I will be checking the coolant system operating temp soon.
 

dieselfuel

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Please keep me posted on a higher temp thermostat. Ideally, I'd like one for 210F.

I wonder is then gassers use a higher temp thermo and if so, would it fit our ALH.
 

josh8loop

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DF,

Newer gassers will usually run higher T-stats. I have seen some off the shelf units at 205 deg F. I recently used one of these in an attempt to create my own hybrid T-stat that would allow me to run a higher coolant system temp. I haven't finished the project yet, mainly due to the inability to have the stainless steel housing and spring retainer securely tack welded enough for my liking. It is around 30 thousandths SS. I am however looking at other options to secure the two without distorting the metal sealing surfaces.
 

dieselfuel

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Will the that 205F 'stat you speak of fit an ALH?

Really, 210F would be perfect, (when using the Evans HDTC Waterless Coolant) imo.

BTW, I was in Death Valley 2 weeks ago. The first day, it was 80F. I never removed my "winter front end". The temp guage never moved off the center (190F) mark. Maybe half way off. I doubt the coolant got over 200F. If even that high.
 

josh8loop

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DF and All,

A little progress into this venture........

I called a Stant Technical Engineer today to inquire if it would be possible to get a thermostat specially made that would be rated for 205 Deg F for our A4 ALH TDI's. He told me that it would be extremely expensive to have them made, and he would have a hard time talking his boss into making a small quantity. I then asked him if he had any other thermostats that used the same flange dimensions that would have the bypass section on the rear of the thermostat that aren't necessarily made for a TDI but might work. he said he didn't, but he cross referenced a t-stat that had the same flange dimensions in the 205 temp range but didn't have the rear bypass section. He mentioned the bypass section was simply pressed onto a normal thermostat heat motor, and it would be simple to remove the bypass section from a stock TDI thermostat(stant 13379) and press it onto a 205 degree thermostat(Stant 13352).

The result would be in his opinion a 205 degree thermostat that would physically fit an ALH TDI motor that has all the working features of the original t-stat except it would now have a higher operating temperature. The major advantage to me is that no welding or major modification would be needed to the thermostat besides gently pressing a new rear bypass portion onto it. He also mentioned that thermostats made by Stant begin to open(minimum of 3 thousandths) at 5 degrees below the specified temperature and open up to maximum travel(300 thousandths) at 22 degrees past beginning opening temperature. I have ordered two thermostats that should be here first of the week. Here is what I have ordered:


Stant part number 13379 (195 degree direct TDI replacement T-Stat)
I will be scavenging this T-stat for the rear bypass section only-the rest is not needed


Stant part number 13352 (205 degree T-stat without a rear bypass section)
I will be pressing the rear bypass section from the 13379 onto this t-stat for the final modified 205 degree version.








Here is a photo of the 13352:

http://www.google.com/imgres?imgurl=http://ecx.images-amazon.com/images/I/41NZM4PBV6L._SL500_AA300_.jpg&imgrefurl=http://www.amazon.com/Stant-13352-Thermostat-Degrees-Fahrenheit/dp/B000E43A0O&usg=__onJbNkmc094wxB5KLel89ry7JYU=&h=300&w=300&sz=13&hl=en&start=0&zoom=1&tbnid=paEx0qxDEpkrqM:&tbnh=138&tbnw=174&ei=1YxxTe70PI-q8Abwq-X4Dg&prev=/images%3Fq%3Dstant%2B13352%2Bthermostat%26um%3D1%26hl%3Den%26safe%3Dactive%26sa%3DN%26biw%3D1024%26bih%3D572%26tbs%3Disch:1&um=1&itbs=1&iact=hc&vpx=143&vpy=80&dur=1980&hovh=225&hovw=225&tx=117&ty=110&oei=1YxxTe70PI-q8Abwq-X4Dg&page=1&ndsp=15&ved=1t:429,r:0,s:0


Here is a photo of the 13379:

http://www.google.com/imgres?imgurl...88AanrvSPDw&page=1&ndsp=15&ved=1t:429,r:3,s:0






According to the Tech Engineer it should be an easy and straightforward modification, and all the dimensions are the same between the two. I guess I will find out when they arrive. We will see what happens...........
 
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jayb79

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This is the 205 degree stant 13352:

Here is the 195 degree stant 13379:


It would be nice to see a pic of the modified one. Thanks for the research.
 
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josh8loop

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jayb79,

Thanks for putting up the photos, that is a real asset to discussion and understanding. To answer your question, the modified T-stat should look physically no different than the 13379. I will get some photos once it is complete early next week, and maybe get it installed next week end for testing if all goes to plan. Thanks again!
 

dieselfuel

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Josh,

Thanks for the update and all your time and research.

Please take some photos of the modification along the way for a "How TO".

If you can't post the photos, I'm sure someone here would do it for you.

Do you plan on going the Evans HDTC coolant route?

I plan on doing ARP headbolts, Evans HDTC, thermostat, new (larger) nozzles, new clutch and a new downpipe (mine's shot).

Thanks again,
 

dane101

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Fe

How many miles can you get out of 2500- 4500 dollars of diesel.Cause that's what your gonna spend to put a new head or a new mtr in your car once you cook it.Remember they use stretch bolts on the head.They just don't stop stretching.The hotter you get the motor, the more they will stretch= blown head gasket at the least.Drive it to far,scored pistons.And so on.Personally have replaced 100 heads,and as many motors.That's like driving around to find the best price on fuel.Then standing in line at Arco for 20min , just to save .05 a gallon.So you saved a whole dollar or two, plus the gas you used looking for that big savings.Who hooo!Don't spend that dollar all in one place.:p
 

Fix_Until_Broke

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Will the that 205F 'stat you speak of fit an ALH?

Really, 210F would be perfect, (when using the Evans HDTC Waterless Coolant) imo.

BTW, I was in Death Valley 2 weeks ago. The first day, it was 80F. I never removed my "winter front end". The temp guage never moved off the center (190F) mark. Maybe half way off. I doubt the coolant got over 200F. If even that high.
The temp gauge won't move off dead center until >225F coolant temp (and it gets to dead center at ~165F).

I suggest using a scangauge or similar to montior actual coolant temperatures.

That said, I keep my "winter front" on all year long as well and don't see coolant temps over ~210 even in the summer with the A/C on unless I'm pulling a trailer (at which point I take the winter front off).
 

Fix_Until_Broke

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DF and All,

A little progress into this venture........

I called a Stant Technical Engineer today to inquire if it would be possible to get a thermostat specially made that would be rated for 205 Deg F for our A4 ALH TDI's. He told me that it would be extremely expensive to have them made, and he would have a hard time talking his boss into making a small quantity. I then asked him if he had any other thermostats that used the same flange dimensions that would have the bypass section on the rear of the thermostat that aren't necessarily made for a TDI but might work. he said he didn't, but he cross referenced a t-stat that had the same flange dimensions in the 205 temp range but didn't have the rear bypass section. He mentioned the bypass section was simply pressed onto a normal thermostat heat motor, and it would be simple to remove the bypass section from a stock TDI thermostat(stant 13379) and press it onto a 205 degree thermostat(Stant 13352).

The result would be in his opinion a 205 degree thermostat that would physically fit an ALH TDI motor that has all the working features of the original t-stat except it would now have a higher operating temperature. The major advantage to me is that no welding or major modification would be needed to the thermostat besides gently pressing a new rear bypass portion onto it. He also mentioned that thermostats made by Stant begin to open(minimum of 3 thousandths) at 5 degrees below the specified temperature and open up to maximum travel(300 thousandths) at 22 degrees past beginning opening temperature. I have ordered two thermostats that should be here first of the week. Here is what I have ordered:

Stant part number 13379 (195 degree direct TDI replacement T-Stat)
I will be scavenging this T-stat for the rear bypass section only-the rest is not needed

Stant part number 13352 (205 degree T-stat without a rear bypass section)
I will be pressing the rear bypass section from the 13379 onto this t-stat for the final modified 205 degree version.

According to the Tech Engineer it should be an easy and straightforward modification, and all the dimensions are the same between the two. I guess I will find out when they arrive. We will see what happens...........
Excellent research and information! Great work. Especially the opening distances and temperatures.

I think it's time to replace my thermostat again (long warmup times even when it's in the 30's) and will definately keep this option in mind. I'm currently running a NAPA (92C or 95C) that runs at ~202 consistantly with the winter front on all the time.

Keep us posted on what you find and how it works please
 

josh8loop

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Fix et all,

I will keep everyone posted as I progress. I have already begun to snap some photos to document the procedure. I'm not sure I will go the waterless coolant route yet, but I will need to make sure my coolant is spot on to help with cavitation, and hot spots as mentioned earlier. If the T-stat modification process is simple to do, which I think it will be, it would be neat if a few people try it out and report their results aswell. Especially those with a Scan Guage.
 

yaknowthatguy

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Fort Collins, CO
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I'd be quite happy to do a thermostat and watch the results on my scangauge. I monitor tire pressure and such pretty habitually, so I'd be good for it. Please keep us posted and if you would PM when you have a way to get the thermostats (I dont hit this site as much as I'd like).

There are lots of guys with 7.3 liter Powerstrokes, myself included, that have done the upgraded thermostat option. I've been running the 205 tstat for about 100k miles with regular oil sampling on one brand of oil - I've seen no change in wear characteristics of the motor during this time, and that includes watching oil samples for the first 45k miles on the truck. While it's an apples to oranges comparison to a degree, there may be some application to our 1.9 motors.

FWIW I know a guy that disconnected his radiator fan and just ran Evans coolant by itself. Of course, with a gauge and an eye glued to it. No significant issues running it....and that's in Florida in the summer. He also bumped up his mileage on a powerstroke by 2mpg, and that's nothing to shake a stick at. No information on emissions data though.

I think there's a lot of opportunity here, if we can just source the right product. Thanks for all your work on this Josh!
 

josh8loop

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Yaknowthatguy,

I just called Advanced Auto locally, and they have my parts. I will pick it up this afternoon, and see if things are compatible like they should be. Thanks for being willing to give this a try along side me. I will shoot you a PM on the project. I REALLY hope this all works out(increase in MPG w/o engine damage), and hope that I get a WARM;) and fuzzy feeling about this. I will be getting some photos, and will keep everyone posted. Also, this weekend I read a little in the new Bentley that I got recently about the cooling system, and will posts some thoughts soon.
 
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dieselfuel

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Remember, Evans HDTC is only $40/gln. ALOT less money that a head and/or engine.

Just something to keep in mind.
 

jayb79

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Location
Exeter,NH
With scangauge to monitor temp he won't have any trouble. I have seen my temps climb up to about 214F on a long up hill grade. My current stat runs about 195-205 most of the time. I just got the luck of the draw that my 195 stat works on the hi side, its been in for about 4 months now and 214 is the highest that i have seen. My grill is totally blocked off except for the air cleaner and inter cooler intake.
 

josh8loop

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Fellas,

Good news, I picked up the parts today and they are perfectly identical except for the temp rating. I went ahead and removed the bypass section from the 195 deg T-stat and pressed it onto the 205 deg T-stat. I measured the dimensions of the 195 T-stat before disassembly so I would know exactly how far to press the bypass section onto the 205 unit. I have taken some photos, which I will see if I can get someone to post on this Thread ,and some videos that I can put on U-Tube.
 

josh8loop

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All,


First let me start off by saying that this modification has not been proven to be effective or be safe for our engines. There have been quite a few very knowledgeable guys here that have warned that raising the temp of ALH Type TDI engines could cause engine damage to occur. There have also been some very knowledgeable guys that have said that the increased temperature should be fine for the engine and that no damage would be expected. One thing is for sure the TDI engine doesn't seem to produce a lot of excess heat under normal driving conditions and on non modified engines. Modified engines(Larger Injectors, Tune Etc) however could potentially create excess thermal energy that may prove difficult for the coolant system to remove, and running a higher temperature T-stat in these circumstances may be questionable. I am willing to take a certain amount of calculated risk, and I fully understand that I may cause damage to my engine by running at higher temperatures for the admittedly small(and not proven) increase in MPG. My hope is that this modification works well with no increase in engine wear, and gives a small increase in fuel economy. Here is a video of the initial disassembly of a Stant 13379 (195 Deg F) for the beginning of a "Hybrid" 205 deg F thermostat.

http://www.youtube.com/watch?v=AU8IAcGIYVo


http://www.youtube.com/watch?v=x7hodv7Rsvg



Don't laugh to much-It was difficult to video with one hand, and demonstrate with the other! :)
 
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Nich

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Um..... But where is the added efficiency comming from? Hard to imagine 10 degrees temp change would eliminate that much enthalpy losses.
 

dieselfuel

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Nice video, Josh. Good job! I'm anxious see see if it works and what temp you are able to get the coolant to.

If this works out, maybe you can make a few and sell them to us, since you already have the tools.:D
 

UFO

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Um..... But where is the added efficiency comming from? Hard to imagine 10 degrees temp change would eliminate that much enthalpy losses.
I gained 3 mpg from replacing my bad thermostat (160F) with a new one (190F).

10F more? Maybe 1 mpg more...
 

josh8loop

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DF,

What I liked about this was that the "tools" needed to perform the Hybrid conversion are very few, and can be found in most home garages. I am running a few tests on my car this week with the old T-stat in, mainly keping a watchful eye on my coolant temp via a calibrated thermometer in my overflow tank. The thermometer is a large 6" faced analog unit with a 6 foot capillary tube that goes to the bulb on one end. This allows me to run the car and monitor the temp from the inside while driving. Albeit the rad cap is off while doing this. The temp at the coolant reservoir is a couple degrees different than the coolant outlet flange temp. The highest I saw yesterday was 184 Deg F, the outside temp was about 60 degrees or so. I am surprised to see I am only getting 184, and not the 195 that the T-stat is rated for. I do seem to remember through testing a while back it started to open just barely at 184, so that seems consistent. I will probably not run the new "Hybrid" T-stat until I have a good feel for what the car is doing now.
 

jayb79

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Hi Josh,
For some reason the image does not show only the link i sent to you, this is what happens when I copy the link and past it.
If i edit out the word thumbs from the links you will get the full size photo.






A few more photos from Josh:

"These just show that the two types are identical except for the rear bypass section(has been removed in these photos). "





 
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dieselfuel

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Josh,

I just checked my coolant temp, and it was about 184F, too. Outside temp was 50F here.

I think it my cool a little by the time it gets to the coolant tank.

If the hybrid gets you to 205F in the coolant tank, that'd be awesome!

If your hybrid t-stat works, I'll be doing this later this year, after the ARP head studs are installed.
 
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