Modified Thermostat for higher MPG's...

josh8loop · Jun 6, 2011

DF,

Hopefully you got your car issues sorted out on the tensioner/alt pulley deal. This weekend while driving(my wifes gasser as mine is under the 01m-5 speed knife) I was thinking about our issue with the fans kicking on too early for our "Hybrid" T-stats. I was able to look at the Bentley, and it seems that we can cut one wire on the radiator thermal switch and install a toggle switch which will disable the Stage 1 fans from coming on. This will render the Stage 2 fans operable, and also the fans would be operable when required by the AC but the low temp slow fan kick on would be disabled. If I wanted to go back to normal I could just flick the switch back one, and all would be back to stock.

Stage 1
Switch on .......................197-206 deg F(92-97 DegC)
Switch off........................183-195 deg F(84-91 Deg C)

Stage 2
Switch on ........................210-221 Deg F(99-105 Deg C)
Switch off.........................195-208 Deg F(91-98 Deg C)

In the latest days testing the "Hybrid" T-stat I did notice the fans kicking on, so I know that is sapping some MPG's from my numbers. Looks like this will be an easy way to make our fans not kick on until it reaches 210 Deg F.

dieselfuel · Jun 7, 2011

Hi Josh,

Yes, I got my TDI back from Jon Hamilton on Sunday evening. Jon's great! He's booked 3 weeks out, but he said if I got the car to him, he could order parts up to 7 p.m. and he'd try to squeeze it in. The tow truck driver got my Jetta to his shop around 3:30 p.m. Friday afternoon.

Jon called me aroiund 6:30 p.m. Sat. evening and told me I could pick up the car. I couldn't get it til Sunday evening because I was too busy.

Anyhow, it was a seized alt. And, my battery was fine. I was worried it had a couple of dead cells from driving the 30 miles or so on the battery.

So, how's the 5 speed swap going?

Good news on the fan switch.

Got to get to Advance Autoparts and see it my 'stats are in yet.

I hope your wife is doing fine.

shizzler · Jun 8, 2011

Or, you could just have a situation like mine:

- Supposed "195 F" stant t-stat that really runs at 204-206 F.
- No working rad fans (not good, I know, but it's manageable)
- Grill blocks in place even on 95 degree days (not a good idea, will remove before driving home today)
- A/C not working, who the heck knows why (so no extra thermal load)

My cruising coolant temps are in the 209-213 F range. Oil passes 200 F quickly and steadily climbs towards 240 the longer I drive.

Really this situation is no problem at all, unless I have to drive up a big hill and then want to turn the engine off. It's not very pleasant to blast the interior cabin heat to cool down the engine, but it is very effective. Only takes about 30 seconds on max heat to bring coolant temps down from 213 to 207 or less (where I feel comfortable shutting the engine off). I usually step out of the car for this part,, haha.

Anyway, mpg is solid ~50 in daily driving even with the car lifted and 50% biodiesel. Can't really credit the coolant temps for much of it though.

Good experimenting here nonetheless.

josh8loop · Jun 9, 2011

dieselfuel said:
Hi Josh,

Yes, I got my TDI back from Jon Hamilton on Sunday evening. Jon's great! He's booked 3 weeks out, but he said if I got the car to him, he could order parts up to 7 p.m. and he'd try to squeeze it in. The tow truck driver got my Jetta to his shop around 3:30 p.m. Friday afternoon.

Jon called me aroiund 6:30 p.m. Sat. evening and told me I could pick up the car. I couldn't get it til Sunday evening because I was too busy.

Anyhow, it was a seized alt. And, my battery was fine. I was worried it had a couple of dead cells from driving the 30 miles or so on the battery.

So, how's the 5 speed swap going?

DF,

5-speed swap is going okI guess. Alot more involved than what I first though! Hopefully I will get my passengers side suspension assembled and torqued this afternoon, and be running it tomorrow. Not a good time to have a project like this when my wife is diagnosed with cancer again. Good thing is that they can radiate her shoulder arm with very minimal effect on the rest of her body, and her cancer looks to be fairly stable. Thanks for asking.

Glad to hear your car is back on the road, crazy that the alternator seized up on you. Something to watch out for I guess. When you get your T-stats just shoot them over, and I will get them set up for you. I would like to do another experiment to extend the rear bypass section about 20 thousandths and see if I can get the temp to come down right at 205 degrees F instead of the 209 it is at now. Now that I have some photos of how much room I actually had behind it when it is installed in the car, I know I can go quite a bit further. I would like the thermostat to be actively controlling temp at 205 deg F meaning that it is allowing a certain amount of coolant through the radiator at that temperature. The way it is now, the coolant would rather(it has less restriction) go through the bypass loop in the car until it is around 209 degrees, and then the T-stat opens enough so coolant flows through the radiator. By placing the rear section of the T-stat closer to the block it will be more likely to flow a larger volume of coolant through the radiator at a lower temperature, and hence be actively controlling it at 205 degrees. I would just like to know I have a temperature ceiling that it will not go over, and how to adjust that ceiling.

I also plan to install my fan thermal switch stage 1 bypass switch to try it out before I claim victory on that front. Now is a good time to do it since the car is apart. The bypass switch will be extermely easy to install too.

josh8loop · Jun 9, 2011

shizzler said:
Or, you could just have a situation like mine:

- Supposed "195 F" stant t-stat that really runs at 204-206 F.
- No working rad fans (not good, I know, but it's manageable)
- Grill blocks in place even on 95 degree days (not a good idea, will remove before driving home today)
- A/C not working, who the heck knows why (so no extra thermal load)

My cruising coolant temps are in the 209-213 F range. Oil passes 200 F quickly and steadily climbs towards 240 the longer I drive.

Really this situation is no problem at all, unless I have to drive up a big hill and then want to turn the engine off. It's not very pleasant to blast the interior cabin heat to cool down the engine, but it is very effective. Only takes about 30 seconds on max heat to bring coolant temps down from 213 to 207 or less (where I feel comfortable shutting the engine off). I usually step out of the car for this part,, haha.

Anyway, mpg is solid ~50 in daily driving even with the car lifted and 50% biodiesel. Can't really credit the coolant temps for much of it though.

Good experimenting here nonetheless.

Shizz,

I am glad over the course of this experiment, and in it's inception stages you mentioned you were running without major trouble at the higher engine temps. That has made me feel a little better about experimenting on my own along those lines. I figure if I can fenagle a way to operate with the car basically in a stock configuration(with everything functional) at the higher temps that would(or could be) a benefit. I am thinking your T-stat is probably a slight bit shorter(10-20 thousandths) than others of the same rating-that would account for the higher temps. I will endeavor to persevere!! Thanks again for the encouragement here.

josh8loop · Jun 13, 2011

All,

I have finally finished my 01M to 5-speed swap. The 5-speed has a .680 fifth, and i am currently using Lubro Moly GL-5 oil in it. I had to do quite a bit of fidling with the IQ after the swap-It seems the automatic fuel map is quite different than the manual fuel map. I am closer to having it dialed in, and had to go a little lower in IQ than I was at previously. Still seems like it doesn't have the oomph that it should. It will be nice to get some fuel mileage numbers after this swap.

I went ahead and turned the EGR back to stock setting just to see if that will help the mileage. It semed to decrease a bit with the 01M when I set it to minimum in adaptation. My temperatures were about what they used to run with the "Hybrid" T-stat so that is good, although it does appear to me that the system has a bit less thermal energy added since I switched from the automatic. I will post some numbers with the new setup once they are available, and perhaps with my new to me 5-speed my MPG numbers will be a bit more apples to apples comparison with many out there.

One thing I am glad that I was able to do was to replace the hard coolant pipe seal that sits under the IP. This is the rubber seal that interfaces the hard coolant pipe that wraps around the engine to the block inlet under the IP. It was a pain in the butt to replace, but after seeing it's condition it was a good thing I thought to do it-probably would have started leaking very soon! I also replaced the coolant line that runs to the bottom of the coolant reservoir, and the lower radiator hose while I was doing all the work. If I could have gotten ahold of the upper rad hose, that would be new too. Perhaps in the future it will be done along with some additional smaller diameter coolant lines. BTW, the reason I started doing the lines is I noticed that the rubber material was deteriorating inside them, and with higher temp coolant temps and hence higher presures I thought this would be prudent to do.

dieselfuel · Jun 13, 2011

5-spd swap, cool! Glad you're done.

Hammer mod the IQ to 5-7 and then adjust it in the software. Also, set the time to 5 BTDC. That setting will give you more power and increased mpg. It will also clatter a bit louder at idle. Not a deal breaker for me, though.

Got my other t-stats the other day. I'll get them boxed up and off to you in the next day or so.

Enjoy the 5-spd!

dieselfuel · Jun 13, 2011

Found this link for timing:

http://forums.tdiclub.com/showpost.php?p=2473291&postcount=1

Go to the graph in the VDCS and adjust the timing for 70-72 (ideal, imo.) Get that yellow line right up to the green line but not over. It will probably get a reading of 72.

Do this with the engine at full operating temp.

Then set the pump IQ (5-7), then use the VCDS to adjust the timing to 5 BTDC. Next use the VCDS to adjust the IQ setting so as to produce a light gray haze at WOT. If you get black smoke, your running to rich. Raise the IQ to lower your fueling (remember, they are opposite).

Let me know how you make out.

josh8loop · Jun 14, 2011

dieselfuel said:
Found this link for timing:

http://forums.tdiclub.com/showpost.php?p=2473291&postcount=1

Go to the graph in the VDCS and adjust the timing for 70-72 (ideal, imo.) Get that yellow line right up to the green line but not over. It will probably get a reading of 72.

Do this with the engine at full operating temp.

Then set the pump IQ (5-7), then use the VCDS to adjust the timing to 5 BTDC. Next use the VCDS to adjust the IQ setting so as to produce a light gray haze at WOT. If you get black smoke, your running to rich. Raise the IQ to lower your fueling (remember, they are opposite).

Let me know how you make out.

DF,

Good refresher on the timing thanks. I am mechanically just slightly above the top of the timing graph. Also my requested timing and actual timing are around 5.5 degree BTDC at idle and operating temp. My IQ is around 3.8 mg/stroke. Not sure if that means anything or not.

dieselfuel · Jun 14, 2011

How is it running with those settings?

Also, I'm not quite sure yet, but I believe that seized alt has been costing me a few mpg. I believe my problems with the alt started shortly after I had the TB kit installed (at 108,000 miles). The day after the kit was installed, I had that battery light on the dash flicker on and off a few times, and then nothing until it failed last week.

Anyhow, I've been driving the car hard lately (and with the A/C on ) and I know my mpg has gone up since my new alt was installed. I'll know when I fill up in a few days.

Honeydew · Jun 14, 2011

josh8loop said:
I am mechanically just slightly above the top of the timing graph. Also my requested timing and actual timing are around 5.5 degree BTDC at idle and operating temp. My IQ is around 3.8 mg/stroke. Not sure if that means anything or not.

It should be running strong like that, you say it's doggish? Have you tried it with IQ and adaptation advance set where it is but with the mechanical timing pulled back into the specified range?

josh8loop · Jun 15, 2011

Honeydew said:
It should be running strong like that, you say it's doggish? Have you tried it with IQ and adaptation advance set where it is but with the mechanical timing pulled back into the specified range?

Honeydew,

I was hoping to not have to readjust the mechanical timing, but I may have to. I am still monitoring my turbos health as well, so if it's losing effectiveness that could explain it. Actually, it may not be a bad idea to visit with you some time, and let you drive it since you are familiar with what it should do.

boertje · Jun 15, 2011

When I did my swap my IQ went from 6 to 4 and I had to readjust it using the hammer mod back to 6 ( have bosio DLC520 nozzles) since I had too much smoke. You might want to set all your timing and such back to stock including EGR and then check your mechanical timing to make sure its in range. Mine is at 70 at op temp. My bug stock IQ with the 5 speed was 2.8 and my Jetta with auto stock from the factory was set to 4. I think with the stock nozzles Josh that in the 3 to 4 range is pretty good. On WOT, do you get any haze? That is your indicator.

Honeydew · Jun 15, 2011

Josh see if you can stop by the shop after work Th or Fri. I'll drive the TDI to work and we can test drive each other's cars. Bring the vcds (only need cable not laptop) so I can adjust my IQ and then you can hang onto it for a while longer.

josh8loop · Jun 15, 2011

dieselfuel said:
Found this link for timing:
http://forums.tdiclub.com/showpost.php?p=2473291&postcount=1
Go to the graph in the VDCS and adjust the timing for 70-72 (ideal, imo.) Get that yellow line right up to the green line but not over. It will probably get a reading of 72.
Do this with the engine at full operating temp.
Then set the pump IQ (5-7), then use the VCDS to adjust the timing to 5 BTDC. Next use the VCDS to adjust the IQ setting so as to produce a light gray haze at WOT. If you get black smoke, your running to rich. Raise the IQ to lower your fueling (remember, they are opposite).
Ok, sounds good Travis let's plan for tomorrow then
Let me know how you make out.

Honeydew said:
Josh see if you can stop by the shop after work Th or Fri. I'll drive the TDI to work and we can test drive each other's cars. Bring the vcds (only need cable not laptop) so I can adjust my IQ and then you can hang onto it for a while longer.

Sounds good Travis, let's plan on tomorrow afternoon then if that will work. I will bring tools for the hammer mod if it is needed too. Looking forward to it!

dieselfuel · Jun 15, 2011

Filled up tonight,first time since alt was replaced. I seriously believe that faulty alt was robbing me of about 2 mpg.

I'm 2 mpg higher after that alt replacement. Less drag (freer spinning) from the new clutch pulley, imo.

josh8loop · Jun 16, 2011

dieselfuel said:
Filled up tonight,first time since alt was replaced. I seriously believe that faulty alt was robbing me of about 2 mpg.

I'm 2 mpg higher after that alt replacement. Less drag (freer spinning) from the new clutch pulley, imo.

Nice! 2 MPG, that's not bad. I could see how that could be from a bad alternator that has seized. Looking forward to getting your T-stats so I can get them together for you like we talked about. Really looking forward to your MPG numbers once they are in!

josh8loop · Jun 16, 2011

First 5-speed fill up since swap...

Filled up this evening, and calculated I got 52.17 MPG in town. This was with some spirited driving, but no AC. I expect if I was really trying, I could do a little better even still. Will try disabling my stage 1 radiator fan thermal switch soon to see if that helps too. I will have to review other members MPG numbers to see how I am stacking up.

dieselfuel · Jun 17, 2011

O.K., I'm going to the basement to look for a box....

Turbospool · Jun 18, 2011

well.... I've been lurking on this thread for some time now... just removed my original thermostat (I'm at 180k) and placed a new one .... Autozone 190 stat. Wow!!! now my scan guage reads 190 - 200 f, most of the time upper 190"s. I used to never see over 170-175 F . Now I'll need to see if there's any gains to be had milage wise. ???? I;ll post back later if there's anything significant.

b13bliss · Jun 18, 2011

I've been lurking also. My Scangauge showed that my coolant temps were running 172-173 once up to temp, but that takes up to 15 miles on my mostly downhill 4am jaunt to work. I tried your modified stat build and put it in keeping an eagle eye on the temps. They now climb to 206-207 and stabilize, and pulling a long grade I've seen 213, but never more. I'm not concerned with that, but I certainly don't want them any higher! I have a good mix of G12 (60-70%) to prevent boiling. My fans never come on that I know of as I only have the high setting wired to the fans that only comes on at 210-220 in the radiator. My radiator seems to be doing it's job very well seeing as the lower radiator hose is barely warm to the touch even after pulling a five mile grade at 60mph on an 80 degree day at the end of my commute.

My first fill-up with the 205 degree stat was up 4 mpg to 57.6. So far, so good. We'll see what happens when it gets really hot

jayb79 · Jun 18, 2011

213 after or during a long pull should not be a problem at all. I have seen that in the winter when its 20f outside. The temp sensor is showing the coolant as it exits the head on it way to be cooled off.

josh8loop · Jun 19, 2011

Turbospool said:
well.... I've been lurking on this thread for some time now... just removed my original thermostat (I'm at 180k) and placed a new one .... Autozone 190 stat. Wow!!! now my scan guage reads 190 - 200 f, most of the time upper 190"s. I used to never see over 170-175 F . Now I'll need to see if there's any gains to be had milage wise. ???? I;ll post back later if there's anything significant.

Please do post your results, they will be nice to hear

. Not at all a bad thing to have the engine temp where it should be! From what I see MPG Vs Temperature, that should get you 1-2 MPG more. Just curious why you didn't get a 195 Deg F T-stat? Nice work.

josh8loop · Jun 19, 2011

b13bliss said:
I've been lurking also. My Scangauge showed that my coolant temps were running 172-173 once up to temp, but that takes up to 15 miles on my mostly downhill 4am jaunt to work. I tried your modified stat build and put it in keeping an eagle eye on the temps. They now climb to 206-207 and stabilize, and pulling a long grade I've seen 213, but never more. I'm not concerned with that, but I certainly don't want them any higher! I have a good mix of G12 (60-70%) to prevent boiling. My fans never come on that I know of as I only have the high setting wired to the fans that only comes on at 210-220 in the radiator. My radiator seems to be doing it's job very well seeing as the lower radiator hose is barely warm to the touch even after pulling a five mile grade at 60mph on an 80 degree day at the end of my commute.

My first fill-up with the 205 degree stat was up 4 mpg to 57.6. So far, so good. We'll see what happens when it gets really hot

B13bliss,

Obviously I'm sure your aware that this is all experimental, and it has not been proven to be safe for the engine/turbo. With all that out of the way, great work! Did you use a similar method of fabrication like I did or did you come up with something that's the "Cats Meow"? Also, on your wiring, did you just cut wire number 1 on the switch pigtail to disable stage 1 fans? I haven't tried this yet, but it is on the to do list once I find a suitable VW plug to put in series with a nice switch. Does your AC engagement for the fans work as normal with the stage 1 fans disabled? Also, perhaps you could update your User CP information so we can see what type of car you have, and mileage/Mods etc. Great work-it is nice to have a parallel path for feedback on this mod as it relates to MPG. 57.4 MPG is not too bad IMHO, curious of your previous MPG numbers before the "Hybrid" T-stat.

b13bliss · Jun 19, 2011

Josh,

I realize this is experimental, but I've been interested in slightly elevated operating temps in my diesels for some time, but stalled out on finding a high temp thermostat. Thanks for your footwork on making one that fits and works! I just followed your build video, and it was easy.

My fans weren't even wired in before as this is an ALH fitted into a 1991 Jetta that always ran low temps without them due to the huge passat radiator the previous owner installed. I looked up in the Bentley which terminals operate (on the fans) for the high fan operation and wired a relay into them to be switched on directly from the radiator fan switch (the two terminals that connect at the higher temp) when it grounds at the specified temperature. The A/C isn't 100% installed yet (need to get custom lines) but I'll integrate by supplying power to the relay when the compressor clutch sees 12v. Not the most elegant, but it should work.

My MPG history is shallow as this car is new to me. My previous fill-up was 53.5mpg with the exact same usage and driving conditions with great consentration on best MPGs (driving 85% highway at 55-65mph.) I've been driving the same route for a couple of years with my 85 Jetta 1.6TD (usually 50-51mpg.) So not very conclusive as to percentage improvement, but encouraging so far.

The car is set up more for performance than mileage with an 11mm pump, race 520s, 2256vnt turbo, MAP based tuning, 205-45-16s on 7.5" wide Borbets, etc., but I think it great fun to try for best MPGs at least some of the time

josh8loop · Jun 19, 2011

b13bliss said:
Josh,

I realize this is experimental, but I've been interested in slightly elevated operating temps in my diesels for some time, but stalled out on finding a high temp thermostat. Thanks for your footwork on making one that fits and works! I just followed your build video, and it was easy.

My fans weren't even wired in before as this is an ALH fitted into a 1991 Jetta that always ran low temps without them due to the huge passat radiator the previous owner installed. I looked up in the Bentley which terminals operate (on the fans) for the high fan operation and wired a relay into them to be switched on directly from the radiator fan switch (the two terminals that connect at the higher temp) when it grounds at the specified temperature. The A/C isn't 100% installed yet (need to get custom lines) but I'll integrate by supplying power to the relay when the compressor clutch sees 12v. Not the most elegant, but it should work.

My MPG history is shallow as this car is new to me. My previous fill-up was 53.5mpg with the exact same usage and driving conditions with great consentration on best MPGs (driving 85% highway at 55-65mph.) I've been driving the same route for a couple of years with my 85 Jetta 1.6TD (usually 50-51mpg.) So not very conclusive as to percentage improvement, but encouraging so far.

The car is set up more for performance than mileage with an 11mm pump, race 520s, 2256vnt turbo, MAP based tuning, 205-45-16s on 7.5" wide Borbets, etc., but I think it great fun to try for best MPGs at least some of the time

B13bliss,

Thats really neat! Glad to hear the video/information was helpful in creating it. That was the intention, but you never know until someone tries it

ALH into the '91 Jetta, that's cool! A little different than the "norm". Whats interesting is that you are getting that kind of mileage with the power mods too. That is very encouraging. To my knowledge you are the first to have an ALH with hefty performance mods to make use of this "Hybrid" T-stat. Will be fun to follow your MPG results. DieselFuel will probably be the next to test the 205 T-stat, so it will also be nice to get his feedback too. Keep up the good work, and let us know whats going on with things.

dieselfuel · Jun 20, 2011

I hope to be the next! I'm heading to USPS to ship those 'stats' to you.

Check for a PM from me by midnight tonight. :>)

josh8loop · Jun 20, 2011

dieselfuel said:
I hope to be the next! I'm heading to USPS to ship those 'stats' to you.

Check for a PM from me by midnight tonight. :>)

Gotcha, will do

Dieselgeek · Jun 21, 2011

I use a 95C tstat in my 1.8T Focus and regularly run 225F coolant temp on the highway in summer (according to scangauge). I am using 100% Evans coolant so no boil over or localized boiling issues. The motor is spotless inside. I haven't gotten below 30mpg since I switched tstats and coolant. I average 32 in town which is mostly where I drive this car. My coolant fan is set to come on at 227F.

Turbospool · Jun 21, 2011

josh8loop said:
Please do post your results, they will be nice to hear . Not at all a bad thing to have the engine temp where it should be! From what I see MPG Vs Temperature, that should get you 1-2 MPG more. Just curious why you didn't get a 195 Deg F T-stat? Nice work.

I don't feel real comfortable running in the 200 + numbers all the time , especially when I want to pull some of these steep long mountains here in the blue ridge ..... I mostly ride at 195- 200 F and that feels safe, occasionally I can take it well over 200 ... but I don't feel good hitting 220 F and over. Yeah, ok I''ll post back once I know if any gains where realized. Thanks for your input.

Modified Thermostat for higher MPG's...

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