[Darwood]

Originally Posted by Rich

I would like the needle hitting the red zone to indicate the need to stop immediately and let the engine cool down.

It all depends on the context, in general, if the engine were running at say a steady 220° F, in a situation where running hot is to be expected, I.E. heavy loads, steep mountains in the summer desert, then I think that is acceptable. A spike to 230° F near the top of a steep pass wouldn't likely cause me to stop.

In contrast, seeing 220° F on a cool fall evening driving the flats lightly loaded would merit serious attention, and that's why I mention context matters.

I'd like have the gauge setup such that having the needle near the red should be concerning and having the needle in the red should demand action, and for me, 216° F seems too low to demand stopping the vehicle when operating with high loads in very hot ambient conditions.

In general, I think that the red zone should be used to indicate that the danger of boil over is being approached, and having 240° F at the beginning of the red leaves a large margin of over 20° for that.

Hi Rich I fully agree with you. I finally posted an equation up in the development thread. I'll post some more info later.

http://forum.ih8mud.com/showthread.p...28#post1251128

I really think you might like the 150 ohm RD1 and 100 ohm R1 replacements. With this setup the needle should look like this at 238 degrees F:

[RCFloyd]

Dang, gang...

I just did the math for the conversion too...
82C does equal 179.6!! Now where did we get the idea that the OEM T-stat was 195?

Oh well, the OEM does seems to be more HD...

On another note, Darwood's new calculations with the accompanying suggestions for different resistors is about a week late! I really would have liked to go with these other units too, because is just seems that the original modification was a little to 'loose' in what the interpetation could be.

Could we have some part #'s please for the newest rendition?

Thanks,

Robert

[Rich]

Thanks Derek. Looks like that should do the trick. Thanks also to Raven for doing the great ground work.

[Darwood]

Looks like I need to post some more info. 180 ohms for the diode replacement is another option. With this resistor 238 degree F should look something like the attached. Right now I have the 100 ohm and 150 ohm resistors in my truck. I like it so far. When it got up to 221 the needle was about 2 needle widths below the red line and 218 was at about the 34 mark. 200 degrees is centered and 194 is just below center where the stock gauge would never move from once warmed up.

I'd also like to point out that the temp to needle values (except for my limited real world experience) are all calculated off or Raven's data and might vary slightly from their real world performance due to some assumptions I have to make when calculating. For the most part what I've expected and what I've seen have been pretty consistent when I've tested out the modified gauge vs the OBD II scanner.

[Darwood]

Oh yeah I should also mention that without Raven's help none of my tinkering would have been possible. He discovered what the circuit was and provided me with invaluable data. I'd also like to point out once again that any values I suggest are still experimental and I only put them out there for those who understand the risks.

In my truck I'm actually on my 3rd modification to my gauge.

[extremetoy1]

has anyone sent in a 91 gauge or pics yet? i am patiently waiting!!

[tarbe]

Originally Posted by Darwood

Right now I have the 100 ohm and 150 ohm resistors in my truck. I like it so far. When it got up to 221 the needle was about 2 needle widths below the red line and 218 was at about the 34 mark. 200 degrees is centered and 194 is just below center where the stock gauge would never move from once warmed up.

I like the sound of that set-up. Any part #s or links for electards??

[Darwood]

Originally Posted by tarbe

I like the sound of that set-up. Any part #s or links for electards??

The 100 ohm resistor replaces the 75 ohm resistor and the 150 ohm resistor replaces the diode. These are the same type and brand that Raven sourced.

Mouser Part #: 71-RS2B-100
Manufacturer Part #: RS02B100R0FB12
Manufacturer: Vishay/Dale
Description: 3watts 100ohms 1%


Mouser Part #: 71-RS2B-150
Manufacturer Part #: RS02B150R0FB12
Manufacturer: Vishay/Dale
Description: 3watts 150ohms 1%


Here is the 180 ohm reisistor is anyone feels so inclined to use that. Note however that I haven't tried out this value.

Mouser Part #: 71-RS2B-180
Manufacturer Part #: RS02B180R0FB12
Manufacturer: Vishay/Dale
Description: 3watts 180ohms 1%


(I'm having issues with posting functioning links)

[tarbe]

Cool - thanks Derek!

I'll use the link on the first page and hopefully navigate my way to the two correct animals.

[tarbe]

I just ordered 5 each of the 100 and 150 ohm. I have two extra pairs available.

Anyone in the greater Houston area...you can pick up a pair...for free...first come first served...at the next monthly meeting of the TLCC-H at Matagorda Beach. See the TLCC-H link in the club section.

Buck and Ross...I have a pair for each of you if you want them!

[Buckru]

Tim,

Done deal for me on the resistors and I'll see you Sat. for wrenching session.

Buck

[tarbe]

Originally Posted by Buckru

Tim,

Done deal for me on the resistors and I'll see you Sat. for wrenching session.

Buck

Got home from work today and the garage was a nice 103 degrees. That was with the two bay doors open about 18" and the side door wide open.

That PHH is gonna be fun! I think I'll start hydrating about now...

[Cattledog]

Thanks RavenTai great mod.

Sunday afternoon beers with Landtank conviced me to mod the guage. Very easy mod. I would recomend a cloth towel over the steering wheel assembly. It will help avoid any scratchs to the clear housing on assembly. And remember that the steering wheel tilts that helped alot for screws and assembly.

BTW, My truck is running hot... I will be doing the landtank fan clutch mod and new drive belts this weekend.

Thanks

[landtank]

Originally Posted by Cattledog

BTW, My truck is running hot... I will be doing the landtank fan clutch mod and new drive belts this weekend.

I've got a half bottle of 3000k around somewhere. Your welcome to it. I needed a botlle and a half on mine but I had lost some on the many times I took it apart.

[Cattledog]

Thanks Landtank! I will take you up on the offer. Are you around this weekend, I can bring the beer!

[landtank]

I think so, I'll know more when I get home tomorow. You could throw on that old clutch and bring down the new one and we could go threw it at my place.

As for the beer, peepers left a bunch when he was here last so that's covered. I'll pm him and maybe he'll show up and we can get his dual battery going.

[tarbe]

I did the mod with 150 and 100 ohm and I am a bit frustrated...my gauge sits a needle above horizontal instead of a needle below.

Brand new OEM T-stat, new blue clutch, fresh coolant, recently cleaned fins on rad and condenser.

Didn't matter if I let it idle with the A/C on, drive 60 with or without A/C, stop and go...wouldn't really move...just sat there above horizontal a needle or so.

I thought it was supposed to be below horizontal with this set-up?

Maybe I'll have to scrounge a real-time scanner to plug in and see what my temps are....

[landtank]

i realised yesturday it depends on how I look at it. Just glancing down from my driving position it looks to be horizontal, but if I crouch down and lean to the left to look more straight on it looks to be just a little higher than horizontal.

Part of the error you get with these types of gauges.

[Darwood]

Originally Posted by tarbe

I did the mod with 150 and 100 ohm and I am a bit frustrated...my gauge sits a needle above horizontal instead of a needle below.

Brand new OEM T-stat, new blue clutch, fresh coolant, recently cleaned fins on rad and condenser.

Didn't matter if I let it idle with the A/C on, drive 60 with or without A/C, stop and go...wouldn't really move...just sat there above horizontal a needle or so.

I thought it was supposed to be below horizontal with this set-up?

Maybe I'll have to scrounge a real-time scanner to plug in and see what my temps are....

I PM'd you back. That would be frustrating. By changing the 110 ohm resistor that Raven recommends to a 100 ohm resistor the center should be at an even warmer temperature which translates to the needling being lower when warmed up. If somehow the 150 ohm resistor replaced the 75 ohm resistor the center would be a lower temperature which would result in the gauge needle being higher than center when warmed up. Either that or the truck runs warm. I have a sneaking suspicion that the resistors got swapped somehow.

The 110 resistor should center at 189 where as the 100 resistor should center at 194 when used as a replacement for the 75 ohm resistor.

[Buckru]

Are the resistors clearly marked?

Sorry to hear about your frustration Tim but you know I can sympathise with ya.

Buck

[tarbe]

I did replace the diode with the 100. I have swapped them around and will test drive at the earliest opportunity and report back.

In the original mod, the higher ohm resistor replaced the original resistor and the lower replaced the diode. I kept that relationship in mind as I was doing my 100/150. Assumption got me again!!

[tarbe]

Everything is fine now...needle is one full width below horizontal at normal operating temp. Should be 200 at horizontal.

Thanks RT and Darwood!

[tarbe]

Add another to the list...we just finished Buckru's gauge with the 100/150.

Testing on the beach tomorrow at the TLCC-H monthly meeting!

[RavenTai]

Derek I was going to PM you but aparetly I have lost that ability,

the alternate resistor setups are going well, nice work

If you have some time and you think they are ready could you do a write up about the alternate resistorss and I will put it in the first post in this thread, what resistors, what the results are and anything else you think might be needed.

let me know
Raven

[Buckru]

Temp guage is now modified with 100 and 150 resistors.
Truck has a new blue clutch, new t-stat, new phh and fresh green coolant.

On the highway the guage sits between the cold line and horizontal and really hasn't moved up much at all. Based on what I have read I would say that equates to 180-190 degrees.

While driving seven miles down the beach, some deep sand mostly fairly well packed in 95 temps, the guage stayed below horizontal the entire time.

This week I will be driving into Arkansas with a loaded truck and will have a chance to see how she does in hills

Another big thanks goes out to Tim for helping me with this.

Buck

[Rookie2]

Hey RT,

Just checking to see if you had planned on doing the fan clutch mod. I know you were concerned that your engine temps may be running slightly on the high side. FWIW, I drove down to Orlando a couple of weeks ago and here's what I observed: Daytime, 80 mph, AC on, and generally flat terrain... needle go to around near 3/4 on a fairly consistant basis. At night the gage seemed to stay within a needle or two of middle. On one occasion when I stopped for fuel, when I restarted the engine, the needle was right at the red, but settled back down within a few seconds.

I was kind of waiting to see how the mod pans out in regards to what is the best approach.. higher viscosity fluid or a combination of timing advance and higher viscosity. Be interested in hearing what you decide to do.

Hope everything's going well with your new job.

Regards,
Rookie2

[tarbe]

Originally Posted by Rookie2

Daytime, 80 mph, AC on, and generally flat terrain... needle go to around near 3/4 on a fairly consistant basis. At night the gage seemed to stay within a needle or two of middle. On one occasion when I stopped for fuel, when I restarted the engine, the needle was right at the red, but settled back down within a few seconds.

Which resistors are you running?

[Beowulf]

Originally Posted by Rookie2

On one occasion when I stopped for fuel, when I restarted the engine, the needle was right at the red, but settled back down within a few seconds.

Rookie2,
This is normal. I don't have the RT mod; mine is an aftermarket coolant temp gauge with the probe in the water neck. I will see large rises in the gauge during high ambient temps after the engine is shut down following a trip at highway speeds.

-B-

[Rookie2]

Originally Posted by tarbe

Which resistors are you running?

I've got the original RT version. I can't remember the resistor values.. 50 and 100 maybe..??

Originally Posted by Beowulf

This is normal. I don't have the RT mod; mine is an aftermarket coolant temp gauge with the probe in the water neck. I will see large rises in the gauge during high ambient temps after the engine is shut down following a trip at highway speeds.

-B-

Thanks B. I wasn't really concerned about it and thought it was somewhat to be expected. If I was one of those that's got a vehicle that's running hot (AC cutoff hot that is), I'd be worried about it. That extra spike at shutdown can't be good if you're already at 225 to 230.


Rookie2

[Darwood]

Originally Posted by RavenTai

Derek I was going to PM you but aparetly I have lost that ability,

the alternate resistor setups are going well, nice work

If you have some time and you think they are ready could you do a write up about the alternate resistorss and I will put it in the first post in this thread, what resistors, what the results are and anything else you think might be needed.

let me know
Raven

Sure thing. I'll have to find some time

So you guys with the alternate resistors, do you think where it centers is too low or do you like where it is?