93-97 Coolant Temperature Gauge Modification

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@bmwjnky Hey that is different! Not seen that pressure sensor before, what does it do when the engine has little or no pressure when cold?

@orttauq It was a long while back so cannot remember (50/10?), but I used whatever was listed by the OP, IMO one of the best mods ever.

regards

Dave
 
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Staying tuned.. it would be nice to have a warning light or buzzer when loss of pressure is realized. But I am also curious as to how it would behave when cold.
 
Dave 2000 said:
@bmwjnky Hey that is different! Not seen that pressure sensor before, what does it do when the engine has little or no pressure when cold?

Dave
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The light is on when the engine is cold but it doesn't take much time for the engine to warm enough to build pressure to turn the light off. In the shop with the race cars it only took a min. of idling before the light would go off. For our truck on a cold winter day it may take more time but I'd rather have the warning light to let me know when there is a cooling system failure.
 
Like the sound of the pressure sensor. I am going with a 'loss of water level sensor' with a light and buzzer but, I could always parallel that pressure sensor in. My only thought about it is, in a race car environment fluids are always checked prior to a race, and during a race the loss of pressure would bring on the light but, what would happen if in a DD scenario you lost water overnight? Unknowingly, you could start the engine and drive for awhile expecting the light to go off, and if the normal mode in a cruiser is say three minutes? Then that is still some time for the things to get a little warm?


EDIT: Just looked at the specs and goes off at 3 psi, so doubt it would be more than a couple of minutes? My system uses a buzzer so it is silent as soon as all three warnings systems are good, oil pressure, high temp and low water. So in reality it is the few seconds for the oil pressure to reach 21psi that I need to hear the buzzer for.

Regards

Dave
 
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I sure didn't, I'm pretty lazy.
 
Anyone has a spare 110 resistor?
part# RS02B110R0FB12
Mouser has them backordered (eta 18 weeks)
They carry plenty of 50ohm.
 
E4B8C81E-D660-4825-B760-76B6613521E5.webp
I just bought a LC with the temp mod done. I seriously don’t know why anyone would want to do this mod as it psychologically stresses me out because with all my vehicles that I ever driven the needle stays in one spot and does not move until it senses that the engine is actually overheating. Lol.

Since the needle moves in positions that really make me feel uncomfortable, I decided to install a more accurate temp sensor which is the KOSO temp sensor with a 40mm adapter between the engine and the top of the radiator.

I just wanted to show a picture of “normal” temp display on a temp modded dash. The OEM thermostat opens completely at 180. And to me this picture would scare then sh!t out of me because of the position of the needle, which is no where near overheating.

If your bored and just want to stare at the needle all day while you are driving, by all means do the mod. But if you want an accurate display do a more accurate way of displaying the temp by installing a aftermarket temperature gauge IMhO.
 
Sorry guys, but the coolant pressure warning idea will not work.

The coolant system normally pressurizes right up to the radiator cap's pressure rating.
It then pushes a little coolant into the overflow (expansion) tank.
The radiator cap spring acts as a pressure regulator, so the cap's rating is the maximum system pressure.
The normal radiator cap is rated at 0.9 bar (13psi).
I also have a 1.1 bar (16psi) version for experimental purposes.

Before getting out of the neighborhood, from a cold start, coolant temp still climbing rapidly through 155F, I am seeing the pressure limit being hit.
It does not stay at the limit, but it always hits it for at least a few minutes.
I have a pressure gauge on the system to watch this stuff happen.

A Coolant System Pressure Test

Addendum:
Have recently learned - coolant system pressurizing up to the cap's pressure rating is normal with some radiators, but not with others.
CSF 2517 - brass/copper - hits pressure cap limit and overflows often during any trip.
TYC 1918 - aluminum core/plastic tank - normally fairly steady at 6-8psi.
Will still hit pressure limit when RPMs jump.
 
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As per my earlier post, I went for actual level as opposed to pressure. I think the pressure sensor may be ok if the rad cap lifts momentarily to allow water into the expansion tank. I would have thought the pressure drop would not drop to the 3 psi which is the point the sensor would respond, if it did how long before it recovered to 3 psi?

Once the initial expansion has occured, there would be few if any further expansion events once running temps have been reached. My only reservation that I mentioned in an earlier post is the overnight loss scenario, the light or buzzer would be on whilst coming up to pressure, but with no coolant in the system due to a hole somewhere no pressure will be built, during this time the driver assumes all is well and damage may be occuring.

Having said that, at least making the attempt to have some kind of warning of loss, is certainly better than none.

Regards

Dave
 
cybrstar said:
View attachment 1698832 I just bought a LC with the temp mod done. I seriously don’t know why anyone would want to do this mod as it psychologically stresses me out because with all my vehicles that I ever driven the needle stays in one spot and does not move until it senses that the engine is actually overheating. Lol.

Since the needle moves in positions that really make me feel uncomfortable, I decided to install a more accurate temp sensor which is the KOSO temp sensor with a 40mm adapter between the engine and the top of the radiator.

I just wanted to show a picture of “normal” temp display on a temp modded dash. The OEM thermostat opens completely at 180. And to me this picture would scare then sh!t out of me because of the position of the needle, which is no where near overheating.

If your bored and just want to stare at the needle all day while you are driving, by all means do the mod. But if you want an accurate display do a more accurate way of displaying the temp by installing a aftermarket temperature gauge IMhO.
Click to expand...
Where did u get that gauge?
 
Spending most of my time in the desert, I expect to run a little hotter and would like to mod the gauge so centered in the red is 230. Both my other vehicles run 190-200 normally so I'd like to setup the gauge so 190 is a little below center. So I'm clear on what I'm tinkering with, what does each resistor do? Does the 110 set the center point and the 50 set the span? I have seen a few alternate resistance values floating around anyone know what is needed for a 200 center and 230 centered on red?
 
motormayhem said:
Spending most of my time in the desert, I expect to run a little hotter and would like to mod the gauge so centered in the red is 230. Both my other vehicles run 190-200 normally so I'd like to setup the gauge so 190 is a little below center. So I'm clear on what I'm tinkering with, what does each resistor do? Does the 110 set the center point and the 50 set the span? I have seen a few alternate resistance values floating around anyone know what is needed for a 200 center and 230 centered on red?
Click to expand...

UltraGauge OBDII Scan tool and Information Center
 
I took apart the temp/oil pressure gauge to fix the oil pressure gauge. I removed the actual needles from both gauges and took the faces off. When I reinstalled, the temp gauge reads nearly maxed out, in the red, when the car isn't even warmed up yet. It returns all the way below C like normal when not receiving power. Anyone know a specific way the needle needs to go in to work properly again?
 
wrxFTWdey said:
I took apart the temp/oil pressure gauge to fix the oil pressure gauge. I removed the actual needles from both gauges and took the faces off. When I reinstalled, the temp gauge reads nearly maxed out, in the red, when the car isn't even warmed up yet. It returns all the way below C like normal when not receiving power. Anyone know a specific way the needle needs to go in to work properly again?
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Unless anyone knows of a better way, you can pull out the cluster, remove the clear lens, and re-install the cluster in the dash. Then go for a drive to fully warm up the engine. Once hot, pull over with the engine running and pull the needle off the temp gauge, then put it back on in the center position (assuming an un-modified gauge). Continue on driving to make sure the gauge remains stable. HTH
 
landcrshr said:
Unless anyone knows of a better way, you can pull out the cluster, remove the clear lens, and re-install the cluster in the dash. Then go for a drive to fully warm up the engine. Once hot, pull over with the engine running and pull the needle off the temp gauge, then put it back on in the center position (assuming an un-modified gauge). Continue on driving to make sure the gauge remains stable. HTH
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That’s exactly the way I actually corrected it actually. It was impossible for me to get the needle in the right spot without getting the car to op temp. Thanks!
 
I would just offer this as an update. When a modification is made to a vehicle it is usually done to improve said vehicle, perhaps reliability, or from a personal POV perhaps something cosmetic. But whatever is done is must have OE reliability or better. I did the temp gauge mod a number of year ago now and it still works perfect. The gauge no longer hits 'normal' within 3 - 4 minutes of driving, it takes a more realistic 20 minutes. Once the engine is warmed to operational temperatures if I climb a long steady hill I can see the gauge reacting to that workload, I also know the temperature shown is perfectly correct, I use an all electric cooling system and the temperatures the fan starts at are also verifiable. For me it was a way of getting ALL of my gauges reading perfectly accurate, this mean no extra unnecessary duplication of systems from the OE install.

I think many purchase 'stuff' (mechanical or electrical) more for 'looks' or 'pub talk' value, which is a shame because it lacks imagination when the OE which worked fine when new and is now in need of just a little fettling keeping it accurate.

Just my 1 euro.

regards

Dave
 
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