Guys,

I am trying to devise a system to warn me in a shockingly obvious manner when my LT1's coolant temperature exceeds a certain safe threshold. With an electric water pump and the money in this motor, I'm concerned about any kind of subtle failure. The stock "check gages" light just doesn't cut it and may not light up until the coolant temperature has already touched too high of a level for my taste. And the electric water pump warning light circuits I've seen only really test for a positive power source going into the water pump (i.e., wire connections and the relay). I'd like something more.

Anyway, I could either utilize the stock coolant temperature sensor signal or an aftermarket temperature switch. Regarding the stock sensor, I found this chart regarding resistance readings from the sensor at various coolant temperatures, but I have no idea how to use that information to create a trigger for a light or buzzer at a certain temperature:

http://shbox.com/1/4th_gen_tech2.html (ctrl-f for "ECT temperature")

Regarding aftermarket temperature switches, I've found these two:

http://autometer.com/cat_accessoriesdetail.aspx?vid=182 (220 degrees)

http://www.speedwaymotors.com/Water-...Kits,7806.html (230 degrees)

And this line of fitings to mount the aftermarket switch in a coolant system hose:
http://www.autometer.com/cat_accesso...il.aspx?vid=50

If I go with an aftermarket temperature switch, I would consider locating the switch in hose #14 on this diagram:

http://shbox.com/1/95-97_hoses.jpg

So, my questions to anyone who feels inclined to help:

(1) What is the feasibility of using the stock sensor signal to trigger a big warning light or buzzer at a given temperature (say, ~230 degrees)? How would I do that?

(2) Regarding the use of an aftermarket switch, what do you think about the location I am considering for the switch?

(3) Also regarding an aftermarket switch, do you think the temperature triggers (220* and 230*, respectively, for the models I found) are appropriate? I know the stock sensor is in the cylinder head, and I'm worried that 250* coolant in the cylinder head may only result in, say, 215* coolant in the hose I'm planning on tapping into.

(4) What do you think is the actual operating coolant temperature (per the stock sensor) for a healthy LT1 with a 160* thermostat after a "vigorous run" in the summer? Maybe 200*?

Thank you

 

Maybe look at this.
http://www.ultra-gauge.com/ultragauge/index.htm
Should work so long as your car is still OBD2 and it has configurable alarms.
Not terribly expensive, super easy to plug in and setup compared to wiring something.
Would let you monitor some other functions full time not just temp.

The stock dash temp sender is in the head, the pcm uses the one in the waterpump.
Which is the only maybe downside to this, it might be better for you to monitor the head rather than at the pump.
BUT with this you could also adjust the alarm temp so you could make it more sensitive than a 230degree switch so you should still be able to find out about a problem sooner even if the pump shuts off there will be slow residual circulation for a few moments.

I would expect the engine to run high 170s on the highway, cooler at low speeds, maybe mid 170s. The electrics do COMPROMISE cooling capacity so if you run it hard you might get it to warm up a bit, I still would not expect 200 with the 160 stat though.

I bought one of those for my truck and haven't played with it much yet, if nothing else the instant MPG is amusing. I needed a code reader this does more than that and was reasonably priced.

 

ChrisLS1Bird:
Why not use the cooling system port on the passenger side head? The temp switch can provide a ground for a light and/or buzzer. Radio Shack has a 12vdc buzzer for $2 or $3. ISTR the pipe plug needs a 8mm square drive plug tool to remove it.
Stewart-Warner has the switches available that can fit in the head (3/8"npt):
#83300 200°f 1/4"npt (requires 3/8' x 1/4" bushing)
#83304 200°f 3/8"npt
#83305 220°f 3/8"npt
#83306 235°f 3/8"npt
I believe all the switches reopen at ~10°f below the closure temp.
I'm using the 83300 switch which does close during city driving in warm weather but reopens after a few minutes driving above 20mph. I've found that the head coolant temp between #6 and #8 runs 10 to 15°f above what the temp sensor in the water pump reports to the PCM. I've never had the switch close during "spirited" highway or back road driving, even in 100°f weather.

 

I put an additional sensor in the coolant return line from the back of the heads. The temp is similar to the gauge reading and the CTS in the water pump housing. The main difference between a 97 and a 94 is the routing of the line from the back of the heads. On the 93/94 it goes directly to the connection on the radiator. On the 95-97's it runs to the throttle body first.

http://www.injuneer.com/images/photo...ne/DualIAT.jpg

http://shbox.com/1/93-94_hoses.jpg

http://shbox.com/1/95-97_hoses.jpg

 

Thanks for the replies, guys. I like all of your ideas better than mine. Very helpful.

Dwayne, regarding the UltraGauge - that thing is pretty inexpensive. I have some concern about the quality at that price. And I wonder how loud the alarm is. But that does look pretty cool.

Not sure which route I'll go (car's in the shop having the motor pulled), but I (and others now) have some good templates to follow. Thanks again.

 

The alarm was enough to get my attention when I floored the truck. Apparently the default rpm alarm is like 4000rpm. I just have it set in the center console so not really in my line of sight. I began flashing too.
If it were mounted conspicuously I think it would do the trick.

 

Here's a tip of the hat to NJ-LE. I went his route and I feel confident in my new coolant temperature warning system.

Parts:

Stewart-Warner #83305 (220%u00B0f temperature switch for installation in the unused coolant sensor port in the passenger side head)

Stewart Warner 83305 - Stewart Warner Sending Units - Overview - SummitRacing.com

Grey Pneumatic 3/8 Dr X 5/16 Square Male Pipe Plug (for removing the factory plug in the coolant sensor port in the passenger side head)

Grey Pneumatic 3/8 Dr X 5/16 Square Male Pipe Plug Sk | Wayfair

Cole Hersee "Dual Alarm"

Amazon.com: Dual Alarms 12V Dual Alarm, Red Lens: Sports & Outdoors

You simply run switched power from the cabin fuse block to the alarm and a ground wire from the alarm to the temperature switch. Mount the alarm near the fog light switch and use the hole in the firewall on the passenger side (underneath the glove box) to run the ground wire.

I hope this helps others. The factory coolant temp warning system is woefully inadequate...especiallly when you have a lot of money under the hood. And the warning light circuits floating around for electric water pumps really only test for a good relay. That's narrow insurance.

 

I haven't built mine yet, but I got a 12V Sonalert that I'm going to use in conjunction with a temp switch of somekind. The Sonalert make a fairly loud sound so that your eyes wouldn't have to be on the dash if the engine was to get too hot. Sonalert are like the ones for forklifts up warnings.

 

The Dual Alarm that I am using has both an ~80db buzzer and an approx. .5" diameter red flashing light. It's an all-in-one unit that makes the wiring simple.

 

Why not just put an isolator and buzzer on the "check gauges" light???????? Not only will it let you know about high temperature, but anytime any other gauge gets near the extreme point of it's dial.