I was flipping through my GM book, looking up something for the LG4 (305 carb) motor, and saw a picture of the low coolant probe wiring. (Section 8A-201 for guys with similar books, around page 11 or 12.) The caption underneath said "2.8 (S) Engine". Huh?!

My original radiator had no coolant temp probe. The junkyard one I put in ("88 Camaro" was written on it in red) had the coolant temp probe. If my '86 GM book shows a picture of it, why don't I have it on my car? I couldn't dig it up in the wiring diagrams either; although it was late at night, maybe I missed something?

Any ideas? Anybody got it hooked up? Oh, it's located on the radiator, on the plastic side tank, on the driver's side.


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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

 

Ah HA! Well, I dug & dug yesterday in the GM book, and finally found the low coolant probe information! I figured it went to a warning light on the dashboard, so I was searching the "instrument panel" section of the wiring. It wasn't part of the warning light panel. It wasn't part of the gauges panel. It's not part of the digital panel! Guess what it's part of?

I found it in my DIC section! (laughs) That's "Driver Information Control"... it was a digital panel that showed two things- a picture of a Firebird, and a small 7 character scrolling digital display. It could tell the driver info such as "door ajar", "light out", and "low coolant"! No wonder I've never seen that low coolant probe wired up on another f-body!

Here's the deal on the sensor. It's a one-wire sensor that "somehow" grounds to the car. (I don't see how, it's in a plastic side tank??) The sensor gives a resistance of 10K ohms when the coolant level is perfect- as in, the probe is covered. As the coolant level drops, the resistance of the probe increases. When the probe is completely uncovered, the final resistance is 50K ohms. The DIC was programmed to only look at 50K ohms and above... so this presents a problem for rigging up a warning light!

A logic circuit will need to be implemented to allow a turn-on at a certain threshold. I believe this can be done with the LM339 comparator IC. I'm going to check this out either tonight or tomorrow night. From what I remember of days ago, the LM339 can drive an LED or lamp directly. One wire would be all that's needed to go through the firewall, and the circuit board could be made as small as half of a post-it note.

Do any of you guys have that low coolant probe sticking out of the radiator's side tank on the driver's side? Or did I just "luck out" with my junkyard radiator?

[edit] ..Or, was this "88 Camaro" radiator not originally meant for a Camaro, and the owner of that '88 used a different radiator? Hm... Anyone else have the probe?

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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

[This message has been edited by TomP (edited May 16, 2001).]

 

That's really weird. One thing that I noticed about my Firebird is that it goes through that coolant tank like it's nothing, AGGHHH!!!! But here is the weird thing, there are no leaks of ANY fluid what so ever. The Radiator is full & in perfect shape. The coolant tank doesn't leak at all. Where the hell is this stuff going????

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- Mike Harvey -
1986 Firebird S/E

 

well harvey do you have the 2.8/3.1?...if so look at a small aluminum cooling tube that comes out of the intake below the throttle body. This was made of aluminum and it breaks easy. when it leaks it usually goes around the water pump and cannot be seen.

 

you are boiling all that coolant off because it has nowhere to go. if you look at the overflow bottle, you'll see that there is a cold level, which is near the bottom, and a hot level near the top. you are NOT supposed to fill this bottle up. when coolant gets hot, it EXPANDS. if that bottle is full cold, when it gets hot, where's the coolant gonna go??? nowhere. it boils into steam.

now, if the fluid level in your radiator is going down, then you have a problem.



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Dan
1990 3.1L RS
80 Series Flowmaster
It's fast(er than a 3 cyl metro)

 

Rcently continued to have that happen to me.
I was ONLY RUNING STRAIGHT WATER, as I wnated to check for leaks, etc. before I threw in/away my antifreeze.
I was "steaming" away teh water.
Radiator fan kicks in at 220* & water boils at (told) 210*.
So, it went away, continually.
Soon as I put in antifreeze, radiator sprang a leak (the cause for my thread how to find a good radiator).
Radiator fixed (it's a made in China brand replacement-hanging in there), fluid stays proper.
My way of filling/burping a radiator is to fill it to the top, tanks, radiator, let it over flow, itself and settle down to whatever level it wants. MAKE SURE YOU RUN YOUR HEATER, TOO!! Seems to work, well.

Dan, you're gonna do GREAT on an ASE Mechanic test!!
Tom, this cheapo replacement radiator has that "fitting" to insert that probe, in, also.

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Chat Soon,
KED85
Karl
1985 Firebird 2.8 to 3.4 swap project for Smog Happy LA, CA

 

Tom....several years back I replaced my radiator with an Advance Auto unit.It had the hole for the "probe".Unfortunatly I don't have that option on my RS.I had to plug it up.BTW...the radiator was all aluminum.
Just befor my 2.8 died on me I had to replace it agian.POS Advance stuff!!!!!.I returned it for a new one and this radiator has the plastic sides.It also has the area for that sensor.This one has a lid covering it.I guess it's incase I do have that probe I can remove the cover and install it.

Would it be possible it uses the coolent as a ground????I would like to figure a way to make it work but have run out of ideas.

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Kevin S
89 RS w/2.9
modded some but not heavily


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