PhantomTPI

Ok....quick question...bought a 170 thermo a year ago, and the car ran cooler. It has so since...for the most part. The thing is, that sometimes, just sometimes, like once in a while, very rarely, the car seems to go past the 220 degree mark. Like yesterday it did that and it was the first time i have seen it happen in a long time. Even in traffic, at idle, it hasnt gone past 180 or so since the new thermo was put in. Just rarely. What could cause this? Is it a problem? A sign of something going bad like the thermo? One other thing i notice...i could be running the car all day, and it stays at 180 the whole time....when i go to park, and shut off the car, as i get out, i hear the fans stopping...meaning that they were on the whole time. I thought the fans dont come on till the engine reaches 220 degrees or so. I have no fan switches or custom prom. Any ideas?? Or is my car possessed as i originally suspected? Dont get me wrong...i dont mind that the car mostly never goes over 180 degrees...i'd rather have it that way

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1986 WS6-Equipped 5.0 TPI Trans Am
Random Tech High-Flow Cat
Two Chamber Flowmaster Muffler
Megs Custom 4.5" Stainless Steel Rolled Tips
1999 Grand Am GT In-Dash CD Player w/Equalizer(fits like '86 original)
5% Tint On Rear, 35% On Sides
http://www.pitt.edu/~zyhst/trans86/

OTHER RIDE:
1998 C5 6Spd. Corvette Coupe
Silver w/Gray Leather Int.
12/14 Options
Stock(for now)
Best 1/4th: 13.5 @ 104.4MPH

Stuart Moss

Before trying to guess, did the car ever get that hot (over 200°-210°) while the car was moving at highway speeds or let's say, faster than 35-40 MPH?

87formula

With no custom PROM or manual switch your fan(s) will come on at 222* but they don't go off till the car hits 180*. Also if this is with the car moving more than 30 mph then I would check to make sure the front valance is in place, like the black thing under the radiator, not the metal that supports it but the rubber piece. This piece pushes air up to the radiator to cool the car. Anyway more on the fan(s) issue, you can get a switch to make the fan(s) kick on sooner and stay on longer. I think this covers everything you should need to cool that ON-firebird off. Oh, one more thing, running the air may/will cause the fan(s) to kick on as well.

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1987 Firebird Formula
305 LG-4
GM Vortec heads 2.02x1.6 valves
Crane CompuCam 2030
700-R4 Trans
4 barrel quadrajunk remained by holley (this carb stinks!!!)
edelbrock performer intake
Hypertech Thermomaster Chip
Open Element Air Filter
No Cat with Straight pipe (Dynomax muffler rusted apart and fell off probably could not stand the heat )
Accel H/P Coil

- Soon to be installed
383 stroker (built and ready)
NO MORE COMPUTER CRAP
700R4 Lockup kit
Edelbrock TES
True Dual exhaust or 4 inch single pipe to dual 2 1/4"
Stall convertor

Guest

The off temperature is more like 200.

Was the AC on? That will turn the fans on all the time.

PhantomTPI

Stuart...

YES...in fact, the car did get that hot over 200-210 degrees while it was moving at highway speeds. This is what got to me at first. Becuase, since i changed the thermo, 90% of the time, even in stand-still traffic, the car never went past 180 or so. All this is happening with the AC OFF. The AC doenst work, so i dont use it right now.

87Formula...

Every front piece is intact and in place. The valence is there...everything..nothing is missing. What confuses me, is that the fans are already on when i run the car all day, and even if it never goes past 180 degrees...when i shut the car off, you can hear the fans comming to a stop. Strange, since the car never reached 222, and i dont have the AC on at all.

Madmax...

This is what i mean....no AC...so how are my fans running what seems like right when i start up the car? I am suspecting this, becasue i am not sure wether or not i have heard them before when my hood was up while the engine was on.

To sum up, i am confused as all hell. AC is always off....fans are on at 180 when i shut car off...car heats up to 220+ very occaisionally(no idea why, if 90% of the time, it doesnt do this)...but sometimes, it does, even at highway speeds. So...is my car posessed?

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1986 WS6-Equipped 5.0 TPI Trans Am
Random Tech High-Flow Cat
Two Chamber Flowmaster Muffler
Megs Custom 4.5" Stainless Steel Rolled Tips
1999 Grand Am GT In-Dash CD Player w/Equalizer(fits like '86 original)
5% Tint On Rear, 35% On Sides
http://www.pitt.edu/~zyhst/trans86/

OTHER RIDE:
1998 C5 6Spd. Corvette Coupe
Silver w/Gray Leather Int.
12/14 Options
Stock(for now)
Best 1/4th: 13.5 @ 104.4MPH

Vader

Phantom,

You said "fans" - like there is more than one. A typical '86 305 TPI has ONE electric cooling fan, no more. It is possible that the AC pressure switch is shorted, or the fan relay has welded contacts (stuck ON), or you have a grounded green/white wire from the fan relay.

It's also possible that the dash gauge is indicating incorrectly, and/or the CTS that reports to the ECM is shorting, causing the erroneous fan operation. You might also have an air obstruction in front of the radiator, or between the AC condenser and the radiator. The radiator could also be plugging internally, preventing heat transfer from the engine coolant.

Or your car is possessed!

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Later,
Vader
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"Let the bodies hit the floor!"
Adobe Acrobat Reader

PhantomTPI

Vader,

Sorry about the "s" after the word "fan" in my posts.

Anyway, I hope the gauge reads correctly...i dont mind it staying so cool all the time at all. I suspect the FAN comes on when i start the car automatically, and stays on. This i think, is the reason why the car doesnt usually go past 180. Also, another thing i thought about....sometimes, if i was heating up the engine to check the tranny fluid, the fan wasnt on...and the car would be going past 220 degrees....and the fan still wouldnt come on. So i let her cool off a bit longer, and then later, i would start it up, and viola....the fan was on, the car didnt go past 220. For this reason, i suspect its what you said-a short somewhere, the CTS, fan relay is stuck on, etc. By the way, how do i check to see if the fan relay is stuck on? Or is that not checkable? Where is the fan relay? I'd like to know to see if any wires are grounded. Again, i dont mind the fan staying on, and keeping the car nicely below 220. I just hate it when it gets up that high. Thanks for all your help, Vader.



------------------
1986 WS6-Equipped 5.0 TPI Trans Am
Random Tech High-Flow Cat
Two Chamber Flowmaster Muffler
Megs Custom 4.5" Stainless Steel Rolled Tips
1999 Grand Am GT In-Dash CD Player w/Equalizer(fits like '86 original)
5% Tint On Rear, 35% On Sides
http://www.pitt.edu/~zyhst/trans86/

OTHER RIDE:
1998 C5 6Spd. Corvette Coupe
Silver w/Gray Leather Int.
12/14 Options
Stock(for now)
Best 1/4th: 13.5 @ 104.4MPH

[This message has been edited by PhantomTPI (edited June 16, 2001).]

Vader

PTPI,

The fan relay is "checkable" and is located at the right end of the radiator. It should have a green/white, black/red, tan/white, and an orange wire on the connector. If you had a shorting wire, I would suspect the green/white one. Whenever this wire is grounded, the fan relay operates. This should start the fan. Make certain the connector is clean and tight.

A replacement relay is about $10.00, but you can check the contacts first or test the operation by inserting a probe in the back of the socket and grounding the green/white wire. Inceidentally, the orange wire should have a constant 12VDC, and the tan/white wire should have 12VDC whenever the ignition is ON.

This wire is driven directly by the ECM. The ECM will operate the fan whenever the CTS has reached 223°F and has not yet cooled to below 210°F. The CTS is located at the front of the intake manifold and has a yellow and a black wire in the connector.

The AC high pressure switch is located at the rear of the AC compressor and has a black/white and a dark blue wire in the connector. The switch should close when the high side pressure reaches 235 PSIG. This will also signal the ECM to operate the cooling fan. You can test this by grounding the dark blue wire.

All of these systems rely on a good ground from the engine to the chassis, and the ECM to the chassis.



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Later,
Vader
------------------
"Let the bodies hit the floor!"
Adobe Acrobat Reader

[This message has been edited by Vader (edited June 17, 2001).]

Stuart Moss

Phantom,

Goodness, if it's getting hotter than 200-210° at highway speeds and everything is in place (air deflector), then I would suspect that the thermostat is sticking closed sometimes (remember you stated that it only happens sometimes).

The same thing happened to me once. The thermostat had been stuck open for months (unknown to me at the time - I had just purchased the car and never gave the temperature a second thought - I just thought that that temperature was normal). Then one day it suddenly stuck closed and the temperature shot up to ~220° or more on the highway! It was wintertime, so I rolled the windows down and turned the heater on high which brought it down a little.

Since the problem is intermittant, I suspect the thermostat which only costs a couple dollars. Testing it (in boiling water) may not show a problem if the problem is intermittant.

You could just remove the thermostat and see if it ever gets above 200° (if you don't want to spend the $2.50 for a new one). If it still gets too hot, then the problem is probably not with the thermostat. Then I'd start checking the radiator for an obstruction or the water pump for proper operation.

For months, the drivers side fan was always on (I didn't realize it at the time) from the time I started the car to the time I turned it off. The problem was the coolant fan switch was stuck in the closed (on) position keeping the relay on whenever the igntion was on. Replacing that switch solved the problem. If your ECM controls the fan (as Mr. Vader says), read the following paragraph.

On another Camaro, I had the opposite problem. The fan would never come on. The problem was the coolant temperature sensor (CTS) located in the middle-front of the engine. Replacement allowed proper fan operation. I seem to remember that disconnecting the two wires to this sensor would cause the fan to come on (via the ECM). So if the problem is intermittant, make sure this connection is good and clean. If it is, then this sensor may be bad.

Because of those problems, I installed two L.E.D.'s in the gauge cluster so I'd know exactly when my fans are operating. This will not only let me know if there is a fan problem, but also alert me to a high engine (coolant) temperature or when the A/C compressor is being used (such as sometimes when the defroster is used), abnormal CTS/ECM operation, and so forth. Plus it look neat.

[This message has been edited by Stuart Moss (edited June 17, 2001).]

PhantomTPI

Vader...

Thank you for all your help. I really do appreciate it. I checked the car today, as i started it to check something else....and the fan DOES come on right when the engine starts right away. So, now, i suspect that the switch is the cause. It seems like what you and Stuart Moss said is happening..the fan switch is getting stuck in the "on" position, therefore causing the fan to come on when the ignition is on. As for the problem that i described about it heating up intermittently, i am suspecting that the switch sometimes doesnt get stuck in the "on" position, and then the fan operates when the engine reaches the 220+ degree mark. Why it does this at highway speeds, i have yet to determine....maybe the thermo needs to be replaced again...i just replaced it about a year ago or so.

Stuart...

The LED's is a great idea!! I am thinking about doing this to avoid future problems, confusion, and uncertainty. If you could send me an email about how you wired this, that would be great. My email is PhantomLo@aol.com.

I dont know what else to say. The only time this bothers me is when the temp goes above 220....i hate it even running at 220. If i can keep it at 180 or so constantly, like it usually is now, i would be happy. BTW, my transmission fluid seems to be lasting longer since the engine is running cooler. I dont know if the engine running hot/cold has a direct impact on how long the tranmission fluid lasts, but after checking it hot, it still seems like the fluid has been staying pink longer.

Anyway, thanks for the help guys. It has given me some direction. I really appreciate it. Thanks again.

------------------
1986 WS6-Equipped 5.0 TPI Trans Am
Random Tech High-Flow Cat
Two Chamber Flowmaster Muffler
Megs Custom 4.5" Stainless Steel Rolled Tips
1999 Grand Am GT In-Dash CD Player w/Equalizer(fits like '86 original)
5% Tint On Rear, 35% On Sides
http://www.pitt.edu/~zyhst/trans86/

OTHER RIDE:
1998 C5 6Spd. Corvette Coupe
Silver w/Gray Leather Int.
12/14 Options
Stock(for now)
Best 1/4th: 13.5 @ 104.4MPH

Vader

PTPI,

The "switch" is actually an analog sensor on your car, not a hard contact thermal switch as is found on TBI and secondary fans for TPI cars.

A low resistance at the CTS would act like a stuck switch, causing the ECM to interpret a higher coolant temperature. Or it could also be the relay or AC pressure switch wiring as suggested.

If you want to determine the source of the problem, unplug the AC pressure switch to eliminate that possibility. Shut the engine off and remove the fan relay, then meter resistance between the 'A' and 'E' terminals. There should be infinite resistance unless the relay is stuck (welded contacts). Also meter resistance on the dark green wire to ground. There should be several hundred ohms at a minimum unless the wire is grounded somwhere or the ECM output transistor is shorted E-C.

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Later,
Vader
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"Let the bodies hit the floor!"
Adobe Acrobat Reader

[This message has been edited by Vader (edited June 17, 2001).]