RESOLVED: Cooling System Troubleshooting
#1
RESOLVED: Cooling System Troubleshooting
Hey ThirdGen'ers!
While idling, I noticed that the Temp Gauge went up past the 220 mark but no Cooling fan. When the car reached the 3rd line, before the red zone I shut her off. There was no gurgling or boil over in the overflow tank, physical radiator was just reaching luke warm to the touch at best, and I could hold the upper rad hose bare handed. Grabbed the GMSM, used a fused jumper wire between the RED wire & BLK/RED wire terminals on the Fan Relay connector, fan came on instantly. Two questions...
1. If the Temp Sensor for the gauge is shot, can it show a false overheating condition and the motor not really be at operating temp to activate the fan switch? If it's wire from the connector is resting on a spark plug wire will it cause resistance issues leading to a false reading?
2. If anyone has ever changed a Radiator Fan Switch on a 92 or similar w/ 305 TBI how did you access it? Tried from below, but there were to many obstacles... Couldn't even reach the connector to disconnect it to attempt grounding it for further troubleshooting...
While idling, I noticed that the Temp Gauge went up past the 220 mark but no Cooling fan. When the car reached the 3rd line, before the red zone I shut her off. There was no gurgling or boil over in the overflow tank, physical radiator was just reaching luke warm to the touch at best, and I could hold the upper rad hose bare handed. Grabbed the GMSM, used a fused jumper wire between the RED wire & BLK/RED wire terminals on the Fan Relay connector, fan came on instantly. Two questions...
1. If the Temp Sensor for the gauge is shot, can it show a false overheating condition and the motor not really be at operating temp to activate the fan switch? If it's wire from the connector is resting on a spark plug wire will it cause resistance issues leading to a false reading?
2. If anyone has ever changed a Radiator Fan Switch on a 92 or similar w/ 305 TBI how did you access it? Tried from below, but there were to many obstacles... Couldn't even reach the connector to disconnect it to attempt grounding it for further troubleshooting...
Last edited by 92RS-HeritageEd; 05-21-2019 at 09:30 PM.
#2
Supreme Member
Join Date: Jun 2015
Location: Austin, TX
Posts: 1,906
Received 176 Likes
on
135 Posts
Car: 90 Formula / T-tops
Engine: 305 TPI
Transmission: MD8
Re: Cooling System Troubleshooting
on q1. part a - sensor is unlikely to fail safe. in other words, unpredictable. q1 part b, remove off wire and find out. but i would doubt it. most sensors operate over a voltage range that is converted to a reading. spark plug wire would cause a frequency reading issue if anything
#3
Supreme Member
Join Date: May 2015
Location: Florida
Posts: 1,703
Received 237 Likes
on
183 Posts
Car: 1991 Z28
Engine: 305 TPI
Transmission: 700R4
Axle/Gears: 3:42 Auburn
Re: Cooling System Troubleshooting
My buddy has a 92 Z and his acts the same way. the fan does not come on until 240! The Other fan only comes on when he turns on the AC. GM programmed these cars to kick that fan on @ 235. I believe. His car does get hot, his gauge is accurate. I really don't know how that thing has not blown a gasket by now.
When I was having issues with my cooling system I purchased, for $5 on sale @ HF a inferred temp sensor, one of the laser ones. You can use it to get the temps of the head, rad hoses and the radiator itself. This will tell you if your temp gauge is working or not. That gauge may just be your only problem.
When I was having issues with my cooling system I purchased, for $5 on sale @ HF a inferred temp sensor, one of the laser ones. You can use it to get the temps of the head, rad hoses and the radiator itself. This will tell you if your temp gauge is working or not. That gauge may just be your only problem.
#5
Sponsor
iTrader: (92)
Re: Cooling System Troubleshooting
If it’s the factory connector squeeze and pull. The connector gets brittle with heat. If you need a new one here’s a link.
https://www.ebay.com/itm/Knock-KS-De...AAAOSwd9Za6d2k
https://www.ebay.com/itm/Knock-KS-De...AAAOSwd9Za6d2k
Last edited by Tuned Performance; 03-18-2019 at 09:07 PM.
#7
Re: Cooling System Troubleshooting
If it’s the factory connector squeeze and pull. The connector gets brittle with heat. If you need a new one here’s a link.
https://www.ebay.com/itm/Knock-KS-De...AAAOSwd9Za6d2k
https://www.ebay.com/itm/Knock-KS-De...AAAOSwd9Za6d2k
Trending Topics
#9
Re: RESOLVED: Cooling System Troubleshooting
Is there somewhere on the forum some photos of the different sensors/switches from the cooling system ? I read a few topics about that but even if I'm starting to be familiar with the different elements of the system, I still don't know how they look like and where they are located on the engine.
I know where is the fuse box but it's almost the only thing I'm sure. I don't know exactly where is the relay (someone told me, I didn't have time to check right now), I don't know where is the fan switch or the sensor (sender) for the gage.
I think this is the fan switch and I'm supposing that in my case (similar to 92RS' case) it is faulty but I have to be sure that I'm looking at the right part and I must find a way to test it.
I know where is the fuse box but it's almost the only thing I'm sure. I don't know exactly where is the relay (someone told me, I didn't have time to check right now), I don't know where is the fan switch or the sensor (sender) for the gage.
I think this is the fan switch and I'm supposing that in my case (similar to 92RS' case) it is faulty but I have to be sure that I'm looking at the right part and I must find a way to test it.
#10
Re: RESOLVED: Cooling System Troubleshooting
Is there somewhere on the forum some photos of the different sensors/switches from the cooling system ? I read a few topics about that but even if I'm starting to be familiar with the different elements of the system, I still don't know how they look like and where they are located on the engine.
I know where is the fuse box but it's almost the only thing I'm sure. I don't know exactly where is the relay (someone told me, I didn't have time to check right now), I don't know where is the fan switch or the sensor (sender) for the gage.
I think this is the fan switch and I'm supposing that in my case (similar to 92RS' case) it is faulty but I have to be sure that I'm looking at the right part and I must find a way to test it.
I know where is the fuse box but it's almost the only thing I'm sure. I don't know exactly where is the relay (someone told me, I didn't have time to check right now), I don't know where is the fan switch or the sensor (sender) for the gage.
I think this is the fan switch and I'm supposing that in my case (similar to 92RS' case) it is faulty but I have to be sure that I'm looking at the right part and I must find a way to test it.
behind ESC Module thing in that bracket
Last edited by 92RS-HeritageEd; 05-24-2019 at 11:54 AM.
#11
Re: RESOLVED: Cooling System Troubleshooting
Thanks for the relay pic Do you know where is that fan switch please ? I think that I located the sensor on driver's side head but I can't find the switch.
#13
Re: RESOLVED: Cooling System Troubleshooting
I thought it was the contrary (sender on drivers side and FS on passenger side).
And sorry about the next silly question but SP means ? (I'm not used to English initialisms yet).
And sorry about the next silly question but SP means ? (I'm not used to English initialisms yet).
#15
Re: RESOLVED: Cooling System Troubleshooting
My apologies, I was trying to help while on lunch at work so I was speeding through. BUT anyone who knows SBC's & their plug locations should have been ok. After all I did give the CORRECT physical locations... such as the gauge sender being by SP or Spark Plug # 1 which is on the Driverside, and the physical fan switch being by plugs #4 & #6 which is on the Passenger side. Also, as stated DO NOT confuse the Knock Sensor lol.
#16
Re: RESOLVED: Cooling System Troubleshooting
By the way, is there somewhere I can find the OEM part number in order to find replacements ? When I was working on my BMW we had something called RealOEM which allowed to find a part number based on schematics after entering the VIN (which would make sure the part fits the model, even if you have specific options). Is there something similar for the 3rd gens ?
#17
Supreme Member
iTrader: (11)
Join Date: Sep 1999
Location: NJ
Posts: 4,345
Received 298 Likes
on
234 Posts
Car: 92 Firebird
Engine: 4.8 LR4
Transmission: T56
Axle/Gears: 3.45 9 Bolt
Re: RESOLVED: Cooling System Troubleshooting
You can figure it out from Rock auto usually. Or you have to look in the GM parts book, someone made a CD for it, a long time ago, and you could use it on your PC
The following users liked this post:
Flat-twin (06-25-2019)
#18
TGO Supporter
Join Date: Sep 2000
Location: So.west IN
Posts: 6,775
Likes: 0
Received 26 Likes
on
23 Posts
Car: 87 Formula/ 00 Xtreme
Engine: TPI 305/ v6
Transmission: struggling t-5/ 4l60E
Axle/Gears: 3.08/ 3.23
Re: RESOLVED: Cooling System Troubleshooting
That is the Fan A/C pressure switch. For a TPI and v6 car, if the a/c works, it causes the ECM to trigger the fan(s, year depending) when you turn on the a/c. On a TBI engine, it is a redundant ground to the fan relay (it isn't needed). The a/c high pressure cutoff switch is mounted on the back of the a/c compressor.
Last edited by deadbird; 06-25-2019 at 05:58 PM.
#19
Re: RESOLVED: Cooling System Troubleshooting
That is the Fan A/C pressure switch. For a TPI and v6 car, if the a/c works, it causes the ECM to trigger the fan(s, year depending) when you turn on the a/c. On a TBI engine, it is a redundant ground to the fan relay (it isn't needed). The a/c high pressure cutoff switch is mounted on the back of the a/c compressor.
Thread
Thread Starter
Forum
Replies
Last Post
customblackbird
Engine/Drivetrain/Suspension Parts for Sale
8
07-27-2011 10:31 AM