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| Engine temps all over the place (Page 4/9) |
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theogre
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NOV 21, 05:00 PM
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Cliff Pennock
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NOV 22, 02:02 PM
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I was finally able to check if the fan was running after driving the car for about 5 minutes, and temperature showing 230F. Fan wasn't running. So there was either a huge temperature difference between the temp gauge sender unit and the fan switch, or the temp gauge sender unit is defective. Assuming of course the fan switch isn't defective.
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steve308
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NOV 22, 02:56 PM
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| quote | Originally posted by Cliff Pennock:
I was finally able to check if the fan was running after driving the car for about 5 minutes, and temperature showing 230F. Fan wasn't running. So there was either a huge temperature difference between the temp gauge sender unit and the fan switch, or the temp gauge sender unit is defective. Assuming of course the fan switch isn't defective. |
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Fan could also be failing (as mine did). Fan motor replacement is easy assuming it's available. It is a generic GM part.
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Patrick
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NOV 22, 03:57 PM
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| quote | Originally posted by steve308:
Fan could also be failing (as mine did).
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That should be easy to determine by checking to see if the trunk blower is running, or by simply grounding the single wire to the fan switch.
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Mike in Sydney
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NOV 22, 11:57 PM
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Like Patrick said, ground the fan switch sensor to see if the fan is operating. It's located here (https://www.fiero.nl/forum/Archives/Archive-000001/HTML/20110502-2-101002.html). Turn on the ignition and using a piece of wire, screwdriver, etc. ground the wire to the block. The fan should start. If it doesn't there is a problem with the wiring or the fan. If it runs, the likely culprit is the fan switch and the connector that gets brittle with age.
One other thing, it could be is low water in the system. After replacing a hose that Customs cut when I brought my GT into the country I would get occasional overheating. I pulled the T'stat to check for flow. Water was flowing but not much. (The mechanic who replace the damaged hoes was not familiar with the cooling system on the Fiero and tried to fill it from the radiator, not the engine.) I think there was an air bubble somewhere in the system so even filling from the block still left me with the problem. Here's how I resolved the problem:
1. I made sure the fan operated from the fan switch and the A/C.
2. parked the car on a hill with the nose and radiator considerably lower than the engine.
3. I removed the radiator cap completely.
4. I removed the pressure cap over the t'stat and the t'stat itself.
5. i added a 50-50 mix of antifreeze and distilled water and kept pouring it in until the mixture came out of the top of the radiator.
6. I replaced the radiator pressure cap on the radiator and made sure it was tightly closed.
7. I continued to fill the system from the block until the water overflowed the t'stat housing. I did not put the cap on the system.
8. I cranked the car and observed the water flow in the t'stat housing. I ran the car for a few minutes and watched the coolant level. It dropped a bit and I topped up the system again. I did this a couple of times and when the level stabilised, I replaced the t'stat and the pressure cap.
After I did this, I had no more problems with the car overheating. It sets rock-steady at 160°F which is what the T'stat is rated for.
I don't know if tis will work for you but it did for me.
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Cliff Pennock
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NOV 23, 01:40 AM
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I'm pretty sure the fan is working properly. After driving the car for about 5-10 minutes, it's always on unless it's really cold outside. Most of the time I can hear it switch on when it's idling like at a traffic light.
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Patrick
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NOV 23, 02:01 AM
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| quote | Originally posted by Cliff Pennock:
I'm pretty sure the fan is working properly. After driving the car for about 5-10 minutes, it's always on unless it's really cold outside.
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"Properly"?  As Ogre has pointed out, it isn't normal (nor desirable) for the fan to "always" be running . Did you install an aftermarket extra-low temperature fan switch?
| quote | Originally posted by theogre:
When Coolant System is Working Right... Rad Fan, & aux blower for V6, Does Not turn on all the time even when Engine is @ operating temp.
See my Cave, Rad Fan
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[This message has been edited by Patrick (edited 11-23-2022).]
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Cliff Pennock
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NOV 23, 02:46 AM
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Just now, the temperature gauge went up pretty fast again until it reached 260F (highest it can display) and it stayed there for quite some time before dropping off to slightly more sensible temperatures (still high, but not rediculously high).Since the ECM never threw a Code 14 (and the Check Engine Light is working), I'm pretty sure the temp gauge sender unit is not working properly. So that at least is part of the problem.
Still leaves the problem why it's losing coolant.
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Cliff Pennock
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NOV 23, 02:57 AM
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| quote | Originally posted by Patrick:
"Properly"? As Ogre has pointed out, it isn't normal (nor desirable) for the fan to "always" be running . Did you install an aftermarket extra-low temperature fan switch?
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Let me rephrase that. It's running when I expect it to be running.
Every morning I drive the same 7 miles with an average speed of about 50-60mph. At the end of those 7 miles when I stop the car, the fan is running. Unless it's really cold outside. Then it isn't. When driving short distances where speed never gets above about 40 mph and I stop the car, the fan isn't running.
| quote | Originally posted by Cliff Pennock:
After driving the car for about 5-10 minutes, it's always on unless it's really cold outside. |
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I meant 5-10 miles.
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Mike in Sydney
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NOV 23, 06:10 PM
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| quote | Originally posted by Cliff Pennock:
Every morning I drive the same 7 miles with an average speed of about 50-60mph. At the end of those 7 miles when I stop the car, the fan is running. Unless it's really cold outside. Then it isn't. When driving short distances where speed never gets above about 40 mph and I stop the car, the fan isn't running.
I meant 5-10 miles. |
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Cliff, for comparison, I drove my '86 2.8 GT 30 km to work this morning at speeds of 80 - 100 kph. The temperature never went above 160°F. The outside air temperature was 9°C. My coolant fan never came on. My car has 107,000 miles on it.
| quote | Originally posted by Cliff Pennock:
On the other hand, I am loosing coolant.
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Where from? How much? Any strange puddles under the car? Like I said in a previous post, I had low coolant levels and I saw problems similar to what you are describing. I was able to identify the leak because of a big puddle of coolant.
Does your oil look like a chocolate milk shake? Got any sweet smelling exhaust (if you have antifreeze, anyway.)? What do your plugs look like? Do you have any that are really, really clean? These are usually indications of a faulty head gasket or something worse.
One other thing, when you replaced the water pump did the replacement have a plastic or metal impeller? I've heard that plastic impellers will sometimes slip on the shaft and nor move the coolant very well.
(edited for spelling)[This message has been edited by Mike in Sydney (edited 11-23-2022).]
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