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Hey everyone
I got what seems to be a mix of two problems.
when going slowly uphill (due to traffic and what not) my engine temp. seems to go steadily up without setting the fan off. turning the heat on full blast does take the heat down to normal. the cooling fan seems to kick in every once in a while (as if the engine is not overheating).
another phenomenon I’ve noticed, is this: when the temp. gauge’s needle starts to rise, turning the parking light on cause a spike in the temp. read. turning it off cause it to go back down again (immediately).
I have no coolant loss, no oil in the water or water in oil (does seem like it anyway-probably not the head gasket), taking the radiator cap off and opening the throttle (while engine is cold-don’t worry), doesn’t cause a rise in coolant level (so no gases coming from the cylinders, coming in contact with coolant).
Swapped a couple of relays to rule it being faulty.
No obstruction in the radiator preventing air flow.
Radiator cap seems fully functional (springs and seals are okay).
It could be the electric switch that sits in front of the thermostat (the one in charge of switching the fan on and off), how can I rule that one out?
And about the spikes, It could be a bad ground somewhere, but that is assuming the symptoms aren’t connected, which is usually wrong.
Any Ideas? I love this car, and am willing to fix the problem, but cash is a bit tight, and I wanna know a 100% which part is the culprit before spending…
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Bleed the system of air-Eric has a video on how. Then we’ll go from there.
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Hey everyone
I got what seems to be a mix of two problems.
when going slowly uphill (due to traffic and what not) my engine temp. seems to go steadily up without setting the fan off. turning the heat on full blast does take the heat down to normal.That points in the direction of a fan issue. Several causes come to mind:
1. the fan itself is defective
2. power lines to the fan are defective
3. control to the fan is defectiveYou’re going to want to systematically eliminate possible causes. Here’s one way to do it:
Thanks for your replies guys!
I will bleed the air out of the system on the weekend, just to be sure.
about the fan-Its working, but not as hard and consistently as one might expect during an overheat. I think Its control switch is busted, but i don’t know how to confirm that…
edit: saw the video-will do, thanks!The quick and easy way to confirm the fan works is to unplug it from the switch and stick a paperclip into both terminals completing the circuit. If the fan and wiring are good the fan should kick on to it’s highest setting. Ensure your hands and other important items are no where near it when doing so though-for obvious reasons.
So I Have a bad fan switch, But that still doesn’t explain the temp. read spike when turning the parking lights on.
It surely is an electrical problem, You guys have ideas where to start looking for the bad wires?In addition to verifying coolant level/bleeding air from the system, I would install
a new thermostat (under $10).First, I do appreciate your responses!
1. The coolant level is OK-no losses in radiator nor in the reserve tank.
2. As far as the thermostat goes, I don’t see any reason in replacing it (absolutely nothing points to it).
3. This is almost certainly an electrical thing, since the spike is immediate and momentary-meaning, Temp. spikes the moment I turn my parking lights on, and drops back the moment I turn them off. this Phenomenon is more pronounced the hotter the engine gets-When in operating temperature, There is no spike (or very little), when it gets hotter the spike gets bigger. more mathematically: Spike~dT; dT=T-To, To is operating temperature.
Or, spike is proportional to the difference between the current coolant temperature and the operating temperature.
also the turn signals do not cause the same spike, only the parking lights/low/high beam.By temp spike do you mean the gauge goes up a bit or are you reading temps with a scan tool or IR thermometer? The cluster gauge is just an approximation and has nothing to do with the temp sent to the ECU, there are 2 different sensors located just under the distributor 1 sends signal to the gauge and the other sends the actual temp to the ecu. I would strongly suggest going to a Pull A Part or local junkyard and grabbing a new OEM fan switch, and the 2 sensors. If you have an aftermarket fan switch installed they can and do fail. Just replace all 3 of them with OEM parts, which I just did about 2 hours ago myself-my fan, gauge and temp sensor all work properly now.
I’m looking at the gauge read-I know the temperature itself doesn’t spike, but rather the read on the gauge and i think it’s voltage (current to be precise) leaking from the headlights’ harness to the gauge’s signal, through bad grounding or a short circuit due to stripped insulation somewhere along the harness’s path or maybe from the relays or fuses…
Does someone have any experience with a similar situation on this model?edit: Just had a thought: do the two temperature sensors (the gauge sensor and the ecu sensor) have the same connector? can I switch them to isolate the problem?
I’ll also try measuring the resistance on the sensor while flicking the lights on and off to rule the sensor out.Nope they have two different connectors and are idiot-proofed the one you’ll want to look at is a small single wire one prong plug. Also there is supposed to be a ground wire attached to the thermostat housing, if that is loose or missing it could cause what you are describing, there is a ground that runs from the engine to the body just above and another just below the driver’s side headlamp assembly-those also have a habit of coming loose and/or breaking.
Finally what model of Civic is it? DX, LX, EX, etc
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