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My RDX seems to have an overheating problem now. It doesn't go to fully hot, but the temp gauge goes a little bit higher than the middle. I've watched the temps get to operating temperature (90 degrees celcius) then after about 10 minutes of driving and idling it starts to creep up to 95, then back down to about 86 and then sometimes it gets to 100 degrees celcius. I've already replaced the thermostat and did the coolant drain and fill at the same time. There aren't any pending codes or anything. It's always been steady at 90 degrees before this. I feel as if the car drives rougher so I'm suspecting it could be the engine coolant temperature sensor, but this car has 2.
if it were me; i'd do a full coolant tune up, including the water pump.
- change water pump
- drain all coolant from engine block and radiator
- uninstall radiator, flush with garden hose then reinstall radiator.
- fill with coolant
but since you said you already drained and filled...it could possibly be air in the line..
or perhaps the water pump is bad
I did burp the cooling system and when i drained it i relieved the radiator from the petcock and then also took out the lower rad hose. While it was all disconnected, I did flush out the rad with distilled water. Is the water pump a big job to replace on these?
I didn't see it mentioned so I have to ask...since this is happening while idle, have you made sure the fans are coming on? At 100C, the fans should definitely kick on.
I’ll have to check that. I know both fans come on when I turn the ac on though. I think it’s the temp sensor but not sure which one, the one in the rad or the one on the block
Perhaps a different temp sensor or relay that controls the fan when a/c on vs off? Not completely sure how the electronics work, but definitely recommend letting it warm up to see if the fan kicks on at idle with no a/c. If not, at least you have a solid lead.
Did you ever get the idling rpm in your tune adjusted from 950 to something else?
Btw, the radiator fan sensor is plugged in at the bottom of radiator right near where the warmer/cooler transmission fluid flows by.
The AT fluid also gets hotter in stop/go & idling situations... starts to cool off easier with higher rpm. How often do you replace the transmission oil depends on reached temperatures.
If you saw 100C/212F for the coolant, the oil has already reached much higher due to low flow idling. Plan for a drain and refill rather soon, once you get the fan under control, generic chart from the www.
For my base 2008 RDX, found signs of previous overheating from previous owners, decided to change the radiator. Only after removal I found a pinhole leak&corrosion in the front sufficient to lose pressure and overheat infrequently. Was hidden by the A.C. unit, and corrosion building up around the AT oil plugs. Drained and refilled the AT as preventive measure.
^yup, that's why I suggested flushing the radiator with a garden hose.
you'll be able to see if there is anything clogging the radiator by water not coming out the other end...and hopefully you could force it out with the garden hose...
it will also reveal pinhole leaks...
Radiators are cheap!!!!!!!!! so, in case you need a new one...Dont overspend at the dealer.. at MOST they are $200. the dealer will MARK it up an additional $200 to make it around $400. Dont spend $400...
Did you ever get the idling rpm in your tune adjusted from 950 to something else?
Btw, the radiator fan sensor is plugged in at the bottom of radiator right near where the warmer/cooler transmission fluid flows by.
The AT fluid also gets hotter in stop/go & idling situations... starts to cool off easier with higher rpm. How often do you replace the transmission oil depends on reached temperatures.
If you saw 100C/212F for the coolant, the oil has already reached much higher due to low flow idling. Plan for a drain and refill rather soon, once you get the fan under control, generic chart from the www.
For my base 2008 RDX, found signs of previous overheating from previous owners, decided to change the radiator. Only after removal I found a pinhole leak&corrosion in the front sufficient to lose pressure and overheat infrequently. Was hidden by the A.C. unit, and corrosion building up around the AT oil plugs. Drained and refilled the AT as preventive measure.
HTH
I checked my transmission fluid and it was still bright red/pink from the last time I changed it. Do you think I should switch the relay and try that? I've ordered the temp sensor for the bottom of the radiator. If I leave the cap off the radiator on a cold start, once the car gets to operating temperature, I do see the coolant start to flow. What is the engine coolant temperature sensor on the block used for?
When I flushed out my radiator with the water it was not obstructed and came out clear once the coolant was all out. I did an oil change a few days prior and there was no sign of coolant mixing with the oil.
When I flushed out my radiator with the water it was not obstructed and came out clear once the coolant was all out.
Water flushing did not go through the oil circuit. Think many fine passageways just for oil, can't flush them, can't test either, yes they exhibit decreased flow in some cases over time (ie. oil not changed on time) Also have the cabin heater: How is cabin heating when idling versus highway cruising?
Originally Posted by mistryp
I checked my transmission fluid and it was still bright red/pink from the last time I changed it. Do you think I should switch the relay and try that? ...What is the engine coolant temperature sensor on the block used for?
Two sensors, one reports the temp to the ECU, the other from radiator activates the fan through the fan relay.
I used a telephone wire with exposed terminals to test so far:
the harness to each fan-both fans are ok.
the relay socket (pin1 to pin2) to each fan, so circuits are ok.
Have not yet tested each sensor, work in progress.
You had several leaks so far, now temperature fluctuates, is there a hidden cause? What is your idling rpm now? Any loss of pressure would lower boiling point to about 225F, right between the temp you saw and the likely 235F+ AT oil temperature at same time. Reaching boiling point would decrease the transfer of heat from engine to radiator, leading to pockets of overheating. One symptom would be fluctuating fluid level, COLD, check both inside reservoir and inside radiator, repeat over time.
The civics from 2001-2005 had similar series of symptoms: fan, sensors, relays, fluctuating temps, many finding a blown Head gasket as their root cause.
If you check for leaks from cooling system under pressure, cylinder compression and for combustion gases in the coolant and find no problems to be fixed then you can consider the comment below:
Originally Posted by justnspace
...
Radiators are cheap!!!!!!!!! so, in case you need a new one...Dont overspend at the dealer.. at MOST they are $200. the dealer will MARK it up an additional $200 to make it around $400. Dont spend $400...
With AT probably around 235, the chart suggests changing the oil about every 12000 miles. When is yours due?
I used a phone to reach in and take pictures before deciding to remove/replace radiator. The Ridgeline forum found the corrosion builds from inside, a compression steel washer, see picture. By the time rust appears outside, on the nut, there is already pressure pulling the joint out of the internal oil cooler.
So my choice was simple, risk a radiator failure at an unknown approaching time and place in jeopardy the transmission-thus the entire car, or replace the radiator at home, on a day marked to replace the AT oil, all in for less than $200?
Water flushing did not go through the oil circuit. Think many fine passageways just for oil, can't flush them, can't test either, yes they exhibit decreased flow in some cases over time (ie. oil not changed on time) Also have the cabin heater: How is cabin heating when idling versus highway cruising?
Two sensors, one reports the temp to the ECU, the other from radiator activates the fan through the fan relay.
I used a telephone wire with exposed terminals to test so far:
the harness to each fan-both fans are ok.
the relay socket (pin1 to pin2) to each fan, so circuits are ok.
Have not yet tested each sensor, work in progress.
You had several leaks so far, now temperature fluctuates, is there a hidden cause? What is your idling rpm now? Any loss of pressure would lower boiling point to about 225F, right between the temp you saw and the likely 235F+ AT oil temperature at same time. Reaching boiling point would decrease the transfer of heat from engine to radiator, leading to pockets of overheating. One symptom would be fluctuating fluid level, COLD, check both inside reservoir and inside radiator, repeat over time.
The civics from 2001-2005 had similar series of symptoms: fan, sensors, relays, fluctuating temps, many finding a blown Head gasket as their root cause.
If you check for leaks from cooling system under pressure, cylinder compression and for combustion gases in the coolant and find no problems to be fixed then you can consider the comment below:
With AT probably around 235, the chart suggests changing the oil about every 12000 miles. When is yours due?
I used a phone to reach in and take pictures before deciding to remove/replace radiator. The Ridgeline forum found the corrosion builds from inside, a compression steel washer, see picture. By the time rust appears outside, on the nut, there is already pressure pulling the joint out of the internal oil cooler.
So my choice was simple, risk a radiator failure at an unknown approaching time and place in jeopardy the transmission-thus the entire car, or replace the radiator at home, on a day marked to replace the AT oil, all in for less than $200?
I checked the transmission cooler lines and fittings, no rust or loose connections. I bought a Honda ect sensor for the bottom of the rad that I will swap out today. Radiators here are at least 250, not from a dealer. I tried swapping the #3 and #5 relays and the same issue occurs. The air conditioning is working with the relay that was thought to have been faulty. Will report back once i change the sensor and do some testing.
I checked the transmission cooler lines and fittings, no rust or loose connections. I bought a Honda ect sensor for the bottom of the rad that I will swap out today. Radiators here are at least 250, not from a dealer. I tried swapping the #3 and #5 relays and the same issue occurs. The air conditioning is working with the relay that was thought to have been faulty. Will report back once i change the sensor and do some testing.
So I drained the fluid and changed that sensor. Refilled and burped the air. Fan still didn’t come on at 90 degrees. Maybe the other sensor? I’m going to disconnect the battery maybe do an idle relearn
So I drained the fluid and changed that sensor. Refilled and burped the air. Fan still didn’t come on at 90 degrees. Maybe the other sensor? I’m going to disconnect the battery maybe do an idle relearn
Nice job. I think you are using the obd2 port to see exact temperature which should be the second one.
With new radiator sensor, maybe the fan does activate at 90 radiator temperature, whereas the obd2 reports a different number engine temperature, either by malfunction or exact reality. In either case they can be different.
Word of caution: test immediately after a long drive 30'+. A cool transmission oil, immediately after cold start would depress the radiator fan sensor temperature during its own warm up time of maybe more than 30'. The engine coolant warms up in less than 5' driving.
I've changed both ECT sensors and the problem persists. I've also swapped the relays and checked all the fuses. Everything seems normal except the fans still don't kick on at 90 degrees. I followed the troubleshooting for the relays and radiator from the service manual, and everything is working correctly. The fan's still don't turn on at 90 degrees. The coolant is also brand new oem honda/acura coolant and there are no leaks in the cooling system (not loosing any coolant)
I've changed both ECT sensors and the problem persists. I've also swapped the relays and checked all the fuses. Everything seems normal except the fans still don't kick on at 90 degrees...
I take it that you already tested the harness from the radiator sensor, by shorting the disconnected end towards the engine, it should activate the fan?
Also, you had a custom tune. See if you can check if the fan activation value has been changed from expected 90C.
I take it that you already tested the harness from the radiator sensor, by shorting the disconnected end towards the engine, it should activate the fan?
Also, you had a custom tune. See if you can check if the fan activation value has been changed from expected 90C.
Hth
Yes, I've tested the harness and the fans did turn on. I jumped the connected for the relay as part of the test in the service manual and the fans turned on. I'll have to check the fan activation value. Do you know if I can check that through a datalog? or would I need to have my laptop hooked up to the flashpro and car.
...Do you know if I can check that through a datalog? or would I need to have my laptop hooked up to the flashpro and car...
I can find out, if you no longer need the flashpro, just send it over!
All joking aside, i would imagine a laptop would give you access to the control values, the datalog might be just actual recorded values. Alternatively save your performance tune, restore OEM settings and reexamine the situation.
Did you make a note what are the temperatures at which the fan actually turns on and separately off, as reported by the OBD2 port?
I'd consider putting the stock tune back on but I have 1000CC injectors installed. I believe the fan kicks on at 100 degrees, then cools down to 90. If im driving the temp goes down to 86-87 sometimes then climbs back up.
I'd consider putting the stock tune back on but I have 1000CC injectors installed. I believe the fan kicks on at 100 degrees, then cools down to 90. If im driving the temp goes down to 86-87 sometimes then climbs back up.
I see. I was hoping for more outrageous values. Changing the tune can be a backup plan if you are not able to confirm tune details via Flashpro.
In the past when I did check & monitored my temps, fans were activating at 212F 100c as yours does now, car idling parked in the driveway. I cant retest at the moment, planning to change my coolant over the weekend.
For the record afaik mine is unmodified, i contacted hondata to check if they had any records of flashing it at any time.
For the oem part number 37870-RTA-005 could only find this easy to digest thread
Well, for what its worth, I saw the temp gauge go up by 1,2 bars up to about half and it got me thinking to check the temps. As far as I know, the temp stayed like 90 degrees last summer. If yours is acting the same, then it could be just normal. Mine has new coolant in it again and the sensors are new so it should be running fine.
Well, for what its worth, I saw the temp gauge go up by 1,2 bars up to about half and it got me thinking to check the temps. As far as I know, the temp stayed like 90 degrees last summer. If yours is acting the same, then it could be just normal. Mine has new coolant in it again and the sensors are new so it should be running fine.
...
Thank you for the parts numbers.
Hmmm, I am planning to do the third coolant change in 2 years, cant consider mine normal yet-though it might be. I do have the transmission warmer bypassed, so potentially another difference from yours.
For the purpose of this discussion I also saw the display move, a single bar, I was watching for it and activated the cabin heat right away, not normal, IDLING, hot summer day and cold snowy day- different seasons did not make a difference.
I have a stable 7 tiny bars in the display, with new pump in 2017, new radiator last year. Assuming a straight line from 0C, each bar is about 30F. That is why I also started checking things like you are too. If you saw two bars, 60F over the normal range =~>272F... are you sure you ever saw two extra?
Maybe I am paranoid but I did ran a combustion gas test on the open radiator after seeing just one extra, and happy that no combustion byproduct showed up at the time.
Am hoping you might find a relevant temperature in the tune as you said are suspecting to be the case. What would be the odds that my engine is just "tuned" in a similar fashion?
06-02-2019, 11:59 AM
