Anyone ever watch the engine temperature gauge as they're going up a somewhat steep incline? My gauge will go about two bars past the half way mark as I go up the such inclines. That seems kind of hot, no? On level surface and not so steep hills, the temperature will stay normal even when it's 90 degrees outside.

 

Welcome to the board!

Have a base rdx 2008 with 270k km.

Watched the temp bars display being steady while cruising, on rolling hills, towing a two axle trailer, while the catalyst sensor was showing ~1500F. A light touch to reduce rpm below 3000 also reduced exhaust below 1300 rather quickly (maybe 80km/hr).
I did see one bar higher twice, while idling/moving slow both times, summer afternoon and cold winter windy snowy night did not seem to make a difference.
Parked idling have observed exactly 7 bars while OBD2 smartphone app reported coolant temperature 186-212F, which is close to 30F per bar. The same 7 bars for a temperature up to 212 averages about 30F per bar.
If you saw two bars higher, thats two bars too high, the sensor would have been at least 30F higher than 212F maximum operating temp without the fans on.
If that was the temperature of the coolant, any loss of cooling system pressure could quickly lead to boiling gases and pockets of water vapour, while the function of engine cooling becomes instantly impaired.
The turbo unit and exhaust manifold (back of engine, below the intercooler) both have a coolant circuit and can reach high temperatures. There are forum reports of extensive corrosion, leaks and or failures in that area. There is a triple pipe "pipe, install" just below the intake curbed rubber boot that carries coolant from the back of the engine to the throttle body in front/below the intercooler, subject to extensive corrosion due to temperature cycling and lower grade material.

Without a reasonable explanation, maybe its time to check all components of the cooling system methodically, look for any coolant leaks, and catch up with maintenance if so needed. Please keep in mind there are exactly two coolant sensors: one at bottom of radiator that activates the fans and is not reported to the ECU, the second only reports the temperature to the ECU/OBD2

Additional info: I use either Iphone/dashcommand or android/torque for exact temperature readings. Had the AC clutch relay replaced with the new upgraded one, verified both radiator and AC fans activate with cabin AC button, and the radiator fan activates by itself at no more than 212F. I do not run the AC system. Water pump and thermostat changed with the accessory belt @214k km. Then got new radiator, new radiator cap, and new coolant changed yearly after flushing with distilled water 3 times, cabin heater is working very well. I did run a radiator test for exhaust gasses twice, both times none was present. In winter I occasionally activate a block heater plug which was installed after I got the car used@208k km.

Of particular note, I since bypassed/eliminated the <warmer> circuit for the transmission fluid within the bottom of radiator only because I manage to avoid daily driving in stop/go traffic conditions.

Any questions, just ask

Hth

 

The temperature indicator on the dash is not linear. If you can connect a sensor to see actual temp, you'll see it stays at 1 bar till well over 100 F, then goes up a bar every 9 F / 5 C (if I recall right...been a while since I last checked the exact numbers). The "7 bar" reading has a range of somewhere around 30-40 degrees F - I want to say it's 20 C which would be 36 F, above which it starts ticking up every 5 C. So, 1 bar is roughly 9 degrees F above the normal range, 2 bars is 18, etc. This is why that once the car is warmed up, it seems to always read the same. But it's normal for it to go above that range when the engine is working hard, so long as it drops back down when you're back to steady cruising on flat ground.

You can mitigate this to some extent by down-shifting (higher rpm increases the coolant circulation, which can carry more heat away from the engine), driving slower, or turning off the a/c, but really none of that is necessary when you're only a couple ticks up from the normal range.

 

So you are saying found documentation regarding temp indicator for the RDX 1ST Gen: at 7 bar can be in a ~36F range... 9 bar to expect at or above 230F. Source for details?

I do expect a car in summer hot conditions, towing on a long stretch to run hotter, and half expected the rdx to show it in the coolant temp especially when running the turbo hot, the CAT temp reached 1500F but IT DID NOT HAPPEN, 500ft ASL. So for my car, conditions short of dragstrip or race track should not budge the indicator beyond 7 bars. Image my surprise finding it at 8 in stop n go, my mistake for not running the AC in anticipation... it dropped immediately once I activated both AC * and maximum cabin heat.

Tomtwtwtw, did you mean the opposite perhaps, driving faster ... even turning AC * on ? I wont delay taking action in any case should I see the MID show more than 7 bars, while revving up in stop n go is hard to do, (and is much slower to reduce coolant temp in my tests even closer to 2000rpm, choking point being airflow through radiator). * the AC forces both fans on, perhaps it worked for me because the clutch does not engage yet so it did not increase the temp of the condenser upfront...

08RDACK, whats the altitude level for the hill in question?

 

I don't have documentation on the temp, these were my own observations while reading the actual coolant temp via an OBD2 scanner during initial warm up. I'll find that reader and run through it again to get you all some accurate numbers, at least for warm up. I have no plans this weekend to do any hill climbs. But basically the digital temp gauge is basically like the "dummy" gauges of yore, where the needle stays put so long as the value is within a given range. I get it, too. My previous car only had an actual temperature reading, and people freaked out when it varied by more than 5 degrees.

My comments for keeping the temp down were in reference to while climbing hills and what not. At speed, the fans aren't helping and a/c running puts additional load on the engine on top of an extra element requiring cool air (condenser which is in front of the radiator). Driving slower will reduce the load on the engine as well (we're talking maybe 55 instead of 75 if you're on a hilly highway). At idle, the fan(s) should kick on automatically (1 at a set temp, both if the car gets hot enough). A/C shouldn't be required to force the fans on unless there is a bad relay or other issue.

 

I see, data from stock run would be appreciated.

Agreed on measures if "over" heating at higher speed, some work opposite at slow speed as described above.

Blasting cabin heat works the same way in both cases, irrespective of season...

 

I would expect a vehicle with this level of sophistication to have a very clear overheat indicator; what you're describing does not sound harmful whatsoever and not at all worrying. Coolant temps in the 240F/115C range should not be problematic for a correctly working cooling system.

Source: am automotive engineer.

 

Following up, this is what I can see as far as temp gauge reading and actual temp:

1 bar: < 136.4 F
2 bars: 138.2 - 145.4
3 bars: 147.2 - 152.6
4 bars 154.5 - 158
5 bars 159.8 - 161.6
6 bars 163.4 - 165.2
7 bars 167 - 203+

Decimals are due to actual reading being in degrees C and conversion. Each reading is +/- 1 degree C in case of my adapter not being completely in sync with the gauge. Didn't hit any steep hills, but saw just over 200 F during normal driving, so the temp range of the 7th bar is at least 36F, but probably more because I'm pretty sure it'll get closer to 215-220 before moving to bar 8.

 

I've been thinking about this and observed the temp gauge in my '11 a little more closely. 7 bars is normal operation for me, regardless if I'm cruising or hooning. 7 bars is below half on the scale. The likelyhood that HMC would allocate over half the gauge to dangerous temperature ranges is nil IMO. The last three segments or so, sure, but 8 or 9? Nah.

 

Thank you for the followup, great reference points!

I have monitored and recorded temp while idling, fans kicked in at maximum then dropped without going over 212F. So 7 bars range is quite wide, should be maximum 167-212 or 45F.

I do believe both sensors are original, 2008. I did try to find any specs for them without luck. The only unspecific references were for sensor aging, a deterioration of reported temperature ranges, ie. a gradual slide towards higher temps with the age/mileage of the car.

This 212F is boiling point of water at sea level, beyond it any loss of pressure will cause the fluid to pass it and to start generating vapours with immediate loss of cooling abilities exactly where and when the need is highest based on temp, (turbo, cylinder jackets or exhaust manifolds, all critical points). The volume expands a minimum of 1700 times upon evaporation, there is nothing gradual about it. In our cars, when in good operating conditions, this is prevented by the radiator cap, marked for maximum release pressure 15psi or 1.1bar, by raising boiling point to estimated 268F circulating temperature,

https://www.dewitts.com/blogs/news/1...g-should-i-use

Your estimate of 2 extra bars and 18F suggests less than 230F for OP, well below that limit.

As explained below

In my case had to consider that driving at 55mph did keep temps below that point despite a triple threat of summer temps, heavy load and long uphill stretch. I got worried and decided to replace radiator despite having observed less, just a single bar, unexplained at the time (also checked and found rust marks around the AT connectors, etc). Wouldnt you know it, there was a pin hole complete with drip and corrosion marks on the front of the radiator, high, in an area not visible for observation.

Hence my question regarding hill altitude and suggestion to OP, having observed 2 unexplained bars, to look for any leak signs, doesnt cost anything to check thoroughly. Keep an eye on the expansion reservoir level, should remain at same consistent level when cold, if not then pressure test the system to be sure. Do a followup here, when you have more info.

Hth

 

I have noticed the same issue with my 07 rdx. going up a hill my temp will reach half way then coasting the temp will be less than half way. I also have coolant pushing out to the overflow and not returning back to the radiator.

 

Sorry to hear that,

Here are other related aspects to consider

Transmission connection, splash signs
https://acurazine.com/forums/1g-rdx-.../#post16452916

Idling check
https://acurazine.com/forums/1g-rdx-.../#post16443007

Radiator diy
https://acurazine.com/forums/1g-rdx-.../#post16412868

Post details for reference

Hth

 

Rented the engine block tester from Autozone. The blue liquid turned yellow

Got a quote for $2200 Parts include compelete head gasket set,Timing chain set and water pump. Labor include cylinder head resurface from machine shop.

Not sure if its worth putting that money into this car with 215k miles.

 

I am sorry Atomsplittr that you have uncovered such an extreme issue after all. At least you now know what it could take to fix it, and that it is fixable.

That is a lot, after deducting parts cost, mostly labour isnt it? Get competing quotes anyway, could "save" part of the money if you have some big maintenance coming up like the 100k service with belts, valves, wp, sp..., dont forget a new radiator thermostat and sensors if you go for it.

Cars are not necessarily investments, and more of a cost center in the case of a daily driver, minimize it when given the choice. Sometimes a fixed up old car for few years could save some money vs buying other one, sometimes not.

If you search I am sure you could find a discussion regarding one owner, our car model, closer to either 400 or 500k miles, several years back, had a major sudden breakdown on the road, ended up fixing it, very similar amount different issue.

Welcome aboard!

 

Honestly if everything else is still in good shape, especially the transmission, I'd say go for it. $2200 is a lot, but it's also about 6 typical car payments. Can you get at least 6 months of quality use out of the car with this fix vs buying new? I think the chances are good. But that's the decision we all face sooner or later with aging cars.

 

I would agree. If the rest of the car is in good shape and the car will likely be fine for a long time after this repair, I'd do it. This is assuming you would actually keep the car for a long time.

 

I went for the cheap fix an used BlueDevil LOL! I drove my normal commute which is 120 miles. It fixed the bubbling issue but now my water pump started to leak. I ordered a new WP from rockauto for $27. It will be here today. I will report back after i swap it out.

 

Nice going Atomsplittr!

Impressive quick timing for fix as well, I guess 60-70% sodium silicate wont wait to crystalize after all. Will keep it in mind in case of need, thank you for the info!

Any unusual idling noise with the bad WP, or just a beginning drip leak?

As discussed above, high demand tasks in hot environment do not appear to blow headgaskets, overheating can and eventually will... check the fan activation temp to be below 212F (change sensor if higher than that and let us know the new temp activation level when you have the time).

Cheers!

 

Quick update: No noise on the water pump...just started to drip through weep hole.

I replaced the water pump to and so far its been good. I did have to replace the water pump pulley cause i bent it trying to remove the 3 bolts holding it. So far my temps tonight city driving only are between 196 - 201 fan was kicking on and off at idle. I will be driving my normal 120mi commute then i will report back.

 

Looks like you kept it under control and the fix seems to be holding!

Did you ever have changed the temp sensor at bottom of radiator or the radiator itself? My sensor (assuming its the original 2008 unit) kicks in at 212 and off @ 186, idling from cold start.

Cheers

 

When i swapped the radiator...i used the original sensor. I am also using BlueDriver Pro to monitor the temps while driving. This is a snapshot of a quick run to get some Mcdonald's once i finished replacing the WP. LOL!


BlueDriver Data Log
12-Nov 2019
Time(s) Engine Coolant Temperature (°F)
0 190
0.1 190
252.8 190
1131 196
1131.1 196
1131.2 196
1338.1 201
1338.2 201
1338.3 201
1338.4 201
1338.5 200
1338.6 198
1338.7 198

 

That's the way to do it.

In my tests found idling and stop&go as critical moments for overall temperature control, not so much while driving@speed.

Specifically, if my measurements were correct, the transmission fluid would rise 3F for every minute of idling while parked, cooling off only after reaching above 40-60km/h. Was unsettling to see its steady rise way ABOVE the coolant temperature, unmitigated by the radiator fan activation (despite the engine coolant showing the drop off at that moment to about same as you are getting ~196F). Stopped testing I think around 225-230F iirc, just over 10' of idling. May explain in a large part why very frequent ATF are helpful on this car model for some owners but not all.

The only plausible explanation I could find/come up with would be much lower flow from the AT when not at speed, (despite significant temperature increase and no practical way to monitor it either, solely driven by rpm), ymmv. This was before I did the radiator warmer bypass.

Cheers