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Thermostat normal or overheating?

10K views 42 replies 4 participants last post by  surgeon 
#1 ·
I need help to check if I have a possible thermostat issue. I had a chance to

drive about 150 mi today. Most of the time it stayed 69-70 deg C above 75mph. When I slowed to below 60mph for about a minute I could see it go close to 74. After speeding up it would go down within a 1-2mi. When I was back on the street it was 71-75 deg C. After stopping with engine off for few mins and starting again I could see it start from 79-80 deg C. ECO time. From there I was reaching destination with 2-3 miles. I did not see it go down to below 74 yet within that short distance. If I had continued maybe it would have gone to 70s? During the entire drive I did not see ECO except for the last short distance. It was hot outside today.

I don't know if the cool down time is correct or it should have already gone down quicker.

I tried it without the muzzler on another 20mi drive yesterday local. The temps seem to be higher than on freeway. I saw ECO a few times, each time slowing below 50mph.

Is this behavior about normal or time to change thermostat?





I'm assuming you mean 77-80 degrees C? Is that with or without the Muzzler? That equates to 170-176 degrees F which is above the 167 degrees F that VCM is looking for to kick on. If that's with the Muzzler installed that means your actual coolant temp is at least 185-196 degrees F or more. I only see close to that kind of temp when the vehicle is stopped and is just idling.


I drove to the store to get some tools about 2 miles.

Started with 70ish. At 75 and up, ECO was coming during this small drive above

30mph. It happened both ways. I used to see it go up from 64 to 80. Will try

again Sun. Tonight its on jacks set for tomorrow.

As for the scanner it was a defective ELM. Unless I keep moving it, wont work.

Loose connection. Wired scanner works fine.

ECO will come on when the indicated temp is 75.

That's the temp threshold for VCM. The problem is that your vehicle is

running hotter than most, so even when you install the Muzzler your temp is

still going above the 75 degree threshold, even with the red resistor. You

don't have a problem with the Muzzler. You may have a bit of an overheating

problem.

I'd remove the Muzzler and monitor the temps. Let's see where it's running

normally, without the series resistor in there skewing the temp.

Some info via Search Function for ref:

There is a ScanGuage on our '01 and the "normal" coolant

temperature was always 182 degrees. On long downhill runs, it could drop as

low as the high 160s and on a summer uphill in the hot country it could go to

a bit over 210 degrees. As all this was happening, there was NO movement on

the OE guage. The bottom line is that you cannot tell much by watching the OE

guage, which is damped to keep us drivers from going into a panic, unless it

suddenly heads for the top of the scale, in which case you are having a

serious overheating problem. For anyone who is concerned about the coolant

temperature fluctuations, I strongly recommend the ScanGuage, which provides

many other realtime bits of information, as well.

Jerry O.

Mine points directly to the green 'D' symbol, and

temperature hovers between 179 and 182F (on ScanGauge). In-town gas

consumption is around 19 and 20 MPG.
Do not idle for too long, 1-2 minute is enough, then drive off as you'll heat

up the engine quicker while driving, as also your overall MPG will improve.
160 °F 71.11 °C
170 °F 76.67 °C
180 °F 82.22 °C
190 °F 87.78 °C
200 °F 93.33 °C
212 °F 100 °C
 
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#2 ·
I need help to check if I have a possible thermostat issue. I had a chance to

drive about 150 mi today. Most of the time it stayed 69-70 deg C above 75mph. When I slowed to below 60mph for about a minute I could see it go close to 74. After speeding up it would go down within a 1-2mi. When I was back on the street it was 71-75 deg C. After stopping with engine off for few mins and starting again I could see it start from 79-80 deg C. ECO time. From there I was reaching destination with 2-3 miles. I did not see it go down to below 74 yet within that short distance. If I had continued maybe it would have gone to 70s? During the entire drive I did not see ECO except for the last short distance. It was hot outside today.

I don't know if the cool down time is correct or it should have already gone down quicker.

I tried it without the muzzler on another 20mi drive yesterday local. The temps seem to be higher than on freeway. I saw ECO a few times, each time slowing below 50mph.

Is this behavior about normal or time to change thermostat?

Are the temps you have listed here WITH or WITHOUT the Muzzler installed?
 
#4 ·
Your temp readings are skewed with the Muzzler--that's how it works. There's no point in checking your actual temps with the Muzzler installed. I would think that with the red resistor you wouldn't see ECO very often, that's why the check of what the normal temp is without the Muzzler.
 
#6 ·
Um, well, without the Muzzler you're SUPPOSED to get the ECO light.

I'm just trying to help you with your complaint of the ECO light coming on a lot WITH the Muzzler installed. You already have the higher ohm resistor installed which brings down the indicated coolant temperature quite a bit and you're still seeing a lot of ECO. I just thought it was worth checking to see what your actual coolant temps were running.
 
#7 ·
No Muzzler. Took a 5 mi drive fwy+street. Started with 3 hrs after last drive. Temp started with 69 and went to 79. It stayed steady 80-81 until I got off the fwy. It went to 84 and after more wait+idle at one point 95. Then back down 83... 81. On the way back 5 mi same thing. Constant 80-81. Exiting fwy and waiting at lights 84-85. At driveway it was 88. So seems to be 79-81 on most drives. This time A/C was off.
 
#8 ·
Do you "normally" drive with the AC off in the summer time? If not, please drive it with no Muzzler, as you normally would. That means with AC on just as you normally would drive it. Again, the point of this is to see if it's getting too hot under certain conditions. Also, can you take a close up picture of where your temp gauge on the dash is running when it gets to its hottest point?

If it's not overheating but just running hotter than others it could be several different things. It could be the temp sensor itself is off a bit. It could be the thermostat opening at a higher temperature than normal. If it's actually overheating it could be a radiator that is partially blocked or it could also even be a head gasket(s). Are there any hills you can climb? You're trying to see how hot it will get. You just want to make sure it isn't getting too hot.

If you read the FAQs for the Muzzler it does say that in a few cases a higher resistance (higher than the blue or even the red) resistor will be necessary. I think he offers a white resistor. If the red resistor still allows VCM to activate while driving normally on the freeway then you may need to switch to the white one but you'll have to order that from Verbatim.

I think if it were me I'd change the thermostat just to see if it brings my temps down a bit. If you have 100K or more miles it's good preventative maintenance anyway to prevent a stuck thermostat and a real overheating event. Stick with an OEM thermostat and be sure and use the Honda blue coolant--don't mix other coolants. Then check your temps again. If they're the same then you could try replacing the temp sensor if it's not too expensive ($28-41 online) or just order and run the white resistor.
 
#9 ·
I had these pics from prev no muzzler post. Since I cannot edit I will post here. I couldn't get them off my phone at the time. I will start with new thermostat during coolant drain task. The highest this car went was 95 at full idle during that last post once I reached driveway before engine off. During drive highest was 89.


Auto part Vehicle Car Measuring instrument Speedometer
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Car Vehicle Auto part Measuring instrument Speedometer
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#10 ·
If 95 is the highest it ever goes it's not overheating but does run a bit warmer than other similar vehicles. Replacing the t-stat and changing coolant if you're over 100K isn't a bad thing to do regardless. If a new t-stat doesn't make any difference I'd try the red resistor again. If you still get ECO light too much while driving down the freeway then order up a white resistor (I think that's the next one up) and give that a try.
 
#11 ·
Update. Finished the 1400 mi trip last week. During the entire drive scanner showed temp 69-72 degC @75mph or above. Only when congested traffic and local, temp was 74-80. Local normal driving always 74+ from cold start (I mean once it reached normal operating temp).

Due to hectic schedule and packing, I did not get to do thermostat and coolant change.... along with other suspension to-dos.

It ran smooth the whole time and a/c was always on using auto setting. Trip went well... First long road trip in this car.

Then yesterday during normal/local use around town, wife got the engine light for ECT1 sensor. Checked with scanner and cleared code. So once in a while the light comes on... Would that be an indication of weakening sensor that I should replace sometime? So do thermostat, sensor, and coolant change? Just asking, it seems to be running fine most of the time.
 
#17 ·
You'll have to go back to the blue resistor if you want to keep the CEL off. If ECO continues to come on too often then you will have to try getting the average coolant temp down a bit, either by replacing the ECT1, new thermostat, and/or cleaning/replacing the radiator.

The problem is it's taking too much resistance to get the indicated temp below 167 most of the time.
 
#19 ·
I ordered the thermostat and sensor. Last night the engine light came back. This time 2 codes P0118 ect1 circuit high and P0128 coolant temp below regulating temp. So next week I will change both thermostat and sensor with coolant change.

For now I put the blue resistor back on.
 
#20 ·
Did you buy the OEM thermostat? That's what I'd recommend. I'd probably stick with OEM on the ECT1, too.

I honestly don't know if either of these items will fix your issue. Your van just seems to run a few degrees hotter than most. Changing the t-stat and/or ECT1 is just a guess.
 
#23 ·
Yeah that is a standard coolant additive. It is especially helpful in "racing" environment where more water ratio is used. Odyfamily was going to try hyperlube. I did purchase redline few weeks back and I was going to swap to hypberlube also at the time.
 
#29 ·
They're both decent products. Red Line is primarily for users who use 100% water for coolant, and it is tremendous in a 30/70 coolant/water mix. Hy-Per Lube will also do well in a pure water coolant environment, but it does better than most other wetting agents in a 30/70 coolant/water mix.

See this testing done by the guys on Superstreet Online

I'm using Hy-Per Lube right now in my 2003 EX after a recent 50/50 coolant change, and it is fitted with an 82-deg C Motorad tstat. The wife's 2002 EX, with a 78-deg C OEM tstat will get a 50/50 coolant change and the Hy-Per Lube in the next few weeks. This winter will be a side-by-side test to see if the Hy-Per Lube wetting agent is enough to help combined heat exchange from the block and at the heater core for windshield defrosting and de-icing purposes for her 2002 EX with the cooler OEM tstat.

I installed the 82-deg C Motorad tstat in our 2003 EX since this van gets the bulk of winter use, while the 2002 EX stays garaged in ice storms (wife uses the 1998 Accord, in this case). If the results are good this winter, I'll change to fresh, new Honda OEM thermostats and gaskets in spring of 2007. I consider thermostats to be a "wear" item, just like tires. At 14 years of service, the OE tstat in our 2002 EX is due for a refresh; the slightly hotter Motorad tstat in my 2003 EX has been doing great for several years, and was our "go-to" van during freezing precipitation, since the 78-deg C OEM tstat could not cut it in abysmally cold weather with ice sticking to the windshield.

If the Hy-Per Lube does the job with the cooler tstat, I'll post back. For our VCMuzzler users in areas where winters get cold, replacing the stock 78-deg C tstat with a Motorad 82-deg C tstat could give the same indications surgeon is getting. If Hy-Per Lube added to coolant helps enough with heat exchange at the interior heater core while using the OEM 72-deg C Honda tstat, we may have a winner.

I'll post back on this topic in the spring.

OF
 
#24 ·
Just try a new t-stat and some fresh coolant (only use Honda coolant) and see if that helps. It's good routine maintenance after 8 years anyway even if it doesn't do anything for this issue.
 
#25 ·
#26 ·
So, did you actually replace the thermostat? Your other post is a bit confusing.

For purposes of resolving the VCMuzzler temp issues it's best to keep your posts in the same thread. I'll be curious to know if the indicated temps change any.
 
#27 ·
Replaced thermostat and coolant sensor. Sorry just wanted to put related pics where they go; that is why I mentioned pics went there and then posted note back here to continue.

I still have the red resistor on. During coolant change with scanner hooked up fans came on at 79 degC. When I went for local drive yesterday, ECO came on 3 times between 45 and 55 mph. Also noticed the temp needle sits below the symbol on gauge and then goes up to it slowly and then comes back down a bit. No cel though since last clearing at thermostat install.

Today if I get the chance to drive van, I will take out the resistor and keep scanner hooked up. Will take some readings and pics.
 
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