2004 Running A Little Hot

Sorry for the long story, but...

I had my 2004's coolant flushed and replaced last summer.  Ever since then it seems to run a little hotter than it ever had - to the tune of 2-5 degrees (F) most of the time.  I used to see 168-170 most of the time, but since the flush it was 170-173.  It also seemed to me that the fan was coming on at a higher than usual temp, but otherwise working normally.  I asked the shop mechanic about it but he said the temps were within normal range.  He kind of alluded to "setting" the fan starting temp to a higher temp, but I've never heard of this.

Running a few degrees hot is not a huge deal for me, but is a little annoying because it means it will run that much hotter in city traffic, etc. and may cause a bit more wear and tear on the fan and cooling system.

I should also mention when the bike started running hot after the initial shop flush I decided to do my own coolant flush, but botched it and killed my fan switch when coolant spewed out of the filler opening on the right front of the bike.   :sad:  Even after the switch was replaced (and coolant flushed again) at the shop, the bike was still running a few degrees hot.  I can live with it but I also know it's not normal.

Also, I've been running slightly heavier motor oil (15W-40 and 15W-50) since last summer to alleviate front CCT noise, which works OK most of the time.  I thought maybe the heavier oil might be causing the motor to run a bit hotter than usual.

Last night I changed my oil and filter, and used 10W-40, and today was seeing temps of 173-175 on the open road at 73-75 (F) ambient temps.  I should also mention I slightly overfilled the oil last night.  Last night it was at the top mark (after filling, running, and then topping off), then today after a 50-mile ride the oil level is 1/8" to 1/4" over the top mark.  Not a big deal and as far as I know it's not a problem to leave it as-is.

Questions:

-Has anyone else ever had an issue with their 6th gen. running a little hot under similar conditions?

-Is it possible to get my bike's operating temps back down to what I know was the norm for 5 years?

-Is it even plausible for a fan's start-up point to be set to a certain engine temp?

Thanks in advance for any help or advice!   :smile:

I  did  mine  a  couple  of  summers  ago  and  had  the  same  results. Only  thing  i  did  different  was  I   did  not  use   Honda  antifreeze,  time  to  do  it  again  and  I  will  use  Honda  af  this  time  and  see  if  it  makes  a  difference.

The only thing I can think of that might be directly related to the coolant might be the ratio of water vs ethylene glycol that's not the same as it was before.  Water has a higher specific heat index (can absorb more heat) than the glycol can, so if the glycol content is a bit higher that could contribute to it.  When I did my first coolant change this spring I went with a slightly higher percentage of water - about 60%, but didn't really notice much difference in the typical running temp.   Another possibility might be that the thermostat is getting a bit lazy or something got dislodged when the coolant was changed and is somehow preventing the thermostat from operating quite the same.  That seems like a long shot though.  Actually, given that temps around 220 to 230 are pretty common, a few degrees here and there around 170 is probably not too big of a deal.  Maybe only worry about it if the trend continues to worsen. 

Non-coolant related though - I was surprised how much debris had managed to lodge itself in the right side rad toward the back.  I didn't notice it until I had the body work off.  Some compressed air sent backward through the rad (from the outside inward) produced a cloud of bugs, dirt, grass blades, etc etc.  Getting a lot of debris blocking the air flow might also influence it, but the thermostat should be able to regulate around that except at much higher temps. 

Make sure the system is fully "burped" of air. Any pockets of air in the cooling system can cause hot running.....

I agree with the above. If it's been burped properly I'm guessing the ratio is slightly glycol heavy.

For comparison sake My fan comes on @ 222* and turns off @ 209*. 225* is the hottest that I've seen in stop & go traffic.

 However it's difficult to say what is a normal temp on my bike. I replaced the coolant with Water Wetter & distilled water. It still runs just as hot as it used to. The recovery times have improved, she'll cool down a lot quicker than with standard coolant.

  Today it was 95* ambient & 99% humidity ( :wacko: sweat box) & on the highway at 80mph I was seeing 210* with a car in front of me (183 in an open lane)  I've come to realize that these bikes need a good 5-6 car lengths of space before they get adequate flow thru the rads.

I think the FSM specifies 174-175F as the opening temperature of the thermostat. I wouldn't worry about it; your bike sounds fine.

Thanks, everyone!  I appreciate the input.

I burped the system when I tried the flush job, and I know the shop mechanic did it.  I used pre-mixed Prestone 50/50, and the shop mechanic used the official Honda coolant.  When I do this myself in the future I'll use the Honda type and maybe add a little water to the mix.

I'm going to let it be.  As I said above, I'm OK with it running a few degrees hotter than it used to, but it will still bug me.   :wink:

complaining about 176*... come spend some time in orlando.

Change the temp gauge to ambient. Watching the coolant temp will drive you crazy. It it gets too hot it'll shut down before it burns up.

Tim,

I would be more worried about the thing running Too Cold, not too hot!!!  I'm guessing the t-stat is hanging open slightly as those temps are Cold IMO for anything less than winter temps. The cooler it runs the more fuel you'll end up using to as it's designed to run 200 + and blow that the ECU is most likely sending a richer mixture.

These things ideally should be running 195-220 range and when pushing it 235-245 in not uncommon.  Hot is 255+ as far as Honda is concerned! :wink:

BR

Thanks again, everyone!  I'll try to stop thinking about it, but you know who obsessive we are about our motorcycles.   :wink:  

Yeah if all your seeing is 175 degrees, in the summer, its running too cool, you should see the 190's minumum at times, and post 200 degree temps also, as in NORMAL.

I got stuck in Chicago rush hour Friday afternoon.   :angry:

Long story, short version:  I've never seen my VFR's engine temp go that high.  It reached 250F once.  The bike worked properly, and since I've now seen it go to 5F under the auto-shutdown point and still work correctly, I don't think I'll be too worried about running a few degrees hotter anymore.   :wink:

here in southern ontario where the temps have been constant between 95 to 105 f...my gen 6 has hit 230f while sitting in traffic at lites...and then rolls down to mid 180s to 190s once i get moving. at these temps for the last few days the bike performs like normal. normal running temps in non heatwave weather is 175 to 180.

damn hot to be sitting on top of a 230 degree stove amigos...

I'm in Sarasota, FL and even on a night where the temperature outside is 85 my 08 VFR runs 200-230 depending on my speed, etc....

Seems to be the nature of these bikes, as I have seen the same info. on another forum...