Coolant Flush on my 6th Gen or "The Philosophy of Cooling According to Honda"

OK, summer is here in South Texas. I live in San Antonio. It gets pretty hot here. It doesn't bother me, but temps are almost always 90 and up, and often 100 every day for weeks on end.

I've owned my 2007 RWB since March, 2012. I bought it with 7500 miles on it and it now has 25,000 miles on it. About 5,000 of those miles were added during my April-June trip to and from New Jersey, along with a 2-month stay there.

I did a lot of maintenance to the bike before I left Jersey, but flushing the coolant I did not do. It was a non-issue because all that super-slab riding kept the bike below 180 degrees or so, no matter what.

But when I pulled into a gas station in Tyler, TX (East Texas, I love this place!) it was 97 degrees. I had all my gear on (ATGATT my ass!) and the afternoon sun was roasting me as I rode west. I was burning up! The bike was running perfect, however.

Now I might break a VFR Commandment here ("Thou shalt not criticize the maker of thy VFR....") but, as we know, these bikes get hot! At 97 degrees ambient, at 60 MPH, the bike is at 199. At 35 MPH the bike is at 212. And stopping for a red light quickly puts the bike at 223 which, for my bike, triggers the fan. The fan is effective, and brings down the temp at a modest pace. My bike has never overheated, even in traffic at 106 degrees (though it did kill off ALL the sperm I was transporting at the time). As far as I can tell, this is how Honda designed the VFR to operate. So, if the bike is operating in the manner designed by Honda, it is not "overheating," or being defective in any measurable way, right?

Not so quick there, Soichiro. Does the bike have to run so hot even if no engine damage will result? I'm not so sure. I think the cooling fan should start sooner, and I think there should be two of them (GASP!). But my opinion is worth squat because I won't make such a modification. At least not yet.

What I will do is change the coolant. I had never changed it, and I don't know if it had ever been changed.

Some thoughts on the process:

• The service manual doesn't indicate before you remove the coolant drain bolts that you'll need new washers, but you do. Buy them first. I re-used mine. If it leaks, I'll deal with it.
  
  
• When you remove the drain bolt on the water pump, it shoots out - FAST, FAR, and HOT. Be careful.
  
  
• The service manual doesn't really tell you where the "cylinder drain bolt" is. It's got to be near a cylinder, right? It is, but I had to ask on VFRW because I couldn't find it on my own. My gift to posterity: the "cylinder drain bolt" is about two inches above your oil filter! You're welcome.
  
  
• Gift to Posterity 2: The cylinder drain bolt sits slightly further back than the oil filter. It can be a PITA to get to unless you remove the filter, so you may consider doing the coolant flush while doing an oil change. You're welcome.
  
  
• Gift to Posterity 3: Don't even bother with the facking cylinder drain bolt! When I finally got it removed, maybe a teaspoon or so of coolant came out. Waste of time. You're - oh, never mind.
  
  
• Even a teaspoon of used coolant is incredibly slippery, garage floors are always hard, and wives could really care less about your possible subdural hematoma, especially when you STILL haven't cleaned the toilets! Do you NOT want to get laid? FFS!
  
  
• When you refill with fresh coolant, do it slowly. This minimizes air entering the system, which means less to burp out later.

So, the end result of the coolant change? The bike still operates as Honda designed. The fan still comes on at 223. What IS different is that the temperature change takes longer to occur. In other words, where the bike would very quickly hit 223 at a red light before, it still does now, but takes a lot longer to get there. I noticed the same across the entire temperature and speed range. It gets hotter slower. It seems to me that this means the heat is being more effectively transferred by the new coolant.

Now, let's get some caveats out of the way. I don't know what type of coolant it had in it before, whether the ratio was right, or how old it was. It was full, and had no leaks, though. Also, the old coolant was an ugly blue-green, whereas new coolant is pretty and bright green. Normal for old coolant? I don't know.

In any case, I hope this post helps you in some way.

Rich

 

I replaced my coolant with Engine Ice and it seemed to help all around in the fashion you mentioned above.

These bikes run hot! Last weekend it was 92 and VERY humid and I was on the expressway doing 70 but with a strong wind at my back.....bike sat at 199-201 but that's what they do. You want hot...spend some time on an RC51, hehe

 

Thanks for sharing your thought Rich, that was quite funny :thumbsup:

 

Sounds like one of them thermodiabolical laws about efficiency being related to the difference in heat energy at the start and end of a cycle. Glad to find out where that useless drain bolt is located...

 

I replaced my coolant with coolant, it worked perfectly after that.

 

Mine got up to 239 sitting in a traffic jam in DC. I got worried but the bike never hiccuped. No problems since. My only concern is whether or not this contributes to stator failure.

 

Thanks for pointing out how to locate the engine block coolant drain. I just did a coolant change and wasn't able to find it, but forum members have pointed out that very little drains from it anyway.

 

You spozzta to keep the cylinder drain bolt AND the waterpump bolt OUT while you flush the system through with a garden hose.......

 

No, not likely.

 

I kind of thought of that but I was going according to the Honda service manual, which doesn't indicate such.

But the bigger reason was the tiny amount of coolant that came out after such frustration to find the cylinder drain bolt.

Maybe next year

 

Bolting on a blackbird FPR that bumps your fuel pressure from 36psi to 43psi would help it run cooler.
I have had the Rc51 oil cooler and the FPR mod blows it away.

 

I tried the bolt on a window AC unit MOD but the damn extension cord isnt long enough for me to go anywhere
Any help here?

 

I have found this to be the case.

 

I dont pull the cylinder dran plug. Not worth the trouble for me. I fill with distilled water run the bike up to operating temp and let the water cycle then drain. Filll with HONDA 50/50 and 10 capfulls of water wetter. All done then back out on the road.
I figured the coolant would shoot out far so I used a long funel to catch it and keep it directed to the drain pan.

 

As bitterpil indicates, I too use distilled water to flush the cooling system after draining the coolant. I've been told by friends who service their own bikes that it is best not to introduce the minerals contained in non-distilled water into the cooling system.

Something I recently read in MCN and that I tried with my Triumph Sprint is as follows. "If you want proof of the mischief that's been taking place inside your engine, try pouring a 50/50 mixture of distilled white vinegar and distilled water into your cooling system. Button everything up and run your engine long enough to reach full operating temp. Turn it off and wait for everything to cool down, then drain again and behold all the little particles the vinegar (acetic acid) liberated. That's the oxidized scale that had collected inside your engine's passageways like plaque in your arteries. Now pour some more distilled water through to flush out any remaining particles and remnants of the vinegar solution, and refill with the coolant mixture of your choice." For me, I always use the Honda HP Coolant, which is already premixed.

Anyway, as indicated, I tried this on my 2004 Triumph Sprint. I purchased this bike new and have changed the coolant religiously every two years since. After trying the 50/50 mixture of distilled white vinegar and distilled water, I was absolutely amazed at how much oxidized scale was removed and sitting in the drain pan. I continued to refill the system with distilled water to flush the system until the water coming out was as clean as that going in, which was three times.

In the future, I will use this method to clean the cooling system each time I change the coolant with my bikes. I have not had any issues with overheating but now the cooling system has to be operating more efficiently. I say this based on how much oxidized scale was removed. Hope this info is useful to all!

 

Wow, lots of info there guys, Sooooooooo how many miles to put on your coolant before changing ?

 

So is it every two years or 25,000 miles ???????

 

Coolant should NEVER go more than 2 years.

It breaks down & loses it's lubricating properties for water pump seal.

 

Well, looks like I'll be changing my coolant ASAP. I know mine's been in there longer than two years. Thanks for the vinegar tip as well, I'll definitely be trying that!

 

Yeah your VFR will still run hot with new coolant. Correct me on this but there's a coolant valve that will open when cooling temp is at 70C that will allow full circulation of coolant (to radiator)(?)..I notice on my 5Th gen that new coolant performs better = better heat absorption & shedding (when rolling).