Help......Overheating after replacing thermostat, hoses, & cap

Here is where I’m at with my VFR.

I took it for a ride today after slowly filling the antifreeze and massaging all the hose I could get my hands on to give a squeeze. I let the bike warm up to about 125 degrees to burp the system and check the level and top it off before I take it out. It was 89 degrees out today during my ride.

I rode the bike for about 15 miles very gentle on the back roads. I stayed within 55 to 65 mph. I kept a good eye on the temp for most of the ride. I did do a couple of strong pulls just to see how much the temp would rise and cool back down.

The temp bounced around 150 to 165, which seemed like it never opened the thermostat. Once I made a couple of stops at stops signs the temp got to 170 then came back down to 160 while riding. When I came to the last mile before getting home the temp went up to 190 then climbed up to 220 before stopping to cruise it down my dirt road very slowly. I thought for sure the temp was going to climb to overheating levels. What happened next had me shocked as I was very slowly cruising down my road the temp fell sharply and quickly back down to 190 by the time I pull into my driveway. I figured the fan kicked on and cooled it down quickly. I was tickled pink to see that. I still want to continue to ride the bike around kind of close to the house to see if the bike does any more over heating before I take it on the long trip to work.

I put about 84 oz of Honda antifreeze in the cooling system, but filled the reservoir between the upper and lower lines. When the bike got home the reservoir was almost full then as it cooled it pulled coolant back into the bike until the reservoir was down to the lower line. I imagine that filled the system back to full. I’m going to fill the reservoir back up to in between the 2 lines before the next ride.

With this info I have provided does anyone think that I blew a head gasket with the high temps it was hitting before I went through all the work to pull the thermostat and check the hoses?

I do believe my overheating issues was air in the system. Thanks to everyone here I have been able to get the motivation to keep working at it to get it back to reliable condition.

With more local rides I will know how well everything is functioning.

 

I think your head gasket is ok. Seeing the reservoir completely full doesn't feel right to me, like it shouldn't be blowing that much out of the main system. Anyone else have an opinion on that?

And you're sure that small hose at the bottom of the reservoir connects to the nipple on the neck for the radiator cap?

 

Yes, all the hoses are correctly ran and connected. I double checked them.
once the bike cooled down it sucked the antifreeze back into the system. You don't think that is correct?
I will be taking out tomorrow to ride it for a little longer to see if it has an issue.

 

Thats a good idea. i will try and keep an eye on it.

Ride today, was 45 miles with back roads and 6 miles on the interstate. 93 degrees out.
The temp stayed at 165 to 170 for 90% of the ride.
I noticed the reservior was full not over flowing but full while riding around. I kept and eye on it and notice once I got stuck in a line of cars at a construction zone the temp went up to 220. I looked at the reservior to see if it was over flowing, it was still just sitting full. Once I started moving about 3 miles down the road the temp went down to 185 and the reservior went down as well to just barely above the upper line and stayed there the rest of the ride.
I'm sure there are no air bubbles in the system now.

I have the old cap on the bike at this time, which could lead to the filling of the reservior so quickly. I'm going to change the cap and put the plastics back on to see how much that will effect the temps for the next ride.

Has anyone ever watched their reservior do the same thing? To me it seems normal. i know Mello said it seems goofy.
Do your VFR's run at about the same temps?

 

You could be very much correct.
I already have one I was just trying to figure things out one step at a time.
If the new cap doesn't work any better then I will use your suggestion and get a higher psi one.
Could it also be this Honda antifreeze being so much better than amsoil? Afterall Honda has a higher boiling point.

 

New cap is installed.
I used type 2 Honda antifreeze, I didn't know there was a type 2.
This is my first Honda.
Wednesday, I will do the long ride to work to see how she does. Wish me luck!

 

BTW, the manual does spec 20psi max on the cooling system.

 

Not so fast there chief.

The coolant expands when hot, so some has to go to the reservoir otherwise all the hoses would probably rupture. The purpose of the sprung cap is to retain a controlled anount of pressure in the engine, the reason for that is physics, liquids boil at higher temperatures when they are under higher pressures. With no pressure a 50:50 water: ethylene glycol mix boils at 107C/225F, with a 1.3 Bar cap the boiling point rises to 130C/270F.

The pressure cap is not a thermostat that responds to temperature, it simply stays sealed until the system pressure exceeds the spring tension.

 

I highly doubt that the different coolants will provide any measurable difference. They should both be 50:50 ethylene glycol and water as a base, plus any corrosion inhibitors (which are just there to prolong the coolant life) and dyes. Back to physics again, the 50:50 ratio gives a very predictable standard boiling point, and also describes the specific heat (how much energy it takes to raie the liqiud temperature by 1 degree). One coolant will take heat from the engine and release it to the air via the radiator just like any other.

I suspect that the act of riding has driven a few more stubborn air pockets out of the engine, so not a surprise if the reservoir drops a little after the first fill and run. My advice is to wait for the level to settle and then set it about halfway between high and low. That should mean that under all forseeable normal operating conditions, you don't overflow any coolant. Personally after I refill a cooling system, I let the engine run right up to fan temperature with some decent rev blips to dislodge air, and then cool fully before I set the final reservoir level.

Normal running temperatures should be around 78-82C when there is plenty of air through the radiator, that is the opening point of the thermostat. If the going is slow the airflow slows/stops and you will reach 100 or more reasonably quickly, and the fan should light up around 103C, sometimes it lags if the engine is idling as the displayed temp is at the rear of the front head, and the themoswitch is out on the radiator which may be a little cooler when the coolant is moving slowly, so you may see more like 107C before the fan comes on, but then the fan should keep running until you see 98 or so, then the cycle continues.

122C/252F is the temperature redline, and if you see that, it is time to shut down and wait for some cooling. That high indicates a fault e.g. low coolant, stuck thermostat , no fan etc.

 

Purple Ice is a corrosion inhibitor so the benefit will be to keep cooling system surfaces cleaner for better heat transfer. If your cooling system is in decent condition I'd be sceptical about any benefit in the running temperature. My 2 cents worth is to use a standard store-brand coolant and replace it every 2 years. Coolant (and the corrosion inhibitors in it) can break down and become acidic if it isn't changed reasonably often, which increases corrosion, causes film build-up, and reduces cooling ability.

 

Top of the morning Gents,

Rode to work today and found that the bike is not done with fighting me.

65 degree morning while on the back roads temps were not going over 181. Jumped on the interstate I saw 210 then came back down to 185 to 195 and settled in there for the remainer of the ride. Once I jumped off the interstate and sat at a light the heat soaked motor raised the temp to 220, once I got going it dropped to 210 then started climbing back up while I was moving about 45 mph. before I knew it I was at 235, 240, 250 and I pulled off the road and shut her down. I was close to work at this point. I let it cool down to 225 then rode and when I stopped at lights I turned it off and ran one light as the temp was getting close to 240. I pulled into work the temp was at 245 and I shut her down and after sitting a few moments she puked coolant on the ground.

The only thing that changed was rad cap and adding the fairings. I wish I brought the old cap with me to see if that would change things. Somehow, I don’t think it will. After reading what Terry said, I'm going to stay with the new cap and point my attention some where else.

Next steps? The one thing I did not do was take apart the water pump. This weekend looks like that is what I’m going to do. I need to know if everything is good in there. It seems like when I’m moving slowly the temps rise, besides the air not flowing I’m wondering if the impeller is not spinning fast enough to keep the coolant moving through the system.
BTW, when warm the bike is idling at 1100 RPM. I will turn it up a little, but it doesn't seem to have a problem idling there.

What do you guys think I should concentrate on?