Gen 6 Thermostat Problem I think?

So I replaced my thermostat before christmas. On removal it was clearly stuck in the wide open position. So a couple of rides after the new thermostat goes in its starts not warming up properly again and I suspect that the new thermostat is bad. The shop tells me that it very unlikely that the new thermostat is bad and it is just the cold weather. To be honest I think the shop guy is talking BS. I know my bike pretty well and it is not warming normally. It gets to 65-66 deg on the highway at about 5 deg air temp. It simply does not get to the normal thermostat activation of 78 deg.

The question is: could it be something other than the thermostat? or do I just have to bite the bullet and try another thermostat. I don't really want to change it again unless I have to as it is a bit of a pain. The other part of the question is: will it damage the engine if I don't change an open thermostat?

 

A bad thermo is bad for the bike. Seems unlikely that the new one could be bad already. But I know of several people that check thermos before installing them to make sure they work.
Cold-very cold weather will not allow a bike to warm up. But there could be some electronic issues like sensors and engine temp sensor...

 

What the bike did in cold weather (-3 deg C), when I first got it, was warm up to 78/79 then drop to 74/75 and repeat the cycle for up to about 30min but once up to temp it would never drop below 74 again. The reason I am asking if it could be something other than the thermostat is that Thermostats are not cover under the warranty but everthing else is.

I am not sure if testing the thermostat would have helped as it worked fine the first time I rode it after it went in. I am concerned because I live in a pretty cold climate and ride most of the year and so it is not operating in the right temperature range a significant amount of the time.

 

Have you done the simple diagnostics for thermostat functioning?
I had one go bad last year on my '04. The operating temperature I saw on the road was about the same as you're seeing. The fuel consumption was notably higher as well. Now it settles at 170 F (77C) even on fairly cold (< 0C) days.
IIRC, the way to test "by hand" (literally) is to start up the bike (cold) and let it idle while watching the temperature display. The right radiator will start to warm up as indicated by the gauge. The left radiator shouldn't warm up until the thermostat starts to open, at about 170F (around 78C, as you said)). If it does warm up before 78C, the thermostat is opening too soon (wrong temperature range?), or it is at least partially stuck open. Could it have unseated and rotated in place (I didn't do my own replacement [extended warranty from first owner took care of it]; don't know if that's physically possible on the VFR)?
Also, is the cooling system properly "burped"? I noticed some funny temperature readings after changing out my coolant as routine maintenance not long ago. I had left some air in the system. Things when back to normal when I topped the system up.
HTH,
Rod

 

Thanks for the tip about the radiators I will check that. I thought about the air thing. There is plenty of fluid in the reservoir. Right up to the full mark so unless there is an airlock that hasn't cleared there should not be a problem. I don't think that this is likely as it operates fine in the higher temperature range.

 

Got a 2000 vfr and relpaced a wide open thermostat about a week ago. Tool it out on a 170 mile ride only to find this new thermo must be stuck open also. The right/left radiator thing I don't believe works, they are in parrelle. Please let me know if you find yoour open again. Thanks, ddb

 

While the Rads do run parallel, the fluid must go all the way around the right side to the left rad. Thats why you check the left rad to see if your thermo is stuck open. You get some residual heating on the right but much less on the left.

Action

 

With a very small temp. probe I could tell no difference from right to left. There is a large hose connecting the front top of each rad. flow has to be about equal. At any rate with the thermostat close you should get no flow to the rads. until the engine get to aboout 170-180 degrees, only coolant recirculating thur a small hose at top of the thermo. housing to the pump and thur the engine. Need to verify that last statment when I get another new thermostat. ddb

 

See if this helps explain why you check the left rad



The rads will have the same temp once the thermo has opened. The Idea is to check to see if the rads are being heated up by coolant at a temp at which the thermo should be closed

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I have a simular drawing in my 2000 shop manual. On my bike I'm sure the thermo is open as I watched the temp rise from a cold start on both sides right in sych with the dash gage. I see nothing in the drawing to cause more or less flow in one side than the other. ddb

 

Its not about flow. When your thremo is working as designed, because of the way the hoses are routed and some seepage past the thermo, the right rad heats up before the left. Thats why it is easier to check to check the left rad to see if your thermo is stuck open. In your case since yours is stuck open you will not see any difference. If you choose not to believe it, suite yourself. I'm out.

Action

 

You may have some junk stuck in the thermostat that broke loose when you changed it. The other guys have done a good job of guiding you, so I won't repeat it.
Cheers
John.