'07 overheating while moving, cools when stopped???

Hey guys,

I'm kinda at a loss here as to what might be up with my new bike. Just turned 1,000 miles and had service done at 600. No problems with the bike until tonight coming home from work. I opted to stay off the interstate and wind my 40 mile commute home via backroads and twisty stuff. After about 20 miles of relatively unspirited riding, avg maybe 60 mph the temp gauge started shooting towards the high mark. Not slowly mind you, but shooting. I kept believing this was going to shoot back down, so whenever it got to it's final bar and started to blink, I immediately pulled over to see what might be up. Within maybe a 30 seconds of stopping while still running, the bike cooled down to mid temp. I checked the coolant and glanced at the oil sight glass. Nothing strange there. I thought it must be a fluke, so I proceeded home. Same thing. I had to stop twice more in the last 15 miles. As soon as I'd stop, it'd come back down. The engine doesn't seem to be working, pulls nicely through rpms with plenty of power. Anybody seen anything like this? I tried downshifting and running at different rpms to see if it would help. It didn't seem to. Thanks for any insight you might have!

Jeremy

Probably a faulty sending unit or indicator. Only a service check and some luck will tell for sure. You can smell an engine that's getting too hot.

I'll hazard another guess.....

Check that the cooling fan is turning the right direction.

Let the bike sit until it warms up enough for the fan too come on and make sure the fan is pulling air thru the radiator instead of blowing it forward. Don't be fooled. Blow some smoke or hold a paper up to the radiator to be sure which way the air is moving.

The cooling fan is a DC motor so it will run in reverse if the power/ground leads are swapped. Without digging into the FJR wiring diagram to see if this is really possible (I'm sure I'll find it isn't....LOL) if the harness to the electric fan is reversed or mis-manufactured (pins swapped in the connector to the fan motor) the fan could be running in reverse.

While not a common thing I have seen reversed electric cooling fans in other applications. Same exact symptoms as you describe. The system will work fine at high speeds as the fan air flow is overpowered by the ram air from high speed operation and/or the fan isn't even running because the engine is cooled sufficiently by the ram air. Then you come to a stop and the fan comes on. It runs in reverse but the reverse air flow is fine to keep the coolant temp controlled at a stop or low speeds. Then at 25-45 sort of speeds the fan is still running but the air flow thru the radiator is stalled by the ram air flow balancing against the fan reverse air flow....i.e....engine overheats. Stop to idle, system cools fine with reverse air flow.

Check the fan air flow direction.

Honda had a problem with this sort of thing several years ago I think...???? To counteract the "hot rider" syndrome on the Goldwings they deliberately ran the coolant fan in reverse to push air thru the radiator, away from the rider, when stopped or at crawling speeds. Trouble is, they must have got their crawling speeds to normal speeds transition messed up. The bikes overheated when ridden in parades or at continuous very low speeds due to the reverse air flow stalling against the ram air flow resulting in stagnant air over the radiator...i.e...engine overheats. I think they reflashed the PCM cal to change the transition speed for reverse to normal fan operation. Some Honda rider probably can chime in that knows more about this than I do from reading.

Fun fact....the caterpillar tractor operators in cold climates reverse the cooling fan direction in the winter to blow the hot air from the radiator back over the driver to keep them warm. In the summer the fan normally pushes the air forward thru the radiator to keep the heat away from the operator. Those move so slowly that there is no "ram air" to factor into the cooling.

Good thought Jestal, I'm impressed.

My bet it's a faulty sensor. I doubt the fans could be wired backwards. I'm pretty sure the wiring harness plugs won't allow it.

Take it to the dealer, it's under warranty.

The reversed fan sounds interesting, but my fan never runs when I'm moving above a crawl. The ram air effect does the job at 20 MPH and above. Do the second gen FJRs run the fan more?

Geezer said:

The reversed fan sounds interesting, but my fan never runs when I'm moving above a crawl. The ram air effect does the job at 20 MPH and above. Do the second gen FJRs run the fan more?

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If you run on the expressway, hop off and come to a stop before starting the lower speed riding I bet the fan will turn on for a moment due to the latent heat inputted into the system and then the sudden loss of ram air causing the temp to rise when coming to a stop. Not necessarily repeatable all the time but it will happen.

That is what is confusing about reversed cooling fans and diagnosing them. It is not easy to repeat the scenario where they cause a problem. If the ambient is cool enough or the speeds are just right the system will work surprisingly well with reversed fans. I've seen development cars run for months and months with fans reversed before someone "noticed"..... Many people with the gold wings never had a problem, either. You had to ride at just the right speed under just the right conditions to get the reverse fan to stall the ram air to get it to overheat.

On cars the reversed cooling fan scenario is even more confusing. Fans are rarely required for coolant temperature. Fans are required most anytime the AC compressor is on, however. Imagine the situation in cool weather where the AC compressor runs occasionally. Every time the compressor kicks in the fans run in reverse and cause the car to overheat, even in the cool weather due to stalled ram air flow.

Inlaw1 said:

My bet it's a faulty sensor. I doubt the fans could be wired backwards. I'm pretty sure the wiring harness plugs won't allow it.
Take it to the dealer, it's under warranty.

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Don't be so sure that the person that built the wiring harness put the correct pins in the correct holes when the wiring connector was built "at the factory"...... Been there, done that, seen it happen. Some person, somewhere had to insert those wires into the correct slot to make your assumption correct....bad assumption.

Whether this is the problem or not it is still a basic thing to check to see if the system is operating correctly and to help give the dealer info to properly diagnose the problem. Too many techs/service writers assume the same thing that you do....that the wiring harness "cannot be wrong" and overlook the obvious.

Wow, Jestal. Right or wrong, I am totally impressed w/ that possible explanation. You done good!

King said:

Good thought Jestal, I'm impressed.

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Don't be. It's just the old been there, done that situation.

Experience is a wonderful thing. Too bad you have to get old to get it.......

brazos parker said:

Wow, Jestal. Right or wrong, I am totally impressed w/ that possible explanation. You done good!

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It's probably not the problem but worth checking...then again.....

My money's on a bad waterpump impeller to shaft fit. Edicated guess, but the symptoms point that way. Impeller is actually attached to the shaft via a rubber dampner, which if bad would allow the impeller to slip at high speed yet flow ok at low speed.

You might also consider that there is air trapped in the radiator; happens on cars. There would be enough flow for low RPM idling, but not enough for higher RPM cruising.

Jeremyandeve said:

Hey guys,
I'm kinda at a loss here as to what might be up with my new bike. Just turned 1,000 miles and had service done at 600. No problems with the bike until tonight coming home from work. I opted to stay off the interstate and wind my 40 mile commute home via backroads and twisty stuff. After about 20 miles of relatively unspirited riding, avg maybe 60 mph the temp gauge started shooting towards the high mark. Not slowly mind you, but shooting. I kept believing this was going to shoot back down, so whenever it got to it's final bar and started to blink, I immediately pulled over to see what might be up. Within maybe a 30 seconds of stopping while still running, the bike cooled down to mid temp. I checked the coolant and glanced at the oil sight glass. Nothing strange there. I thought it must be a fluke, so I proceeded home. Same thing. I had to stop twice more in the last 15 miles. As soon as I'd stop, it'd come back down. The engine doesn't seem to be working, pulls nicely through rpms with plenty of power. Anybody seen anything like this? I tried downshifting and running at different rpms to see if it would help. It didn't seem to. Thanks for any insight you might have!

Jeremy

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Jeremy,

Did you find out what was/is wrong? My 07 started doing exactly the same thing today on the way to work.

Curt

(07 FJR & 06 RSV)

Start it up and let it sit and idle until the cooling fan comes on. Hold a piece of paper up to the radiator to see which way the fan is moving the air. It should be pulling air thru the radiator not pushing it forward. I know this isn't the problem....but....still worth checking just to prove me wrong.

jestal said:

Start it up and let it sit and idle until the cooling fan comes on. Hold a piece of paper up to the radiator to see which way the fan is moving the air. It should be pulling air thru the radiator not pushing it forward. I know this isn't the problem....but....still worth checking just to prove me wrong.

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Hey that is an old plumbers trick with paper.

Their choice of paper is toilet paper to check the "fart fan " to see if it is exhausting.

weekend rider

To get the bike to heat up enough use a hair dryer to blow hot air over the radiator till the fan comes on.Run the bike for about 3-5 minutes while you set the hairdryer up when it is at normal turn the dryer on .

The reverse fan is a good possibility ,also consider a faulty fan ,some do not fail completly at first, they just get " stiff to start" so they do not work all the time ,then fail completly.

Do have a good dealer as this is realy a warrenty type problem ,test as above but let them "find the fault and fix it ", YOU paid for a warranty use it .

radman said:

My money's on a bad waterpump impeller to shaft fit. Edicated guess, but the symptoms point that way. Impeller is actually attached to the shaft via a rubber dampner, which if bad would allow the impeller to slip at high speed yet flow ok at low speed.

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This is a common problem with BMW cars that use Plastic impellers. It usually shows up with symptoms like a bad thermostat.( hot engine and radiator is much cooler) You might see an engine temp of 190 F and the Radiator is 130 F or cooler.

Just an update about this problem! After reading all these posts, I looked over the entire bike again. In the process I rechecked the Radiator overflow reservoir cap. It was not down tight, so I popped it back down. I have put another 3,000 or so miles on the bike and it hasn't happened again. Must have been a fluke. Still loving this bike!

Jeremyandeve said:

Just an update about this problem! After reading all these posts, I looked over the entire bike again. In the process I rechecked the Radiator overflow reservoir cap. It was not down tight, so I popped it back down. I have put another 3,000 or so miles on the bike and it hasn't happened again. Must have been a fluke. Still loving this bike!

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Which would have absolutely no effect on cooling whatsoever-you could remove it and throw it away, the system will operate the same. The reservoir is vented, so it's already open to the atmosphere.

If the bike is going 60mph it shouldn't over heat no matter the fan rotation direction. The over flow cap won't do it either. Sounds like a sticky thermostat IMHO.