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Temp Fan Question


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I have a '98 VFR and have noticed lately the fans never come on, despite the rather high engine temps.  Saw 142 F today and the fans didn't come on.  Is there a set temp where they're supposed to come on?  I know I've heard them in the past after a hot day-stopping the bike and the fans were running at around 128 to 134 degrees.

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3 hours ago, interceptor69 said:

I have a '98 VFR and have noticed lately the fans never come on, despite the rather high engine temps.  Saw 142 F today and the fans didn't come on.  Is there a set temp where they're supposed to come on?  I know I've heard them in the past after a hot day-stopping the bike and the fans were running at around 128 to 134 degrees.

 

Do you mean 242 degs? I think that's a typo.  At any rate, on US bikes it should cycle on at 220 and go off somewhere around 205 to 210.  That could vary +/- by individual unit.  The first thing I would check is the that you have battery voltage to the wire leading to the thermo switch with the key on.  If no power, check the fuse and / or source of problem.   If that tests good, next is to check the coolant level.  Remove the right fairing after plenty of time to cool off - overnight is good.  Coolant should be up to the top of the fill neck.  If coolant is low enough and does not cover the fan switch which is near the top of the left rad, the switch will not close and cause the fan to come on.  That's a common issue for no fan op.  If power is good and coolant full, then I'd suspect a faulty switch.  My $.02 is that it's either no power or I think more likely low coolant.  Let us know what you find.

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5 hours ago, interceptor69 said:

 Is there a set temp where they're supposed to come on? 

 

If you see *continuous* temps higher than 220ºF or below 180ºF then
trouble shooting is in order:

 

Continuous engine temps above 220ºF or 104ºC is a problem and the proper
order of items to trouble shoot are:

1)Faulty radiator cap... system should hold 1.1 pressure ratio...
2)Insufficient coolant...
3)Passages blocked in the radiator, hose or water jacket...
4)Air in the system...
5)Thermostat stuck closed...
6)Faulty temp meter or thermo sensor...
7)Faulty fan...
8)Faulty fan switch...

 

Engine temps below 180ºF or 82ºC is an problem... it means that the
moisture produced during combustion is not getting hot enough to
evaporate out the pipe as steam... instead that moisture will migrate
to the oil and produce a milky white contamination...

Note normal by products of combustion is water... . Every gallon of gas
creates roughly 8 pounds of water vapor... we all have witnessed water
escaping out of tail pipes on cold mornings...

 

The sequence of events to trouble shoot are:

1)Faulty temp meter...
2)Thermostat stuck open...
3)Faulty fan switch... (stuck on)

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07 VFR800

 

Quick question.  I never see over 220~225 here on on east coast (fan cools the bike back down typically).  

 

Same coolant (I really need to replace soon) but i'd see 230+ continuous while traveling cross country (especially desert in Nevada or Cali).   Palmar MTN especially caused the bike to be at almost at 240.  Besides that day its been working correctly (fluid level verified and engine ice coolant currently installed,  I did f

 

As far as i can tell the system is operating correctly.  Only say those temps a few times.  

 

(Set points on fan are correct here on the east coast, so i can pretty much rule out all of your isuses to check?)

 

figured I'd ask the West coasters there thoughts.

 

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My temps will get that high and stay pretty high when it's Africa hot.  Some people have theories on air flow direction, stalling, etc. if you Google through.  Have never had it stay high after I stop or get somewhere where it should cool though (down hill, coasting, stopped with fan kicking on, etc).

 

That's in the same rides too, like Palomar. Do not remember what it was like in Virginia as I didn't ride it much there.

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Duh-it was supposed to be 240, not 140 F.  Temps hover around 176/177 almost all the time despite the season when moving.  In the city, especially in stop and go traffic it will hit 240 easily and stay there until I begin moving over 40 mph or so then slowly drop back to 176/177.  Pretty sure the coolant level in the reservoir is ok but will check again today before my ride.  I got stuck in downtown Nashville yesterday-wasn't hot but warm in the mid 80's-and that's when it hit 240 or so.  In the past when I'd pull up at my driveway and stop the bike with anything above 220 the fan would be on so knew something was amiss.  I'll check the things mentioned above and let you guys know what I find.  Thanks for all the great advice and tips.  This forum in invaluable.

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15 hours ago, BusyLittleShop said:

 

If you see *continuous* temps higher than 220ºF or below 180ºF then
trouble shooting is in order:

 

Continuous engine temps above 220ºF or 104ºC is a problem and the proper
order of items to trouble shoot are:

1)Faulty radiator cap... system should hold 1.1 pressure ratio...
2)Insufficient coolant...
3)Passages blocked in the radiator, hose or water jacket...
4)Air in the system...
5)Thermostat stuck closed...
6)Faulty temp meter or thermo sensor...
7)Faulty fan...
8)Faulty fan switch...

 

Engine temps below 180ºF or 82ºC is an problem... it means that the
moisture produced during combustion is not getting hot enough to
evaporate out the pipe as steam... instead that moisture will migrate
to the oil and produce a milky white contamination...

Note normal by products of combustion is water... . Every gallon of gas
creates roughly 8 pounds of water vapor... we all have witnessed water
escaping out of tail pipes on cold mornings...

 

The sequence of events to trouble shoot are:

1)Faulty temp meter...
2)Thermostat stuck open...
3)Faulty fan switch... (stuck on)

My bike, even when new never ran over 177 degrees when moving at a normal speed.

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18 hours ago, triharder said:

 

07 VFR800

 

Quick question.  I never see over 220~225 here on on east coast (fan cools the bike back down typically).  

 

Same coolant (I really need to replace soon) but i'd see 230+ continuous while traveling cross country (especially desert in Nevada or Cali).   Palmar MTN especially caused the bike to be at almost at 240.  Besides that day its been working correctly (fluid level verified and engine ice coolant currently installed,  I did f

 

As far as i can tell the system is operating correctly.  Only say those temps a few times.  

 

(Set points on fan are correct here on the east coast, so i can pretty much rule out all of your isuses to check?)

 

figured I'd ask the West coasters there thoughts.

 

What type/brand of "ice" coolant did/do you use?

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Roll over image to zoom in
 
 
This type of coolant.  Use it in all my stuff as its available at my local powersports store.
 
I also have a on-going issue with a CBR that i trouble-shot and determined everything checks out (thermostat replaced with new but verified on stovetop (old and new) for set points, new cap, new hoses, new coolant .  But it still climbs over 230 when in traffic. 
 
Last i rode in VA its was October (2012 yikes) so no issues with cooling and crossing into Cali from Vegas when it was 100+ outside still no issues.  Just those days on the VFR at Palomar Mtn (in 2016) where it was creeping to 240 while i was moving got me worried. 
 
 
Can anybody confirm the bike will shut off at high temp or just give a warning light?
 
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1 hour ago, triharder said:
Roll over image to zoom in
 
 
This type of coolant.  Use it in all my stuff as its available at my local powersports store.
 
I also have a un-going issue with a CBR that i troubleshot and determined everything checks out (thermostat replaced with new but verifed on stovetop (old and new) for set points, .  But it still climbs over 230 when in traffic. 
 
Last i rode in VA its was october so no issues with cooling and crossing into Cali from Vegas when it was 100+ outside still no issues.  Just those days on the VFR at Palomar Mtn where it was creeping to 240 while i was moving got me worried. 
 
 
Can anybody confirm the bike will shut off at high temp or just give a warning light?
 

 

The 240 you were seeing was, IMO, likely because the fan was running.  The system is "dumb" and has no idea whether the bike is moving at speed or not - just that it's at 220+, so "turn the fan on".  The problem is that the fan's direction of flow is opposite that of the natural flow over / through the fairing, stalling air movement over the left rad when running down the road.  That can be solved with a SPDT fan over-ride switch.  Turn the fan on, off, or let the normal temp sensor switch do it.  I don't use the "off" mode often, but once in a while in that type of situation it's come in handy - at road speed, temps above 230 came down quickly once the fan was turned off.  Then move the switch to feed ground through the thermo switch once again and it's back to normal.  All the SPDT switch does is re-route ground - either directly to ground (fan on), through the thermo switch (normal operation), or no ground (fan off).  Just re-route the power wire from the thermo-switch to the SPDT switch and then use it to ground as desired.   I had thought about installing a VTR fan blade, but got the switch installed first.  Once that was operational, I realized I didn't need to change the direction of flow over the rad so never installed the blade.

 

 

 

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2 hours ago, triharder said:

Can anybody confirm the bike will shut off at high temp or just give a warning light?

Just gives a Warning. There is no auto overtemp shutdown.

However ignoring this warning will naturally bring about some form of catastrophic shutdown!

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Thanks for the responses guys.

 

I thought about adding the override switch but forgot to do it before traveling for work (on the bike of course).

it hasn't been an issue in Connecticut this year so far (i'm working shifts around traffic and in this area its not much of concern). 

 

Really only saw the problem in Cali that summer.   But I like the idea of getting the air moving in traffic before the 220 set point if its going to be a bit of waiting.   Any weekend i try to head home on 95 north in the summer.  I was worried that maybe the dry air was causing issues as I'm used to the humidity on this coast.  Granted we don't have anything around here that's close to Palomar MTN for elevation change and temperatures. 

 

Will have to wire  that SPDT switch  up when i tear the bike apart for the valve adjustment (i'm over do for) and for general cleaning as its been raining here for the last 3 days. 

 

I've only seen that light on the dash once on my CBR 929 after accidently disconnecting switch.  never saw it on the VFR but typically the light is lit only when you're way over where you want to be. 

 

For whatever reason the CBR seems to run hot in traffic with the silicon hoses i added (only thing that changed before i saw that was higher than 220 degrees on that bike).

 

 

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In my attempts to solve the CBR concerns (probably not really an issue if it doesn't go higher than 240, but seeing it up go up on a hot day with the fan on and it not settling down was concerning).

 

I noticed that the radiator doesn't accept air pushed from the back and only really allows air to flow from front to back.  I haven't blow down the radiator in the VFR.   

 

So i guess my next question is pushing air through the radiator on the VFR possible as opposed to pulling it?

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8 hours ago, Cogswell said:

 

The 240 you were seeing was, IMO, likely because the fan was running.  The system is "dumb" and has no idea whether the bike is moving at speed or not - just that it's at 220+, so "turn the fan on".  The problem is that the fan's direction of flow is opposite that of the natural flow over / through the fairing, stalling air movement over the left rad when running down the road.  That can be solved with a SPDT fan over-ride switch.  Turn the fan on, off, or let the normal temp sensor switch do it.  I don't use the "off" mode often, but once in a while in that type of situation it's come in handy - at road speed, temps above 230 came down quickly once the fan was turned off.  Then move the switch to feed ground through the thermo switch once again and it's back to normal.  All the SPDT switch does is re-route ground - either directly to ground (fan on), through the thermo switch (normal operation), or no ground (fan off).  Just re-route the power wire from the thermo-switch to the SPDT switch and then use it to ground as desired.   I had thought about installing a VTR fan blade, but got the switch installed first.  Once that was operational, I realized I didn't need to change the direction of flow over the rad so never installed the blade.

 

 

 

That's fascinating-the fans actually make the bike hotter.  Brilliant engineering! I wouldn't know as I ride w/ earplugs in and can't hear much.  I'm going to take the fairings off this morning and check everything.  

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Well, it appears it was the simplest of problems-low coolant.  couldn't see it when opening the radiator cap.  Filled it and "burped" the system and going for a ride.  Hope this solves my problem.  I think I may have lost some coolant when routing the wiring for the PC3 USB which required taking the overflow tank off-some must have leaked out.

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There’s no single thing that’s going to make a great difference; you’re going to have to address the whole system. 
 

I’d pull the bodywork, fuel tank, TB/airbox assembly, radiators, every hose and fitting, and start going through everything. There are two fittings in the valley and two above the stator cover that’ll need the O-rings replaced. Replace the thermostat with an OEM replacement and the housing’s O-ring. Get the AS3 hose and clamp kits for replacements, which are UK-made and found on eBay. IIRC, there are 14 or 15 hoses, depending on MY, and they all need replaced. If your water pump isn’t dripping, there’s no real need to mess with it, since it’s easily accessible. Soak your radiators in vinegar or have them dipped by a radiator shop and backflush them. Replace the fan switch with an OEM replacement. Replace the radiator cap with an OEM replacement. Install the VTR fan blade (Honda #19020-MBB-003), as it blows outward with the natural airflow and is a more efficient blade design. Install an expendable, 12V fan onto the right radiator that’s powered anytime the key is turned on. They’re available from all over the internet. 25mm is as thick as you can go, because of limited space between the radiator and cylinder head. You can refill with a high performance coolant, but, the common, Asian automobile coolant is plenty adequate. 


I’ve setup my ‘99 exactly as described above and my bike rarely exceeds 200°F, living in Floriduh. However, when I’m in stopped traffic, I shut off the engine. There’s ~3L of coolant in the system, the thermostat doesn’t fully open until ~200°F, and there’s only a single, small fan that has to try and get everything pulled back down, once it’s all heatsoaked. It’s best to stay ahead of the heat, by keeping the cooling system as cool as possible, which is where the additional fan really helps.
 

Again, you’re going to have to address the whole system and get every aspect of it to its absolute best operating condition. 

3B653DD7-A4EB-4BD3-96D7-948917C7B277.jpeg

BF6B1B48-B497-43D1-A290-D70D3AD54D3E.jpeg

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^^^ That is very true.  One thing that surprised me was how much crud had built up in the fins at the back of both but particularly the right side rad.  A lot of grit, tiny stones, a gum wrapper, bugs - all sorts of things.  Once removed from the bike, gently backflushing the fins from the outside in with tap water (I performed this in a scrub sink) will flush a lot of crap out of it.  The other maintenance item is to straighten the fins as much as possible.  They should all look like the photo, above.  I have a small, flat blade dental tool that fits perfectly in the gap between fins - they'll straighten right up.  It may not sound like much, but junk clogging the fins, bent fins from bug / debris strikes, and it would not surprise me it's possible lose 5% or even 10% of cooling ability - it all adds up. 

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Took a long ride-hotter today than yesterday and never saw temps higher than 187 when moving.  Got home and let it sit on the driveway and idle and when it reached 220 the fans came on.  I could only feel air exiting on the L side-does the R fan pull outside air onto the engine?

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1 hour ago, ducnut said:

There’s no single thing that’s going to make a great difference; you’re going to have to address the whole system. 
 

I’d pull the bodywork, fuel tank, TB/airbox assembly, radiators, every hose and fitting, and start going through everything. There are two fittings in the valley and two above the stator cover that’ll need the O-rings replaced. Replace the thermostat with an OEM replacement and the housing’s O-ring. Get the AS3 hose and clamp kits for replacements, which are UK-made and found on eBay. IIRC, there are 14 or 15 hoses, depending on MY, and they all need replaced. If your water pump isn’t dripping, there’s no real need to mess with it, since it’s easily accessible. Soak your radiators in vinegar or have them dipped by a radiator shop and backflush them. Replace the fan switch with an OEM replacement. Replace the radiator cap with an OEM replacement. Install the VTR fan blade (Honda #19020-MBB-003), as it blows outward with the natural airflow and is a more efficient blade design. Install an expendable, 12V fan onto the right radiator that’s powered anytime the key is turned on. They’re available from all over the internet. 25mm is as thick as you can go, because of limited space between the radiator and cylinder head. You can refill with a high performance coolant, but, the common, Asian automobile coolant is plenty adequate. 


I’ve setup my ‘99 exactly as described above and my bike rarely exceeds 200°F, living in Floriduh. However, when I’m in stopped traffic, I shut off the engine. There’s ~3L of coolant in the system, the thermostat doesn’t fully open until ~200°F, and there’s only a single, small fan that has to try and get everything pulled back down, once it’s all heatsoaked. It’s best to stay ahead of the heat, by keeping the cooling system as cool as possible, which is where the additional fan really helps.
 

Again, you’re going to have to address the whole system and get every aspect of it to its absolute best operating condition. 

3B653DD7-A4EB-4BD3-96D7-948917C7B277.jpeg

BF6B1B48-B497-43D1-A290-D70D3AD54D3E.jpeg

Thanks-great advice.  My hoses are original (I know-they should have been replaced long ago) so I plan on taking the tank off this fall, send the injectors to be cleaned and replace all the hoses and the thermostat.  I've already replaced the radiator cap w/ OEM.  How do you have that fan secured?  clever.

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1 hour ago, ducnut said:

There’s no single thing that’s going to make a great difference; you’re going to have to address the whole system. 
 

I’d pull the bodywork, fuel tank, TB/airbox assembly, radiators, every hose and fitting, and start going through everything. There are two fittings in the valley and two above the stator cover that’ll need the O-rings replaced. Replace the thermostat with an OEM replacement and the housing’s O-ring. Get the AS3 hose and clamp kits for replacements, which are UK-made and found on eBay. IIRC, there are 14 or 15 hoses, depending on MY, and they all need replaced. If your water pump isn’t dripping, there’s no real need to mess with it, since it’s easily accessible. Soak your radiators in vinegar or have them dipped by a radiator shop and backflush them. Replace the fan switch with an OEM replacement. Replace the radiator cap with an OEM replacement. Install the VTR fan blade (Honda #19020-MBB-003), as it blows outward with the natural airflow and is a more efficient blade design. Install an expendable, 12V fan onto the right radiator that’s powered anytime the key is turned on. They’re available from all over the internet. 25mm is as thick as you can go, because of limited space between the radiator and cylinder head. You can refill with a high performance coolant, but, the common, Asian automobile coolant is plenty adequate. 


I’ve setup my ‘99 exactly as described above and my bike rarely exceeds 200°F, living in Floriduh. However, when I’m in stopped traffic, I shut off the engine. There’s ~3L of coolant in the system, the thermostat doesn’t fully open until ~200°F, and there’s only a single, small fan that has to try and get everything pulled back down, once it’s all heatsoaked. It’s best to stay ahead of the heat, by keeping the cooling system as cool as possible, which is where the additional fan really helps.
 

Again, you’re going to have to address the whole system and get every aspect of it to its absolute best operating condition. 

3B653DD7-A4EB-4BD3-96D7-948917C7B277.jpeg

BF6B1B48-B497-43D1-A290-D70D3AD54D3E.jpeg

Are these the O rings I need?   

O-RING (13.5X1.4)
91307-611-000 
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3 hours ago, interceptor69 said:

Took a long ride-hotter today than yesterday and never saw temps higher than 187 when moving.  Got home and let it sit on the driveway and idle and when it reached 220 the fans came on.  I could only feel air exiting on the L side-does the R fan pull outside air onto the engine?


There is only one fan on the left radiator and it sucks inward. In stop-and-go traffic, the air gets jammed up in the frontend of the bike and there’s no real airflow through the left radiator. Replace the fan blade with the VTR blade I mentioned and the air will be blown through the radiator, along with the air coming into the frontend of the bike. 
 

When Honda released the GL1800, they had inward sucking fan blades. After numerous overheating complaints by owners, Honda released an update with replacement blades that blow outward.

 

2 hours ago, interceptor69 said:

Are these the O rings I need?   

O-RING (13.5X1.4)
91307-611-000 


In Honda’s schematic, you’ll need numbers 2, 16, 17, and 18. 

F7D79047-4135-4DA5-8CBF-C1B9BC9F183D.png

ECA32ACE-37BD-4F20-A2CB-F49C9425B843.png

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Thanks Duc for all the info.  I have the new fan in the cart and will add these o rings to it.  I believe I'm going to order a hose kit from AS3.  Should I order all new clamps as well?  Or will they be reusable?  I'm worried about how much crud will be in/over them.  Also I was looking through a few other threads relating to replacing the hoses/thermostat and noticed 2 gaskets that were completely disentegrated.  They didn't appear to be rubber but not sure.  I was wondering if you knew which ones I'm referring to and if so are they in the above list?  Sorry for so many questions but this will be the only time these hoses will be replaced (hopefully) and I want to do it right.

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1 minute ago, interceptor69 said:

Thanks Duc for all the info.  I have the new fan in the cart and will add these o rings to it.  I believe I'm going to order a hose kit from AS3.  Should I order all new clamps as well?  Or will they be reusable?  I'm worried about how much crud will be in/over them.  Also I was looking through a few other threads relating to replacing the hoses/thermostat and noticed 2 gaskets that were completely disentegrated.  They didn't appear to be rubber but not sure.  I was wondering if you knew which ones I'm referring to and if so are they in the above list?  Sorry for so many questions but this will be the only time these hoses will be replaced (hopefully) and I want to do it right.


You want the AS3 clamp kit, as they’re wider and of more substantial design in the screw/tightening area. Silicone hoses don’t compress like rubber, so they require more clamping force and the AS3 clamps reliably get that done. 
 

There are no paper gaskets; only O-rings. However, aged O-rings can look paper, in poor pics. 

783CDD5D-CDFA-4B47-8137-FCB30C6F3514.jpeg

721C3BD9-BFBE-4E10-8554-19EEE8A8127C.jpeg

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