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Discussion Starter #1 (Edited)
alright, so as the title says, my coolant fans on my '01 929rr aren't turning on until 232-234 degrees. before today, everything was fine, the fan would kick on rigth around 220. i noticed this problem today, where on my ride, i noticed it went up to 252+. I pulled over immediately, let it cool down, and then on my return ride home, which included being stopped in traffic for 5 or so minutes, the bike didnt over heat, only the temp gauge went up until 234 or so utnil the fans kicked in and cooled it back down.

yesterday i fixed my problem of a bad ground, causing my turn signals and headlights not to work. that problem is good to go, but now this is happening. is it just coincidence, or is there something related? Again, the fan IS working, just no until 234...

Also, this oil is dripping, around 2-3 drops from the bottom of the bike, here's a pic.
[/IMG]

I dont think the coolant itself is leaking actually
 

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Discussion Starter #2 (Edited)
jesus christ i'm so stupid. that bolt is the drain plug on the oil pan. oil was replaced around 300 miles ago by the previous owner who was a car mechanic who bought this bike off an insurance company. he fixed this bike up himself, which it didnt need much fixing in the first place, and had replaced the oil too. Any chance that the drain plug just isn't tightened properly? the last week i've been riding it, i never noticed the leak until today. it runs fine. no oil light for low oil pressure or anything. It seems like over this last week of riding, either the theoretically un-replaced crush washer gave out, or an improper torqued bolt showed its consequences. sucks that I dont have a torque wrench..or i'd retighten it right now and see if it helps
 

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The fan on the 929 is controlled from a "sensor" that bolts into the radiator that completes the circuit to the fan when it hits a certain temperature. It's likely that's the bit that needs to be replaced.

Did he use a crush washer on the oil drain bolt?
 

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Discussion Starter #4
The fan on the 929 is controlled from a "sensor" that bolts into the radiator that completes the circuit to the fan when it hits a certain temperature. It's likely that's the bit that needs to be replaced.

Did he use a crush washer on the oil drain bolt?
the fan seems to be working perfectly to be honest. Maybe since the oil is leaking a bit (like 4-5 drops after a ride), it's causing the engine to run a bit hotter, possibly causing that problem?

I have no idea if he used a crush washer or not. For some reason, I doubt he knew about replacing that crush washer/and or the importance of properly torquing the drain plug.

OH and are you saying that if the sensor is old/or possibly bad, that that is causing the fan to kick on a bit later than usual? what is that sensor called exactly?
 

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Part 20

Ronayers.com Microfiche Honda>Motorcycle>2001>CBR900RR>RADIATOR 1

The switch is fed a constant 12 volts when the bike is on, and just closes the switch to ground when the temp is high enough, allowing the fan to come on. Just saying it's working (in that it's making the connection), just doing it 15 degrees higher than it should.
 

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Discussion Starter #6
Part 20

Ronayers.com Microfiche Honda>Motorcycle>2001>CBR900RR>RADIATOR 1

The switch is fed a constant 12 volts when the bike is on, and just closes the switch to ground when the temp is high enough, allowing the fan to come on. Just saying it's working (in that it's making the connection), just doing it 15 degrees higher than it should.
thanks for the part #! I was just wondering though, could the sudden higher temp be related to the little oil leak from the drain bolt? When i got back after my ride 1 hour ago, and when i kept it running to see if it overheated, the fan came on constantly right around 229 +/- 1,then the temp would go to like 233 while the hot coolant cycled through, and then drop..etc etc. I'm just wondering if it actually needs replacing
 

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Discussion Starter #7
I also checked the coolant in the reservoir tank while it was running. it looks clean, there was no foam/bubbles. I'm more familiar with cars and diagnosing symptoms with them, so maybe a blown hg on a bike would yield different problems? I'm not sure. all i know is, from what i saw it looked good, and there were also no visible leaks around the heads or anywhere on the motor
 

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Bad water pump or thermostat maybe (or starting to go)? You didnt say if you took the radiator cap off and checked the coolant level right? Or maybe it could even be a bad radiator cap? Just throwing ideas out there. 250+ damn! You r in PA. Its not that hot there. I was riding in 90's last year and my temp never went over 208 on my 900. But i didnt stop for long in traffic either. And i have bent fins all over my radiator.
 

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Discussion Starter #9 (Edited)
Bad water pump or thermostat maybe (or starting to go)? You didnt say if you took the radiator cap off and checked the coolant level right? Or maybe it could even be a bad radiator cap? Just throwing ideas out there. 250+ damn! You r in PA. Its not that hot there. I was riding in 90's last year and my temp never went over 208 on my 900. But i didnt stop for long in traffic either. And i have bent fins all over my radiator.
it went to 250+ when something went wrong I guess? because on the way home, and when I went out again, it didnt happen :huh: I dunno.

And no, I haven't taken the radiator level off, only the reservoir tank, and the coolant was almost right up to the neck, but that was when the engine was already hot, and there was no other signs to make me suspect that there was air going into the coolant system via a blown head gasket or anything. There were no bubbles coming up, no oily residue, nothing, so i'm hoping at least that the head gaskets aren't bad.. The only time it went to 250 was when i was stopped in traffic for around 5-10 min after a 25 min ride.

Also, I do believe that the coolant level has increased in the reservoir tank. when it was hot, like i said, the coolant was almost up to the neck, and even now when i checked on a totally cold engine, the coolant looked to be above the upper level.
 

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Discussion Starter #10 (Edited)
is there any way of getting to the rad cap without taking the front fairing off? or do i have to take it off?

EDIT: I just took the radiator cap off and it is completely full, as it should be. coolant looks great in color. Also, the rad cap didn't give me any reason to believe it is faulty. I took another good look around the heads/block and have found nothing suspicious. I looked at the oil through the glass and looked down the fill plug. Oil was changed 300 miles ago, and it still looks very clean/good.
 

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Discussion Starter #11
guys, could it be that if the coolant is new - it looks really clean - that the guy i bought it from didnt burp it right? I know how to burp it, but i'm just wondering that wouldnt the bike have been running hot right away if there is air in the system, like when i got it last week, and not start now all of a sudden?
 

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I have a couple ideas after reading this thread. My hunch is the coolant, rad cap, thermoswitch & fans, and maybe waterpump.
Make sure the cap is indeed good.
Do the 929's have an inspection hose for the water pump seal? Anyway, I'd inspect the waterpump too.
If there's any doubt about the history of the coolant, as important as it is, change it!
After you know the radiator is properly full of new coolant, empty the overflow bottle, and put the cap back on. Then burp the system. Let the bike cool completely: the radiator should be completely full, then check the overflow bottle. Add coolant to the level marks on the bottle.
When your bike is running, the overflow bottle should be less full, when the engine cold, more full. When you said it was full because it was hot, that's not how it should be. Air in the system could swell and push coolant to the overflow bottle and fill it up like you described.

I've tried Prestone, Dex Cool, and Engine Ice. All are free of silicates-that's important.
The Engine ice works best by an honest 5F degrees or so cooler than the others.

I'd inspect the thermoswitch for good contact, and the fan for overall condition. Shouldn't be any drag when you spin it by hand. Verify it's kicking on and off after your done burping.

I haven't been around bikes as long as some of the guys around here, but I haven't heard of thermoswitches failing. I'm sure they do, but I just haven't heard of it. I don't know how to test it, so I guess I'd replace it if you can isolate the problem to the fan Not kicking in at the right temp. 219-220

Keep a close eye on your engine oil or if your coolant turns a funny color since you got so hot the other day. I'd change that oil. Got pretty hot...
 

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I believe you have to get a cap pressure tested. U can't tell by looking at it or just get a new one. They're inexpensive.
is there any way of getting to the rad cap without taking the front fairing off? or do i have to take it off?

EDIT: I just took the radiator cap off and it is completely full, as it should be. coolant looks great in color. Also, the rad cap didn't give me any reason to believe it is faulty. I took another good look around the heads/block and have found nothing suspicious. I looked at the oil through the glass and looked down the fill plug. Oil was changed 300 miles ago, and it still looks very clean/good.
 

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alright, so as the title says, my coolant fans on my '01 929rr aren't turning on until 232-234 degrees. before today, everything was fine, the fan would kick on rigth around 220. i noticed this problem today, where on my ride, i noticed it went up to 252+. I pulled over immediately, let it cool down, and then on my return ride home, which included being stopped in traffic for 5 or so minutes, the bike didnt over heat, only the temp gauge went up until 234 or so utnil the fans kicked in and cooled it back down.

yesterday i fixed my problem of a bad ground, causing my turn signals and headlights not to work. that problem is good to go, but now this is happening. is it just coincidence, or is there something related? Again, the fan IS working, just no until 234...

Also, this oil is dripping, around 2-3 drops from the bottom of the bike, here's a pic.

I dont think the coolant itself is leaking actually
If the fan is coming on late then the problem must be with the fan switch. I can't see any other cause of this. The obvious alternative is that your temp gauge is not reading accurately.
Remove the switch and test it in water on the stove.
 

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Discussion Starter #15 (Edited)
If the fan is coming on late then the problem must be with the fan switch. I can't see any other cause of this. The obvious alternative is that your temp gauge is not reading accurately.
Remove the switch and test it in water on the stove.
wow guys, thanks for all of the replies! Bladeracer, I'll probably go ahead and replace the fan switch, just like sky91 and you both suggested. I don't think i'll be able to do it myself due to a lack of supplies, so I'll take it to a shop. shouldn't be more than $100 for the job should it?
 

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You'll just need to unplug the electrical connector, unscrew the old sensor, and put in the new one (don't forget the teflon tape!!). Chances are you'll lose a bit of coolant so that'll need to be topped up as well. Grab a copy of the service manual - it gives a walkthrough in there. If you've got the toolkit that came with the bike, you have more than enough for the job :)
 

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Discussion Starter #17 (Edited)
there was a good 6-10 oz of excess coolant in the reservoir tank on a cold engine which i siphoned out just now. Wonder if that could have anything to do with the problem
 

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Discussion Starter #18 (Edited)
You'll just need to unplug the electrical connector, unscrew the old sensor, and put in the new one (don't forget the teflon tape!!). Chances are you'll lose a bit of coolant so that'll need to be topped up as well. Grab a copy of the service manual - it gives a walkthrough in there. If you've got the toolkit that came with the bike, you have more than enough for the job :)
Sorry for asking noob questions The part that I'm replacing (part #20 switch/thermostat), In the service manual it talks about thermostat removal from the thermostat housing, is that what I'd be doing? I've just heard some guys refer to it as a switch, others a "sensor", and also a thermostat, so that's thrown me off a bit
 

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Discussion Starter #20
No - it's not the thermostat you'll be removing. That's to the rear of the engine and slows the flow of coolant when the engine's cold. It's the switch that plugs into the front of the rad you need to replace.

The thermostat it part 2 on this page:

Ronayers.com Microfiche Honda>Motorcycle>2001>CBR900RR>THERMOSTAT
ah okay gotchya. i appreciate your's and everyone's help! are there any replacement parts for part #20 so that I could pick up at a store so i dont have to wait to get it shipped? This bike is my only mode of transportation at the moment lol
 
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