Problem with overheating!!

[Kenand1988]

Ok so, the bike is a 1991 Honda CBR600F2 and has 15,000 miles on it. Before buying the guy told me the only issue with it was it can overheat after being ridden awhile, he thinks its the water pump. Turns out the bike has sat since last june and he had to flush then replace the fuel in the tank, clean the bowls and get new sparkplugs. He finally got it to start so I then bought it. Well my first ride two things were apparent. 1. The bike overheats very easily after being ridden maybe only 30 minutes. 2. it is in desperate need of the carbs being cleaned and adjusted. The overheating was such an issue i pulled over twice to let it cool down before making it back home. I need help figuring out what it's deal is. I don't think I heard a fan come on, it certainly wasn't on after I turned it off when the temp was in the red. The bike sounds like its running on the choke and I was wondering if that could be from the thermostat not opening, which could also be causing the overheating. I want to check the inexpensive stuff first.

Thermostat
Water pump
Fan motor

But, this bike is completely new to me and I don't know how to do these things. I'll aslo be flushing the coolant at the same time. If anyone could help I would much appreciate it. My name is Kenan and I live off Roswell Rd. near the hooch. PM if you think you could give me a hand.

[MX Tuner]

If it were a faulty water pump, it would overheat a hell of a lot faster than 30 minutes. Same if the thermostat were stuck shut.

Is the cooling system full?

[Kenand1988]

The resevoir isnt filled to the top but it looks like theirs plenty in there. Anything else?

[Over TWO Customs]

Air pocket in the coolant system, insufficient water/coolant mix. Water boils at 212, coolant allows the fluid to boil at a higher temp. Your reservoir is there to fill the radiator if its low and accept the excess when it boils over. If the fan doesnt come on your bike will overheat in most every case.

I will agree with the above post in that the water pump not functioning will cause immediate overheat as well as the thermostat. Most water pumps are gear driven internally so there isnt much to "stop working" unless something is broken.

Flush the coolant system and check wiring on the fan. Most fan wiring is a basic ground to power setup. When the sensor is tripped to turn on the fan it actually grounds the fan to complete the circuit. Unplug the fan and place a jumper in the fan plug. If it comes on then great, if not then its dead.

[MX Tuner]

In weather this cool, with everything working normally, the fan(s) may never come on unless the bike is sitting still idling. Then it'll eventually cycle on and off. If the thermostat were stuck in a position that restrics coolant flow, that can make it overheat slowly while riding. Even if it had straight water, straight coolant or any mixture between, that wouldn't make it overheat. The only coolant related issue you might have is if you switched from normal ethylene glycol coolant to a propylene glycol coolant (such as Engine Ice) without thoroughly flushing the old coolant. The two can create a gel if mixed.

One other possibility is if the radiator is externally restricted preventing airflow through the radiator. Excessive dead bug guts, dirt, sand, leaves, etc can cut down airflow through the fins to the point of causing a slow overheating like you're experiencing. Carefully washing it in both directions repeatedly can wash the trash out of the external fins. This can also easily be checked with an infrered temp gun. Check the coolant inlet and outlet temps and make sure you're getting more than a 15-20 degree difference in the two. You should be getting closer to 40-50 degree difference between the two. That will also show up if the radiator is restricted internally.

[Kenand1988]

I tested the fan by taking the wire and grounding it to the frame and sure enough the fan came on. As I said I just bought this bike so I have no idea what coolant is in it or at what ratio the last owner used. What I'm thinking is although 15,000 miles on a 1991 bike is great mileage the problem was that this bike sat for long intervals. I don't think the previous owner ever flushed the system or really did anything to it. I'm thinking all that sitting has caused a clog somewhere in the cooling system. I'm going to flush it and replace with a coolant tuesday. I need some suggestions on what coolant to run, what to flush the system with and anything else a novice like myself should know.

Thank you all for your inputs.

I also want to note that the bike is very hard to get started when cold. When the choke is on full or half the bike wont start. The way I got it started today was with the idle screw turning it clockwise. I'm not sure what it did but after repeated attempts the bike finally did start. I let it sit for approximately 10-15 minutes after the oil change I did on it today and the temp was fine.

[NiceGuysFinishLast]

Turning the idle screw in raised the idle. Could this all be a problem with the carbs being severely clogged? That would create a lean condition, causing extra heat, overheating. Having to raise the idle to get it to run would be consistent, I think? Just a thought.

[Kenand1988]

Turning the idle screw in raised the idle. Could this all be a problem with the carbs being severely clogged? That would create a lean condition, causing extra heat, overheating. Having to raise the idle to get it to run would be consistent, I think? Just a thought.

Sounds plausible. Although, after the bike gets running i will adjust the idle so that its idling at around 1,000 to 900 rpms. The bike still sounds like its running off the choke though like its muffled.

[Sanchez]

I believe it's possible for the water pump blades to become corroded. If that's the case and they're rotting away, then your pump would still work, just not very well. I can't speak for your bike, but that happened to a Jeep I owned.

Or perhaps the cooling system is clogged up. Or there could be air in the system like someone else mentioned. At 19 years old, it's probably long overdue for a coolant flush anyway.

Since you've verified the fan works, but you know it isn't activating when the bike is hot, then perhaps you need to replace the temp sensor. You can test the sensor by immersing it in boiling water.

[TLR67]

Are you bleeding the Pump?

[forlorn]

I would also check the cooling fan switch.. Also pull the carbs and clean them, it will definitally run a lot nicer after that.

[Gmoney]

Water boils at 212, coolant allows the fluid to boil at a higher temp.

thats out int he open not in a closed system under pressure...

[Kenand1988]

I'm going to run a lot of trial and error tests and see where I get by the end of them.

Clean carbs

Flush system

Inspect Pump

Inspect Radiator

Immerse sensor in boiling water

Anyother things I'm forgetting

Oh and what coolant should I use and what should I use to flush the system?

[TLR67]

Again have you bled the waterpump?

[Kenand1988]

No, wouldnt I have to flush the system for me to bleed it?


If not how do I do it? Just loosen the bolts and let it bleed?

[TLR67]

You should have a bolt at the top of it.. Remove it.. then fill your rad.. When it starts pissing put the bolt in and fill the rad up.. Leave the cap off.. fire it up.. run it.. squeeze the hoses and when it gets to the top put the cap on.. Fill the overflow to the appropriate level and that will do it. If you dont bleed the pump there will be a air bubble in there and cause your bike to run hot quick...

[TLR67]

You should have a bolt at the top of it.. Remove it.. then fill your rad.. When it starts pissing put the bolt in and fill the rad up.. Leave the cap off.. fire it up.. run it.. squeeze the hoses and when it gets to the top put the cap on.. Fill the overflow to the appropriate level and that will do it. If you dont bleed the pump there will be a air bubble in there and cause your bike to run hot quick...

Its probally this bolt circled in red on riders left... http://img.photobucket.com/albums/v189/TLR67/cbr.jpg

[Seca]

Also make sure it is on its side stand and not a race stand. You do not want the bike to be straight up and down when bleeding the system. That can cause an air bubble to get stuck in the system also.

[Kenand1988]

Well a new problem has arose, probably from my doing. I decided to wire the negative wire from the fan straight to the negative terminal on the battery to see if having the fan on would keep it from overheating. I never got to see if the fan would help. I left my home and under some moderate acceleration I tried switching from first to second and nothing happened. Now the bike wont go into second and has a very hard time going back and forth between 1st and neutral and back.

I rode the bike just the previous day for around an hour stopping to let it cool down and everything worked fine with the transmission. Not a single odd thing happened.

My only guess to what the problem could be is I changed the oil yesterday and instead of buying the $10 a quart honda stuff I just went to autozone and put in an atv/motorcycle 10w 40 oil. I had used this oil in my 1995 Yamaha YZF600 and nothing bad happened with the engine or gearbox. Changing the oil went well and I put in the reccomended 3 qts. The bike sat and got cold before I started it after the change, when I did it rattled and knocked for about 30 seconds. Definitely was coming from the enging and the oil light stayed on. After that 30 seconds the bike normalled out the light went off and everything seemed fine.

What could this gearbox trouble be from? The clutch still engages.

[Seca]

Hate to say it but it sounds like you bought a bike with more than overheating issues that the previous owner didnt tell you about.

[MX Tuner]

Not buying the $10 a quart Honda oil didn't cause your shifting issue. Either something went wrong with the oil change or it had issues previously.

[Gmoney]

yeah its not the oil u used.....

[Kenand1988]

Ok so its not the oil. I did the oil change just like I've done many times before. Run for 5-10 minutes till warm, take out dip stick take out drain bolt, let drain, take off oil filter, insert new oil filter, replace drain bolt, fill in oil as reccomended, reinsert dip stick. Crank and let run. Also everything was cleaned before put back. I don't think it was the oil change. I'm completely open to the fact that it could be the gearbox, but what could be wrong with. It shifted fine just a day before in all gears.

[MotoMike]

I've always used the Honda pre mix coolant in the blue bottles when doing coolant changes on my 46k mile F2. After having some issues with temps rising in traffic, I added some Water Wetter and that problem went away. The temp gauge will climb to about 3/4 or so on the scale before the fan kicks in. These bikes are known for having some cam chain tensioner rattle sometimes at startup which mine does occasionally but in my bike's case it clears quickly and the oil light doesn't stay on any unusual time.

[Kenand1988]

Never have i loved being wrong so much. When I changed the oil I also adjust the angle of the shifter, by doing that I didn't ive that piece of metal attached to the rod on the engine enough space to make a full travel. It was hitting the water pump! That's all, God I feel retarded, this is way better than having to pay $500 to get it fix or take the loss. Haha I guess I'm back to the original problem now. I'll update you guys on that as I get things done.

[ga_skyline_rydr]

Kenan your problem almost sounds like a sticky or hung up thermostat. I say flush the whole system and install a new thermostat. Have you checked the fuses that go to the fan? My yzf had the same problems you are describing and this is what I did to correct it.

[TLR67]

I guarantee the pump just needs the air out of it.... Takes 2 Minutes to do...

[Gmoney]

yeah - i don't buy the thermostat and the crazy one about not having enough coolant mixed with water or whatever - burp the system.

[Kenand1988]

The thermostat was broken and there wasnt nearly enough coolant in it. Problem solved. Thanks for all the help guys!

[wallypiper]

Occam's razor wins again.

[Back Marker]

i'm late into this discussion... yah, the t-stat would of been my first recommendation. they are cheap to replace. while you are at it, get a new radiator cap with oem specs.

to test the t-stat, from a cold engine, remove the radiator cap and start the engine. let it get up to temperature and watch for coolant to start flowing. if it flows when engine is hot, then t-stat is working. if no flow, then t-stat is bad (does not open at required temperature).

use normal coolant with 50/50 water mix.

next problem i noticed you mentioned was that the cooling fan didn't help. if it doesn't turn on, then you need to check the fan switch. again, you can test this by letting the bike sit and run until the temp gauge starts to hit critical. fan should turn on. if it doesn't, replace the fan switch.

-a|ex

[DoctorDug]

before reading all the post . my first guess is your head gasket is shot. hope the heads not warped from too many over heats. id start there. the 92 gasket was thicker than the 96 but it gave ponies. both will work

[R3dneckboy2008]

jet the carb out to clean the car adjust your idle screw jus tweek it till its junnin around 1000 rpms but no lower then 500 and the overheating can be caused by the water pump not kickin on a bad thermostat or bad radiator fulid soo flush it and put brand new fluid in there and check the thermostat and make sure its not a bad connection or its jus gone.

[DoctorDug]

jet the carb out to clean the car adjust your idle screw jus tweek it till its junnin around 1000 rpms but no lower then 500 and the overheating can be caused by the water pump not kickin on a bad thermostat or bad radiator fulid soo flush it and put brand new fluid in there and check the thermostat and make sure its not a bad connection or its jus gone.

what?:eek:

[wallypiper]

Can you guys read? In post #29, the OP said "The thermostat was broken and there wasnt nearly enough coolant in it. Problem solved. Thanks for all the help guys! "
On the other hand, cleaning the car and adjusting the idle till its junnin around 1000 but no lower than 500 might be good advice. Not sure it helps with a motorcycle overheating. And the water pump definitely needs to kick on a bad thermostat. Bad radiator fulid is just scary. I hope it's not gone.

[Gmoney]

have you checked your tire pressure?

[wallypiper]

I checked mine last night but my battery was still nearly dead when I left for work this morning.

[MX Tuner]

Can you guys read? In post #29, the OP said "The thermostat was broken and there wasnt nearly enough coolant in it. Problem solved. Thanks for all the help guys! "
On the other hand, cleaning the car and adjusting the idle till its junnin around 1000 but no lower than 500 might be good advice. Not sure it helps with a motorcycle overheating. And the water pump definitely needs to kick on a bad thermostat. Bad radiator fulid is just scary. I hope it's not gone.



*whew*

I thought it was just me......

[Todd]

jet the carb out to clean the car adjust your idle screw jus tweek it till its junnin around 1000 rpms but no lower then 500 and the overheating can be caused by the water pump not kickin on a bad thermostat or bad radiator fulid soo flush it and put brand new fluid in there and check the thermostat and make sure its not a bad connection or its jus gone.
where in the **** did you go to school??????????? or did you?

[Kenand1988]

Yeahh I do appreciate all the posts but, like I said the overheating was due to low coolant. When I pulled the thermostat out it was stuck open. What could cause that? The bike overheating and the thermostat maxing out? We were able to push it back down and close it. We dumped it in some boiling water and it opened slightly. Not all the way. The water was well over the 82 degree celcius mark the thermostat was supposed to open at so, i've ordered a new one.

A friend and I are cleaning the carbs this weekend and I was wondering if anyone had a carb synchronizer I could borrow. I don't really want to go pay $40-$60 for one so if anyone had one on hand I could use that would be awesome.

Thanks in advance.

[wallypiper]

Thermostats go bad. Go to a parts store. They have dozens of them on the shelf. Pretty common, actually.

[MX Tuner]

So it *isn't* fixed yet? NEver force a thermostat to move. They are cheap enough and can cause an expensive repair if they malfunction.

Did you ever find where the coolant went? Why is it low?

There are certain things some people shouldn't try to do themselves. You may be at that point, especially with the carb/running issue.

[Kenand1988]

When we realigned the the pin in the thermostat it was already out of the bike. We never put it back it. No local store around me had this part they all were goin to have to order it and it would have costed ~$35 dollars. I went online and found it for $26. Unfortunately they didn't tell me it wasn't in stock so now they've got it back ordered and once again I just have to wait.

I don't know why the coolant was low to answer your question. We pressurized the system and looked and listen for any leaks after it had been running awhile. We found no leaks. Everything works as it should except for the thermostat.

You're right I am getting in over my head. I think someone up there knew that and yesterday I met a guy who has owned 4 cbr's including the F,F2, and 2 F3's. He knows every part of these bikes and is now willing to help me with whatever I need provided I supply the parts and liquids. Pretty cool huh? That is who is helping me on Saturday with the carbs. Now again does anyone have a carb synchronizer I could borrow for saturday?

[wallypiper]

I didn't really mean a local store would have the right stat for your bike, just that they have tons of them in stock because they fail all the time. On the other hand, some time spent comparing yours to ones they have might turn up a suitable substitute. If it fits and opens at the right temp, that's all you need.

[Back Marker]

test your radiator cap... maybe releasing under spec

-a|ex

[DoctorDug]

it could be a tail light issue.... once the head gsket goes alot of other problems will arive.once it overheated it may have stuck the thermostat.i think you going to have to put a haed gasket on it. and NOOOOOO i didnt read all the nonsense i saw, i just responded to the 1st post. so if i give an answer someone else did . the sun will still rise tommarrow

[DICKIEDOO]

Take the old thermostat and drop it in a pot of boiling water and see if it opens all the way. If it does it wasn't the stat. I don't run them in any of my bikes, but I don't commute on any of my bikes.

If your head gasket is blown you'll have chocolate milk oil and a rather crappy running machine. Check the oil.

My guess is you still have air in your system and it's causing it to overheat.

[DoctorDug]

Take the old thermostat and drop it in a pot of boiling water and see if it opens all the way. If it does it wasn't the stat. I don't run them in any of my bikes, but I don't commute on any of my bikes.

If your head gasket is blown you'll have chocolate milk oil and a rather crappy running machine. Check the oil.

My guess is you still have air in your system and it's causing it to overheat.
ive not had the oil get milky for a head gasket but i have for the freeze plugs. the best way i can check is looking at the plugs. one of them or more will be black and shinney at the tip. oily is different. look for irregular burn. thats one thing. you can pressure test the system.thats simple. but you thermo wont make it loose coolant. and check your exaust smell. its smell sweet. thats another sign. any other advise. take it in to a shop. and pay them what they want (within reason) most shops will only charge an hour to diagnose it.i see you getting alot of different info. not all bad. just confusing

[Seca]

need a new flux capacitor

[DoctorDug]

need a new flux capacitor

now that was after he hit my head on the toilet.

gees professor...what were you doing in the bathroom?

[wallypiper]

you thermo wont make it loose coolant

If it doesn't open, the coolant in the engine will boil and that will cause you to loose coolant.

[Kenand1988]

The old thermo did not open. I replaced it, flushed the system and refilled it with some regular ole 50/50 coolant. I noticed the a leak around the radiator overflow nipple and another small leak towar the bottom right hand corner of the radiator. The one on the bottom I couldn't visibly see a crack but coolant was gathering there and I couldn't see any other place it was coming from. I used some liquid steel and applied it around the the overflow nipple and put some automotive stop leak stuff into the radiator. Only half of the little bottle though. After that I cranked it and rode it throughout the day from 5:30pm to 10pm. The bike never overheated or smoked. Everything worked properly. This is most likely a temporary fix but, I dont believe I have a blown head gasket either. White smoke does not come out the tailpipe, the exhaust fumes do not smell sweet, the oil does not have a milky tinge. I haven't checked the sparkplugs.

[DoctorDug]

damn. that's the problem with older bikes. you can inheirant all their old problems. and can cost you more than its worth.but its sounds like you got it going.just bite down and let-er rip!!!lol.

[Kenand1988]

One things for sure I will enjoy it while its junnin right lol.

[MX Tuner]

Adding stop leak to a motorcycle cooling system can cause more problems than it fixes.

[DICKIEDOO]

Adding stop leak to a motorcycle cooling system can cause more problems than it fixes.

I was going to say it but this already such a train wreck I decided to stay out of it, but Mark is dead right. That was a mistake.