He mentioned in his first post that it looked like the cap had been replaced with a new one? They are cheap and might be worth replacing again with a definite new one. Later.
Cooling/Fan issues
- Thread starter Beau254
- Start date
golddrakul
Senior Member
+1 on the cap;it is possible to test but cheaper to replace. There is a post on the site listing standard automotive caps that will work, do a site search on "Stant".
Also, as PaulFun said; bleed the system again and again. I went through the exact same exercise with my brother-in-laws ZL900, everything worked but still overheated. Bled and bled and bled; finally got all the air out and it never overheated again. More to cooling than just the fan blowing...
Also, as PaulFun said; bleed the system again and again. I went through the exact same exercise with my brother-in-laws ZL900, everything worked but still overheated. Bled and bled and bled; finally got all the air out and it never overheated again. More to cooling than just the fan blowing...
What I meant by gurgling is spitting out the overflow hose. (Boiling over.) Supposedly the people I bought it from flushed the radiator. The cap doesn't seem to look that bad to me. The rubber isn't damaged. Guess I could try changing it anyway? They couldn't be too expensive, I don't guess?
One thing I forgot to mention. Every time the red warning light came on close to the house I would crack the throttle back to get home quick & the light would go off; then come back on when I idled again. Wonder if it's the water pump is going south?? I had a truck do that to me years ago. Would cool at higher rpm's but heat up @ idle. Turned out all the water pump fins were corroded down to almost nothing.
I think you might be onto something. Take a look at it. Another thing, you say your bike is very low mileage, it could be a victim of deposits all in your cooling system also that is keeping it from circulating. I've seen this in bikes that were not maintained properly during storage or setting up.
Scoobys_piece
Senior Member
With that said, I would try the ole vineger and water trick....you would be AMAZED at the gunk that it releases. And as mention....BA_LEED....and if you replace the cap, it's just one more thing you DON'T have to factor in your equation.
Well, it definitely wasn't the cap. Tried a new replacement & it still gets hot if I troll around town 20-30mph (with the fan running.) The old one looks to be the original because it's all Black & has some Ching-ping-king written on it, if u know what I mean? The rubber on it looked perfect though. Amazing for 25 yrs old.
paulfun
"King Of The 1/4mi (Internally Stock)"
DId you top off the coolant and then bleed the system before testing after the cap was installed?????
The system wont bleed properly with a bad cap.
So if you didnt bleed the system after changing the cap the system isnt bleed properly if the cap was bad.
The water pumps dont seem to go bad as in moving water threw the system and in most cases if its not dripping oil or water from the weep hole or letting water mix with the oil in the case they are usually working and pumping water properly.
After the cap and bleed if its still not working properly and gugleing You would be best to do a series of flushings the system out Many use vinigar, I use CLR a few times then convert to vinigar then flush everything out several times with clean water. Do yourself a favor and use engine ICE for coolant as it helps keep temps down and also prevents corrosion inside the engine and dosnt build up sludge like regular anti freeze does over time.
One more thing the system is designed to let off excess pressure into the overflow bottle and the bottle should not be overfilled or the excess has no place to go but out the overflow onto the left muffler. If your bottle is overfull remove the extra and try again. Many times even after a proper fill and bleed of the system it will purge the excess pressure once or twice after a ride then level off and if the bottle is full it could be mistaken as an overheat
golddrakul
Senior Member
Another possibility is the radiator itself is so sludged up it can't get enough flow; hasn't been a common problem on these bikes, I've seen it more often on cars. If everything else fails, take radiator off and have it checked at a regular radiator shop; they can pressure test, and most likely flow test, to see if it's working correctly. However, and as you probably gathered from this thread, radiator caps and bleeding have been the main issues.
Another thought, did someone put kink a hose somewhere? Visual inspection should be able to determine if any are bent/twisted to much.
Last resort, bring it to VMD; a number of the experts will be there...
Another thought, did someone put kink a hose somewhere? Visual inspection should be able to determine if any are bent/twisted to much.
Last resort, bring it to VMD; a number of the experts will be there...
I haven't flushed the coolant system yet, but the dealership did right before I bought it. Doesn't mean anything though. Guess i can do it again. I bleed the 2 bolts before changing the cap & no air/hissing. I'll try it again. The overflow level was on the middle line, & there was no mistaking it getting hot. The red warning light came on & after I killed it, it was boiling out overflow & radiator was popping. I ordered a new thermostat. When it comes in I'm going to flush/bleed system when I change it out. We'll see what happens then.
paulfun
"King Of The 1/4mi (Internally Stock)"
To properly Bleed the system you will need to have the tank off with a way of delivering fuel to the carbs in order to have it running.
You then need to top off the fluid and install the new radiator cap.
Start the bike, let it warm up to the point where the fan comes on by itself.
then open the lower bleeder (while Bike is running) first
Then open the bleeder to the rear of the thermostate housing and purge there.
You might not get a hole lot of air the first time and most of us repeat the bleeding process a few times to be sure as we have seen sometimes it takes a couple tries to get it right
golddrakul
Senior Member
Amen to that, the horror stories about dealerships and these older bikes are legion. At best it means you need to inspect very carefully to see if they had a clue, at worst you get to learn to do it yourself when you do it over...
And I totally agree with Paul, I have always ended up bleeding the system at least 3 and more often 5 times until it and I am happy.
helgi33
Senior Member
Are you sure that it is overheating ?
That red light can be false warning.. I had problem like that on my ZL1000 where the red light would go on and off but usually when it was cold so I figured right away it was false.. there are three sensors which can trigger the light.. the 120 degree sensor on Thermostat housing, the Oil Temperature sensor and the oil pressure sensor..
I dont remember off hand which are normally closed and whihc are open but any of the three could have a bad connection or chafed insulation reaching ground or plain faulty sensor...
Just a thought...
That red light can be false warning.. I had problem like that on my ZL1000 where the red light would go on and off but usually when it was cold so I figured right away it was false.. there are three sensors which can trigger the light.. the 120 degree sensor on Thermostat housing, the Oil Temperature sensor and the oil pressure sensor..
I dont remember off hand which are normally closed and whihc are open but any of the three could have a bad connection or chafed insulation reaching ground or plain faulty sensor...
Just a thought...
golddrakul
Senior Member
The fan switches are normally open, and the oil temp is normally closed...
Scoobys_piece
Senior Member
I don't want to say this, but blocked H2O passage? Try to retrace your steps, when did this initially rear it's ugly head. Maybe radiator is bad? I hope that you get this sorted out, HEAT IS THE NEMISIS for anything mechanical.
golddrakul
Senior Member
I can guarantee that if there is air in the system, the manual fan switch won't make a bit of difference [aren't you glad you didn't just throw money at it and buy new switches?
]. Have you checked the thermostat to see if it's working by putting it in a pan of boiling water? The can go bad, or even be bad from the box. At this point, you've tried all the easy fixes, so start with the basics and go through it methodically:
1) Pull the thermostat and validate it's working. Put the housing back together without the thermostat in it.
2) Pull the radiator and flush it yourself with a hose, while doing this check to make sure the dealer didn't pinch a hose while fooling with it. Best would be take it to a radiator shop and have them check the flow rate, but you should be able to tell pretty well with the hose.
3)Put the hose into the top radiator hose [it's still on the bike] and see what comes out the bottom when you run water through it [hence why you left the thermostat out in step 1].
4) If all this is working, pull the water pump and inspect. Are the bearings froze, are the impeller blades separated from the shaft, are the blades worn away?
5) Fix whatever you find [if anything], re-assemble and fill with something like Engine Ice.
6) Bleed, bleed, bleed.
7) Let run.
Bleed, bleed, bleed. [You get the idea].On the last 900 that I went through the overheat routine with, I'd let it run in the driveway until the fans kicked on [yes, I'd already verified the switches worked
], then shut it down, let it cool and bleed it again. Sometimes nothing would come out, sometimes a burp. Did this for an entire afternoon, and bike didn't overheat again the rest of the year. Patience and a methodological approach are pretty much required for working on bikes; reading how someone else solved the "same" problem and then replacing that part without doing some validation is an expensive way to troubleshoot. There can be many different issues with the same symptoms, and few things have a "one size fits all" fix.
Scoobys_piece
Senior Member
I can guarantee that if there is air in the system, the manual fan switch won't make a bit of difference [aren't you glad you didn't just throw money at it and buy new switches?
At this point, you've tried all the easy fixes, so start with the basics and go through it methodically:
1) Pull the thermostat and validate it's working. Put the housing back together without the thermostat in it.
2) Pull the radiator and flush it yourself with a hose, while doing this check to make sure the dealer didn't pinch a hose while fooling with it. Best would be take it to a radiator shop and have them check the flow rate, but you should be able to tell pretty well with the hose.
3)Put the hose into the top radiator hose [it's still on the bike] and see what comes out the bottom when you run water through it [hence why you left the thermostat out in step 1].
4) If all this is working, pull the water pump and inspect. Are the bearings froze, are the impeller blades separated from the shaft, are the blades worn away?
5) Fix whatever you find [if anything], re-assemble and fill with something like Engine Ice.
6) Bleed, bleed, bleed.
7) Let run.
On the last 900 that I went through the overheat routine with, I'd let it run in the driveway until the fans kicked on [yes, I'd already verified the switches worked
Patience and a methodological approach are pretty much required for working on bikes; reading how someone else solved the "same" problem and then replacing that part without doing some validation is an expensive way to troubleshoot. There can be many different issues with the same symptoms, and few things have a "one size fits all" fix.
