Overheating - Please read, this is not another fan switch and blade swap question.

Discussion in 'Mechanics Garage' started by blbvtec, Oct 11, 2012.

  1. blbvtec

    blbvtec New Member

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    2004 VFR800
    4,000 miles

    I purchased the bike with 1,400 miles. The previous owner had one receipt for an overheating problem. Shop pressure tested system, topped off fluids and stated bike is running with paramaters.

    Currently bike is filled with 50/50 mixture. Getting 1 gal in it including the reservoir to top line. I have drained and filled twice recently.

    When filling the system i notice a lot of small bubbles coming up the hose towards the rad cap along with the coolant. They start relatively big, what you would expect when burping the system. By the time the bike is up around 200 they are small, looks like simmering water.

    At idle bike warms to about 190 and then cools down to around 160. Then warms back up to 220 and the fan cycle begins. Cools to 200 and then fan switches off. It will oscillate between 200 and 220 from then on. I have watched it cycle as many as 5 times consecutively with no issues.

    the idle operation seems spot on to me. The problems arise when i start to ride the bike. If i start riding the bike cold, and keep in below about 190 i will never have an overheating issue for that riding session. As soon as i let the bike begin to cycle the fan on an off bubbles begin to come through the radiator overflow hose and in to the reservoir. At 1st its just air, the longer it goes on more and more fluid makes it way over to the reservoir. When i turn the bike off air rushes into the coolant reservoir for a few seconds. There is no coolant being drawn back into the engine when it cools down. The fan also stops working or is very sporadic. It starts turning on and off at higher temps if it runs at all.

    If left to go through several rides the left side radiator pretty much goes cold, right side radiator becomes extremely hot.

    I have tried 3 different radiator caps. The one it came with (stock Honda), a known working cap from a CB (same as the one it came with), and an AutoZone brand cross referenced to Stant part #11233. No change.

    Removed thermostat and tested in hot water (Thermapen used to monitor water temp) 189 starting to open, 205 fully open to 8mm. Dash reading on the bike is in line with these results.

    Removed water pump just for a visual inspection, i see nothing wrong with it. Looks brand new as it should.

    Tested for combustion leak using a Lisle cumbustion leak detector. Negative results.
    Lisle 75500 - Lisle Engine-Related - Overview - SummitRacing.com

    Any insight would be greatly appreciated. I am just about stumped on this one, i have never had a cooling system problem this stubborn.

    Thanks,
    Branden
     
  2. SinNH

    SinNH New Member

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    First thing I would do is flush the system, 4000 miles the bike sat a ton. Seems like your t-stat is working, for a gen five mine opens at about 175, and my 98 fan works at the same temps as yours. Blockage I'd guess.
     
  3. karazy

    karazy New Member

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    I remember this being a problem with the older ST1100s. It turned out to be a crack in the over flow tube. It allowed the fluid to to reservoir, but could not suck it back out.

    :crazy:
     
  4. squirrelman

    squirrelman Member

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    Just about what i was thinking. Once you get the overflow coolant flowing BACK into the system you problems should be solved. Look for a kinked line, crack in line, loose connection in line from rad to overflow tank or plugged air vent from tank to atmosphere.
     
  5. blbvtec

    blbvtec New Member

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    I've ruled overflow issues out. Coolant is boiling inside the engine which is causing excess coolant to flow to the reservoir. It is not just your normal heat expansion and lack of contraction. There are no leaks between the rad and reservoir.

     
  6. Metallican525

    Metallican525 New Member

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    If coolant is boiling inside the engine you have a pressure issue. Coolant should not boil if you have proper pressure, either you have had multiple bad caps, an air bubble you can't get out, or maybe a hose is swelling enough that it won't allow the system to build proper pressure. While flushing the coolant is allways a great idea, I don't think it will take care of this, even plain water alone should not boil if kept under proper pressure within the cooling system.
     
  7. blbvtec

    blbvtec New Member

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    I agree. Every inch of rubber has been checked.

    If pressure is the issue why doesn't it boil when idling in the garage? Temp rises to 220 with no issue.

    The system is holding pressure, at least in the garage.

     
  8. Big_Jim59

    Big_Jim59 Member

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    You see no sign of coolant in either the oil or the exhaust?

    This is really strange but I am leaning toward a blowing head gasket. Not blown but leaking under pressure of combustion into a water galley. This could be where your 'boiling" is coming from and why it only happens at speed and after the engine is really hot. This would be really hard to find under a pressure test because the leak won't be open while the engine is cold.
     
  9. rangemaster

    rangemaster New Member

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    To back up what Big Jim said, does the coolant smell like exhaust when when it does it? Dead giveaway of a bad head gasket.
     
  10. blbvtec

    blbvtec New Member

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    No contamination in the oil.

    A temp related leak in the head gasket is why i purchased the combustion leak detector. I did allow the bike to run to up to temp and blow a considerable amount of air in the the reservoir to ensure that i had combustion gas in the system in earnest (if that was the problem). I tested the air/gas coming from the rad cap and i also hooked it up to the reservoir. There was no change in fluid color in the tester. When i was done testing the bike, blowing on the same fluid turned it yellow instantly. I am confident it is not a leak from the combustion chamber.

    Keep the comments coming, somebody has to have experienced this before.

    Thanks
    Branden
     
  11. karazy

    karazy New Member

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    Just trying to help

    I don't own a 5th gen and my manual for it is on my computer that is in the shop. Doh!

    1. The fan working sporadically problem is due to the thermo switch being in the left rad, which you stated is cool.

    2. If the rt rad is hot and the left is cool, then the connector hose is not circulating it back, or the hose to the pump is not drawing from the left.

    Does the overflow res level remain constant, or does it increase after every ride?

    This problem is 8-9 years old, so may not get solved overnight, but it will be solved. Be patient. It usually takes us a while to draw all the info out of you, until the fix becomes obvious. One of the pitfalls of internet troubleshooting.

    :crazy:
     
  12. blbvtec

    blbvtec New Member

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    The coolant level in the reserve tank increases with every ride.

    Can anyone tell me why an air bleed hose would be placed in this location? Maybe i am not understanding the function of it, but if air flows up this hose from the thermostat housing it is going to be pulled right back into the engine.

    IMG_0001.jpg
     
  13. karazy

    karazy New Member

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    Like a motorboat prop creates bubbles, even though it is totally submersed, the same happens in the pump. It needs a way to escape, to prevent an air lock.

    If your res level is increasing on each ride, you really should check the siphon hose. It is possible to be cracked and show no sign of leaking. If this continues, it will lower the level in the system, causing an overheating problem.

    :crazy:
     
  14. blbvtec

    blbvtec New Member

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    I can buy that, but why does it terminate in the front of the radiator. The flow of the coolant would prevent that air from ever leaving the system. It certainly couldnt get up to the cap with the coolant flowing down and back towards the motor where it is mounted on the rad.
     
  15. karazy

    karazy New Member

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    My physics is a little rusty, but I'm sure that there is some kind of principle in affect there somewhere.

    Afterall, it seems to be working on everyone elses bike.

    :crazy:
     
  16. squirrelman

    squirrelman Member

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    You've done a great job trouble shooting and covered all the bases, but dija try changing the thermostat ??
     
  17. blbvtec

    blbvtec New Member

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    No, but I did pull it out and test it. 1mm at 190 and 8 mm at 205
     
  18. blbvtec

    blbvtec New Member

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    Wonder if it contributes to the issue people have getting the air out after refilling. I'm riding it around now with a set of hemostats clamped on that little sucker. No dice though.


     
  19. Big_Jim59

    Big_Jim59 Member

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    My old boss used to say, "when you have tried all the normal fixes, you have to start looking at every shitty thing it could be."

    This phrase jumps out at me "If left to go through several rides the left side radiator pretty much goes cold, right side radiator becomes extremely hot."

    This is a long shot but have you pulled the radiators and hoses and checked for obstructions? It seems unlikely but the cool radiator suggests an obstruction that might make cooling at speed problematic but cooling at idle fully functional.

    This is irrelevant but bubbles from a churning prop, if fully submerged, is from cavitation or the pulling of a bubble in a vacuum. It would not be from air unless you were getting air into the system which it seems like you are not.

    Story time: We had a customer's BMW that came in for service. We did the normal tune up and installed all the parts provided with the factory kit. (this is an air head) The customer picked up his bike and was back in less than 30 minutes. It was blowing oil out of ever pore. We looked and looked and looked some more. It turns out the rubber factory crankcase vent hose we installed had a bit of rubber flashing from the casting process stopping it up. We opened it up with a pocket knife and it was fine. I tell you this because things like this can happen even in the best of quality control. It sounds like your bike has had this problem for quite a while and the fix will probably be unusual. Stay with it and don't get discouraged. You will get it working.
     
  20. vfr2k2

    vfr2k2 New Member

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    From your description it seems you have covered a lot of bases but you didn't mention bleeding air from the cooling system or "Burping" the system. This is a basic requirement any time you remove the cap. Disregard if you have perfomed the following.
    With the radiator cap off and the coolant level almost up to the base of the filler neck start the engine and and let it run for a few minutes. Throttle up with a quick snap of the throttle a few times so that any trapped air in the system is bled out. Top up the radiator to the base of the filler neck with coolant. I usually give it another sanp here but watch that the coolant doesn't over flow. Install the radiator cap. Fill the overflow tank to the mark and give it a ride.
     
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