M109 Rider Forums banner

coolant boiling in the engine and draining out the overflow tank. mechanic is stumped

22K views 48 replies 25 participants last post by  lb1255 
#1 ·
im a motorcycle mechanic. i work alone so i have no techs next to me for advice. i have this 2008 M109R that keeps boiling the coolant out of the reserve tank. it fills up and comes out of the overflow tube. ive verified the fan temp switch is ok. the fan turns on at the designated temp. i removed the thermostat and put the housing back together and ran it with no thermostat at all. same problem. i ran some cooling system flush through the system for at least 6 hours of running time. then i cleaned it all out of the system. problem stayed the same. i removed the radiator and ran a water hose to it to verify that it had no blockages. it was ok. finns were all clean. i removed the waterpump to verify that it was ok. all parts of the pump looked fine. i put it all back together and the problem is still the same. each time, i bleed the air out of the cooling system according to the factory service manual. at this point i think i verified all components in the cooling system and they all checked out ok. maybe im not getting all the air out of the system and thats causing a vapor lock in the heads or something. i can literally hear the coolant boiling in the engine. heres what i do to bleed all the air out. i fill it with coolant, i rock the bike left to right over and over and keep adding coolant as i get air bubbles out. when i stop seeing bubbles, i leave the radiator cap off and run the engine to get more air out. instead of seeing bubbles come out, coolant just comes out of the radiator. so i think all the air is out. also i put a new radiator cap on to rule that part out. please give me any ideas to help me resolve this issue. thank you
 
See less See more
#2 · (Edited)
My guess is that it's a bad head gasket, and that your actually hearing exhaust percolating in the coolant.

EDIT: I knew there was a way to test this, had to find the info:

One method is to use a block tester, also known as a combustion leak tester, to determine if you have exhaust gases in your cooling system. A combustion test kit can be found at your local NAPA, auto parts store. The part number is 700-1006. The price for this part is less than $50.00.
 
#6 ·
My guess is that it's a bad head gasket, and that your actually hearing exhaust percolating in the coolant.
i didnt think of that. thats very possible. but if it was a bad head gasket, wouldnt the coolant get into the cylinder and cause the exhaust to blow white smoke? my thinking is that its a 2 way street, if exhaust can get into the coolant, it should be able to go the other way too. i have been wrong before tho. lol. obviously nothing else i tried has fixed it yet. thanks hyperpete
 
#4 ·
As per the Service Manual

AIR BLEEDING THE COOLING CIRCUIT
• Remove the fuel tank.
• Remove the right frame head cover.
• Add engine coolant up to the radiator inlet.
• Support the motorcycle upright.
• Slowly swing the motorcycle, right and left, to bleed the air
trapped in the cooling circuit.
• Add engine coolant up to the radiator inlet.
• Start up the engine and bleed air from the radiator inlet completely.
• Add engine coolant up to the radiator inlet.
• Repeat the above procedure until bleed no air from the radiator
inlet.
• Close the radiator cap securely.
• After warming up and cooling down the engine several times,
add the engine coolant up to the full level of the reservoir.
"
(Engine coolant capacity
Reservoir side: 250 ml (0.3/0.2 US/Imp qt)
Engine side: 2 450 ml (2.6/2.2 US/Imp qt)

You mention that you see coolant moving thru the radiator thus I would have to assume you do not have blockages and that yes your water pump is moving coolant....The next thing I would say is to double check all of your cooling system hoses to make sure you have them connected to the proper locations thus the coolant would be flowing in the proper directions etc.
 
#11 ·
As per the Service Manual

AIR BLEEDING THE COOLING CIRCUIT
• Remove the fuel tank.
• Remove the right frame head cover.
• Add engine coolant up to the radiator inlet.
• Support the motorcycle upright.
• Slowly swing the motorcycle, right and left, to bleed the air
trapped in the cooling circuit.
• Add engine coolant up to the radiator inlet.
• Start up the engine and bleed air from the radiator inlet completely.
• Add engine coolant up to the radiator inlet.
• Repeat the above procedure until bleed no air from the radiator
inlet.
• Close the radiator cap securely.
• After warming up and cooling down the engine several times,
add the engine coolant up to the full level of the reservoir.
"
(Engine coolant capacity
Reservoir side: 250 ml (0.3/0.2 US/Imp qt)
Engine side: 2 450 ml (2.6/2.2 US/Imp qt)

You mention that you see coolant moving thru the radiator thus I would have to assume you do not have blockages and that yes your water pump is moving coolant....The next thing I would say is to double check all of your cooling system hoses to make sure you have them connected to the proper locations thus the coolant would be flowing in the proper directions etc.
I've read this procedure before but I've yet to figure out how to start the engine with the fuel tank removed. :joke:
 
#7 ·
I refill coolant systems all the time and here's what I do and it works every time to get the air out.

Make sure the system is full to the cap. Make sure there is coolant in the overflow. Start engine and let idle for 10 minutes. Shut off and wait an hour. Check the overflow and refill if needed. Start engine and let idle for 10 minutes. Shut off and let cool 1 hour. Do that a 3rd time. Once cooled for the 3rd time, check the overflow tank again and then start the motor and let it idle for awhile to make sure that it's not going to puke anymore. Even till the fan comes on if it will (if it's too cool outside it might not run).

If I don't do a 3 times heat/cool, the system will boil over every time because there's still air in it.
 
#8 ·
If you use the probe on an exhaust gas analyser into the top of the expansion tank ( not in the coolant but above it) when the engine is running it will tell you if you have combustion gasses in the coolant.

see here for test you need to use leak detector






Using exhaust gas tester

 
#15 ·
ok, im still stumped. heres what ive done since the last post. i did a compression test. its fine. i did a cylinder leakdown test. no bubbles on radiator from a bad head gasket. i heated the bike up and let it cool about 7 times throughout the day. every time i let it cool i would tilt the bike from left to right about 20 times to allow any air bubbles to work their way to the fill spout. i could not get any bubbles out. it still continues to fill the overflow tank until it sprays out of the overflow tube. when i let the bike idle and warm up, the overflow tank rises a few inches as normal, but once it rises a little, when i give it some throttle, it rapidly fills the bottle to overflow. it will overflow without the boiling sound but if i let it get warmer it begins to boil inside the engine. ive never had an overheating issue i couldnt diagnose. this is a head scratcher for sure. i really appreciate all your help.
 
#16 · (Edited)
could have a crack (in the head or water jacket) that does not leak until it gets so hot it expands...

also when you had the water pump off did you make sure the propeller was affixed to the shaft solid I have seen them where the would start slipping on the shaft looked good but the engine would over heat when running. also did you put the thermostat in a pan and make sure it opened when it is suppose to? I do not know about our bikes but I have heard some cars will overheat without a thermostat
 
#20 ·
Hey like someone said you very easily have a crack that does not open up till it warm or hot I've seen this on alum. heads on cars and is very hard to find find you have removed all the obvious items unless there is some way you got the routing wrong but that's doubtful also when you did you leak down test did you do it as normal top dead as if crack is in the cylinder somewhere it will not show up as rings are holding preside away from the crack you know what I mean anyway that's all that comes to mind keep us up to date
 
#21 ·
i gotta give you total respect for coming on here and allowing some of our experts to assist you....i cant recall one single dealer coming on here to inquire about anything in the year ive been here and yet we continually hear horror stories of how the dealers screwing things up....i would take my bike to you in a heartbeat after seeing this post.....not everyone can know everyhting and clearly you are truly intereseted in solving your customers problem....kudos bro
 
#22 · (Edited)
But if you really have checked and confirmed everything you stated, I still think a blown head gasket. Take it to an automotive shop that has an engine analyzer with the emissions sniffer and check for HC (hydro carbons) coming out of the radiator. Not that it really makes a difference, but what year is the bike and did you take a PH level of the old coolant? If it was high and can damage things like sensors and gaskets. Have you let it run with it being a little low in the radiator with the cap off checked the flow of the coolant once the thermostat opened up?

How did you confirm all of the items you state are good?
Example: thermostate- did you pull it and put it into a beaker or pot with water with a thermometer and check to see when it opened? Or did you just compress it and thought it works, it is not stuck.


If you want to talk about it, Pm me your number and I can give you a call.
 
#23 ·
I don't see where this was mentioned, but have you checked the radiator cap? I'm not sure what pressure these hold, but if one on a car/truck goes bad and won't hold pressure it boils easily and vents into the overflow sooner. At the top end of the temp range where the fan kicks on water is very close to the normal boiling point.
 
#25 ·
I don't see where this was mentioned, but have you checked the radiator cap? I'm not sure what pressure these hold, but if one on a car/truck goes bad and won't hold pressure it boils easily and vents into the overflow sooner. At the top end of the temp range where the fan kicks on water is very close to the normal boiling point.
I posted the samething just abhove yours and then took it off, as it is the last thing stated in his original post. Not to say that it could not be bad out of the box. He should test it, but it is a simple process.
 
#26 ·
still havent figured it out but heres what im finding today. i had removed the water pump, raddiator and thermostat. i made a hose plug with an air blower in it to verify the lines were all clear. everything seemed to be clear. so i put everything back together. today i didnt let it warrm up at all. i started it up and cracked the throttle a few times. maybe 4 or 5. it immediately blew coolant into the overflow bottle to the point that it was full and leaking. the bike was only running for 15 seconds. so the system seems to be over pressurized. i even tried a different radiator from a diffferent bike on it just to see what happened. it had its own radiator fill spout on the radiator. when i ran it, the pressure inside was enough to blow past the radiator cap on the substitute radiator and the cap on the m109r. so its not overflowing due to heat. it seems to be pressure related. like its immediately building up too much pressure when i crack the throttle. not evenn full throttle. just a quick rev.
 
#27 ·
Then you are only left with one conclusion---either a blown head gasket or a crack in the head. That is the only thing that can produce that result.
 
#33 ·
ok, so i have been messing with this thing all day today again. trying to make sure that i bleed the system properly. the only thing that i noticed to share with you guys only helps to verify that air is getting in the system from somewhere. what i noticed was that after bleeding all the air out, i let the bike idle up to operating temp and the coolant will rise and fall in the reserve tank like its supposed to. when i crack the throttle, i can watch significant bubbles come into the reserve tank, then stop. then i crack it again and more big bubbles. it really seems like the cylinders are letting air in. hopefully napa has the testing stuff there tomorrow so i can do that test.
 
#36 ·
Any updates?
 
#37 ·
this will be my final update on this issue. im gonna go into everything i tried and my results. i removed the radiator and flushed it with a water hose to check for flow. it flowed cleanly through every opening on the radiator. it does not appear to be blocked. i checked the water pump for flow by removing the outlet hose from it and turning the motor over so i could watch it spray water all over my floor. it definitely pumps. the problem was there with the thermostat in and out. it made zero difference. i removed the water pump to visually inspect the condition. everything looked perfect. bearing was tight and smooth. i verified the fan temp switch and fan operation. i tried to look at the hoses to see if any were collapsing under pressure and i could not see anything happening. i did a compression test and it was good. i did a leakdown test to pressurize the cylinders and i got no bubbles in the coolant. i also bought the combustion leak tester from napa to see if combustion gasses were somehow leaking into the coolant. i had a hard time using it cuz if i run the bike with no radiator cap the coolant would run out of the radiator and contaminate the chemical in the tester. so what i did was when i would start to get bubbles in the overflow tank, i tested that. never turned colors so that indicates that the bubbles did not com from the cylinders. ive tried everything i know, then ive tried everything you guys recomended and still cant find tthe problem. unfortunately at this point ive exhausted all my efforts and have given up. unfortunately this issue is being sent to another mechanic to diagnose the problem. either i was doing something wrong over and over and over again, or i missed something somewhere.
 
#39 ·
Unknown to almost all, the owner is mobilemichael. This is his mechanic posting for him----or atleast that is what I was told when he called me.
 
#40 ·
All the post in this thread has been the mechanic that has been working on my bike. After about a week of troubleshooting I asked him to use my login and pass to post what is happening on this forum to see what members had to suggest. I really appreciate all his efforts and I know he is a good mechanic with the best intentions. I just got my bike back from him and is now parked in my garage and will be looking for another mechanic, because this problem is above my head for sure.

I really do appreciate all the feedback in the thread by all of you guys .... and thanks for the phone conversation futuR :bigthumbsup:
 
#43 ·
Sorry to hear you spent this much time, It had to be infuriating to deal with!
This almost has to be a head gasket /crack issue, only thing I wanted to add, using the block tester you could have Installed the radiator cap, and tested at the overflow bottle top, with the vent tube capped, exhaust gas almost certainly is pushing coolant out,
the next step is motor removal and tear down
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top