Cooling System and, maybe, Electrical Problem
 

hi,

i've run into a show-stopper rebuilding this bike.
it quickly overheats.

i've done the following:
1. replaced cooling fan motor switch because it was not coming on and fan motor runs when connector is grounded.
2. replaced thermostat because i figured it was toast and wasn't opening after sitting dry through five seasons in the garage.
3. replaced thermosensor.
4. replaced ECT sensor. the continuity between the ECT and ICM connector showed as it should.

i dumped the coolant yet again and swapped in a new ECT sensor yesterday. put the coolant back in a popped the throttle numerous times to get out the air and absolutely no change.

it takes about the right amount of coolant... about 4/5 gallon. if revved to 3000RPM the temp gauge gradually goes up past 3/4 hot in less than 10 minutes, more like 5 or 6, and it will overheat if i allow it to do so
.
the fan motor never does go on, which i don't understand. but even if i ground the fan motor connector and let the fan run continuously from a cold start, it will still overheat.
my buddy, who's pretty good with bikes, thinks there is air in the system somewhere. i squeezed the lower hose and no bubbles and the level comes up and i squeezed the hose to the water pump to try and make sure there's no air in there.

i'm out of ideas. maybe there's a blockage in the system? i get a bit of a clanking sound intermittently that's easier to hear on the right side that could be the water pump, maybe… or maybe it's piston-clap.. i replaced the pump cover after the bike was crashed because the end of one of the hose tubes had been cracked. there was absolutely no direct impact nor visible damage to the water pump.

the radiators do get hot. although the thermostat housing seems to get really hot, really fast... much faster than the radiators.

any advice from cooling system gurus would be greatly appreciated!

thanks,

--fred

Are you using an infared thermometer? How are you determining "overheating"? I wouldn't trust the gauge...I know mine runs at normal temps, but always reads pretty low. Pulling the sensor and cleaning any buildup on the sensor is actually on my list. Though you have replaced all the sensors, so that's likely not the issue. How are you bleeding the cooling system? I don't put a ton of stock in the manual's "snap the throttle procedure to bleed the system"...I'd loosen either the ECT sensor, or temp sensor, or potentially one of the thermostat housing bolts to see if you can get any additional air out. Also, after a crash I'd worry about the water pump impeller drive...you're sure it's turning the pump impeller as designed?

That's all I can think of at the moment.
-R

I'd start by using the worlds best tool for fixing air in coolant hoses... The handle of a screwdriver... ;) Just let the bike idle with the radiator cap of and bang on all the hoses with it for a minute or two... Then go throttle happy for a dozen or so times... And go back to banging the hoses another minute, and finish it with some more throttle... That gets the air out... BTW make sure you are a tad low in the filler neck before you start or it will splash out... Or just stuff a rag around the neck to catch the burps...

About the right amount is not good enough... Look at the specs, there is a number specified sans the catchtank... That amount is going in, exactly that or you have air trapped... And at that point you will have cooling problems...

The fan comes on at a pretty high temperature, I think about 2/3 of the scale to 3/4, certainly above the halfway point... That's normal, the VTR is a hotblooded beast...

Apart from that, I cant give much more help...

Oh... BTW doing the bleeding on a workstand kind of defeats the purpose... Use the sidestand or the filler neck isn't the highest point in the system...

i don't know for certain that the pump impeller is turning. i can drain the system and
pull the pump cover. i'll just reuse the rubber gasket. if it leaks i'll order a new one.
i'll give that a try after i loosen something on the thermo side to free any trapped air.
and i'll also try the "screwdriver" bleeding tool as Tweety describes

thnks!

--fred

i like it. i'll try it. my gargage will be a sweat lodge again for the next couple of days. donno if i can pound on a rubber hose with a screw-driver in there till Thursday.

i will drain the coolant again, too, and i'll pull the drain screw below the front cyl,
and measure what i put in with my good measuring cup.

thanks!! i appreciate all the advice. hopefully it's a big bubble and nothing more.

--fred

Ya know, I was just getting ready to post up with some cooling system problems. Lets see if any of this sounds the same.

My VTR sat in my garage for about two years while I was working out of town. Before leaving I replaced all fluids and drained the carbs. Once back and after a couple weeks of riding I had coolant weeping out the inspection port. So the mechanical seal had gone.

I removed the side cover and took it to the Honda dealer. Had them replace the mechanical seal, oil seal and bearing. Didn't replace the impeller shaft. I put it all back together but being the smart engineer that I am I left the bike on the track stand (not the side stand) when filling it up again. Get it all running and as you can imagine, few coolant related problems. Obviously air in the system.

Back to the garage, on side stand this time. Drain some coolant out. Refill. Run engine. shake vigorously. Run engine. Do a few rides. Sometime it gets really hot and you can hear it gurgling with additional spitting out the overflow tank. Sometimes it does fine.

I'm thinking that I either still have air in the line or the two years of sitting has toasted the thermostat resulting in sticking? Bikes been running kind of rough so I was going to take it into the shop for a full tune up. Figure I'll have them replace the thermostat while they are at it just to be safe.

Do I sound like I'm on the right track?

well, if all else fails, i'm gonna pull the cover off of my pump and make sure that the impeller is wizzing. i don't remember running into air problems when i changed the coolant way back when, before... the bike ended up wedged underneath the front end of a car. my old thermostat was probably still within spec. the advice i got above and from a knowledgable fried is to go all out to make sure all the air is pushed out of the system. that's what i will do. see "handle of screwdriver" above. hope you fix your problem.

--fred

i went at it again tonight. i pulled out my longest screwdriver, my prize 7" Kline #2 phillips, and wacked the crap out of the hoses (Tweety's advice) while idling and then popped the throttle numerous times and then lathered, rinsed and repeated. i did switch to a rubber mallet finally because it packed more punch and i was getting coolant all over my favorite screwdriver. when things heated up and coolant began spilling out of the top, i shloshed on the radiator cap and took a break to let things cool down. after a cigar, a couple of beers and two, well maybe three, glasses of tequila i went back to the garage, who's electrical feed shorted out sometime last night, by the way. long extension chord from the kitchen to halogen lamps did give me plenty of light, though.

with everything sealed, i started up the motor again and watched the temp gauge top out. i decided not to trust it, though (wyldryce's advice), and idled and revved the motor even after the gauge indicated that i was running way too hot. the fan motor *finally* came on and blew out a plum of e-glycolwater steam that had spilled all over the right radiator during the bleeding (i think this is what happened during the earlier test-ride when i was convinced that the bike was overheating). steam was blowing out and up everywhere. i ignored this and let the motor keep running. the motor sounded fine, more or less, and coolant was shooting out the overflow hose down low into an oil pan i'd strategically placed under the bike. after installing the radiator cap earlier, i'd filled the reserve tank more than spec in order to avoid any possibility of it getting sucked dry as the system cooled.

i now believe that my temp gauge is toast and that the cooling system is actually ok. i sure hope that's the case, 'cause i'm gonna get plates, put new rubber (i picked the Michelin Pilot Road 2's over the Pirelli Demon's mainly because i've got Michelin's on my other bike and like them a lot) on the wheels and head up to Wisconsin next weekend. i still need to paint a VTR logo on the the plastic epoxied, painted body work. i'm excited!

thanks, Tweety and wyldryce for your very generous advice!

--fred

Do you have an IR temp gauge that you can use to check the temp of your radiators? I agree that your temp sensor may be incorrect but I would want to confirm before I had to call someone to come get me.

nope. don't have an IR temp gauge. i've never run into cooling issues before. i agree with you that it'd be useful to know For Sure that the actual temperature is OK. i'll see if i can borrow one from somebody.

--fred

Why not verify the temp sensor? Read the service manual and there is a step by step...

the original was probably ok, but i replaced that temperature sensor last week.

my coolant is 50/50.

this evening i topped off the fluid and filled the empty reserve tank to just under the max level mark and put the radiator cap on. i figured that after whapping the sh*t out of the hoses last night that all the air should have been driven out of the bottom of the system. i started the motor and idled and revved to 3K rpm max on and off. mostly the bike was idling as the temp gauge gradually climbed to red and topped out.

in the garage, mostly at idle with an IR temp sensor i ended up with the following readings:
top and bottom of thermostat housing went up and up and up to around 270degF. i believe that is Too Damn Hot! thermostat opens fully at 194degF according to the service manual. no explicit reference to maximum operating temperature.
top hose entering left radiator from thermostat was at around 220degF.
top hose entering right radiator was around 190degF.
right radiator by fan switch temp went up to about 200degF.
reserve tank temperature went all the way up to about 238degF.

over about half an hour with the motor running, the the reserve tank gradually filled up completely and boiled and dumped well over 8oz out the bottom overflow hose.

i guess i have either air or an improperly working impeller. air seems unlikely since i beat the crap out of the hoses last night.

any advice on how i should proceed would be greatly appreciated. should drain the system and remove the pump cover and determine if the impeller is working properly?

thanks,

--fred

If you leave the cap off the radiator and blip the throttle do you see the coolant moving? Or if you fill it all the way to the top does the level go down when to give it some throttle?

It is starting to sound like the impeller isn't spinning.

thermostat stuck in the closed position?

that'll do it for sure...

the level doesn't go down when i blip the throttle and the coolant does not appear to move, aside from the ripples due to the motor vibration. what does happen if i leave the cap off is that when the temp gauge begins to climb from cold, the coolant already begins rising and spilling out of the cap orifice. this may be a normal thing to happen at the start of warm up, i donno.

i think that i will remove the impeller cover today and examine it's motion or lack of motion during short motor runs.

thanks,

--fred

hi. i replaced the thermostat about two weeks ago.

Then I would say the impeller isn't spinning.

i'll find out pretty soon. will post my observations.

--fred

I haven't had coolant problems before but here are some thoughts;

If your radiators are getting up to temp I would expect your impeller is working and your thermostat. As a side note I have had a few people tell me that thermostats aren't built that well and thus your supposed to test them before putting them in. I see this in a lot of manufacturing manuals.

I am not sure from the info above but your fan seems to be turning on after your gauge reads red. Considering you measured such high temperatures I would start trusting that gauge of yours. The fan may not be turning on soon enough. If the fan get's it's "turn on signal" from the radiator temperature then this may indicate that the radiator isn't equalizing temperature with the engine; this indicates that the water might not be circulating.

At the length of time it takes your bike to heat up it probably isn't the engine generating more heat than designed, so I wouldn't worry about the engine running wrong (or at least not right now).

This leaves one thing that I can think of: nasty crud in the water pipes. I don't think I heard you mentioning a coolant flush, just a replace. If you flush the coolant you have used a corrosive chemical to clean out the lines. Think of draino for your bike.

I agree with 8541hawk some though; maybe the impeller is just spinning slow or inefficiently. This would give you noticeable heat in the radiators but wouldn't transport enough heat to the radiators. I never dug into how it's driven (the water pump) on this bike so this may make no sense.

If your concerned about the radiators being clogged you could try connecting the pipes to a second set of radiators or rig up a single radiator just for a test; lots of effort for a simple test though. I don't know if there's an easy way to test radiators off the bike for flow rate...

Good luck!

i have not flushed the system. the right radiator was picked up on Ebay a few years ago and looks ok cosmetically, but i never did test. it is highly unlikely that the radiator is clogged, though. everything about it looks clean.

note that the coolant that blew out the overflow hose under the bike has small shiny particles in it that appear to be little pieces of radiator aluminum...
it's a little late in the day for me to find an open auto parts store to pick up some flush fluid, but i'll call some places and try that as well.

i'm not jumping for joy to pull of the pump housing cover if i can avoid it. i don't have a spare rubber gasket laying around in case it begins to leak. and i fully expect to see the impeller spinning, but have no idea how to ascertain if it is spinning "normally".

i will probably end up pulling the right radiator and figure out how to test it if the impeller appears to be spinning properly.

thanks,

--fred

mystery solved.
 

i started the bike with the water pump cover off and the impeller doesn't even pretend to turn. it just sits there perfectly still, mocking me. it was just sitting there all along hiding underneath the brand new cover i gave it and refusing to turn. and here i am replacing every g*dd*mn sensor in the g*dd*mn cooling system. that impeller made a complete fool out of me. but now i'm gonna replace it's sorry ass.
let me thing... do i have the tools to fix this... mmmm.... no.
there's section 6-11 on replacing the mechanical seal. mine isn't leaking.
i wonder what's broken in there that needs fixing? someone out there knows, i bet.

--fred

you called it.

thanks you, everybody, for your help diagnosing this!

So the question then is.. Is the impeller not fixed to the shaft? Or is the water pump shaft not being driven?

If you do replace the impeller (and bearing & seal).. Be very observant of the depth setting (see service manual) If it is set wrong in the side cover the impeller will rub against the side cover or pump cover.

With my current water pump issues I'm learning more than I ever wanted to about the damn thing.
First see if you can turn the impeller by hand. It should not turn, but I'm guessing it will. The shaft goes through the case via two seals water and oil. Once inside the case the plines on the shaft enter a gear that is driven via a chain from the crank.

In order for the impeller not to spin when the engine is running, either the chain has jumped off or broke or perhaps the impeller itself has separated from the shaft.

Not sure what has caused your problem, but if you need a new water pump chain or gear I might have that for you as I am removing all that and going electric.

Good luck

hey, i might take you up on that. i suppose i'll pull the clutch cover off tomorrow and hopefully be able to tell what is broken.

thanks,

--fred

thanks for the tip! i'm sure owners have come up with novel ways to side-step the need for OEM tools. i'll probably be asking around when i get to that point.

--fred

Wow... That is a crap load of effort to find the impeller is not spinning. I just had the mechanical seal, oil seal, and bearing replaced on mine not too long ago. I removed the side cover and took it to the Honda dealer. Had them replace the actual components Including reinstalling the impeller. Then I put it back together. I'm having the same sort of problems you are. So I'm guessing my impeller is not spinning either. Guess it's time I tear into my bike as well and figure out the impeller issue...

Or I just let the Honda dealer work it out since the bike is going in for a servicing this week?

hey, even a retarded squirrel gets a nut ONCE in a while! ;)

turns out the water pump shaft sheared off where it fits into the water pump driven sprocket. i don't know if that star-shaped piece is welded on or machined from the water pump shaft, but that's the exact location where it sheared. it was a bit of a mystery to me where that piece ended up. i fished around in the sump with a magnet for a bit hoping to get lucky. it is actually back in the cavernous orifice behind the pump sprocket. maybe it will stay there... it probably won't get into any trouble back there. in order to pull the primary drive gear assembly and the water pump driven sprocket and chain i have to remove the entire clutch assembly first, i believe. somehow, the prospect of pulling the clutch doesn't really excite me much. i donno.

--fred