Overheating issues...

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maxystaxi

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Hey I'm back! 1975 GL1000

So, after going for a nice joy ride and putting about 200 miles on the bike this year, everything seemed to be just fine.

Again I took another trip with it on a really warm day (85F) and noticed that temp gauge was in the higher end of the scale to almost in the red.

It would bounce back and forth between the high end of the scale depending if I was going 35-55 mph.

The fan is set on a manual switch and I had it basically running non-stop for the ride.

After I got home I could here it a mild bubbling/boiling sound coming from the area of the thermostat.

Reservoir was really high... but no boil over.

Cap is OEM and it appears to be in good working condition.

Since then I've drained the coolant (no presence of oil) ...and removed the radiator.

I've pulled the thermostat and tested it in hot water. It started to open at 185 and looks as it has good clearance (I will replace this with a new one anyway).

Radiator looks good from the outside, (i've since removed and will be taking it to the local shop to get it de-scaled)

I see the water pump fins. Does the pump rotate freely? Or is there a way to check to see if it rotates with the engine?

From what I've read ... I'm now fearing the worse that it's a head gasket. I've not checked the oil yet... but I'm crossing my fingers that it would have any coolant in it.

BAH! Can anything else go wrong on this thing?! I know it's 40 years old... but seriously?! All this at one time!?
 
Be happy planned obsolescence was in it's infancy back then. Did you have the side scoops on the radiator? Water pump is driven from inside the motor so it should turn much. See if the impeller has any side to side or up down movement. If none it should be good. If the reservoir hose leaks at all it may just have drawn in air instead of coolant on a previous shut down leaving insufficient coolant to do the job.
 
[url=https://classicgoldwings.com/forum/viewtopic.php?p=150758#p150758:9tcucqdo said:
slabghost » Thu Jun 11, 2015 9:13 am[/url]":9tcucqdo]
If the reservoir hose leaks at all it may just have drawn in air instead of coolant on a previous shut down leaving insufficient coolant to do the job.

:yes:


maxystaxi":9tcucqdo said:
..It would bounce back and forth between the high end of the scale depending if I was going 35-55 mph.

To me, that indicates air in the cooling system. A temp sensor will only read if it is submersed in fluid/coolant. When air passes over it, the gauge will go down quickly, until coolant hits it again, then it jumps back up. Check the hose from the rad to the reservoir, the little plastic "L" fitting, and the rubber grommet for any looseness that would allow air to be sucked back into the rad instead of coolant from the reservoir. :yes:
 
I don't believe there was any air in the system... when it cooled and I removed the radiator cover the coolant was right to the top and it did draw the coolant back down from the reservoir. I also replaced the reservoir hose earlier this year, so that should be in good condition with no air leaks.

I do have the scoops on the radiator as well.

As for when I mean "high range" The needle slowly moves between the very top end of the normal to almost the red zone. So it's always "hot" it just depended on if I was moving fast on the highway at 2700-3k rpm.
 
hmmmmmm seems like it might be thermostat in upside down and bypass hole is at the top instead of the bottom....id drill a bigger bypass hole in it and this gets rid of the rivot also providing more flow ....if this dont cool it down ...head gasket is in play maybe
 
I would start with cleaning the radiator first, i've seen many get really warm from the core being plugged some inside, give her a good cleaning. And make sure your fan is running in the right direction too, and not running backwards,,,just something to check.
 
[url=https://classicgoldwings.com/forum/viewtopic.php?p=150770#p150770:31a7fv2n said:
joedrum » Thu Jun 11, 2015 11:15 am[/url]":31a7fv2n]
hmmmmmm seems like it might be thermostat in upside down and bypass hole is at the top instead of the bottom....id drill a bigger bypass hole in it and this gets rid of the rivot also providing more flow ....if this dont cool it down ...head gasket is in play maybe

I thought the hole has to be upwards (top)... I believe it says it in the Haynes manual.
 
it might be so that it says up i am not sure there ....i am sure that if you need effective bypass low is better....down here in fla. i just got finished helping jpwinger prepare his bike for fla weather ....his bike being a 80 yr could not cruise at 80 mph without loosing his coolant ....after a 2hr cruise up the interstate at the 80 yr bikes rpm the cooling would loose ground and squirt it coolant out and pressure gets huge in radiator ....cure was the removal the heat shield and the thermostat ....his bike now runs cool and has no problem in the florida heat ....my bike set up the same way but with one difference ....mine being a 1200 motor that has 12% more coolant flow than 1000s or 1100s i do have a thermostate upside down i guess and no rivit in the slightly oversized bypass hole ....ive been down south for quite some time and the bike has no heating issues what so ever...when your bike looses water a bypass hole in the top just bypasses hot air ...makes no sense to me to have it that way
 
In autos with a bypass hole they say put it in the up position too, I'd imagine they tested this and not just talking out their ass but ya never know, stock way is not always the best way. I hear Florida heat can be a beast all it's own.

I tried running both my 1100 engine and this 1200 engine without a thermostat, both would run warmer and wouldn't hold a steady temp so back in they went.
 
The bypass hole/rivet is to eliminate air lock and excess pressure on the thermostat when it is closed, so up is the normal position when installed :yes:
 
[url=https://classicgoldwings.com/forum/viewtopic.php?p=150850#p150850:23ritclw said:
Ansimp » Fri Jun 12, 2015 12:04 pm[/url]":23ritclw]
The bypass hole/rivet is to eliminate air lock and excess pressure on the thermostat when it is closed, so up is the normal position when installed :yes:

well im far from normal so are my bikes :BigGrin:
 
:smilie_happy: :smilie_happy: :smilie_happy: :smilie_happy:
You said it Joe :salute:
 
Well I did about 60 miles today and it wasn't as hot of a day as when I had issues. But, everything was normal... in fact it was on the lower side of the spectrum.

- Had a local shop de-scaled the radiator, they even re-welded all the fittings just for good measures.
- New Thermostat and removed the floating rivet
- New radiator cap

All in all I'm happy that it wasn't a head gasket.

Thank you Thank you Thank you all again!

:salute:
 
Head gasket is not that bad a job. Also, if everything seems to be running right and cooling properly but the gage is actin up you may just need to replace the 7v regulator. Does the gas gage work? Generally multiple goofy Gage's points at the 7v regulator as the culprit. It's about a $20 fix and takes 5 minutes to install with beer drinking time in between.
 
I like the beer drinking time type of work.

All gauges are working normally. I think it may have just been a scaled radiator with an older thermostat. It runs perfectly now.... until the next gremlin shows it's head.
 
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