Cooling System Problems

[brianlouis74]

I have a 1978 GL 1000 with cooling problems. I have replaced the thermostat and the fan switch. I have even rigged to fan to run on a toggle switch, but I still overheat. Could this be a water pump? Any ideas would be great.....Thanks in advance....

Brian

[Dougal]

It could be a water pump pronblem, but its more likely to be a head gasket gone.

Dougal

[brianlouis74]

Is there any way for me to check?

[Dougal]

First check the coolant level in the radiator and make sure there is coolant in the system, I have seen bikes where the coolant tank has water in, but hardly any in the system. Next check the oil level, sometimes the gasket will blow betwen the water jacket and an oil path, resulting in coolant going in the sump resulting in an increase in the oil level.
Run the bike until it gets warm and then turn the ignition off. Leave the bike alone for at least 8 hours to allow everything to cool completly.
Remove all the spark plugs and cover the holes with tissue paper. With the help of another preson, hold these in place and turn the engine over with the starter motor with the engine kill switch in the OFF position. Should the gasket have failed between the cylinder and the water jacket water will be expelled through the spark plug holes, indicating which gasket has failed.
When replacin the gasket remember to replace the o ring for the oil jet.

Dougal

[Bandanna]

welcome brianlouis74 to ngw.

if you take off the cap from the header tank,then start the machine.
as it gets warmer if the head gasket is gone/going,then you will get gas bubbles venting back into the header tank.
if your cap was on,this would pressurise the tank,ans force it out of the overflow pipe as very hot water(steam)

also as dougal says that is another way to check........

you may find the impellor is u/s on your pump.but also make sure the radiator is flushed out+not full of rust..
also make sure the radiator fins are not clogged with debris/flies etc.........

and as dougal says if the gasket has blown,remember to replace the "O"ring for the oil jet..

if you are unfortunate to have blown the gasket,then may i suggest you replace both sides(if funds allow) you may thank yourself,and at least you will know that they are both new.the other is likely to go after you repair one...

hope this helps..................

safe riding........

[brianlouis74]

Thanks for the replies. Is there anything else I should replace while I have the rocker covers and heads off? Like you said, if I fix one side, the other will break on me. Thanks for the tests, I will try them this week. I most likely will be back for more.....

[Bandanna]

not a problem my friend............

keep us posted as to your progress..

maybe re-seat the valves+de-coke the heads......

[Try]

I have a 1978 GL 1000 with cooling problems. I have replaced the thermostat and the fan switch. I have even rigged to fan to run on a toggle switch, but I still overheat. Could this be a water pump? Any ideas would be great.....Thanks in advance....

Hello and welcome aboard brianlouis74, I hope you like your stay.
It can also be as simple as radiator core externally blocked

[Fat_Wing]

I would also add that unless you find a solid indicator that the head is blown you sould try flushing the system out first. It may very well be a head gasket but use a good process of elimination.

1. Coolant level and condition good?
2. Cooling Fan working? (you already did this. Cool)
3. Coolant pressure check?
4. Air bubbles in coolant while the cap is off? (cylinder compression leaking into the coolant, blown head gasket)
5. Brownish color coolant with an oil film in over flow tank? (oil in coolant, blown head gasket)
6. Milky looking or faomy oil? (coolant leaking into oil, blown head gasket)
7. White smoke in the exhaust? (coolant leaking into cylinder, blown head gasket)
8. Exhaust has a sweet smell? (coolant leaking into cylinder, blown head gasket)

Pulling the heads should be your last choice.

Hope this helps. Also if you do have to pull the heads you can send them to me for a valve job. I'll do a set of heads for $100 labor. Check out my fat wing photos in the wing mans lounge to see the heads I just finished for my bike.

FW

[brianlouis74]

I had air bubbles in the radiator when I had the cap off. It would have one big bubble every few seconds or so. Also, the oil seems a bit on the watery side when I checked it. Sure sounds like the head gasket. I have had the raditator out and have flushed it with a hose, and it does not seem to be blocked. Will I have to re-synch the carbs after I disconnect them from the heads to get them off?

[Fat_Wing]

I had air bubbles in the radiator when I had the cap off. It would have one big bubble every few seconds or so. Also, the oil seems a bit on the watery side when I checked it. Sure sounds like the head gasket. I have had the raditator out and have flushed it with a hose, and it does not seem to be blocked. Will I have to re-synch the carbs after I disconnect them from the heads to get them off?

Brian,

Sounds to me like you are looking at head gaskets. You should be able to remove all the carbs as one assembly. You shouldn't have to re-adjust your carbs. If the engine got really hot you should have the heads checked for cracks and make sure the are not warped on the serface.