'78 GL 1000 cooling system problems

[jacksprat54]

When running at interstate speeds my overflow tank fills up completely, & sometimes overflows, although the bike does not overheat it gets close; main problem is when bike cools down it does not pull coolant back from overflow tank to refill radiator. I have replaced the gaskets on the head elbows & the o-rings on the adjoining tubes. Any suggestions would be greatly appreciated. Thanks!

[PoolDude]

Just a thought, you might try replacing the radiator cap, I've not had this problem on the Wing but toasted an engine in a car because of a cap that was doing just that.

[jacksprat54]

Thanks for the reply PoolDude, I already did that just forgot to put it in my post. I had to use a 16lb automotive cap because the one the bike shop ordered for me was way too small. Could there be a difference in the cap? It looks just like the one that was one the bike when I bought it. Puzzled?

[PoolDude]

16lb is a little high but I would think it would work. Here is a list of caps that do work:
Radiator Cap -- Standard style with 13 Lbs pressure, any auto supply store
NAPA/Belkamp #703-1445 (2/27/13, new #703-1697) or STANT #10229
Murray #7713

[jacksprat54]

PoolDude, my Haynes manual calls for a 17 lb cap, could they be wrong? Guess it's time to check w/ a dealer parts dept. thanks again!

[PoolDude]

The factory manual calls for a cap with a relief pressure of 10.7 to 14.9 lbs. (.75-1.05 kg/sq cm) I think I trust the factory manual over Haynes.

[jacksprat54]

Thanks again PoolDude, I will rely on the factory manual! Guess I better get one.

[bustedwing]

One difference you may not know about is the radiator cap has to have the double seal, some don't have the extra seal and just pop off to the atmosphere. In that case if it is hooked to a reservoir it won't seal all of the pressure or vacuum, and could lead to overheating.

[jacksprat54]

Thanks bustedwing, I bit the bullet & ordered one from Honda, at the ridiculous price of $27.00 but figured that was the cheapest "test" I could do at this point

[bustedwing]

I hope it works for you. I am one that does not believe in throwing parts at a problem hoping to cure it, although there are not many other options you would have. I made the investment into a tester for cooling systems including radiator caps. That would tell you if your cap was sealed or not, along with pressure testing your cooling system. It is , to me, a valuable tool since I own three vehicles and occasionally repair other vehicles. If you are somewhat in the same boat I would suggest you check them out at any auto parts retailer. Good luck.

[jacksprat54]

Not sure why it worked, but so far the Honda cap has taken care of my problem. So I guess it was worth the $27. PoolDude, you were correct, it's a .9 kg.

[PoolDude]

Some times it's the obvious things that work. Glad the problem seems to be solved. BTW a link to download a factory manual: http://www.goldwingworld.com/pages/GL10 ... manual.pdf

Be patient as it tends to be slow.