Overheating problems

[Me_Rock]

Howdy!

I just finished cleaning out the carbs on my '96 steamer project. She's running like a happy tiger, and with the Yoshi exhaust setup that it came with makes it sound like the God of Hellfire is angry - and he wants his motorcycle back!

Anyway, I'm running in to some really irritating issues with the cooling system. I drained and filled everything properly, but for some reason all of the coolant seems to collect in the overflow reservoir and just puke out of it's rubber cap. Interestingly, the puking action doesn't stop there! It continues to vomit fluid through that little cap until the radiator runs dry and the bike overheats.

Any ideas on what might cause this? This site has been immensely helpful with countless other things, but I just can't seem to figure out this cooling problem.

Thanks!

[Mustang]

air in the system
bleed the air off from the screw thats on the left hand side of engine thats about cylinder base high

every time you add coolant to the radiator let it bubble the air out before capping
and the coolant resivoir only likes to be half full or it will piss coolant out

and you could have a radiator cap thats gone tits up and won't hold pressure

[Me_Rock]

I also thought that it could be the cap, so I bought a generic spare from NAPA that goes to a Honda Accord. It's rated for 16 PSI, but the little bugger still spits a little bit of coolant when starting up. The original cap didn't do that.

Is the bolt on the engine supposed to be removed while filling?

[Me_Rock]

Hmm... looks like both of the caps like to leak. Can you recommend one that does work?

[Mustang]

Hmm... looks like both of the caps like to leak. Can you recommend one that does work?

yeah the oem triumph cap

[Mustang]

from the triumph repair manual ...................

[Me_Rock]

Alright, thanks!

I was using that page to figure out this whole filling process. I drained the system through both of those bolts and then refilled it from the radiator cap. I tipped the bike from side to side, allowing the coolant to fill the radiator as bubbles came to the top. After no more bubbles came out, and the radiator could fit no more coolant, I put the radiator cap back on and gave the engine a whirl. Lo and behold coolant just starts bubbling in to the overflow tank again! Am I missing something, or is it just that pesky cap?

Also, where is a good place to look for the elusive OEM caps in the US?

You're a wizard of all things Tiger. Thanks!

[Mustang]

bike bandit for a cap ................

are you sure you dont have a fubared head gasket cuz that will do it every time
check your oil for coolant contamination as well as the exhausts for coolant deposits
isn't this the bike that was in pcs. not too long ago that belonged to some one else ?
were the cylinder liners resealed properly with HYLOMAR sealant ??????????

[Me_Rock]

Yeah, she's in rough shape. The engine is from an Adventurer, actually. The guy said that he replaced the engine because of what he thought was a balancer issue which turned out to be the carbs. Long story short, the bike now has the engine and carbs from an Adventurer.

What does contaminated oil look like?

[Mustang]

it'll be:
A: if just ran the engine it will be white and frothy
B: if left to sit after you drain it the coolant should seperate and be whatever color your anti freeze is

if its an adventurer motor they had a different top rubber hose that had a bleed screw right behind the thermostat , tigers didn't have that ....you may not be getting all the air out

[Me_Rock]

It has the top tube from the Tiger, so no extra bleed screw. Although I did manage to get a few more bubbles out by pinching and wiggling it until I didn't hear any more air moving around. Still no joy.

The oil looks normal, and I haven't noticed anything awry with the exhaust. However, the inside of the pressure cap hole that the rubber gasket presses against looks a little bit chewed up. Could that be the culprit?

[Me_Rock]

Here's a picture of the degraded lip:

[MIMbox]

I imagine that will be very unlikely to seal properly, and may well be a major issue to your cooling woes.
By the way, welcome, and I'd be interested to see a picture of the engine in the bike, I wondered if those engines would fit. Regards Phil

[Mustang]

is that silicone sealant I see smeared all over like someone is trying to seal it ?

if it is and was there from previous owners then it's been an issue before

[Me_Rock]

I did find myself pulling bits of what appeared to be silicone out of the radiator with needlenose pliers... Any ideas on how to fix this?

Edit: I went to the hardware store and found an o-ring that fit between the existing lip and the wall of the hole. It didn't hold pressure. I'm not going to be a happy camper if I have to buy a whole new radiator...