Left side Cooling Tube O-ring Leaking

[dbtroudy]

I'm putting my '76 yellow GW back together and have run into a problem getting one of the cooling tube o-rings to seat correctly. It's the o-ring that fits into the thermostat housing on the left side of the engine. I am using Honda OEM o-rings and have cleaned both the cooling tube collar as well as the housing where it slips into. Prior to this rebuild and re-assembly, I have fortunately never had an issue setting one of these o-rings. This time, I've gone through 3 o-rings and the tube is still leaking at the joint and four attempts to reset the tube. When I disassemble the connection, the o-ring is not pinched or twisted in anyway. The other end of the tube that connects to the elbow mounted on the head is solid and doesn't leak, just the one that connects to the thermostat housing. I'm using plumber's grease to hold the o-ring in place and it feels like it is snapping into place correctly. However it continues to leak radiator fluid after I assembly the joint and fill the radiator with new fluid. What am I missing here?

Don

[gltriker]

Have you considered reversing the coolant tube end for end, and reassemble the components with new orings?

If you have a cooling system pressure tester, or can rent/borrow one, that tool will save quite a bit of previously lost time and avoid leaking coolant onto your engine.

[pjlogue]

Check to be sure your cooling tube end isn't bent slightly out of round. The tubes are thin and can get damaged easily. If it's out of round you can carefully bend it back into shape. Use a lubricant on the O ring when you go to assemble it. Silicone grease, Glycerin will work. You can also use a sparing amount of cooling system sealant (silicone seal)

-P.

[flyin900]

If the interior of the housing is totally clean inside then I would suspect the tube is slightly out of round, or possibly the cleaning has enlarged the hole on the housing. (not likely unless you used some aggressive motorized cleaner/brush.) Turning the tube around as suggested may offer a solution, or point to a problem on that end of the pipe if the leak follows the tube orientation.

[dbtroudy]

"Check to be sure your cooling tube end isn't bent slightly out of round."

Both cooling tubes are in good condition and the ends are round like they are supposed to be.

I solved my o-ring problem this evening. I took a pin flashlight and shined it under the carb rack and under thecooling tubes. What I saw was a small drip coming from what appeared to be the rear thermostat housing bolt at the back of the housing. That seemed odd, so I once again drained the radiator, pulled the carb rack so I could see what exactly was dripping. With the carb rack off, it was easy to see that the left side cooling tube wasn't leaking at all, it was the right side tube o-ring where it enters the thermostat housing. This tube sits just to the left of the engine case seam and any dripping radiator fluid would appear to be coming from the left side cooling tube. I disconnect the right side cooling pipe and found a small flat spot on the o-ring. Replaced the o-ring with a new one, lubed the o-ring with plumbers grease and reconnected the tube and cooling tube elbow. Refilled the radiator and WOW, no leaks from either cooling tube. I'll check it again in the morning, but right now, problem appears to be solved.

Thank you all for your input and recommendations!

Don