Overflow Bottle seeping

[E_Sanborn]

Anyone else seen this? On my YM2010D, the overflow bottle seeps around the cap seal. Fluid levels vary as expected, never an overflow situation. Fluid level varies between the middle of the indicated range when cold, to just over the top on the high mark when hot. Completely normal.

However, it leaks. Not the bottle itself, but from the junction of the cap and bottle.

The cap is a soft and has what appears to be a good EPDM seal. There's a rigid polyethylene washer that encircles the fill tube, everything looks to be good, no cracks. A little variation and flashing at the casting molding marks on two sides. I trimmed that smoother.

Seems like the fluid is agitated and the bottle is under pressure. Seems like I loose a few drops in a few hour's use to a tablespoon on on a long day. Not too big of a deal, but it does make a mess where it drips and after a few weeks of grime accumulates.


I'm going to melt a very small hole in near the center of the cap and see it this will bleed off the pressure that builds when the bottle is being filled, without oozing fluid. We'll see what happens.

 

[LMTC]

In most cases when a coolant reservoir is overflowing or showing any signs of pressurization there is a bad head gasket at a minimum. Head gaskets left unattended lead quickly to damaged heads on these tractors. I have seen a bad radiator cap cause this too, but very seldom.

 

[E_Sanborn]

I know what you're talking about Wayne, but I'm not observing overfilling or pressurization from a blown gasket. I should have given a better description of the problem. In my situation, the bottle is not being over-filled with coolant, the fluid level is normal. The fluid level fluctuates as one would expect - lower when the engine is cold, and near the "max" level line when the engine is hot. I would also note that the engine temps are completely normal, to the left of the center mark on the gauge, and 160-175F measured off the block via infrared sensor, after hours of operation.

The pressurization that occurs in the bottle is minor - normal for what one would expect as hot coolant is shunted into the bottle by the radiator cap as the engine reaches operating temperature. The problem appears to be that the cap seal is seeping small amounts of coolant as the liquid is sloshed around during operation.