Antifreeze Cap leak...

[Joel Langdon]

(Re:'99 340) Prior to spring start up, I noticed a small amount of antifreeze in the engine sump...I cleaned it up, changed the oil, ran engine, and used a flashlight to light th eengine compartment up looking for the leak. It appears to be only coming from the metal cap on the antifreeze reservoir....I figured the gasket was shot...upon installing a new cap, it still appears to leak...any suggestions before I call the shop?

 

[julian]

Tighten!

I have a 99 310 with 2GM20F. Same pool of coolant in sump. replaced cap like you, tightened ALL jubilee clips, but some still dripping. Don't want to overtighten and do damage. Must be a problem with Yanmar. Anyone got any ideas?

 

[Les Andersen]

Leaking Cap

Joel,Not sure which cap you mean. If the leak is at the heat exchanger reservoir with the radiator type cap then take the cap and go to an automotive type radiator shop and have the cap tested. You will need to have the relief pressure data with you. That cap is a couple of $ and easy to replace. The cap should last many years and new in 99 is too early to fail. It might be that you didn't have the cap tight or it was on crooked.If the cap is the one connected to the heat exchanger by a small rubber hose that goes to generally white/clear plastic container (expansion tank) over to the side of the engine then check your coolant level when the system is cold and ensure that it is not too full. There should be a high and low mark on the bottle. That level should be checked when the engine is cold. As the engine heats up it transfer's coolant into the expansion tank and, if there is already too much coolant, it ends up in the sump.Not sure of another coolant reservoir that could be leaking.Good LuckLes s/v Mutual Fun

 

[Joel Langdon]

Antifreeze cap leak

Les- test the cap---GOOD idea...forgot about my old gas station days and the "Stant" radiator cap pressure test display case. I immediately thought of a failed gasket, and bought a new one...($14.95 for a "marine" cap!) and it still leaked. I kept the original one and agree, a orig ('99) cap should last YEARS...My coolant did subside, and I know to check and fill when cold only.whenever I open the regular cap, it clear is up to the neck of the cap and some spills out always. Odds of two faulty caps are slim %... I used my 1.5 Million candlepower searchlight to observe engine at fast idle, and everything was tight, clean and secure except a trickle from the cap...I will nail this down sooner or later, and keep spare antifreeze onboard...Many thanks for the input.

 

[Les Andersen]

Check

Joel,You might check the return hose from the expansion tank for a split or crack where it enters the radiator and also that the short metal pipe on the neck is clear. When the radiator draws up the coolant from the expansion tank it will generally top off the radiator and that might be why the radiator is always full. Mine will spill out also when I check. Guess the metal lip on the radiator might have a ding or scrape that prevents a good seal. Not sure what else could be the problem.Good luck,Les

 

[Gary Wyngarden]

Dribbling

I have a similar problem with my 1992 Yanmar 3gm 30f. I periodically end with up a very slow drip out of the overflow tube. After a couple of hours, it might be a teaspoonful. Just enough to stain the absorbent cloth I keep under the engine and make me worried about what might be wrong. It seems to be worse when the heat exhanger is completely full up to the cap when cold than when the volume is a little lower. Maybe it's overfilled? In any event it's annoying.Gary WyngardenS/V Shibumi H335