coolant leak in Yanmar 20GM...

[smosh]

good morning all! I have a coolant leak seemingly in the top left front corner of the engine. There are no obvious drips from a hose or clamp, but somehow it's collecting on the fuel filter housing and dripping down off the motor. There's also fluid collecting on the block. I just can't see any active drips, or feel any spray. Linking to a video I just made - hopefully someone can point me in the right direction so I don't find myself replacing random hoses, clamps, and seals! Thanks!

 

[Ralph Johnstone]

Please clarify the model of your engine :

It's 2GM _ _ _ . I suspect a 2GM20F but please confirm all digits and letters.

Also it would be helpful if you can supply one or two single shots of the engine, face on and face up showing the source of the leak. There are too many sideways and upside down shots to clearly see anything and I've sweated over my 2GM20F for 25 years and have a pretty good idea of who's who and what goes where.

 

[Ralph Johnstone]

Got to take a break from working beneath the cockpit here so I'll guesstimate your engine is a 2GM20F. Your ID plate looks similar to mine (which proves nothing) :

There are no obvious drips from a hose or clamp, but somehow it's collecting on the fuel filter housing and dripping down off the motor.

With that observation, look here for leaks. The leak is above the level of the seconday fuel filter. Do a TP test and allow the engine to run for a while and is hot :

If no show on a TP test, take the boat out under full load and get it hot ~180° and see if the TP shows yet.

Back to the sweat hole .

 

[kloudie1]

Man, that pink stuff looks like red diesel. Coolant for that engine would not normally be pink, although I know that Tractor Supply has red "heavy duty" coolant.

 

[Ralph Johnstone]

Man, that pink stuff looks like red diesel.

You're eyesight is one hell of a lot better than mine. I've looked at that vid. a dozen times and yes, that liquid looks a little too red for my liking. But then again, I'm blind in one eye and can't see out of the other.

I know that engine better than the back of my hand and yet from frame to frame, I can't tell "where" I'm looking from or "what" I'm looking at. I try to follow the camera angle forward and back starting with the OP's shot of the engine ID label because I know that's taken with the camera turned 90° CW. Either that or the vid. re-orients itself as mine often does. Can't follow after that.

I know the OP is diligently applying separate TP tests as we speak to the surrounding points and we'll see what he comes up with.

 

[Tally Ho]

OP needs to verify that they have red antifreeze in the HX. I agree it looks like diesel fuel leak from the fuel filter housing.

But a few ideas to try and narrow it down:

1) Verify red AF in the HX…or smell, taste if feel the leaky fluid. Diesel is pretty different than pink AF.
2) Is the fluid level in the HX going down? That looked like a pretty good drip, so it should show over time in the HX level. Also check the expansion tank…

If it is diesel, replace the o-ring in the on-board filter housing, check all hose clamps on the fuel line, etc.

If it is AF, tighten every hose clamp on all of the coolant lines. Also, inspect the HX cap. Replace if not inA-1 condition. Check the base of the HX cap neck. Mine leaked there and I had to use some Permatex to regasket that joint.

When I took delivery of my O’Day 322, also with a 2GM20F motor, it overheated about 15 miles into my delivery cruise across Lake Michigan. I nursed her into a port, and upon inspection, found the HX very low in AF. I topped it off and motored home the next day. But I kept losing AF. I was very concerned it was a bad head gasket or something.

I am happy to say that after the steps above, I have not lost AF in a few years.

First step though is to verify what is dripping.

Good luck!

 

[Ralph Johnstone]

I agree it looks like diesel fuel leak from the fuel filter housing.

That's why I made a note to look at the two vents screws on the fuel filter :

​

I didn't expect to see AF coming from the vent screws but the OP may as well be on the lookout for any fluid leaks that might be present while looking for the suspected AF leak.

Your comments about colour (as well as other's comments) add to the thought that this "may" be a fuel leak rather than an AF leak.

 

[Tally Ho]

M

That's why I made a note to look at the two vents screws on the fuel filter :

View attachment 239428
​

I didn't expect to see AF coming from the vent screws but the OP may as well be on the lookout for any fluid leaks that might be present while looking for the suspected AF leak.

Your comments about colour (as well as other's comments) add to the thought that this "may" be a fuel leak rather than an AF leak.

My AF is green, so easy to distinguish between the 2, but if the OP is using red AF, then it could be misidentified as AF instead of Fuel. All other mitigation suggestions really hinge on making sure we all know what is really leaking.

Your photos and annotations are always to spot-on Ralph.

Getting any sailing in this year?

Greg

 

[BigEasy]

My AF is green, so easy to distinguish between the 2, but if the OP is using red AF, then it could be misidentified as AF instead of Fuel. All other mitigation suggestions really hinge on making sure we all know what is really leaking.

IF, your sense of smell is intact, seems that the smell test would quickly & easily determine if the leak is indeed diesel. Nothing comparable to that odor!