Yanmar Distress

[Chef Mike]

This boat I bought has a very low hour Yanmar 3JH3E engine. We have aspirations for many of miles in our voyage to Australia from Baja. I am wondering if any of you may want to chime in on what may go wrong and how to prepare for the worst Yanmar nightmare. Also what tools may be needed in such a distress to fix my baby. I have the basics... what I am looking for is advice on purchasing a tap and die set- I am thinking like what would happen if that bolt that holds the starter in place snaps off or some other random bolt in the cooling system. What size tap would I need? Any advice would be appreciated.

Chef Mike
PacificSailors

[sww914]

I'll only address the taps & dies. I haven't worked on a Yanmar but I do know that the most commonly used taps & dies in metric are 6mm, 8mm, & 10mm.
I was a Porsche mechanic and virtually the only thread pitches used on German cars are 6mm X 1mm, 8mm X 1.25mm, and 10mm X 1.5mm. The only exceptions to these are a very few special fasteners, major suspension parts or a couple of internal engine parts, ie rod bolts, oil pump hardware, and valve adjuster screws.
The reason I mention all of this is that I've seen that most Japanese cars are similar in that 99% of the fasteners on the cars are the same sizes and thread pitches that I've described with similar exceptions. The head sizes are different, however.
A Yanmar dealer will probably be happy to answer any further questions you may have if you're already armed with these clues.

[delmarrey]

How many hours?
If it has low hours and running fine, you should be OK. It also depends on how it's set up to how many hours you'll get before trouble starts.

Some of the things you have to watch for are;
To make sure there is no water draining back into the exhaust manifold. This causes corrosion at the elbow.
Have an extra diaphragm for the lift pump. They do seem to fail frequently.
Check the oil often to make sure it's not making oil. It seems to be related to the seals in the injection pump. Take extra HD motor oil.
Do take extra filters and water pump">raw water pump impellers.

I'm sure others will chime in.........

[jewel114]

I have been running Yanmar diesels and have not needed a tap or die for a repair. Instead of sheared bolts think hoses, belts, duct tape, ss wire, asst. hose clamps, red RTV, and a spare exhaust elbow assemply. Check all exterior oil lines for corrosion, don't miss the one that goes around the back of the engine. Fuel filters! Thats about it.

[Chef Mike]

Thanks Guys that is the kinda advice that I am looking for.

How does water drain back into the exhaust? I have a loop in the wet exhaust hose... Are you thinking of a siphoning action with following seas?

The engine has 300 hours on it.

Chef Mike
PacificSailors

[jewel114]

Originally Posted by delmarrey

How many hours?
If it has low hours and running fine, you should be OK. It also depends on how it's set up to how many hours you'll get before trouble starts.

Some of the things you have to watch for are;
To make sure there is no water draining back into the exhaust manifold. This causes corrosion at the elbow.
Have an extra diaphragm for the lift pump. They do seem to fail frequently.
Check the oil often to make sure it's not making oil. It seems to be related to the seals in the injection pump. Take extra HD motor oil.
Do take extra filters and raw water pump impellers.

I'm sure others will chime in.........

This is good, things I forgot. Harley

[delmarrey]

Originally Posted by Chef Mike

Thanks Guys that is the kinda advice that I am looking for.

How does water drain back into the exhaust? I have a loop in the wet exhaust hose... Are you thinking of a siphoning action with following seas?

The engine has 300 hours on it.

Chef Mike
PacificSailors

At 500 hours it'll be due for some major checks, which should be in your manual. Oh yeah, an extra alt. belt too.

So far, from the forum, I've seen a couple eroded out exhausts manifolds right at the elbow connection. http://www.cruisersforum.com/forums/...ion-71681.html

W/o actually being on their boat I can't really say how the sea water backed up. I'll have to assume that either their loop wasn't hight enough or the drop to the wetlift wasn't sufficient. The chart below gives some good dimensions.



Also there may have been a gasket problem. Aluminum exhaust manifold against a bronze elbow mixed with saltwater is asking for trouble.

[Chef Mike]

As you may have guessed I am no marine diesel mechanic... just a guy that does not like the dull moments interrupted by shear terror when boating.

I am looking at this schematic and was told previously by somebody whom may have heard from somebody else that the part labeled #4 there, which is some sort of breather I believe, was installed from the factory as a Stainless Steel union. Which was replaced with a schedule 80 plastic part.

So because of this SS union that may have corroded away to nothing the engine has corrosion in places that are directly beneath the union (part #4). Or is it because there is water draining back into the exhaust.

With the engine running I do not see any evidence of water leaking any where. So how could I tell if water was actually backing up into the engine?

Chef Mike
PacificSailors

[Hud3]

You're going to have a lot of following seas in the Pacific. If you're worried about water flooding into the exhaust, install one of these flappers. Simple, inexpensive and foolproof.

[Target9000]

Water can back up into the engine from two different places.

1) It can come back through the exhaust from following seas or whatnot.

2) It can come from the raw water intake if there is siphoning or it is all below the water line, thus filling up the muffler and backing up into the engine.

The exhaust should have a loop up to deck level before going through the hull. You can also install a flapper on the exhaust port to prevent too much in the way of waves entering.

The heat exchanger water exhaust line should go up to deck level with an anti siphon before being injected into the exhaust pipe/hose. This will prevent water siphoning from the engine water intake. Also make sure if you install this that you try to keep it in the center of the hull. The alternative to this is to shut off the raw water seacock when the engine is not in use. I've heard of people attaching the start key to the engine water intake seacock.

[delmarrey]

At the moment we don't even know if you have this problem! But the way to find out if it could be a siphon you would need to pull the elbow off after sitting from a shut down. That's if you have the square elbow, which we don't know yet.

We could be getting all excited about nothing here. Personally, if you're not sure, I'd find a reputably mechanic to check out the exhaust system to see what he thinks. The drawing should be a good reference.

The #4 part is a anti-siphon which allows the water to flow from the heat exchanger into the exhaust elbow that should be well above the waterline. When the motor is shut down the valve at the top of #4 opens and allows the water to drain back to sea level or lower.

Maybe this diagram will help. The loop (#4) is just before the #10 on the 3JH drawing. By all rights the water shouldn't get past the pump #2 with the motor off but if it does (old impeller) it can fill the wetlift and back up into the exhaust.

Also in following seas the water can back up the exhaust outlet and fill the wetlift, so it's real important to have the exhaust loop (#8 first drawing) well above the waterline. Which is why if the motor doesn't start in short order, one has to drain the wetlift.

.

[Chef Mike]

Yes I am with you there delmarrey... no need to start jumping to conclusions and causing mass hysteria.

My big concern right now is there is a good bit of corrosion on the back of the engine and I am wondering where it may have come from.

It appears that the anti-siphon hose was replaced. I have been told that the original was SS which may have leaked salt water all over the engine causing the corrosion. That is only a guess. I purchased the boat 2 months ago and there are no leaks now.

So I am wondering where all the corrosion came from? Any guesses?

Chef Mike
PacificSailors

[cfarrar]

The heat exchanger water exhaust line should go up to deck level with an anti siphon before being injected into the exhaust pipe/hose.

Our bronze, Groco, anti-syphon valve has a little "rubber" gasket valve that failed. No big deal, it just spit raw water into the bilge when the engine was running. The spare gasket cost about $20, and now we carry a spare.

[hellosailor]

Pardon the pum, Mike, but to prevent shear terror you might also want to invest in a torque wrench. Properly torquing bolts will ensure they don't come loose, but don't get sheared off while you're tightening them, either. And it you ignore the price of LocTite and NeverSeize and just buy a couple of tubes of each, in the long term it also helps to remember you want one or the other one just about every bolt, every time.

I'd also expect the tap and die set to get rusty very quickly unless you keep a light oil or rust-preventive spray on it, one more thing to get.

And you might want to look into "Helicoils", which are replacement thread inserts, for when you've stripped the threads out of something like an engine block. If you buy 'em and have them available, you'll never need them. (Works for me.<G>)

[delmarrey]

Originally Posted by Chef Mike

Yes I am with you there delmarrey... no need to start jumping to conclusions and causing mass hysteria.

My big concern right now is there is a good bit of corrosion on the back of the engine and I am wondering where it may have come from.

It appears that the anti-siphon hose was replaced. I have been told that the original was SS which may have leaked salt water all over the engine causing the corrosion. That is only a guess. I purchased the boat 2 months ago and there are no leaks now.

So I am wondering where all the corrosion came from? Any guesses?

Chef Mike
PacificSailors

The paint on stock Yanmars sux for sure. If your not seeing any water while your running, you're probably good. I too suspect it was from the old siphon valve leaking. But you may want to clean up the rust with a wire brush, wash down with brake cleaner and give some fresh paint. That way you can see if there is any trouble coming. With rust and dirt it's hard to tell.

If your having trouble with the exh. elbow it'll show signs on the underside right at the gasket.

And do check the motor mounts for cracked rubber, if you have the stock ones. P/S have a different grade even though they look identical. They're known to last 500 to 1000 hours in relation to use. The nice thing about Yanmars is you can get parts most anywhere.

Did you get an owners manual with it? I'd recommend sitting down and going thru the whole thing. Even checking the oil is specialized. If not, here is a link to the manual.>> http://www.sv-zanshin.com/Manuals/Ya...E_4JH4-HTE.pdf