Yanmar Woes

[noelex 77]

Originally Posted by delmarrey

Yanmar put a little yellow tag on my dipstick that says to check the oil 10 minutes after shutdown. I noticed any longer and it will read a bit higher.

My Yanmar 4JH4AE has the same sticker. It does give strange oil readings if you measure at other times. Sometimes after 25min or so after shutdown the oil level will measure very low (below the low mark, when it was near full after 10 mins) wait longer and it goes back to slightly higher than the reading at the 10 min mark.
I have never seen this on any other engine. Normally the oil level just goes a bit higher the longer you wait as the oil drains back into the sump.
Anyone have any theories why this would happen? Is oil getting sucked back up as the engine cools down?

[marina.alex]

We have the same engine in our Bene 50 and I'll share a couple of thoughts.
1) I have over-filled the oil by measuring the oil immediately after shut-down.
2) when I check the oil in the morning it is at least 1/2 to 1 litre lower than if I remove the dipstick, wipe it, replace it, remove it again and take another reading --> and this basically makes no sense to me but that's the way it works
3) we've had a "power" problem intermittently this summer because of fuel contamination. I originally thought it was shavings from when the webasto was installed this winter. We found a number of plastic shavings (almost like glass) that were jamming up the fuel pickup from the fuel tank. This caused smoking, irregular engine speeds, and loss of power. Once the fuel clogs were removed -- no problem. If I keep the revs lower, no problem.
4) the plastic has a real affinity to the fuel pickup tube -- particularly at the elbow and the stop valve -- and therefore doesn't make it to the Racor so there is no easy-to-see evidence of the problem. We've taken to preventive maintenance every 25-50 hours of just taking the pickup tube out and clearing out any plastic shavings.

Finally -- has anyone heard of fuel tanks (we have 2x235Litre black plastic tanks) deteriorating on the inside and shedding plastic debris? I am wondering whether before we owned the boat whether one was stressed by over-filling, or had water in it and froze or some other physical damage that could cause shards of plastic to be released -- thus clogging up the fuel tube. The draw is from the port tank and the starboard tank is only linked into the Port tank -- and the problems started (and continued to get worse) every time we transfer fuel from Starboard to Port. Our immediate fix is not to transfer fuel. Next is an inline filter between the 2 tanks, then removal and visual inspection, and if rotten, replacement.
Any better ideas out there?

[mintyspilot]

Originally Posted by marina.alex

Finally -- has anyone heard of fuel tanks (we have 2x235Litre black plastic tanks) deteriorating on the inside and shedding plastic debris?

I would imagine that whoever drilled holes in the plastic (tubes, feeds, access, etc) never cleaned out all the debris from the drilling. Plastic has a nasty habit of taking a static charge and then the debris sticks all over the insides of the box being drilled and is held there by the static charge.

[Bash]

Originally Posted by marina.alex

--> and this basically makes no sense to me but that's the way it works

even if we're not helping Dockhead with all this, I'm soooooo glad to hear that I'm not the only one having arguments with my dipstick.

[Dockhead]

Update:

I did the "easy stuff" as many people wisely suggested. I changed the fine filter and switched the Racor. Then I pumped out some oil to bring the level down to halfway between high and low. The oil didn't smell like diesel (for what that may be worth).

Then I motored for five hours into a stiff (20+) breeze and sometimes big seas. I motored for a couple of hours at my usual cruising RPM, 2500, getting good speed out of that under the circumstances. Then, I motored for an hour at 2800. Then I motored for an hour at 3000, 3500, 3000 again.

Didn't miss a beat. Engine would rev to 4000 in gear, would make hull speed against a 23 knot wind at 2800 RPM, and generally ran the way it should.

Got back to my slip and let the engine cool down. No coolant lost as far as I can tell.

I did find some cr*p in the fine filter. No water, but some odd bits of debris. It even looked like maybe the soft part of the filter element was separated.

I am completely puzzled. The most plausible thing seems to me to be that the overfilled oil must have sprayed through the breather pipe into the turbo and gummed it up somehow, temporarily. But I"m grasping at straws here.

[Bash]

i'd call that a brilliant fix.

[Dockhead]

Originally Posted by Bash

i'd call that a brilliant fix.

LOL. If only:

1. I knew for sure it is really fixed; and

2. I did it as the result of some brilliant insight, instead of just dumbly doing the first things I could think of.

[never monday]

Originally Posted by Dockhead

I am completely puzzled. The most plausible thing seems to me to be that the overfilled oil must have sprayed through the breather pipe into the turbo and gummed it up somehow, temporarily. But I"m grasping at straws here.

plausible cause.
It will also cause the crankshaft to use more energy pushing through the oil

[delmarrey]

Originally Posted by noelex 77

Anyone have any theories why this would happen? Is oil getting sucked back up as the engine cools down?

I've noticed on mine that the top of the dip stick is a rubber plug, which I believe seals the tube air tight and the bottom of the tube is at the bottom of the pan, way below the oil level.

If I let the motor cool w/o pulling the dip stick and then I do pull the dip stick, the oil level is so low it looks to be out of oil. But, if I put the stick back in and pull it again it shows over full.
I think what is happening is the oil cools and sucks back into the oil pan creating a vacuum in the tube, until I pull the stick, then it comes up to the level that has drained completely. So if you follow the instructions that Yanmar gives in their "Operation Manual" it's averages out the oil level.


.

[noelex 77]

Originally Posted by delmarrey

I've noticed on mine that the top of the dip stick is a rubber plug, which I believe seals the tube air tight and the bottom of the tube is at the bottom of the pan, way below the oil level.

If I let the motor cool w/o pulling the dip stick and then I do pull the dip stick, the oil level is so low it looks to be out of oil. But, if I put the stick back in and pull it again it shows over full.
I think what is happening is the oil cools and sucks back into the oil pan creating a vacuum in the tube, until I pull the stick, then it comes up to the level that has drained completely. So if you follow the instructions that Yanmar gives in their "Operation Manual" it's averages out the oil level.


.

I appreciate any theories, but I do always remove the dipstick, wipe it and reinsert to make the measurement. The Yanmar dipstick does make a good seal and you are correct you can get a very wrong reading if you don’t do this.
The drop in measured oil level between 10 mins after shutdown and say 45 min after shutdown is a still a puzzle to me.
After the last recent oil change I took some careful measurements

10 mins after shutdown 3/4 full
30 mins after shutdown just above the low mark on the dipstick
2 hous after shutdown A bit above full

I have measured the oil level after several runs and the effect was reproducible. There is no net gain or loss of oil, but it is easy to overfill if you don’t follow the instructions and measure it at 10 mins.

[SaltyMonkey]

Firstly, Mr D, as precaution since you might still have issues that you are unaware, I would run an oil analysis next time you do your regular oil change. Some people run an analysis on EVERY oil change as a best practice. Remarkable what these reports show and how they can prevent issues.

Your high rev testing is scary. Check your manual on what the current MAX hours of continual run should be on high RPMs and stick to it if you are doing these tests.

Another key thing to do monthly is run your boat for 4 hours under full load w engine say 2400 RPMs or so, to clean out any moisture.

Im fantasizing here, but perhaps the heat buildup after first shutdown is causing expansion somewhere and making oil dip lower. Then as engine cools it contracts and oil rises.

[Therapy]

Originally Posted by delmarrey

I've noticed on mine that the top of the dip stick is a rubber plug, which I believe seals the tube air tight and the bottom of the tube is at the bottom of the pan, way below the oil level.

If I let the motor cool w/o pulling the dip stick and then I do pull the dip stick, the oil level is so low it looks to be out of oil. But, if I put the stick back in and pull it again it shows over full.
I think what is happening is the oil cools and sucks back into the oil pan creating a vacuum in the tube, until I pull the stick, then it comes up to the level that has drained completely. So if you follow the instructions that Yanmar gives in their "Operation Manual" it's averages out the oil level.


.

OK that is fine but having to check the oil at 10 minutes and not before or after is just plain stupid.

Or is it me that read that wrong?

[Dockhead]

Originally Posted by SaltyMonkey

Firstly, Mr D, as precaution since you might still have issues that you are unaware, I would run an oil analysis next time you do your regular oil change. Some people run an analysis on EVERY oil change as a best practice. Remarkable what these reports show and how they can prevent issues.

Your high rev testing is scary. Check your manual on what the current MAX hours of continual run should be on high RPMs and stick to it if you are doing these tests.

Another key thing to do monthly is run your boat for 4 hours under full load w engine say 2400 RPMs or so, to clean out any moisture.

Im fantasizing here, but perhaps the heat buildup after first shutdown is causing expansion somewhere and making oil dip lower. Then as engine cools it contracts and oil rises.

Yes, the oil analysis is a good idea and I will run one. I ran one the oil change before last and in general, doing one with every oil change is good practice. They are more valuable, the more regularly you do them.

As to the revs, rest assured I am following the regime for this small displacement, high specific output engine. Redline 3800 and max continuous 3700. One hour at 3800 is ok but would never do it. 4000 briefly and out of gear is ok.

The dipstick behavior reported by many is bizzarre. Poor design, if you ask me.

[delmarrey]

Originally Posted by Therapy

OK that is fine but having to check the oil at 10 minutes and not before or after is just plain stupid.

Or is it me that read that wrong?

Yeah! It's seems kinda stupid but there's the yellow tag hanging off the dipstick. There's a lot of stuff that Yanmar does stupid. You should read my posts in:
http://www.cruisersforum.com/forums/...ant-36940.html
&
http://www.cruisersforum.com/forums/...ing-35395.html


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[SaltyMonkey]

Very strange, but I confess I am learning a lot from your experience