READ THIS TODAY-It may save you an engine or at least some time and money!
I originally posted this in a "Hard starting engine" tread. But have decided that it is probably important enough to go out as general info.
What I am about to write maybe common knowledge, but I didn't know about it. The Yanmar rep and two mechanics didn’t guess it would be the problem.
I was having starting issues- or so I thought. 4 year old PDQ 34 with the 4JH3-TE and has always started fine the first try every try. Even the first time this year after having been out of the water for 20 months. Then, the starboard engine wouldn't start after a night on the hook. Checked batteries and swapped batteries with running engine and generator. Nothing. Took 6 hours to get home on one engine. Just for grins, charged battery with generator for thirty minutes- then it started. Started every time I tried for the rest of the day. Next morning, wouldn't start. Installed a new starter, started right away. Next morning wouldn't start. That afternoon wouldn't start. When mechanic came over in the morning it started, and everytime we tried the rest of the day. Since there is no more PDQ Whitby-not that they were ever of any real help, I contacted the Yanmar Distributor here in the Midwest. He guessed that it was at least one leaking injector. Blue Freighted them in- installed, and engine started like a champ. Next morning, engine won't start.
Just to be clear on what was happening when I was trying to start the engine. I would turn the key and there would be a "woo-woo" from the motor and then nothing. Turn the key again, and another "woo-woo" and then nothing. Sometimes after the third or forth attempt, not even a little "woo". More times than not, if the generator had been on and charging the battery, it would tend to start right away or at least within the first couple of tries. Right after the starter and the new injectors were installed, it started right away. But then the next day it would go through it's one or two "woos" and not start.
We even tried a new battery and a remote starter. Again, it would sometimes start after many tries or it wouldn't. It would always start right away if we were able to get it started once. Only after not starting it for 10 plus hours would it have it's problem.
After installing the injectors with no positive results, the Yanmar rep thought the starting issue might have been from leaking injectors and that there might be left over fuel that was not burning off just idling. So he wanted us to get it started and run the engine under load for 1 to 2 hours. It started on the first try. The engine sounded a little different, not bad, just different, and was actually running much smoother than the port engine. I attributed that possibly to the new injectors. The port engine, that has been running just fine showed 60 MP for oil and temperature smack in the middle. The bad engine showed about 55 MP for oil and also smack in the middle for temperature.
After about 10 minutes at 2500, all systems looking good, I ran it up to 3200 rpm (the turbos kick in around 2900 rpm) That is when the MP slowly, and I mean slowly started to drop to 40, No change in engine sound or rpm. When it went below 40 MP I shut down the engine. In the bilge was a whitish gray mixture with the consistancy oil. I check the dipstick and it was very dark.
From start to shutdown was about 30-40 minutes.
We one engined it back and with the mechanic, started to really probe. There was some whitish oil in the crankcase, but just a trace. Lots of whitish oil scum under the oil filler cap and attached to the number three cylinder rods. The oil in the bilge was very whitish gray. Wild case guess, I would say that there was a 1/4 to 1/2 quart of oil that had come out of the relief tube that empties just below the turbo.
Off came the head. What we saw was, that the number three cylinder was 3/4 full of lake water and had rust on the walls of the cylinder. 1, 2 and 4 looked perfect.
Had the head and exhaust pressure tested cold and hot- no cracks or warpage. Cylinders were tested for height against the case, and there seems to be no damage to the any internals.
Now keep in mind, there was no drop in rpm, except for running smoother than the “healthy” port engine, there were no sounds or indications other than the MP drop to indicate any problems what so ever.
There are quite a few people scratching their heads at Yanmar.
In my quest to figure out what my problem was, I was digging around in all sots of websites including the PDQ Forum. I spotted this post from the owners of MV Dana Louis back in 2005:
We suggest adding this to your maintenance checklist - especially after an extended layup/layover:
Sight check the clear tube running from the exhaust riser anti-siphon valve to the inboard hull vent fitting to make sure it is clear.
If that tube is obstructed [in our case by an insect family], on diesel shutdown the tube cannot break a vacuum in the exhaust loop and seawater is sucked back through the exhaust riser into the diesel. You know this has happened when you try to start and get almost no turnover [water does not compress] - or, if you are really unlucky, an engine that starts up on 3 cylinders and mangles the valves, piston etc in the cylinder with the water.
We were lucky on two counts - lots of water, preventing any possibility of starting, and an immediate diagnosis and recovery instructions from Chris Calvert. Three hours later, including the oil change, we were running nicely at 3200 rpm. Whew!
Well I check the anti-siphon tube on the bad engine and it was clean, but full of water and some anti-freeze. The valve that is the exit for the anti-siphon hose from the boat on the other hand had two small larvae and black fluid completely blocking the hole. When the hose was attached, I was unable to blow air through the valve. Once I cleaned it, air passed through the hose and valve unrestricted.
ARGGGGGH! So did I have two problems: a bad injector and larvae. Or just one problem: larvae.
This has been pretty expensive and time consuming. It could have been worse and still may be.
So all of you Yanmar owners having or not having some starting problems, check the anti-siphon system from the anti-siphon valve all the way to where it exits the boat.