Starting Issues - Yanmar 4JH3E

[Labatt]

Hello all -

We have a Yanmar 4JH3E engine, installed in 2004 by the prior owners of Pelican. A few weeks ago we started having an issue with it - when you hit the start button, it slow cranks, almost sounding like there's a hydraulic lock, but you can still hear the piston sliding in the cylinder. We stop cranking after 3-4 seconds. We then wait a few minutes and try again. After 8-10 times, the engine will finally turn over, but it "winds up" to actually turning over - it's not like it used to be, starting up within a couple of seconds and immediately turning over, like a good diesel should.

We have a second issue, maybe related, maybe not, maybe a contributor, maybe not. The engine is rated for 4,000RPMs at full open throttle. The maximum we can push it to with the transmission engaged is 2,600-2,700RPM. If you go over 2,400RPM for any longer than 2-3 minutes, the engine overheats. With the transmission disengaged, you can push it to the full 4,000RPM. Obviously there's an issue with the prop - it's a Gori, so it's either not opening correctly or is overpitched. The prior owner seems to recall cruising RPMs being around 2,800-3,000, which is where they should be. I've never seen it at these RPMs. LET'S NOT FOCUS ON THIS ISSUE, BUT I WANTED TO PUT IT HERE JUST SO EVERYONE CAN GET ALL THE FACTS.

Here are a bunch of notes from various diagnostics we've done and some done by a very good diesel mechanic here in Charleston:

• Blew out the first starter by overcranking, so the starter was replaced 2 weeks ago with a brand new one.
• We get a little white smoke from the exhaust
• We get a small amount of unburnt diesel from the exhaust
• Both of the prior two items can be explained away due to the possible issue with the propeller
• No black smoke
• No blue smoke
• Slight moisture on oil fill cap. Still have to do oil change, but took some oil from dipstick, put it in foil, heated it and no crackle. Checked cap again today, no moisture.
• May be a SLIGHT sheen on coolant, but difficult to tell
• Did load test on battery and it was fine. Showed a weak ground on the engine, so regrounded directly to starter. Does not appear to be a problem with the switch - same issue occurs when bypassing the panel

All of this led us to check the mixing elbow:

• Thought there may be a carbon buildup in engine due to prop issue, so we pulled off exhaust elbow
• Good news - no carbon buildup
• Bad news - water came out, some sludge in there - obviously not a good thing
• Replaced the mixing elbow with a new one
• Unscrewed each injector nut and engine reacted properly
• Did compression test of cooling system and showed no pressure loss
• Have not done cylinder compression test - yet
• First time we started the engine after replacement it started right up - no delay, perfect start
• Turned on engine the next day, problem returned
• Ran the engine for 4 hours yesterday, checked mixing elbow today (12 hours later) and NO moisture.

A few more comments:

• When engine is running, very smooth - no misfires, no weird sounds - mechanic said it purred.
• Can restart engine easily if it's been running for a while, you turn it off, and then turn it back on
• Seems that any time you change something (i.e. starter, filter, reground, etc.) engine starts right up, then is back to its old tricks the next day.

So with all of that said, any thoughts? Our current thought is leaning towards the head gasket leaking - perhaps not fully blown, but on its way. I'm trying to figure out if there are any other things we can check before we take apart the engine.

Thanks!

Chris
s/v/ Pelican
s/v Pelican - Following A Dream

[Mainebristol]

My immediate thought is the transmission. I'm sure you've checked, but is slop in the shifter leaving it in gear some of the time? Has the transmission been serviced recently? I know, this is far fetched, but you didn't mention it, so I thought I would. How is the oil? Again, obvious. Air filter? Restricted breathing might cause this, and it's easy to check.
My point is that something is restricted. If your starter is working that hard, it's clearly fighting something. A siezed pulley leaps to mind. All of these are dead easy to check, and should take less than ten minutes, tops. Alternator siezed? Again, obvious.
A quick test. How does it turn with the cylinders opened up? Mine spins like crazy, which is a quick way to lube the engine before starting it. If yours does too, you've just eliminated most of my ideas. But not the airfilter. A locked water pump could do this as well. So very easy to check.
All of the accessories drag on the engine, but if any one of them seizes, that would account for your symptoms, which leads to another obvious question; how is the belt? Is it leaving black powder all over the engine space? A dead giveaway that it is slipping on something. In all of this I am assuming that something cheap and far more prone to failure than the engine has done exactly that.

Best of luck!

Maine Bristol SV Eider, B32 (Yanmar y2f)

[Labatt]

Belt is good... it was throwing some black powder but we replaced it and still have the issue. The airfilter appears to be in good condition. We have to do the cylinder test still. I agree - something is stopping it up and it's just a matter of finding it. Good suggestions.

[Chief Engineer]

I would put a new battery in first. (Load tests don't always give a good picture)

Are the cables heating up when attempting to start?

Does the shaft attempt to rotate when you start it?

Have you hooked up a remote starter switch? (To eliminate any ignition switch problems?)

[boden36]

The reluctance to crank (maybe water in a cylinder),the low revs under load,and the overheating all point to a blown head gasket, cracked head or similar. If you can, look into your coolant header tank with the engine under load - if there are bubbles coming up that would confirm the diagnosis. Regards, Richard.