[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

 

[timebandit]

You don't leave much to check do you?

I'm thinking electrical------

Is the starter solenoid on the start and replaced with the new starter or is it a remolt ford type (big heavy duty switch mounted on a wall somewhere?

An engine with low compression usually will crank faster.

I would go back and check everything conected with the starter.

You didn't mention if you checked the front end accessories to be sure they are not the cause of the drag.

The winding up at start up and then low power at cruise leads me in the direction of not enuff fuel being metered by the system. The no smoke after a long crank kinna hints at that.

Lets us know what the gremblin is when you find it.

 

[timebandit]

You don't leave much to check do you?

I'm thinking electrical------

Is the starter solenoid on the start and replaced with the new starter or is it a remolt ford type (big heavy duty switch mounted on a wall somewhere?

An engine with low compression usually will crank faster.

I would go back and check everything conected with the starter.

You didn't mention if you checked the front end accessories to be sure they are not the cause of the drag.

The winding up at start up and then low power at cruise leads me in the direction of not enuff fuel being metered by the system. The no smoke after a long crank kinna hints at that.

Lets us know what the gremblin is when you find it.

 

[T37Chef]

FWIW,

If I remember your on your way back North and mentioned being in Rockhall sometime soon, one of the best Yanmar mechanics is there...PM Chef2sail, he just had some maintenance done to his. He and many others I know have said they (I Cant remember who they is) are the best around.

 

[SteveInMD]

An over pitched prop would cause black smoke not white.

If the injectors are dripping fuel it would cause white smoke. If they dripped enough to partially fill a cylinder it seems like it might cause slow cranking until the cylinders cleared. When is the last time the injectors were rebuilt?

 

[donradclife]

This is a tough one, because you have checked most of the probably causes, and you probably need to check them again.

Some thoughts:

Try turning the engine by hand--big wrench on front pulley. When the starter is having trouble, is it harder or impossible to turn by hand??

Water in the exhaust elbow is troubling--could it be from extended cranking without shutting off the raw water intake, or could it be the anti-syphon valve on top of the cooling water loop is blocked??

The starting symptoms could be caused by water in the rear cylinder. When it won't turn over, remove the rear injector and try again for improvement.

Measure the voltage at the starter terminal when cranking--should be above 10V if your connections and batteries are OK. Compare it when engine struggles to when it turns over easily. If the voltage is lower when it struggles, there could be water. If voltage is same or higher, it could be starter/solenoid issue.

 

[labatt]

The company that repowered Pelican 7 years ago is fairly confident that 1) The problem is a partial hydraulic lock and is very likely the siphon break, so we got a new vented loop and when we relaunch Pelican later this week (out of the water for maintenance right now) we'll see if it makes a difference, and 2) The US distributor for Gori is pretty sure that our prop is not coming out of overdrive mode, although we sent it back to them this week for examination and they didn't see any issues with it. They did pull it apart, clean it, replace a couple of things and put it back together, so we'll see if it works any better now. With Pelican being out of the water right now it's hard to troubleshoot.

 

[timebandit]

So the siphon break just works sometimes and why does it only fill the cylinders partially and not all the way when it is not working?

Easy way to check for water is to pull the injector put a rag over the hole and crank--if the cylinder is full of water you will know it at one revoloution--be sure the rag is over the injector hole.

A lean engine----
Hard to start cold
No smoke
No power
Over heats when under a load

I seem to remember someone having a problem with power at cruise and it turned out to be and adjustment screw, not in the linkage but some sort of enrichment screw. Guess I will go hunting.

 

[timebandit]

Here is that link--
http://www.sailnet.com/forums/gear-maintenance/54986-fixed-my-new-diesel-engine.html

I think you are looking for just a adjustment as small as this.

 

[timebandit]

bump!

 

[labatt]

We've been hauled for two weeks and are splashing tomorrow. We haven't been able to test any engine stuff out but will be getting back to it after launch.