YANMAR 4JH4-HTE low Power

[Bart Harold]

This sailing catamaran has 2600 hours on 12 year old engines. No electronics.
One engine runs up above 3200 rpm in neutral but only 2000 in gear. I new to the boat and not sure if it ever hit rpm.
I am running out of a bucket, gravity feed with clear hose and new fuel
Throttle linkage removed
Just had the injector pump overhauled
Just had the injectors tested
Tested injector tubes for obstruction
Checked valve lash
Took turbo to the shop and was told the bearings are good, blade and case erosion minimal. no oil leaks or carbon buildup so I just cleaned it.
Intercooler was just cleaned but had not fouling
No intake filter beyond screen which is clean
No leaks on intake or exhaust plumbing
New exhaust riser
No carbon buildup in exhaust manifold
Replaced 3 inch exhaust hose to water lift
Measured 38 inch water back pressure about equal to the the column hight to goose neck
Propeller shaft is free turning by hand
fixed pitch folding props are original running without vibration. Just cleaned by diver and reported good.
ZF trans has clean oil and turns freely
Minimal crankcase blow-by. No oil in air cleaner.
No exhaust smoke
Starts easy

I am only seeing 5 psi of boost and don’t hear the turbo while I am testing in the engine room
The tack was not strobed but reads 800 at idle and 3300 at wot without load

Next I will reconnect fuel metering instrumentation and plot curve I guess.
Today Im diving to check the prop stamps in the case that one was changed but that is crazy.

Topic

[john Langendijk]

what was the problem ?

Dear Bart Harold,<br />I have the same problem with my yanmar 4jh4-hte, it’s driving me crazy.<br />Have you found the solution?<br />Like to hear from you<br />Kind regards, John Langendijk

[Clark Leighs]

Did you get it sorted out?

I realize this is year late so the question, did you get it sorted out.     

 

If not then retry but also be clear about what you are ASKING about and what help you hope for.

Just a comment is do not just assume the props are OK because the diver say they are.

I am not a prop guy but I have seen enough of them where there is a damaged blade that is NOT readily noticed while on the boat.   On a flat bench  the damage become much more visible.

Also when you are checking tachs then be carefull.   Analogue tachs can often be off enough to be a real problem.    Get a laser pointer digital phototach from Ebay  or  Amazon for ~ $20.00 and then do your testing including actuall dash tach testing at , for example, 200 rpm intervals.     

 

Hope you had success.

[Bart Harold]

Also the Accessory Alternator removed for testing

[Author]

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