Loss of Power on Yanmar 4JH3-HTE

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Posts: 272
Joined: Fri May 07, 2004 9:29 pm
Location: Punta Gorda, Fl 33955

Loss of Power on Yanmar 4JH3-HTE

Post by Allezcat »

I've had this happen twice now and thought I'd pass it on for info.

Symptoms: Engine will not come up to full power (RPM's) and black smoke emitting at half throttle and above.

Remedy: First - Check all fuel filters clean.
Next - Remove the air cleaner on the engine and with your finger reach in and try to spin the turbocharger rotor.

If it is frozen or difficult to turn (like mine) remove the turbo charger (big job).
Separate the cast iron exhaust section from the intake (compressor) portion (with the bearings)
If the rotor now spins freely, clean the interior of the cast iron exhaust section (I used a Dremel tool)
If not, replace the turbo charger
Reassemble the exhaust and intake sections. Check to make sure the rotor still spins freely
Reinstall the turbocharger using new gaskets and seals (keep oil passages in turbo clean and oil them on assembly)
Sea trial for proper power output. Give yourself a pat on the back.
Time for a Sundowner!!

1st mate
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Re: Loss of Power on Yanmar 4JH3-HTE

Post by Nick »

Here’s a variation on the theme. We are suffering a loss of power on the starboard engine. Will spool up, but nowhere near as fast as the port side and won’t get beyond about about 3,200rpms. No black smoke. Replaced the primary and secondary fuel filters to no effect. The primary filter (the Racor not attached to the engine) was slightly deformed (twisted) which is something I’ve never seen. Oil pressure is good, temps are good and no unusual smoke. Have not tried to remove the air filter, but have looked at it and it seems really tough to access and manipulate....like many things in the engine compartment.

Still underway and heading to Stuart and hope to have someone there give it a look. Of course any thoughts are welcome.
Nick & Barb
2005 PDQ34 #66

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