Yanmar 4JH3-TE missing impeller blades...

[Tspringer]

I am hoping someone has some experience and good ideas on this.

I changed the impeller on our Yanmar 4JH3-TE last year and it was missing part of one blade. I spent about an hour trying to figure out where it may have gone and how to get it out but gave up due to time constraints. Running the engine it runs fine and pumps plenty of water out the exhaust.

Now I am doing maintenance and would like to try and find the piece and any other pieces from previous owners that may also be trapped somewhere.

There does not appear to be any way to remove the end fitting on the heat exchanger without basically disassembling all components off of the port side of the engine. Turbocharger - entire fresh water cooling system - exhaust elbow - everything. Estimate 2 full days. I'm not going to do that unless or until I am replacing one of these main parts.

Anyone know of a better way?


Terry

[skipperpete]

Does your 4JH3-TE have an oil cooler across the top of the flywheel housing, on the 4JH4’s the cooler is connected in the raw water output pipe just before it enters the heat exchanger so you could be lucky and only need to remove the oil cooler. Not all missing impeller blades migrate through, sometimes they remain in the pump, often in the intake port at the cam

[Tspringer]

I think I found a solution. Reverse flush the entire raw water system.

Going to disconnect the raw water line from the exhaust elbow and output line from the raw water pump. Then connect a hose from the raw water pump output hose that can drain to a big bucket. Next I will use the dock pressure water hose to flush through from the exhaust elbow raw water hose and out the raw water system into the bucket. I figure any impeller blade pieces will get flushed out with this method and nothing has to be completely removed.

[Shrew]

I would think you'd risk back flooding the engine through the exhaust ports.

I'd just follow the raw water cooling system from the raw water pump. If it's not in the hose from the water pump to the oil cooler, or the oil cooler, and it's not in the hose from the oil cooler, then I'd expect to find it in the end cap of the heat exchanger.

[ScottRhodes13]

Back flushing sounds like a good idea, but I'd do each component separately, gear cooler, oil cooler, heat exchanger. Otherwise you risk pushing a piece back and getting it stuck elsewhere.

[hpeer]

Yanmar 4JH4-TE here. I bought the boat with 672 hours on the engine.

At 2,000 hours I had a Yanmar mechanic do a 2,000 check part of which was removing the heat exchanger and cleaning it. This was preventative maintenance, the engine had no issues aside from a totally unrelated turbo matter. The engine ran fine with no over heating.

He found an ENTIRE set of impeller blades in the heat exchanger. He was amazed at what he pulled out and made a point to show me the fist fill of rubber. IIRC the blades were just at the entrance to the exchanger and never entered it, as far as we know.

Last year the water pump was starting to leak oil. I engaged a well respected mechanic. What I was told was that some parts of MY water pump we very difficult to rebuild. I can not recall the details but there was some part that was very fragile and difficult to install properly. So this mechanic would only replace the entire pump with new. On my engine is very difficult to get this off without removing an engine mount, maybe impossible? I am around 2,700 hours so I had the pump replaced AND the engine mounts at the same time. The engine now has less vibration. I used the asymmetrical mounts. Difficult to get a firm recommendation on that, but they worked for me.

Best to make sure you are born lucky.

Last year I had some damn big barnacle growth in my water intake that did give me some temp issues.