3YM30 broken impeller blades

[Ken Honeycutt]

Posting this as a follow up to an earlier post about retrieving broken impeller blades from a 3YM30 on a Hunter 36. I followed Kloudie and JohnT's suggestions on where I might find the broken blades. Posted a few photos of where I found them in case anyone else has this kind of problem. It was a fairly simple procedure but somewhat time consuming and after awhile it was a little hard on the knees. I removed the alternator after disconnecting the battery ground wire so that there wouldn't be any chance of melting a wire. When I first looked at the alternator I thought Yanmar had run a bolt all the way through the mount (somewhat like an automobile alternator) looked like the bolt head was facing toward the engine block so it would be impossible to pull the bolt out. No problem though as I quickly found that wasn't the case (if I had bothered to look at the shop manual before starting I would have seen it was bolted on both ends). What I did find out though, was that the clamp holding the sea water inlet hose to the HX was loose enough that I could rotate it by hand. Hate to think what might have happened if the hose worked loose while motoring. Probably not an issue though because it was impossible to move the hose. If it ever needs to be removed will most likely either have to cut it off or apply some heat.

The heat exchanger cover was held on by 3 allen head bolts, the bottom bolt requires a short allen head wrench in order to turn the bolt head. The blades were laying in the bottom of the HX right where Kloudie said they might be. The O ring was still in good shape so I was able to re-attach the cover and after running the engine for a sail later in the day I experienced no leakage.

Bottom line - not a hard job but be prepared to spend a couple of hours and few cold ones. Also helps if the boat is sitting fairly still as I got a slight case of sea sickness leaning over the engine while the boat was rocking at the dock.

Later in the day after coming back from the sail, I opened up the galley sink drain seacock and water poured out of the broken fitting on the drain hose where it attaches to the seacock. Naturally the local WM didn't stock a 1" pipe to 1 1/2" drain hose.

 

[Allan12210]

I did not catch your earlier post but I did the following with my friend's 4 cyl Yanmar. Took the plate off the raw water pump and removed what was left of the impeller. Stretch a sock over the pump. Disconnct the water hose at the mixing elbow and jam the water hose from the dock into it. Have someone turn on the water. The backflush pushed all the fragments back from the heat exchanger face into the sock. Have not had an issue with temperature so we figured we got all the debris.

Allan.

 

[kloudie1]

Good job, Ken.. Glad that worked for ya.

 

[seadaddler]

Great

Nice job and glad it all worked out for you and will need to check that out if ever happens on my 36 with same yanmar,thanks for info.
Nick

 

[Ken Honeycutt]

Re: Great

Thanks Nick. Hopefully you won't have go through it on yours. Might want to check that clamp though - don't know if it was something they missed at the factory or even if it is something to worry about but I was kind of suprised when I was able to move it by hand.
Allans idea of backflushing the HX from the mixing elbow sounds like a plan to try in the future before pulling everything apart..but if you're stuck somewhere offshore pulling the alternator off is probably the only alternative.

BTW, say hello to Joe when you see him down there. We were club members together here in Chicago.

 

[John T1594]

Nice job

Loose clamps are also a problem on my engine. I can run all summer and not get a drip from any hose on my engine or loose (or smell) any coolant - but come winter, with below freezing temps when the engine is in storage and I find a small pool or two of engine coolant under the engine, and once behind the domestic water heater. Only a a small amount, less than an ounce, but troubling and this happened year after year. I systematically went around the engine and tightened every clamp I could find (and reach) and the problem has seems to be solved. My current theory is that the the extreme cold shrinks the metal barbs on the engine just enough to let the coolant leak around the hoses.

Just a note on the lost impeller blades - on my engine 3GM30F - the heat exchanger is up high and unobstructed, making it a simple job to remove the inlet cooling hose or the front cover without removing other engine components.

 

[Marc14857]

Loose clamps are also a problem on my engine. I can run all summer and not get a drip from any hose on my engine or loose (or smell) any coolant - but come winter, with below freezing temps when the engine is in storage and I find a small pool or two of engine coolant under the engine, and once behind the domestic water heater. Only a a small amount, less than an ounce, but troubling and this happened year after year. I systematically went around the engine and tightened every clamp I could find (and reach) and the problem has seems to be solved. My current theory is that the the extreme cold shrinks the metal barbs on the engine just enough to let the coolant leak around the hoses.

Just a note on the lost impeller blades - on my engine 3GM30F - the heat exchanger is up high and unobstructed, making it a simple job to remove the einlet cooling hose or the front cover without removing other engine components.

John

Many of us get that small pool of coolant under the engine during winter storage. I did on my H356 and on my H44. One possible explanation offered up on this site awhile back is that under the winter cold temps, the forward seal on the cooling water pump shrinks just enough to leak some coolant. Sounds plausible to me.