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Engine woes ... Yanmar 1GM

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Jan 20, 2009
15
Endeavour 32 Fredericton, NB
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Hi Scott,
Twice I've had problems like that. First time it was old impeller pieces that had been lodged in a benign place that moved to a smaller gap downstream and partially plugged the system. Delayed problems from a prior owner's negligence. In the other case I replaced my circulation pump (raw water cooled engine) with a more powerful pump thinking that would address my occasional overheating. Whenever I revved the engine the now stronger suction would close the hose upstream between the pump and the strainer by the through hull. The hose worked fine at low revs and with the less powerful pump. I replaces the heater hose that was there with suction rated hydraulic return hose and the problem was gone. The hose I used was from Parker - cheap, resists heat, oil, pressure and suction - and probably available off the shelf in your town from the local industrial hose/hydraulic supplier.
Paul
New Brunswick, Canada
 
Oct 26, 2008
4,269
Starwind 27 Barnegat, NJ
Well, I am basically concluding that I've got worn piston rings. I had a lot of engine oil in my air filter, and I get "blow-by" when I open the oil fill cap or dip stick. I don't appear to have any water in my engine oil so I don't think I have a problem with the cylinder head or head gasket. The weak flow from the exhaust seems to be another issue that I haven't resolved. I don't over-heat, but it seems that I am collecting warm water in my bilge when running ... I have to find the source and I haven't looked very hard yet. It hasn't been obvious, though. All the hoses and fittings are clear so I am still somewhat mystified. I seem to get less flow as the engine warms ... I removed the thermostat and it seemed in working order. I am going to take it out and put it in a pot of water on the stove at home to see what happens.

When I removed the air filter, the smoke went from gray to blue-white. I noticed last year that I did have to add oil near the end of the season, which was unusual. This weekend, I am going to check compression with a guage. I spoke with the folks at Mack Boring and the gentleman said to see if I have any problem removing the injector (hopefully it's not corroded tight), but since I am in fresh water, it shouldn't be a big problem. I am going to have them do a service call to test the valves and injector.

I guess I'm looking at about $3,200 for a re-build of a 1GM possibly unless I can get the cost down by doing a lot of the work myself (not the honing and that stuff), but this would include a new piston and new rings, 1,000 hour warranty, and a new paint job and hopefully a nice long extended life.

OTOH, I've been mulling it over and I kind of like the idea of installing a new 2YM15 whichis 2-cylinder and fresh-water cooled with a heat exchanger and all the new technology. Assuming my tranny is good and fits, (it was re-built recently) I would spend about $7,000 for the engine (w/o tranny). I can exchange my 1GM, or sell it, as it seems there is a market. The footprint and space seems to fit, although a little more tightly. It weighs about 60 lbs more.

hmmm......

I can probably sail the boat this summer and run the engine at a bare minimum if the conclusion is piston rings are wearing and the re-build can take place in the winter anyway. Or, I may just yank the boat and spend a summer taking care of business and put sailing on hold .... haven't decided for sure. I'll see what the service tech says ...
 
Apr 15, 2009
76
Hunter 27 beacon ny
Anodes are necessary thats why all domestic hot water heaters have them. It is an open system mixing oxigen/heat/water = CORROSION. Chances are a chunk of rust is lodged in the Cylinder jacket or Head and restricting flow and your engine is over heating. Couple that with a possibly worn engine to begin with plus mismatched prop. Most of the little single cylinder marine diesels (under 10hp) have the same design parameters. As mentioned above, you need to stay within op. temp. I would try to flush and back flush cooling circuit.
 
Apr 15, 2009
76
Hunter 27 beacon ny
BTW if your on that lake you could easily get by with a 6hp 25inch outboard and ditch the diesel and save $$$.( Cost of motor more than boat value?) I sail on the Hudson by Beacon NY and have been using that set up on H27 no problem as temp solution . Even motored to NYC with it. Just found replacement diesel so I'll be swapping it out soon. Not the most attractive but could have advantages in you particular case..(no tide/current/lighter boat/room below). Contact me if more info needed I'M not far away.
cheers Frank
 

jrowan

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Mar 5, 2011
1,291
Catalina 30 N/A
Scott, My neighbor at my dock also sails a 27 ft. Starwind, an '85 model I believe. I recall his engine blowing out a good stream from the transom discharge, so you've definitely got a water flow blockage somewhere. I used to have a YSM8 - very similar to your 1 cylinder Yanmar. When I replaced my water pump, I recall that the shaft which runs from the engine drive to the pump was built in two pieces, split down the center. I also remember that it has to be installed & seated with perfect alignment to the engine, or it wont turn correctly. Have you verified that the pump impeller is turning correctly? Also check that the cam inside the pump hasn't slipped, etc. I think your cooling problem is probably with your pump or blocked from the zinc you installed. If it worked before you made these changes then assume its something you changed out which is not installed correctly. Before you consider a rebuild, have a pro. diesel mechanic perform a proper compression test. If the rings were really worn on the piston, then the engine wouldn't even start, as a diesel has to have at least a decent amount of compression to start in the first place. Sometimes its cheaper in the long run to get professional advice & not keep wasting time & money. Just make sure U get a really experienced mechanic, & one who's not just trying to sell you on a rebuild to line his pockets.
Ps. My neigbors Starwind also through off a lot of belts on the alternator pulley because it likes to loosen up on its own at the retaining bolt. Check it for proper tension. Good luck.
 
Dec 30, 2009
679
jeanneau 38 gin fizz sloop Summer- Keyport Yacht Club, Raritan Bay, NJ, Winter Viking Marina Verplanck, NY
Try pulling the raw water intake hose off the valve and drop it in a 5 gal bucket, see if flow improves. Red
 
May 24, 2004
6,045
CC 30 South Florida
Cylinder blow-by? Increase the viscosity of the oil. I have ran well worn engines past past their death throes by using oil additives designed to increase the viscosity. By increasing the viscosity you actually increase compression and reduce blow-by.
 

jrowan

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Mar 5, 2011
1,291
Catalina 30 N/A
Slightly higher viscosity, especially in the summer months is o.k. But the problem occurrs when you run the engine in cold temps the oil gets so thick when its cold, it takes longer for the oil pump to send it through the internal components. Very thick oil gets gummy and can actually start to block the oil flow through the engine block jackets. In the end it will do more harm then good. But if the engine is already blowing by oil, then its probably on its way to a rebuild anyway.
 
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