Exsisting Engine Or New

[Noreastern]

We are refitting our sailboat for full time cruising. We have a 1998 Yanmar 3GM30 28 HP diesel that has always run fine for the seven years we have owned it but has never had a hour meter. Since we have owned it we have put less then 500 hours. We have never had to add oil between oil changes however it has always let out a grayish blue smoke from the exhaust. We will have to remove engine to change shaft, stuffing box and cutlass bearing during the refit. If a compression check on engine is good should we still think new since the engine will have to come out anyway? New $12,000, around $9000 total after selling old engine we are told.

Appreciate any thoughts, we know this could go either way.

[atoll]

chances are the engine has less than 1500 hours on it,unless it has serious corrosion issues keep it and spend the money on important stuff like sails, wind pilot,solar and inverter which will reduce engine hours when cruising long distance.

[mbianka]

Well my diesel died at 1900 hours. Was a pretty good engine until one day I started it and a plume of grey smoke came out and it went from a good engine to no starting in six hours. Engine gasket leaked water onto one of the cylinders cracking it. Decided at first to go with new diesel then explored going to electric propulsion and could not be happier. That was six years ago.

I sold the non working engine to a fellow who rebuilt it. Did all the work himself and it cost him $3,500 in parts alone. Engine ran for two years and then had injection pump problems so the guy scrapped it. I would say if the compression test comes out ok stick with what you got. Save the money but, put some money in the budget for repairs down the road. Also remember it is a sailboat.

[sailorchic34]

If its not using oil then most likely the engine is fine.

The blue grey smoke may just mean that the injector limiter got loose and needs to be turned clockwise a 1/4 turn or so to stop the smoking. The injection limiter is under the acorn nut on the front timing cover below the injection pump and is basically a stop for how far the injection pump will open.

Normally set at factory and never ever messed with. Small changes counter clockwise will make the engine smoke and too far clockwise will cause cause poor acceleration.

As someone who just rebuilt her 3gm30 (dropping it back in tomorrow) I say if it starts easy and does not use oil then the engine is fine. Might want to check the valve lash and discharge elbow for blockage but that's about it.

[Noreastern]

Thanks all, So far your responses are making Tara and I happy.

[Bruce B]

Hi. I offer up one additional issue to consider - it favors keeping your existing engine. New Yanmar engine clutches are not designed to prevent the prop from freewheeling by putting the engine in reverse when you shut the engine down to go sailing. In fact. the warranty expressly excludes this type of operation, which is pretty common among sail boat operators. OK, if you have a folding prop, but a pain and a major issue otherwise. I bought a new Yanmar & the clutch (forward) failed w/i 200 hours. First question from the installer - did you ever sail the boat with the transmission locked in reverse. Installer declined to cover since I had (on three occasions) locked the shaft in reverse on the way to feathering my folding prop. Ultimately the repair was covered (since it was forward gear), but it took some effort (and lawyerly persuasion). My prior Volvo transmission was a tank, and I'm not sure I did the right thing in replacing rather than rebuilding when it swallowed a valve. B

[gordwedman]

In addition to checking compression you should check oil pressure when the engine is fully warmed up. See if it meets the specs at idle RPM and at whatever higher RPM is specified. A mechanical pressure gauge is probably more accurate than the electric version. If the compression and oil pressure are good and it starts easily it will probably go for many more years.