Generator using oil

I have. Westerbeke 7.5 generator. It's using about a quart of oil every 10 hrs . It doesn't get much of a load only small refrigerator and roof top air . The meter is showing 1,100 hrs . I think it's only had a light load all its life . Could the cylinder walls be glazed over , the rings stuck or is it just worn out ?Is there a way to check off all of these possibilities short of removing the head ?

Sorry if I'm misunderstanding, but it sounds like you think light​ loads are a good thing?

That is not the case. Low loads cause insufficient heat in the combustion chambers to burn the fuel properly. This causes carbon to build up and shortens engine life.

john61ct said:

Sorry if I'm misunderstanding, but it sounds like you think light​ loads are a good thing?

That is not the case. Low loads cause insufficient heat in the combustion chambers to burn the fuel properly. This causes carbon to build up and shortens engine life.

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No I think light loads are a bad thing . I would put more on it if I had something. I'm thinking that the light loads might have caused the walls to glaze over .

Not familiar with the unit but does it have any sort of oil cooler. Is the any oil in the coolant? Does lube oil look and smell normal? Are you using the proper weight non synthetic oil?

Pack Mule said:

No I think light loads are a bad thing . I would put more on it if I had something. I'm thinking that the light loads might have caused the walls to glaze over .

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Heating water, A/C and making ice are the more useful load dumps. But even a useless one like searchlights would be better than nothing.

Light load, particularly where you run the genset at night and the A/C is cycling mostly off can certainly glaze the cylinders and cause high oil consumption. And if that is the way you have run it from new, it may never have gotten broken in.

Years ago on boatdiesel, Tony Athens said that he can often bring these back by loading them continuously to 80% load- 6 KW for your unit, for eight hours.

It will take some creativity to do this, maybe by hooking up four 1,500 watt space heaters. But that much power will probably overload your convenience outlets so it may take a direct wired heavy cord to do that. Also depends on whether your genset is wired for 240/120V or just 120V.

If that doesn't work, the only other solution is remove the genset, disassemble head and piston and run a hone down the cylinders.

It is very unlikely that your genset is worn out.

David

bayview said:

Not familiar with the unit but does it have any sort of oil cooler. Is the any oil in the coolant? Does lube oil look and smell normal? Are you using the proper weight non synthetic oil?

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I don't think it had an oil cooler but I will check .No oil in the coolant. Lube oil seams darker than the main engine and changed almost at the same time . No funky lube oil smell , but can smell burning oil while running .

if it has smell while running most likely problems with rings, and given the apparent low hours, you may have had some kind of premature failure, not just wear. I have a really old wb 8kw with 2k hours that (once I fixed the oil leaks) uses nothing between oil changes. Also, many different opinions about loading or lack thereof causing failures vs. longevity - bottom line, it is what it is, I think I'd do a compression check.

If you have a cap or plug in the valve cover do you see steady smoke there. What does it smell like? any regular puffing?

The roof air should draw about 10 amps, and you probably have a couple of out let's to plug in other items. Also I would go with a straight 30 weight oil, not the thin multi weights that are popular today. I use straight 30 weight in boat and truck engines. Old school.

The big queston is did the high consumption start all at once, or did it creep up over time?

A quart of oil every 10 hours does't just disappear. I can think of four places the oil can go:

Leak in oil system to outside of generator. Should be visible in bilge. What is underneath your generator

Oil leaking into the coolant. I don't remember that the 7.5 has an oil heat exchanger. If the oil is leaking into the coolant then you would be increasing the coolant level in the overflow container.

Oil is leaking into the exhaust water, this would be easy to spot as you would have a sheen on the water outside of the boat. A single drop of oil causes a sheen that is visible.

Oil is burning, most likely, two indications are blue or grey smoke.

Good luck. Something is wrong and you need to find out what.

A small generator always run under light loads will usually glaze the cylinders, burn oil, sometimes in 1000 hours. Wet exhaust engines usually leave some sheen. 1800 rpm engines are not as bad as 3600 rpm engines. 1200 rpm engines are usually heavy duty and not bothered as much. There is really only 1 solution. Pull the pistons, lightly hone the cylinders and restore cross hatching, install pistons with new rings. That should give close to new results.
My current boat came with and Onan and Perkins, both 14kw, both run many hours on light loads. Honing and new rings fixed the Onan. I did a full overhaul on the Perkins because of age (1972). Good time to change crank seals, too.
While you're fixing stuff, most generator ends are single bearing. The engine is one bearing and the back of the generator has a sealed bearing that needs to be replaced every 5 years because the grease gets used up. Letting the bearing go until it fails costs much more.

Thanks everyone. I've got a good checklist. I may have to run the rest of the summer without ac while cruising . I may be wrong about a quart every ten hrs . I'm going change to the oil and run it a while and keep a check . It's not leaking anywhere . I almost don't need it except for the ac. We're light weights and don't anchor out much., mostly stay in a marina at night .

Mule

It may be worthwhile to load your genset way up, heaters, hot water, AC, stove or whatever to get it maxed out. Then run it for an hour or so watching temperature gauge, water flow and color of exhaust. Loading it will maybe clean it up a bit or better show where a problem may be.

Knowing nothing about this 'glazing' problem, I Googled. Here's an interesting tidbit from Fischer Panda: http://www.fischerpanda.com.sg/uploads/4/3/5/6/43569463/carbon_build-up_and_cylinder_glazing.pdf

There were a few hits for various magic additives but none from later than 10 years ago and none from reliable sources.

Bummer!

David Marchand and Sunchaser both suggested loading the unit up with whatever - baseboard , portable 1500w heaters, what ever will add a bunch of load. Borrow some, ask around. Run the gen. seriously loaded for a bunch of hours and maybe it will clear up the glaze.
Worth a try.

I've known people who do that, run their baseboards to add to the load simply to prevent glazing and leave the doors open in warmer weather to dump the heat.

Pack Mule, Just after acquiring my boat,I think managed to glaze mine by running it for maybe 8 hours no load, until I realized the eutectic refrigeration compressor had died and was drawing zilch. There was blue smoke wafting from the exhaust and it was using oil. I realized what was happening and gave it other loads, but it stayed smoky.
I researched on the internet(uhoh)and came up with a diesel engine additive(uhoh snake oil alert!) made by reputable Australian engine oil supplier Nulon,which Nulon claimed would remove glazing if used at double strength. And it did. I hear all the background chortling laughter, but it worked. The thing stopped smoking and using excessive oil. That was 7 years ago, the Onan 6.5 3 cyl genset runs fine and uses little oil. Out of respect and because there is a possibility of underloading I still use the stuff in the genset oil at the normal dose,I don`t bother for the main engines, no glazing there.
If you believe any of that, try some internet searching. No way you will find that Aussie product over there, but there may be something else similar. And the advice to run at 80% load for an extended period might be right on the money too.

These days shipping costs can be minimal, I buy stuff from New Zealand all the time, gear from Taiwan, Hong Kong, Shenzen, Singapore, even with shipping cheaper than driving down to my local big box.

Glazing might be difficult to remove with chemicals but I would think stuck rings are more possible.

Low load gives low combustion pressure , and it is the combustion pressure flowing behind the rings that cause a good seal.

AS an experiment I would add some of the de-carboning stuff the outboard shops use , and attempt a hard run 80-100% load for 4-8 hours , then a hot oil change to straight oil.

The cost of the experiment would be very low and the results could be worth the effort.

Good Luck!

seafoam will help with glazing and coked rings if thats the problem, you can run the gen on it alone. if you can get a small borescope in the injectors hole you may be able to see if its glazed.

I am not recommending this solution because my experience with it is far too old to remember the precise details, but I present it only to support the possibility of a simple "snake oil" like solution to cylinder glazing.
In the early 1970's we had some new Cat motor graders with a totally new engine design (if I remember correctly they were the first series of 3406's). They had chrome faced rings, and in some new engines the rings simply would not seat, with resulting huge blowby and oil consumption. In due course Cat came up with a "kit" to correct this problem. The "kit" came in an official Cat box, with an official Caterpillar part number. Inside the box was a can of Bon Ami cleaner, and an instruction sheet telling you to remove air cleaner, shake the Bon Ami into the intake of the running engine, change oil and carry on. It worked.

When I was looking at buying my current boat, I asked a mate of mine who works on massive power generation units for the mines all over Australia, about what to look for with the old Onan 6.5kw genset installed on the boat. He told me not to worry if the Onan had glazed bores, he said he would just load up the generator with load and shove some Ajax powder cleaner into the air intake which would scour the bore, I looked at him with disbelief, but he assured me that was what they do in the power generator industry with glazed bores, anyhow my Onan checked out ok, but I load it up everytime I run it