Westerbeke BCD 5 generator low oil pressure

[bfiegener]

I have a westerbeast BCD 5 generator with approx 1,300 hour on it. It starts up good, runs for a while then the oil pressure starts to drop. It will eventually shut itself down.

I changed the oil, filter, oil sender and checked the gauge and still have the same issue.

I have read that a drop in oil pressure could be caused by worn bearings. Im hoping this isnt the issue but I cannot figure out what would cause it.

Hoping someone can shed some light on this. I assume replacing bearings is a major overhaul.
thanks
bill
s/v Aquila

[a64pilot]

It could be the oil bypass stuck open, or it could be a worn oil pump, or even a cracked dip tube, the tube that connects the oil pump to the sump.
It could even be the wrong grade of oil. I assume you have an oil pressure gauge on it?

Just based on your question about bearings I'm guessing your not a competent Diesel mechanic? I do think one is called for here, I'd say if your sure oil pressure is dropping as it warms up, it's time to call a mechanic

[Lepke]

As oil warms, it gets thinner. Thinner oil has an easier time of escaping the bearings, the oil pump gears, and so on. As a64pilot says there are several items that could be bad. Just changing the bearings doesn't always do it.
Using a thicker oil or a thick oil additive may help. In my day it was STP. Maybe going from 30w to 40w, etc. Also, make sure there is no diesel in the oil. (gaining oil on the dip stick) A common problem with low oil pressure is a seal failing and diesel getting into the oil, making it thin and low pressure.
Use Plastigauge (available at autoparts stores, Ebay, Amazon) to measure bearing clearances first. Info and how to use is online. No point in changing the bearings if the old ones are ok.
I don't consider bearings only to be a major overhaul, but you might. In a small space it can be a difficult and dirty job.

[redsky49]

Replacing the hearings would certainly require removal of the generator which could be a major challenge.

What are the pressures you are observing. My Westerbeke 4.4kw genny usually settles in at about 55 psi when warm, but starts out much lower. I am aware of a main crankshaft seal that is problematic, and a bad water pump">raw water pump seal could allow sea water into the lubrication system.
Other than those issues there are no widespread concerns that I am aware of.

[Captsteve53]

At 1300 hrs only I would be looking at oil pump relief valve spring or similar issue but that means a major strip down,Also confirm there's no diesel getting into the sump-you should notice a rise in oil level/smell

1) What grade oil are you using(regular mineral or synthetic)?
2) Have you double checked with Mechanical pressure gauge?
3) What does the temp gauge show over this period?

Cheers Steve

[bfiegener]

Captsteve, I use 10w-30 which is recommended. I just changed the oil yesterday and no diesel in it. temp is normal after it warms up. Havent tried a mechanical temp gauge yet.
Did read that it could be a bad switch. I dont have a mechanic near by so Im trying to solve this myself.
thanks
bill

[bfiegener]

redsky, It starts off around 50 -55psi then slowly drops to under 25psi. When I put a load on it drops more to the point that it starts to idle down and eventually dies. Sometimes it will idle down and then come back up to full rpms.

[Captsteve53]

OK,

Dug out my Work shop manual and found a couple of interesting points

1) From my manual as below,

ENGINE OIL
Use a heavy duty engine oil or a synthetic oil with an API
classification of CF or CG-4. Change the engine oil and filter
after an initial 50 hours of break-in operation, and every 100
hours of operation thereafter. An oil viscosity of SAE 15W-
40 is recommended for this engine in all conditions.

2) This engine uses an oil pressure sender unit then after that there's a possible two oil switches (one to shut down and one additional if there's an alarm fitted to your panel), so both the sender unit and the switches should be checked/replaced,This mentioned in the fault manual in nearly all possibility of engines nearly stopping and possibly re starting so obviously a known probable failure

OIL PRESSURE SWITCHES
There are two oil pressure switches. One is wired to the
automatic shutdown circuit (see safety shutdown switches)
to protect the engine from a sudden loss of oil or very low oil
pressure.
The other oil pressure switch is available for connecting to
an (optional) audible alarm that would sound a low pressure
alarm (before the shutdown switch activates and shuts the
engine down).
Note that this audible alarm will sound momentarily when
the engine is started and sound again when the engine is shut
off. this occurs as the oil pressure drops below 10 psi.

The manual check would be for the oil pressure not temp! but the above is a good start point,

I also note that it looks like the oil pump is not in the sump at all and sucks the oil up via a long feed tube, the main thing with this the pump and the relief valve may be able to be serviced with out removal of major parts,(I need to do a little further reading to be 100% sure of that first as i was just looking at the schematic of the oil passage,

I did personally feel that your 10-30 was light for this set up, I run nearly the same gen set but an Onan and run straight 40 grade with no issues at all (and good stable oil pressure!)- I prefer these mono grades if not in freezing weather type countries,

Will get back to you after some reading when i get a minute

Cheers Steve

[Captsteve53]

Just to be clear my previous post and inserts are from the Westerbeke technical service manual (i have an electronic copy should you desire)

Summing up I would do the easiest thing first and that is:

1) immediately try running standard mono grade 40 weight

2) Change out the oil pressure switch(you said the sender unit was new correct?)or if your model has the two switches swap them over and check what happens
3) Install a mechanical oil pressure gauge to check real pressure, it should screw in place where the oil sender unit is mounted,

I note that the oil pump is located in behind the front timing cover(so also a big job if needed),

Lastly the normal running oil pressure for this generator/engine is 30-55 lb's so @ 25 its not far off and a change of oil viscosity may just do it, obviously higher (to a point ) is better but any thing over 30 is fine,

With only 1300 hrs on the clock money is on the oil viscosity or faulty oil switch/sender unit


Cheers Steve

[Dave22q]

My westerbeke 4.0 manual says loss of oil or bad pressure switch and you checked both of those. You might also check 25A breaker tripping and/or loose wiring or switches. Also possible fuel starvation lift pump going bad, fuel valves. As your temps are correct you can rule out cooling and exhaust systems. You might try calling a local distributor. In South Florida it's R B Grove 305-477-0277

[bfiegener]

CaptSteve, correction on the oil type. I did put 15w-40 in it. Havent checked the switches but the problem seems to have gotten worse. We are sailing over to a westerbeke dealer marina on Tuesday for them to have a look.
Thanks for all your help and I will keep you informed as to what is found.
bill

[bfiegener]

Hi Dave, mine only has one switch. I havent replace that one yet. Going to let a mechanic look at this Tuesday. Im not a diesel mechanic. I can do the basics and have a good understanding of them but thats it..
thanks for the help.
bill

[Cheechako]

I'm not sure the model but when I worked at the boat shop we installed a couple small WB generators. As I remember we had a lot of issues with auto shutdowns on them. But you have had yours awhile and I assume it was good before. At any rate, before getting into something that is a lot of work, make sure it isnt shutting down when it doesnt need to.
BTW... what is the oil pressure when it's "low"?

[bfiegener]

Cheechako
Starts off around 50psi, drops to around 25psi and eventually drops to low and shuts down.

[bfiegener]

Got the genset fixed. Turns out it was the fuel shutoff switch heating up and slowly starving the generator of fuel. Would never have suspected it. $500 later and its running great. Thanks everyone for your input.