Westerbeke genset 8.0 btd won’t stay running

Oil pressure, exhaust temp, water temp. Checking for short to ground
 
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Sorry, should have known that. It's just checking continuity on them. They should all have continuity I believe. Something goes wrong, sensor opens and kills circuit.

Oil pressure might be opposite, can't recall.
 
image.jpg I need to brush up on some dc electrical knowledge. I replaced the diode in the control box that was testing bad. I still have the short to ground however. I tried bypassing the oil pressure switch by just connecting the 2 wires and still blew the 8amp fuse at the control box. I then tried plugging those wires back in and bypassing the water temp switch doing the same thing and fuse blew again.

another thing I don’t understand is that I have what appears to be 2 oil pressure switches next to each other but the book doesn’t show 2. Could these wires have been connected incorrectly between the 2 switches?
 
Unlikely that your oil pressure sending units’ wires were mixed up since it worked previously.

My last Generator, same brand, had the exact same symptoms you do.

I don’t recall what eventually fixed it and I did just what you’re doing now but one day I said F the investigating and testing and replaced every sensor (maybe there are only 3 of them) and both oil pressure sending units and then put the fuse and diode back in and all worked.

The oil pressure switches may actually have some resistance parameters other than something as binary as open or closed.

Sorry I can’t be more specific and good luck.

J
 
First thing is to test that the 3 switches are not grounded. There are 3 switches to be concerned about. The exhaust temperature switch, water temperature switch and the oil pressure switch. They all have 2 connectors. Pull off both spade connections on one switch at a time.

Use the continuity or resistance setting on your DVM. I like to use the sound on mine so I don’t have to look at the meter. You want to touch one probe to one spade connector at a time and the other probe to the body of the switch or any other good ground point on the block. You should have an open circuit ie no continuity between the switch spade connector and ground.

In my case one of these had failed to ground. They are cheap and easy to replace.

Edit: I added this picture...you want to check the switches between the spade terminals, and the switch body...there should no continuity or infinite resistance.

AAA.PNG







9D964751-87E2-4477-9A52-C933F30A05C0.png
 
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The second test you can try is to jumper out the switches to remove them from the circuit.

Get a 6” length of wire and crimp on a male spade connector on both ends. Remove the wires from one switch at a time and insert the jumper into the wire harness connectors. Start and run the generator. If the generator runs, that’s your bad switch.
 
TRG said:
View attachment 133106 I need to brush up on some dc electrical knowledge. I replaced the diode in the control box that was testing bad. I still have the short to ground however. I tried bypassing the oil pressure switch by just connecting the 2 wires and still blew the 8amp fuse at the control box. I then tried plugging those wires back in and bypassing the water temp switch doing the same thing and fuse blew again.

another thing I don’t understand is that I have what appears to be 2 oil pressure switches next to each other but the book doesn’t show 2. Could these wires have been connected incorrectly between the 2 switches?
Click to expand...
The second switch is for the SR Systems Monitor
 
One other note…the wires don’t have polarity, so wires don’t have to go one a specific connection.
 
One other thought...

Is your new diode connected in the correct orientation/polarity? There are essentially one way current valves. If installed backwards, that may still cause your fuse to blow. Post up a couple pics...close up and a little wide out so we can see whats going where.
 
dtfeld said:
One other thought...

Is your new diode connected in the correct orientation/polarity? There are essentially one way current valves. If installed backwards, that may still cause your fuse to blow. Post up a couple pics...close up and a little wide out so we can see whats going where.
Click to expand...
It shouldn't the generator simply wouldn't start. All the diode does is bypass the oil pressure switch so the unit will start without oil pressure closing the switch.
 
ttmott said:
It shouldn't the generator simply wouldn't start. All the diode does is bypass the oil pressure switch so the unit will start without oil pressure closing the switch.
Click to expand...
So much for my memory...should have had that second cup of coffee this morning.

If installed incorrectly, no power to the K2 Relay, no start.
 
dtfeld said:
So much for my memory...should have had that second cup of coffee this morning.

If installed incorrectly, no power to the K2 Relay, no start.
Click to expand...
I've been up and working on the B-O-A-T since 6; coffee already done. Replacing the sanitary lines; I can surmise this is like roofing a house - these are things to pay someone else to do.
 
So were back to a bad switch grounding out....

See above :)
 
I have checked all the switches touching 1 lead from the multimeter and the other two the outside of the switch with no paint on it. I get a reading of OL which is open I believe. I have checked both posts on all 3 switches and all show OL. I also jumpered each switch 1 at a time and blow the 8amp fuse each time still. Could this be an alteranotor problem possibly as shown at the end of ttmott’s link in this post?
dtfeld said:
First thing is to test that the 3 switches are not grounded. There are 3 switches to be concerned about. The exhaust temperature switch, water temperature switch and the oil pressure switch. They all have 2 connectors. Pull off both spade connections on one switch at a time.

Use the continuity or resistance setting on your DVM. I like to use the sound on mine so I don’t have to look at the meter. You want to touch one probe to one spade connector at a time and the other probe to the body of the switch or any other good ground point on the block. You should have an open circuit ie no continuity between the switch spade connector and ground.

In my case one of these had failed to ground. They are cheap and easy to replace.

Edit: I added this picture...you want to check the switches between the spade terminals, and the switch body...there should no continuity or infinite resistance.

View attachment 133109






View attachment 133108
Click to expand...
 
F3836E54-D1C8-4293-AD88-D71895A90596.jpeg One other thing is this is a new to me boat. Previous owner owned boat about 9 months and the generator has had this issue since the owner before him. I am wondering if through different people working on this issue if wires could have been hooked up incorrectly at some point. Specifically at the oil pressure switch and what I believe is the oil sending unit which are directly next to each other? I have 2 black wires which have a pigtail type twist in them a 3rd black wire that is covered in red paint and a red wire covered in yellow paint (see pic). Though probably not smart I tested what would happen if I hooked up the 2 pigtailed black wires to the switch and the 2 straight wires to the oil sending unit rather than how it was originally. When I did this the generator still dies when I let off the preheat but it does not blow the fuse when I have all the leads hooked up to all the switches. Wondering if this is a revaluation or if I just broke the series of connections to the switches?
 
What you did won’t break the switches.

But there is a pretty clear wiring diagram that shows you exactly where the wires to the oil sending unit go.

Just check those, and then also buy yourself two new sending units to replace those that are there now so you’re done checking that part of your troubles at least, which also may (likely in my mind) fix this problem.
 
Here’s how all three safety switches work:

Oil pressure switch: open when engine oil pressure is below shutdown pressure. Around 8 psi. It’s closed when pressure is above that 8 psi. When open it shuts down the generator. That’s why there is a preheat bypass of that switch to start the generator. And why you have to keep that bypass active until the oil pressure is above 8 psi

Engine temp switch: closed at all temperatures below its shutdown setting. Somewhere around 200F. It opens when the temperature exceeds that value. When open it shuts down the generator.

Exhaust temp switch: same as engine temp switch.

There is a second oil pressure switch dedicated to the System Monitor. It is not part of the shutdown circuitry. It’s closed below the 8psi threshold. And open when above that psi. So when oil psi drops below 8 psi it sends a signal to the Systems Monitor to sound an alarm. That is why you hear the alarm when engine is first started and pressure hasn’t reached 8psi yet. On most of these generators the two oil switches are vertically right next to one another. It’s easy to get them confused. See this post on how to tell them apart:

http://www.clubsearay.com/index.php...da-kicking-my-arse.102186/page-2#post-1199931
 
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ZZ13 said:
Here’s how all three safety switches work:

Oil pressure switch: open when engine oil pressure is below shutdown pressure. Around 8 psi. It’s closed when pressure is above that 8 psi. When open it shuts down the generator. That’s why there is a preheat bypass of that switch to start the generator. And why you have to keep that bypass active until the oil pressure is above 8 psi

Engine temp switch: closed at all temperatures below its shutdown setting. Somewhere around 200F. It opens when the temperature exceeds that value. When open it shuts down the generator.

Exhaust temp switch: same as engine temp switch.

There is a second oil pressure switch dedicated to the System Monitor. It is not part of the shutdown circuitry. It’s closed below the 8psi threshold. And open when above that psi. So when oil psi drops below 8 psi it sends a signal to the Systems Monitor to sound an alarm. That is why you hear the alarm when engine is first started and pressure hasn’t reached 8psi yet. On most of these generators the two oil switches are vertically right next to one another. It’s easy to get them confused. See this post on how to tell them apart:

http://www.clubsearay.com/index.php...da-kicking-my-arse.102186/page-2#post-1199931
Click to expand...
Do you know if these 2 oil pressure switches are the same part # or different switches?
 
TRG said:
Do you know if these 2 oil pressure switches are the same part # or different switches?
Click to expand...
They are two different switches. One is normally open, the other is normally closed. In that thread I referenced, a few posts back from the reference post, you can read where I installed the wrong one.

Also, later in that same thread you can read where Tom (ttmott) helped me figure out that all the switches were good, but the preheat solenoid was blowing the 8 amp fuse. I worked around that by disconnecting the preheat solenoid since where I boat the generator starts right up without the glow plugs heating up.
 
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