Oil pressure problem or just the gauge?

Shark

Shark

Active Member
Jun 16, 2020
200
Sayville, NY
Boat Info
2001 290 Sundancer
Engines
Twin 5.0L EFI w/Bravo II Drives
Took a 10 min ride to the fuel dock the other day, and noticed the starboard oil pressure gauge was only reading less than 20 psi (port was at 40psi, where they both usually are). We were cruising at around 3400-3600 rpm, both engines seemed to be running great, and synchronized. Throttled down into the no wake zone, and the gauge was at 0. No smoke, no noises, engines synchronized. Fueled up, checked the oil (both clean and in the OK zone), and bilge (no signs of oil or anything abnormal). Started the engines back up and the gauge never moved off 0. Engines ran fine again on the way back.

I think it’s probably a problem with the gauge, sender, or wiring in between, but wondering if anyone has any other ideas or suggestions?
 
If you short your gauge sender terminal to ground with the key in the On position the gauge should go to full (80 psi). If it doesn't you need a new gauge.

Another less reliable way to tell if the gauge is dead is to watch the needle when you turn the key to On. The needle should move a little bit when you turn the key to On. If it doesn't move at all the gauge is probably dead.
 
Another method is to swap gauges and see if the problem follows. Same with the senders.

These gauges are not the best, and failures along with flaky readings can be expected.
 
Thanks for the advice guys. I really appreciate it. I’m going to check it out today.
 
I had exactly the same thing happen in my SR 30 Sedan Bridge years ago.
Was convinced it was the gauge.
Wasn’t!
Blew a hole through the block.
Expensive lesson
 
BEH said:
I had exactly the same thing happen in my SR 30 Sedan Bridge years ago.
Was convinced it was the gauge.
Wasn’t!
Blew a hole through the block.
Expensive lesson
Click to expand...
Oh wow..so the engine was running fine for a while with no oil pressure?
 
Shark said:
Oh wow..so the engine was running fine for a while with no oil pressure?
Click to expand...
Was running great, no warning, nothing.
Was cruising about 3K RPM
Then, BANG, put a rod through the block.
Previous to this I was having problems with the gauge, mainly the one on the fly bridge.
That’s why I assumed it was the gauge.
 
BEH said:
Was running great, no warning, nothing.
Was cruising about 3K RPM
Then, BANG, put a rod through the block.
Previous to this I was having problems with the gauge, mainly the one on the fly bridge.
That’s why I assumed it was the gauge.
Click to expand...
Ok thanks for the heads up. I’ll test the gauge and sender before I go anywhere. Hopefully, I get lucky and it’s one of those or the wire.
 
Shark said:
Ok thanks for the heads up. I’ll test the gauge and sender before I go anywhere. Hopefully, I get lucky and it’s one of those or the wire.
Click to expand...

On occasion a wire at the sender or on back of the gauge will build up some corrosion which will interfere with the gauge operation. Be sure to clean up all connections.
 
I just started both engines and gauges are reading 40 port and 20 starboard..so maybe it’s not the gauge..seems like I might have an oil pressure problem..wouldn’t know where to start with that. Might have to call a mechanic now.
 
Did you swap gauges to see if the problem moves? Or swap senders?

A bad sender will give erroneous info.
 
I only pulled the wire off the sender, sprayed some contact cleaner on it. Wire brushed the post on the sending unit and put it back on. Once I saw a reading I figured the gauge is probably correct. Didn’t think about a dirty connection, maybe at the gauge, could result in a lower reading. I’ll remove the gauge panel and clean the connections. Then if it doesn’t change anything, I’ll try swapping the gauges. Thanks again Ron
 
Chip S said:
You can always check your oil pressure with an external gauge like

https://www.harborfreight.com/engin...MIseCOosaH7AIVjK_ICh3TZQXdEAQYASABEgJo5fD_BwE

to confirm the actual oil pressure you have. That would let you know if your gauge/sender is giving you accurate information.
Click to expand...
I might be able to do that, if I can get the sender out. I was barely able to reach it to clean the connection. Maybe if I really dive in there. That would take the guesswork out. This is my first real boat, so I’m learning a ton - I don’t know how some of you guys work on these engines! Lol
 
CaptRonn said:
Did you swap gauges to see if the problem moves? Or swap senders?

A bad sender will give erroneous info.
Click to expand...
Any advice or warnings about removing the panel with all the gauges on it? Looks simple enough - 10 screws...
 
Shark said:
Any advice or warnings about removing the panel with all the gauges on it? Looks simple enough - 10 screws...
Click to expand...

Can you access from behind it? Otherwise it shouldn’t be difficult.

How easy are the access to the senders on the engines?

If sender access is easier, I would try that first.
 
CaptRonn said:
Can you access from behind it? Otherwise it shouldn’t be difficult.

How easy are the access to the senders on the engines?

If sender access is easier, I would try that first.
Click to expand...
Only access is if I take the panel off. Doesn’t seem difficult. The senders are really hard to get to, especially the port engine.
 
CaptRonn said:
Can you access from behind it? Otherwise it shouldn’t be difficult.

How easy are the access to the senders on the engines?

If sender access is easier, I would try that first.
Click to expand...

Ron - I Removed the panel with all the gauges in it. Was very brittle, corner piece even cracked off, but I can crazy glue it back on, no big deal. Cleaned up the connections, and tested the gauge, by jumping the sending stud to ground, turned engine on - gauge went to full 80 psi like I read that it’s supposed to.

I still might try switching the gauges. I guess I can “switch” them electrically, right? If I make jumper wires, to connect the sending wires to the opposite gauges, and leave everything else as-is. That would basically be the same as physically moving the gauges (which would be a major job), right?
 
Shark said:
I still might try switching the gauges. I guess I can “switch” them electrically, right? If I make jumper wires, to connect the sending wires to the opposite gauges, and leave everything else as-is. That would basically be the same as physically moving the gauges (which would be a major job), right?
Click to expand...

Using jumper wires to switch the gauges would work. Since the gauge went to 80 psi when you grounded the sender wire the gauge is most likely working correctly. Corrosion on the sender terminal could affect the reading but if its still reading 20 psi after cleaning the terminals I'm guessing the problem is not the gauge.
 
You might want to see if you actually do have oil pressure while you fiddle about.
 
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