Jump to content

Welcome to TheMalibuCrew!

As a guest, you are welcome to poke around and view the majority of the content that we have to offer, but in order to post, search, contact members, and get full use out of the website you will need to Register for an Account. It's free and it's easy, so don't hesitate to join the TheMalibuCrew Family today!

Oil Pressure gauge pegged at ZERO


Recommended Posts

I have searched through the Forums for this problem. I found many other topics with somewhat the same issue. Most were very old and I did not want to re-hash them. So here we go...

Here's my story.

We recently rebuilt my motor. After putting the motor back in the boat, we setup the fake-a-lake and started her up. Fired up on the first turn. We checked all gauges and they were working fine. My far left dash gauge has a combination of Volts, Oil Pressure, Temp and Fuel all in one.

We got the motor timed and then shut it back down. We then proceeded to start it back up a few more times and do a double check of everything. Again, at this time, all gauges were working.

Due to the weather I had to let the boat sit for another week before I was able to put it in the water.

So, a week later, we take the boat to the ramp, put it in the water and start her up. I looked everything over again and noticed the oil pressure gauge was not working at all. I immediately shut the motor down and gathered my thoughts.

I just happened to have a mechanical gauge for testing purposes. I took off the sending unit and screwed in the mech. gauge and started the motor back up. It read 50-60psi (perfect). I then removed the mech. gauge and put the sending unit back on. Started the motor and still 0 on the oil pressure gauge. So, I unplugged the wire from the oil sending unit and and grounded it. The oil pressure alarm immediately started to sound.

So, I came here and started searching. I checked my Canon plug, per some advice, and cleaned a little of the silicone out of it. There was no moisture and everything looked fine. I re-checked all grounds etc. and all looks good.

My next step is to replace the sending unit. My question is if the alarm sounded when I grounded the sending unit wire, does that rule out bad wiring? Does it most likely sound like the sending unit is stuck or bad?

I'm a little confused that it worked fine after we reinstalled the motor, then sat for a week and all of a sudden stopped working. Crazy.gif

Link to comment
My next step is to replace the sending unit. My question is if the alarm sounded when I grounded the sending unit wire, does that rule out bad wiring? Does it most likely sound like the sending unit is stuck or bad?

I would think the wiring is good since it is completing a circuit and sounding the alarm.

Change the sending unit for a few buck$ and go from there.

Link to comment

Mike, are you testing the sender for the dash, or the sender for the ECM?

If you ground out the sender to the dash, and the needle does not peg on the high side, you have a gauge/mdc/wiring issue. If it does peg, you have a sender issue. But, make sure you're not testing the sender for the ECM, which does not show on the dash.

Peter

Link to comment

Just a thought... but I seem to recall that there is both an oil pressure "switch" as well as an oil pressure "sending unit". I think the switch is what triggers the audible alarm.

Thought maybe this would help. Dontknow.gif

Link to comment

OK. I replaced the Sending unit(had a spare one for some reason), still Zero on the Gauge.

For now I have a manual gauge on the engine and it looks like I have to chase down a possible wiring issue. UGH!

Swampy or anyone. The oil sending unit is the larger one while the oil pressure switch is the smaller. Which one is responsible for sending the reading to the dash gauge? And what the heck is an MDC?

Also, does one fuse control that entire gauge? or is there a fuse for each reading? i.e. fuse for voltage, fuse for gas level, fuse for oil pressure, fuse for temp.? It's awful funny only one item on that gauge has gone belly-up.

Edited by areamike
Link to comment

The Switch feeds signal to your Engine Management Computer, and is responsible for sounding the audible alarm if your oil pressure drops below 4 psi.

The Sending unit feeds signal to your guage.

Link to comment

Big one is the sending/dash unit. Smaller one is switch.

The wires all go to a Marine Data Concentrator(MDC). It's underneath your dash. I collects all the sensor information & sends it to your gauges on a single 5 wire digital bus.

The oil pressure wire going into the MDC is light blue. If you look at the 18 pin connector. The two mark side on the left & 1 mark side on right, the oil pressure wire will go into the bottom position of the first row to the right of the middle. It should be the only blue wire going into the 18 pin connector. Other wire there are:

Red - Power

Black - Ground

Purple - Ignition

Pink - Fuel

Grey - Tach

Tan - Temp

Blue - Oil Pressure

Possibly - Dk Blue - lights.

I have a troubleshooting guide I got from Medallion site a while back, but can't find it there any more & it's too big to post here. PM your e-mail & I'll forward it to you.

It has happened that just one gauge has gone out in the multi-cluster.

You could try to disconnect your lanyard, reconnect & see if the gauge comes back - this should work similar to rebooting your PC.

Another option is to swap the 5 pin connector on the back of the multi-gauge with one of your tach/speedo. If the oil pressure gauge comes back, the the wiring harness is bad, but since it's working for the other 3 gauges in the multi-gauge, I doubt that is the problem.

Edit: Clarification

Edited by wienrdog
  • Like 1
Link to comment

Adding to Wienrdog's response, I have indeed had one of the four cluster gauges go out. For me, it was the temp, but same symptoms. There was a specific step to reboot the gauges, something like hitting the display button down on Lake Temp and up on the other button until all the gauges went through their setup routine. Someone else here will know the exact button sequence to push, but all the gauges went through their routine except the engine temp, the servo motor for that one had died. If your oil pressure does come off of zero, you gauge is probably fine and you're left to hunt down wiring issues. If it doesn't move during the reboot process, you can focus on the gauge itself I think.

Unlikely since it worked before, but with the motor swap, is it possible you swapped the wire for the oil pressure switch with the wire for the oil pressure sending unit? One is just on / off, and the other is variable resistance for the gauge (I believe).

Link to comment

My oil pressure gauge is doing the same thing. Haven't been able to hunt down the problem thus far. One weird thing about mine, the gauge is pegged at zero, the oil pressure warning comes up on the LCD the whole time but rather than shutting the engine down like it's suppose to, it runs normally. I too have checked it several times with a mech gauge and it reads fine.

Link to comment

It is the oil pressure switch that will (is supposed to) put your engine into 'limp home mode'. Sounds like your switch is working, but there is a problem between the sending unit and guage.

Link to comment
  • 2 months later...
  • 4 weeks later...
so did you ever have any resolution on this, as I am having the same problem?

No resolution yet. I am in the process of trying to find out how to test the wiring. I'm no electrician so I am dumb to these sort of things and how to test wiring. I have a digital multimeter, but have no idea how to use it in this situation.

To recap. The oil pressure gauge worked fine after rebuild while we were running the motor on a fake-a-lake. The boat sat for 2 more weeks before we could get it into the water. Once in the water, I started it up and ever since then the Oil pressure gauge has not worked.

Link to comment
so did you ever have any resolution on this, as I am having the same problem?

No resolution yet. I am in the process of trying to find out how to test the wiring. I'm no electrician so I am dumb to these sort of things and how to test wiring. I have a digital multimeter, but have no idea how to use it in this situation.

To recap. The oil pressure gauge worked fine after rebuild while we were running the motor on a fake-a-lake. The boat sat for 2 more weeks before we could get it into the water. Once in the water, I started it up and ever since then the Oil pressure gauge has not worked.

fI had the same thing happen to mine, after alot of pain, it turned out to be the gauge (3 of the 4 guages in the cluster worked fine). Replaced the guage and it read high, new sender and it reads in the right range .. the other day I noticed the tach was zeroed, later in the day it came back but added about 170,000 hours to the hour meter - you would think for the money these boats cost they could put in some electronics that work.

Link to comment
so did you ever have any resolution on this, as I am having the same problem?

No resolution yet. I am in the process of trying to find out how to test the wiring. I'm no electrician so I am dumb to these sort of things and how to test wiring. I have a digital multimeter, but have no idea how to use it in this situation.

To recap. The oil pressure gauge worked fine after rebuild while we were running the motor on a fake-a-lake. The boat sat for 2 more weeks before we could get it into the water. Once in the water, I started it up and ever since then the Oil pressure gauge has not worked.

fI had the same thing happen to mine, after alot of pain, it turned out to be the gauge (3 of the 4 guages in the cluster worked fine). Replaced the guage and it read high, new sender and it reads in the right range .. the other day I noticed the tach was zeroed, later in the day it came back but added about 170,000 hours to the hour meter - you would think for the money these boats cost they could put in some electronics that work.

Even though it's a boat and subject to occasional high moisture type situations, I agree, for the price they should have "hardened" electronics.

Link to comment

Well I fixed mine. I have NO IDEA how.

First I took the manual gauge off and put the old oil pressure sending unit back on. I then started to take the dash apart and decided to first start the motor to see if with some wild chance the darn thing was working again. I unhooked the lanyard a couple times, then started the motor. BAM it magically started working again and was reading right at 60psi. In the end it could have been the removing the lanyard a couple times that did the trick. I dunno Dontknow.gif

Link to comment
  • 8 years later...

Old post but I am having same problem.  Anyone know how to test the gauges?  A post above talked about a way to have the computer move the gauges.  Also, what is the best way to test the sending unit and pressure switch related to oil.

 

Thanks,

Link to comment
  • 2 weeks later...

Update.  I have replaced the oil pressure switch, oil sending unit and the 4 cluster gauge and I still have not oil pressure and the display shows "NO OIL PRESSURE" even though the engine is producing oil pressure.  What is the next step for me?

 

Thanks,

Link to comment
12 hours ago, MadMan said:

I'd just install an under dash oil pressure gauge. It's what I did for my fuel level.

 

 

I agree with this except the computer display "no oil pressure" and I can not use the depth reading as that is also part of the display.

 

Thanks,

Link to comment

I'd replace the oil sending unit...they are cheap and easy to fix.  If you go tot he local store ask for one on a 1999 Chevy Suburban 350 and I bet it's a match, and under $30.  Do NOT use teflon tape on it, the threads are the ground for the circuit.

2r289lk.jpg

Link to comment

OK, my oil pressure appears to be working now and works while running on the hose.  The canon plug needed to be removed and installed again.  Looks like a weak connection.  I will look into replacing the plug.

 

Thanks for all the help.  I finally read a post that talked about cleaning the canon plug.

Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...