Low oil pressure

[Jen]

Looking to buy an 01 sunsetter lxi. Dropped in the water and discovered low oil pressure warning. It stayed on during initial cruise then went away and came back on when we were idling. It was first time in water this season. Owner claims this is due to new synthetic oil. Any suggestions on repair? Comments? 

[Rednucleus]

By warning to you mean audible alarm?  What's the dash gauge reading. Synthetic oil will not cause this assuming proper weight used. How many hours? Don't touch this boat till you get this resolved! May just be the sensor but could be dying motor. Can have pressure checked with a mechanical gauge to rule out sensor and dash gauge problem. Also would be smart to have local reputable dealer do a pre purchase exam. Good luck!

[Jen]

Electronic gage says oil pressure at 16 should be 20-100. No audible. 450 hrs. How easy to change sensor? We thought maybe that too. Definitely not buying if not resolved but appreciate comments thoughts and experiences 

[Rednucleus]

More info please - pressure at idle, cold vs hot. Pressure running (around 3k rpm) cold vs hot. Would verify with a good mechanical gauge before changing sensor. Could well be a wearing out dying motor.

[Jen]

Running hot. Assuming he already took it on water before we arrive. Electric gage only so don't know pressure at running. Reading at 18 when idle

[kx250frider617]

Are you sure it's not a trans oil light? That's the same era as my old tige. The trans oil light would come on at idle only. Then turn off once throttle was applied. It's completely normal if that's it. 

[RTS]

Assuming '01 Monsoon fuel injected engine...there is no trans oil light.

[Jen]

Yes monsoon fuel injected. 

[MadMan]

59 minutes ago, kx250frider617 said:

Are you sure it's not a trans oil light? That's the same era as my old tige. The trans oil light would come on at idle only. Then turn off once throttle was applied. It's completely normal if that's it. 

 

55 minutes ago, RTS said:

Assuming '01 Monsoon fuel injected engine...there is no trans oil light.

Did you mean the V-drive warning light?  It's normally on at idle and flickering at slow speed.

 

I believe the Indmar/GM minimum oil pressure at idle is some quite low, like 6psi.

Edited May 30, 2016 by MadMan

[RTS]

No V-Drive on any '01 Sunsetter Lxi.

[MadMan]

2 hours ago, RTS said:

No V-Drive on any '01 Sunsetter Lxi.

I guess that means it's a DD.

[braindamage]

The oil pressure on my '00 Lxi is 60-80. I'd take it a mechanic. You have a serious issue if you are in the single digits all the time, though it could be your gauges.

[dlb]

Oil pressure sending unit should be the first thing to replace.

http://www.skidim.com/SENDING-UNIT-OIL-PRESSURE-GM_FORD/productinfo/R020001/

These fail from time to time.  Replace it and see what happens....

I have had them fail.  You will see single digits and bouncing around up to normal.  

Easy fix for a DIY.

 

Edited May 30, 2016 by dlb

[Jen]

He's offered to take to repair shop for replacement of sending unit ( mat least that's what mechanic suspects). If that doesn't fix, I think it's time to keep looking and wish him luck selling. 

[Rednucleus]

I would not purchase until a mechanic verifies engine health. Have a compression test run as long as it's going to the mechanic. Any idea on maintenance history?

[h2oratJR]

some Chevy motors have a known oil pressure issue due to an o ring that was not installed properly from factory but i assume its the 5.7 ?

[MadMan]

I view this as an opportunity to leverage a screamin'  good deal. 

[Eagle River Mike]

Oil pressure switch has been somewhat of a maintenance item on my boat.  Seem to go through them every 2 or 3 years.  $30 part and 2 minutes to replace.

[Woodski]

@Jen:  the potential reason for low oil pressure with fresh oil would be the viscosity not a synthetic v mineral issue, if the owner put a very light oil in there could be lower than normal oil pressure at idle.  Under normal wear, there should not be abnormally low oil pressure at the 4-500 hour mark.  If you continue to pursue the vessel, you might pick up a laser thermometer, available at Home Depot, Lowes, etc. for ~$20 and check the oil temp (hit the pan or the oil filter with the laser) and get an idea of oil temps v temperature.  Note that oil temperature is affected much more by PRM, not so much throttle position or load at slow engine speeds.

[Bozboat]

On 5/30/2016 at 0:13 PM, Jen said:

Electronic gage says oil pressure at 16 should be 20-100. No audible. 450 hrs. How easy to change sensor? We thought maybe that too. Definitely not buying if not resolved but appreciate comments thoughts and experiences 

The oil pressure indicated on the gauge of my 99 SSLXI varies all across the gauge usually in the 60 range, frequently in the 20 range.  Somewhere in one of these threads I came up with the idea that the gauges are not accurate and that I was good to go if the gauge showed any oil pressure.  Same issue with my old chevy trucks.  I was pretty amazed the first time I drove German that the oil pressure gauge acutely seemed to measure oil pressure.   

[GaryB]

8 hours ago, Woodski said:

@Jen:  the potential reason for low oil pressure with fresh oil would be the viscosity not a synthetic v mineral issue, if the owner put a very light oil in there could be lower than normal oil pressure at idle.  Under normal wear, there should not be abnormally low oil pressure at the 4-500 hour mark.  If you continue to pursue the vessel, you might pick up a laser thermometer, available at Home Depot, Lowes, etc. for ~$20 and check the oil temp (hit the pan or the oil filter with the laser) and get an idea of oil temps v temperature.  Note that oil temperature is affected much more by PRM, not so much throttle position or load at slow engine speeds.

Check the oil level, if it reads high,  and smells like fuel, start looking for leaking injectors. 

[Sixball]

My neighbor has an 04 SS lxi His has has a low oil pressure at idle from day one. Had it back to the dealer and after new computer and pressure sending unit no change. I would defiantly put a manual gauge on it before I would be happy  My R lxi runs 50 psi at idle may drop to 47 when hot.

Edited June 1, 2016 by Sixball

[Jen]

What type of oil (weight) should be used on the monsoon 325 hp with fuel injection?

[jwl019]

15-40

Here's a thread with a good parts list in case you do purchase:

 

[MadMan]

On ‎5‎/‎31‎/‎2016 at 8:47 AM, Eagle River Mike said:

Oil pressure switch has been somewhat of a maintenance item on my boat.  Seem to go through them every 2 or 3 years.  $30 part and 2 minutes to replace.

This is the reason I installed a mechanical gauge trio in the engine compartment.  If I get a suspect reading from one of the factory gauges, I open the hatch and see what the mechancal gauge is showing (water temp/oil press/amps).  This is so I don't cut short a day on the water unnecessarily.