Malibu Boats m5di strange oil pressure issues

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It would seem that the running-in oil was likely a *w20 from the factory and it's now been replaced with a 5w30. Certainly nothing to worry about.
 
Originally Posted by Bailes1992
It would seem that the running-in oil was likely a *w20 from the factory and it's now been replaced with a 5w30. Certainly nothing to worry about.


Never in my life have i seen on any of these inboard run 40idle /60 load psi during the first 25 hours and then drastically change. Also it doesnt seem like every engine is doing this, Ive spoken with several people with the same engine and over 100 hours and their gauges do not do this peg to 80psi. Also 40/60.
 
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Update:

Pulled out the Hengst filter and replaced with NAPA. Couple things i noticed, the Hengst has no plastic casing on the inside of the filter, while the NAPA did. Initial crank psi went to 80, but then dropped to the 60 we have been seeing at idle, pretty sure thats from the filter needing to soak in oil?

Overall same issues, boat warms to 160F and PSI is 60idle/80load
about 25mins of varying rpms idle psi drops back to 40 but load is still pegged at 80.
Left engine running in slip to see if in about 45mins - 1hour it will get to 40/60 again.
 
Seems like no change with new filter. Even after 1 hour of running I'm still hitting 80psi in the upper rpms (which is where we run the boat most of the time wake and surf is about 3900-4200rpms)
 
I wouldn't trust a dash mounted gage for serious evaluation of oil pressure analysis, particularly on marine engines. Oil pressure might have never changed, maybe just the gage. Was anything done at the 25 hour service related to engine management? Was ECM reflashed or updated?
 
I think it's time to get a mechanical gage reading off your oil pressure port. It's at the top of the engine at the rear, hopefully a reachable position for a boat motor. Note, on the car version there is a screen below the sensor. The sensor simply unscrews with a socket after detaching the wires. I'm sure the mechanics on this blog can give you advice, but if the mechanical gage confirms the pressure readings I suspect your solenoid that controls the pressure. I heard it's a twenty dollar part.
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One more thing, LS engines have a spring in the oil pump that activates and bypasses oil back to the sump of the pressures get too high. I would say say it's totally strange that the pressure gage would operate at 60 psi one time and 80 psi another time, regardless of the viscosity.

I have run 5w30 and 5w40 in my 6.0 LS with the older style oil system. The pressure at highway speed, at full operating temp, does not change. Both are 40 psi, At idle, the 5w40 runs at a few psi higher.
 
Originally Posted by agarabaghi
Yea could be. which means the manuf spec would be wrong then. Ill have to double check running something like 5w-20 or 0w-20 wont void my warranty.


I wouldn't consider this evidence that the spec is wrong, simply that the break-in oil was likely much thinner than the service fill, which is not uncommon. I'd not worry about it really.
 
Do you know if the gauge is a real gauge (for lack of a better word), or is it like many modern cars where the gauge doesn't read pressure directly, it merely points to normal, low and , maybe high. The domestics started doing this as a way to entertain folks with a gauge, but not get warranty claims/questions.

I hope this hasn't spread to boats...
 
Originally Posted by Snagglefoot
One more thing, LS engines have a spring in the oil pump that activates and bypasses oil back to the sump of the pressures get too high. I would say say it's totally strange that the pressure gage would operate at 60 psi one time and 80 psi another time, regardless of the viscosity.

I have run 5w30 and 5w40 in my 6.0 LS with the older style oil system. The pressure at highway speed, at full operating temp, does not change. Both are 40 psi, At idle, the 5w40 runs at a few psi higher.



Yup we had the 6.0 in the last boat, 40idle / 60psi.
 
Update:

Malibu said that the engine ships with 0w20 like a few people suspected here.
Oil PSI warning comes at 100psi (which we have only seen a few times but that is questionable).
They are asking the dealer to replace the sensor check for any loose grounds as well as kicked hoses then send a diacom reading.

Waiting for dealer to get part in and come dock side.
 
Originally Posted by agarabaghi
Update:

Malibu said that the engine ships with 0w20 like a few people suspected here.
Oil PSI warning comes at 100psi (which we have only seen a few times but that is questionable).
They are asking the dealer to replace the sensor check for any loose grounds as well as kicked hoses then send a diacom reading.

Waiting for dealer to get part in and come dock side.



Glad to read this update, and it confirms what I suspected.
 
yea will see what happens, but if 5w30 is throwing oil psi sensor errors then theres still an issue. The diacom will bring more light hopefully!
 
Originally Posted by agarabaghi
yea will see what happens, but if 5w30 is throwing oil psi sensor errors then theres still an issue. The diacom will bring more light hopefully!


Agreed
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Update:

Tech came out with computer and cable.

Computer said 24 ignitions ago was the last high oil pressure warning but does not tell him what the pressure was. The gauge was reading 40 psi at the time the alarm went off.

Fire up engine ... oil psi shot up to 100 then sat around 93psi while the engine warmed up.
Engine at 160F (650-700rpm) oil psi had dropped to 80-85psi

Engine at 160F (5600rpm) oil psi was sitting right at 99psi for a couple of minutes then slowly started to drop eventually it leveled off to 75psi.

Checked grounds, found one that was not super snug, and a bit painted, so tech scraped it and secured it.
Log have been send to manuf of engine.

Take away:
Engine might engage oil pump to run high PSI till oil temp reached a certain temp.
Engine 5w30 takes bit to heat up to the proper viscosity to level out toe 75 or its just a temp / timing thing then the oil pump slows down.
Curious if the manuf is away that the engine does run 99psi for a bit even after the engine is warmed up.
Is the engines operating range in 75s?
 
If it's like my Jeep it stays in high pressure mode (80+ psi) until oil warms to a certain temp. Then it will go into low pressure mode, 30-35 psi or so at idle. It sometimes takes a solid ten minutes of driving after cold start to switch modes.
 
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