Oil pressure Gone

[gustaria]

just finished 2 week check list, boat running great. Went for 30 minute test ride on the lake yesterday. Rechecking systems today, topped off oil; almost a half quart. Started engine and gauge reads 0. turned it off and restarted; gauge moved a little 3-5 and went back down to 0. Motor is running great. Will not make a move without advice. Oil is new and filter and the level is right on and nothing in the oil. Engine serial number 0W344267 belongs to a 2005 Model number 4311025TT
MERCRUISER 5.7L ALPHA 2005

 

[Fordiesel69]

Re: Oil pressure Gone

Probably a guage, wire, sending unit issue. Try threading in a REAL pressure guage and see what it reads. I bet it reads normal. Real oil pressure failure will result in knocking and clatter.

 

[gustaria]

Re: Oil pressure Gone

thanks, that is encouraging. Once I had a car that had the screen clogged doing that?

 

[jtmarten]

Re: Oil pressure Gone

You can easily check to see if the problem is the gauge or sender. Remove the wire from the sender and ground it, if the gauge pegs, the problem is the sender. If it doesn't peg, its the gauge or in the wiring.

 

[gustaria]

Re: Oil pressure Gone

thanks, this is helpful

 

[gustaria]

Re: Oil pressure Gone

there is a single wire down there and a plug with two wires. i am thinking it is the single wire? What is the other one for? does this mean you are thinking it is not oil pressure; hoping. Also do I need the key on when I do this check. Thanks, Ron

 

[Rocky_Road]

Re: Oil pressure Gone

there is a single wire down there and a plug with two wires. i am thinking it is the single wire? What is the other one for? does this mean you are thinking it is not oil pressure; hoping. Also do I need the key on when I do this check. Thanks, Ron

Yes...the key needs to be "ON" for this test to work.

The single wire should be the one that goes to the gauge....

 

[gustaria]

Re: Oil pressure Gone

thanks, Ron; Destin area

 

[Rocky_Road]

Re: Oil pressure Gone

thanks, Ron; Destin area

Absolutely beautiful stretch of the Gulf...for now!

Let us know if your gauge pegs when you ground the wire....

Happy boating!

 

[gustaria]

Re: Oil pressure Gone

OK, I am going to do it first thing in the morning. I was also reading the manual and saw something interesting. The only thing I did to the boat today was top off the oil that I had changed a few days ago. the manual said if you get too much oil in the mercruiser It will drop the oil pressure and or be eratic. Now it is right there at the full line, but the book said "between fill and full"'. Normally I wouldnt think too much about it but........

 

[gustaria]

Re: Oil pressure Gone

here just for the heck:SERVICE MANUAL NUMBER 31 MAINTENANCE
90-864260 OCTOBER 2001 Page 1B-15
Overfilled Crankcase Oil
An overfilled crankcase (oil level being too high) can cause a fluctuation or drop in oil
pressure and rocker arm clatter on Mercury MerCruiser engines. This condition results in
the engine crankshaft splashing and agitating the oil, causing it to foam (become aerated).
The aerated oil causes the hydraulic valve lifters to bleed down. This, in turn, results in
rocker arm clatter and loss of engine performance, due to the valves not opening properly.
Care must be taken when checking the engine oil level. The oil level must be maintained
between the ADD mark and the FULL or OK RANGE mark on the dipstick. To ensure that
you are not getting a false reading, ensure the following:
? Boat at rest in the water, or
? If the boat is on a trailer, raise or lower the bow until the boat is setting at the
approximate angle that it would be if setting at rest in the water.
? Allow sufficient time for the oil to drain into the crankcase if the engine has just been
operated or oil has just been added.

 

[gofastcrazy]

Re: Oil pressure Gone

the other one ( with two wires ) is your 0 oil pressure / fuel cut off. if it reads a drop in oil preesure it cuts the fuel pump off and shuts the engine off.

 

[Rocky_Road]

Re: Oil pressure Gone

OK, I am going to do it first thing in the morning. I was also reading the manual and saw something interesting. The only thing I did to the boat today was top off the oil that I had changed a few days ago. the manual said if you get too much oil in the mercruiser It will drop the oil pressure and or be eratic. Now it is right there at the full line, but the book said "between fill and full"'. Normally I wouldnt think too much about it but........

If the level shows "FULL"...and your boat isn't way off level...then you are OK.

Don't panic, or overthink all of this, until you see if your gauge is responding.

Like gofastcrazy correctly pointed out: if you were REALLY having 0 oil pressure, the fuel pump would have been shut down the engine.

 

[gustaria]

Re: Oil pressure Gone

Just finished. I drained 17 ounces and oil pressure is one fourth up; that is like 20. I ran it for 10 minutes at 1000-1300 rpm. What say you.
Ron