496 ho oil pump prime

[goldeneyee]

I purchased a boat that hasn't been run in 5 years. Twin 496Ho Merc motors. Next spring will be started for first time in 5 + years. Can the oil pumps be primed prior to firing them up. If so, how? Thanks...

[Ted]

Just unplug the ECU and crank the engine with a good battery till the oil pressure comes up .

[rschap1]

I would think that getting the system pressurized BEFORE rotating is what is being looked for here, and w/o a distributor to pull and access the oil pumps drive shaft that cannot be done as most would normally do.

[goldeneyee]

Exactly. How would I get to the pump?

[Ted]

I would think that getting the system pressurized BEFORE rotating is what is being looked for here, and w/o a distributor to pull and access the oil pumps drive shaft that cannot be done as most would normally do.

I can pretty much guarantee there is enough oil to keep the bearings happy during no load rotation. On many new engines there is no oil pump access and this is the only way to do it. With no heat, and no force against it, even a dry bearing would be fine rubbing against a smooth journal.

[Ted]

Exactly. How would I get to the pump?

You would have to remove the intake and then the oil pump drive that is underneath, then stick a primer down there. #4 is the drive.

[goldeneyee]

Just thinking--an electric pump pulling from an oil source and connected to a oil fitting on the engine would pressurize the system with oil. Then gently turn engine over. Anyone think this would work?

[Ted]

Just thinking--an electric pump pulling from an oil source and connected to a oil fitting on the engine would pressurize the system with oil. Then gently turn engine over. Anyone think this would work?

Sure, they make electric oil primer pumps to do it, kinda pricey though. The issue would be developing the pressure. You could also pressurize a container with air over the oil and force it in that way, like a preluber.

[Raylar]

My two cents here as a 496 expert.
If those engines have not been turned over in 5 years and they have not been fogged or stored in a desert type almost no humidity enviroment, the problem may not be one of how to get oil to internals before cranking as much as how badly cylinder walls, valve seats and faces may be rusted and how dry iron valve guides and such may be overly dry. Sometimes when engines in this state are restarted after such a long storage without fogging or such the damage to the moly on the ring packages and the cylinder and valve sealing charactersistics may be damaged beyond just running the engines in and then down the road these problems may show up as low compression and high leak down rates.
These engines should really be inspected with a minimum of a borescope device before intial cranking and then if in fairly good cylinder wall and valve face condition, the oil system must be preprimed from an external oil pressure port before cranking or starting.
After starting with fresh oil and filters only, the oil and filters should be changed after only coming up to a minimum oil temp (about 160-180 degrees), because the initial debris level from firing them up after setting will be so high that its not going to be a good idea to operate them under load with this possible level of contamination.
This is also the time you would want to do a compression and leak down test to see if the engine is sealing up compression wise.
Just some suggestions and thoughts her.

Best Regards,
Ray @ Raylar

[Knot 4 Me]

What about valve springs after sitting (some) fully collapsed all that time?

[Boat Tech]

I can't remember this to be 100% sure if this engine has this option or not But in the DDT scan tool there is a Function for priming oil in the SPECIAL FUNCTIONS area of the scan tool ,I know some outboards do it for sure, But I can not remember if the 496 engine will do this or not. But It might be worth looking into as a option to Consider before starting the engine. Below is a Functions tree of what it would look like inside a scan tool taken out of a service manaul, Normaly you would be able to read it like a map, But if you copy and paste it, It all blends in together. It's one of those things you don't really know till you try it out. Maybe someone eles will chime in that has tried this out recently. Good luck with this.


SERVICE MANUAL NUMBER 33 TROUBLESHOOTING
Digital Diagnostic Terminal Flowchart using A DDT scan Tool - Start Here,
SmartCraft Monitor
1 -MercuryMarine
2 - Tool Setup
THIS ENGINE IS Axx
MY xxx x.xL xxxPRESS
1 to CONTINUE
Select Function:
1 - AUTO SELF TEST
2 - MANUAL TEST
Select Auto Test
1 - Static Test
Select Function:
1 - DATAMONITOR
2 - FAULT STATUS
3 - SYSTEM INFO
4 - HISTORY
5 - SPECIAL FUNCTIONS
Select Function:
1 - FAULT HISTORY
2- RUN HISTORY
3 - CLEAR FAULT HIST
4 - CLEAR RUN HIST
Select Fault Hist::
1 - FREEZE FRAME
2 - FAULT SECONDS
RUN TIME HR.
RPM 0 -- 749
RPM 750 -- 1499
RPM 1500 -- 2999
RPM 3000 -- 3999
RPM 4000 -- 4499
RPM 4500 -- 4999
RPM 5000-- 5499
RPM 5500 +
BREAK-IN LEFT
RPM LIMIT Sec
GRD LIMIT Sec
CTS TMP Sec
FREEZE FRAME
BUFFERS
0-BREAK-IN
BARO PSI
BATT VOLTS
BLOCK PSI
BOAT SPEED
AIR TMP F
COOL TMP F
DEMAND %
ENGINE RPM
ENGINE STATE
FPC TOTAL
FAULT SECONDS
BATT VOLT HIGH
BATT VOLT LOW
BLOCK PRESS LOW
COMP OVERHEAT
ETC MOTOR OPEN
ETC MOTOR SHORT
FUEL P INPUT HI
FUEL P INPUT LO
GUARDIAN
KNOCK SENS1
KNOCK SENS2
OIL PSI STR
OIL REMOTE STR
OIL RESERVE STR
MAP INPUT HI
MAP INPUT LO
MAP IDLE CHECK
OIL PUMP
OVERSPEED
PORT OVERHEAT
STAR OVERHEAT
WARNING HORN
H2O IN FUEL

Select Function:
1 -OIL PUMP PRIME
2 - CYLINDERMISFIRE
3 - UTPUT LOAD TEST
4 - RESET BREAK-IN OIL
5 - CHANGE FUEL OFFSET
6 - ENGINE LOCATION
Select Load Test:
1 - IGNITION
2 - FUEL INJECTOR
3 - DIRECT INJECTOR
4 -OIL PUMP
5 - FUEL PUMP
6 - HORN
7 - MISCELLANEOUS
8 - TACHOMETER
9 - RELAYS
SELECT LOAD TEST:
1 - IDLE AIR CONTROL
2 - ELECT SHIFT
3 - ELECT THROTTLE
4 - KNOCK
SELECT RELAY:
1 - MAIN POWER RELAY
2 - FUEL PUMP RELAY
3 - STB TAB RELAYS
4 - PRT TAB RELAYS
5 - TRIM RELAYS
6 - START RELAY

[MOBILEMERCMAN]

That is an Outboard function with an electric pump. The oil pump is a mechanical pump in the 496.

[Raylar]

Good Catch Knot 4 ME, yes, valve springs especially GM stock 496 springs will definitly be prone to taking a set after 5 years of being held down on open valves and could fail early on restart under loads. Those motors should probably come out and apart for checking and needed refresh. If they were mine I would! Its probably not worth the risk and if the boat was sitting 5 years you probably stole it anyway!

Best Regards,
Ray @ Raylar

[insanity]

How about valve springs after sitting for 2 years? By the time I get mine put back together it will have been about 18 months since it last ran, I was wondering if I should have popped the valve covers off and loosened the rockers awhile back but never got around to it. For what springs cost, I figured I could install a new set and not be concerned about it when the time comes.