2004 F115 Low oil pressure

[BIGELOW-]

I have a 2004 F115

History- Bought boat as a theft recovery, lower units and hyd steering stolen
Checked compression to ensure good enough to warrant spending money- compression all approx. 180.
bought new lower units/props

PROBLEM- I have crappy useless gauges, buzzer going off intermittently, mechanic said key switches- replaced- NO CHANGE and he charged the crap out of me......

Got tired of it and started diagnosing myself- found out Oil pressure switch is turning on, activating alarm- Hoping bad OPS, put mechanical gauge on and oil pressure drops way low (to (15 psi) after running for a few minutes.. Book specs are approx. 49 psi at idle, OPS turns on below 24 psi

QUESTION #1- Is oil pump only thing that can cause this issue ( no main or rod bearing noises and compression is good). I plan on checking pick up strainer when remove power head.

Question # 2- I'm fairly mechanically inclined, any body have any tips for removing power head to get to pump

PS- This motor is on a 24 ft polar deep v, has twins, the other f115(starboard) oil pressure reads 72 psi at idle, 90ish psi at 2500 rpms (no issues with it).

PSS- I have already changed thermostats, cleaned poppet valves, installed new injectors, changed oil - ( all preventive maintance since was a theft recovery and prob abused)

THANKS GUYS!!!!!!!!

[TownsendsFJR1300]

Have you drained the oil from the engine yet and inspected it for any shiney particles, water intrusion, etc?

[BIGELOW-]

yes, already changed oil twice w/ new filters (using OEM yammy filter). Oil was dark/dirty, but no metal and didn't look like a milkshake (no water in oil).

motor has 1100 hours, except new lower unit, cause the old ones were stolen...

[TownsendsFJR1300]

Well, thats a very good sign.

Others will chime in but it appears you'll be digging in much deeper..

[BIGELOW-]

My parts aren't in, but went out and started working on it. In 5 minutes, I had the apron off- (two phillips head screws on front of apron, 2 bolts that unbolted from top (powerhead side) on the injector side of engine, 3 bolts on starter side)

pulled the apron off, there is a very large hex shaped "stud screw?" under the apron and on the injector side of the engine- is this some sort of inspection hole (if taken out I could fit my thumb in it)?

Keep in mind this is my first power head removal- HAHAHA- I'll keep updating this thread to help other first timers. I see the 6 long and 2 short powerhead bolts, but gotta work tomorrow and going offshore fishing sat (on buddies boat), so will be sun before can get back at it...

[TownsendsFJR1300]

If you go to the RED "Purchase Yamaha parts" section up above, put in your engine info, do some searching, you should be able to find just about anything. Extremly handy...

[rodbolt17]

DO NOT remove that hex nut.
its NOT an inspection port.
you have a couple short bolts fwd, 6 long bolts on the side and either two or three acrossed the back that are difficult to get to.

could be the oil pump could be the pressure regulator.

takes about 31/2 hours to do the oil pump. an additional 5 or so to access the strainer.

[BIGELOW-]

Thanks RODBOLT- I have read many of your posts/replies and you seem to have a very down to earth/ matter of fact/ easy way of explaining things (especially electrical issues). Do I have to come from the bottom to get to strainer?

Could you explain the pressure regulator- that's new to me- where is it, what is it, function- any ways to trouble shoot ?

THANKS!!!!

[TownsendsFJR1300]

IT's probably just the oil pressure sensor (OPS) - imo.

The oil pressure sensor (OPS) will cause the alarm to go off.

Yamaha build some bad ones for my engines (three) F225 (2005) , and they have to be replaced. They are a bit expensive.

If you can check your OP with the YDS, you can find problem as you'll see a HARD CODE (39 I believe) and the YDS will say OPS.

If the YDS says its the OPS (with a code 39 ), just buy a brand new (with the big hex nut) OPS replacement from Andy Yamahas Parts up north andyjr@shipyardisland.com .

I had two OPS failures on my F225s. Both times replacing the OP sensor solved the problem FOR-EVER.

You really need to check the oil pressure with the YDS. See the Code 39 and replace with a new OPS (with the big hex nut).

The op checked it with a mechanical gauge in his first post and got 15 lbs warmed up at idle, way below spec's.

Will using the YDS show a different reading?

[BIGELOW-]

I WAS hoping it was just the OPS- BUT I tested its twin beside it to compare (with mechanical gauge)- It's def low oil pressure- I was hoping it was the OPS ( $49 and a 2 min fix). Not that lucky this time... I did hook the computer thingamagigger up to it- that's how I narrowed it down to either oil pressure or OPS- Mechanical gage narrowed it down to oil pressure. As I learned in one of rodbolts previous posts, the F115 has a oil pressure SWITCH, ("stupidly simple- either on or off"-Quoting rodbolt). Some have a "sensor that sends oil pressure data- F115 doesn't, have to hook up a mechanical gauge.


I have the powerhead unbolted and ready to hoist, just waiting on my parts- so far has been really simple- still wondering how to get to oil strainer though...

[rodbolt17]

be careful with this internet stuff.
lots of well intentioned yet TOTALLY misleading information.
about the only two things the F225 and the F115 share is an 8D paint code and the oil type.\
the F225 uses an oil pressure sensor that the ECU uses to determine if oil pressure is acceptable based on an ECU map.

the F115 uses a SWITCH.
its either on or off just like the light in the fridge.

the oil pressure regulator is just that.
it regulates oil pressure.
I cant remember if its on the block like the F150 or on the adapter like the F350.

however its there.

the strainer is mounted on the underside of the powerhead adapter.
requires TOTAL disassembly of the oil pan.

this requires lower unit and powerhead removal then midsection removal then midsection disassembly.

[BIGELOW-]

Have more detailed photos, but photobucket is acting up...

Anyway... pulled power head, dropped lower unit, took apart and fully dissembled midsection-

1) Old oil pump looked fine, splines were good- replaced anyway.
2) oil pan was clean
3) Strainer was not clogged
4) not sure about oil regulator, as I completely disassembled everything south of the power head and didn't find it....

OUTCOME------> No change in oil pressure, still around 20 PSI at idle- 40-60 at running rpm...

I'm at a loss, I don't know what to check now, unless I can find the Oil regulator (I guess it has one??)

I don't think the motor will blow with the above pressure, but I would feel a lot more comfortable if it were at the 49 psi factory spec at idle...

[BIGELOW-]

I have searched he net, I have looked at parts breakdowns, the only thing remotely close to an "oil pressure regulator" I've found is the poppit/ pressure relief valve for the cooling system..........

Any help would be appreciated.

[boscoe99]

I have searched high and low for an oil relief valve assembly on an F115 and will be damned if I can find one.

Should be a part number ***-13490-00-00 but...

[rodbolt17]

it may be part of the oil pump.
but that motor has to go from 600 RPM to 6000 RPM and somewhere along the line you will need to regulate pump pressure.

its a positive displacement pump. the faster you spin it the more pressure its going to make.

there should be some mechanisim,typically a spring loaded ball and seat, to bleed off excessive pressure.