No Oil Alarm 2000 Johnson 175 Ocean Pro

[chevysam41]

Hello,

I have a 2000 Johnson 175 Ocean Pro on a boat that I bought about 2 months ago. When I took it on test runs on the water it ran like top with no problems. About a month ago my wife and I took the boat out one morning and the no oil alarm came on shortly after leaving the dock. I shut the engine down, confirmed there was plenty of oil in the reservoir, primer bulb hard as a brick, and restarted it hoping it was a fluke but came back on within 60 secs of restarting the engine. I didn't have time to fool with the motor at the time due to work so I dropped the boat off at a reputable (so I was told) local marine repair shop. After picking the boat up twice and almost a month in their shop the issue is better, but still not fixed. The tech at the shop said I had "trash" on my VRO sensor, (if that even makes sense, got the feeling I was getting yanked around).

Yesterday my wife and I took the boat out and to make a long story short, the oil alarm is not coming on immediately as it was before, but now seems to be coming on when I hit around 2800-3000 RPM. We trolled for at least 3-4 miles with no issues at ~1000 RPM, but within 15-30 seconds of being on plane the alarm came on.

Can anyone give me advice or where to start troubleshooting with this issue? I'm very mechanically inclined with a little more time on my hands and really would not like to drop it off somewhere and wait another 2-3 weeks here in the middle of summer.

Thanks in advance,
Sam

 

[Joe Reeves]

I retired in 1991 so the exact design of your engine would be foreign to me, however, some problems such as what you've encountered and their solution remain the same.......................

You say the alarm is the no oil warning BUT you don't say exactly what the warning sound is... however I'll assume that the sound is a short beep every other second.

Brilliant explanation from the mechanic "trash on the VRO sensor?..... a sealed unit! <--- Sarcasm.

The no oil warning is caused by "air in the oil line" OR "a VRO failure" OR " a loss of operating pressure".

The loss or presence of operating pressure can be checked simply by removing the spark plugs, temporarily disconnecting the hose between the VRO and the crankcase, then cranking the engine over... you should get one hellava blast of air out of the crankcase fitting on every down-stroke of the related piston.

Air in the line can be checked via the "VRO Priming Instructions" as listed below.

********************
(Priming The VRO Pump)
(J. Reeves)

When hooking up or installing a VRO whether it is a new or original VRO pump, it must be primed in order to dispel any air that might be in the oil line.

Have the Oil line attached to the engine fitting BUT detached from the VRO. Add a piece of fuel hose if necessary to the oil line so that it can be aimed into some sort of container.

Pump the oil primer bulb, catching the oil flowing out of the line into the container until you are absolutely sure that you have rid the oil line of every bit of air that might have been trapped there.

Now, connect the oil line to the VRO and secure it. When the oil line is secured, apply pressure to the oil primer bulb ONE TIME only. That's it.

********************
(VRO Horn Warnings)
(J. Reeves)

NOTE: I retired around 1991/92. Possibly some of the later V4 engines and others may also incorporate a fuel vacuum switch that would enable a fuel restriction warning to sound as mentioned below, an unknown factor to myself.

1 - A steady constant beep = Overheating - The V/6 engines, possibly some others, have a fuel restriction warning which is also a steady constant beep.

2 - A beep every 20 or 40 seconds = oil level has dropped to 1/4 tank. (Late model engine = Every 40 seconds)

3 - A beep every other second = VRO failure, air leak in oil line, oil restriction, (anything that would result in a lack of oil being supplied to the engine).

NOTE - If the warning horn is the black plastic (overpriced) three wire type horn, the warning horn should beep once when the ignition key is turned to the ON position. If it does not, it is either faulty or someone has disconnected it (a stupid move!). At any rate, if it does not beep which indicates that the horn is non functional, find out why and do not run the engine until the problem is corrected.

********************
If after priming the VRO and making sure that the operating pressure is present, the warning horn sound (every other second) returns... consider the VRO to be faulty which needs to either be rebuilt with a "VRO Kit", or "Replaced", or have the fuel system converted to "Pre-Mix".

********************
(VRO Changeover Judgement Call)
(J. Reeves)

The VROs first came out in 1984 and have been upgraded quite a few times. In my opinion, back around 1988, they had perfected them but I think that they were upgraded even more since then. As long as the warning system is operating as it should, I feel quite at ease with them.

Some boaters have voiced their thoughts such as "What if that overpriced plastic horn should fail while I'm under way for some reason, and the VRO decides to fail five minutes later?" Obviously that would result in a big problem which really brings their fears into view.

The word "ease" is the key word though. If one has the slightest feeling of being ill at ease with that setup, then they should take the route they feel more at ease with. A judgement call each individual would need to make on their own.

********************
(VRO Pump Conversion To Straight Fuel Pump)
(J. Reeves)

You can convert the VRO pump into a straight fuel pump, eliminating the oil tank and VRO pump warning system, but retain the overheat warning setup (and fuel restriction warning if so equipped) by doing the following:

1 - Cut and plug the oil line at the engine so that the oil side of the VRO pump will not draw air into its system. Trace the wires from the back of the VRO to its rubber plug (electrical plug) and disconnect it.

2 - Trace the two wires from the oil tank to the engine, disconnect those two wires, then remove them and the oil tank.

3 - Mix the 50/1 oil in the proper amount with whatever quantity fuel you have. Disconnect the fuel line at the engine. Pump the fuel primer bulb until fuel exits that hose with the tint of whatever oil you used. Reconnect the fuel hose.

That's it. If you want to test the heat warning system to ease your mind, have the key in the on position, then ground out the tan heat sensor wire that you'll find protruding from the cylinder head. The warning horn should sound off.
********************

 

[chevysam41]

Thanks for the fast reply, Joe. To answer your question, the alarm is a solid tone, probably 5-10 seconds long if memory serves correctly. Definitely no beeps, however, every time the alarm came on, I would immediately throttle back, shut it down and restart...so if it was a 20-40 second beep, I would never have heard it. That said, the oil reservoir is about 1/2 full.

Since it seems like a solid tone, sounds like that would correspond to #1 under the VRO Horn Warnings of your last post where it says "...- Overheating...". I assuming that is referring to overheating of the VRO pump and not overheating of the actual motor itself, correct? Hopefully I'm not way off base here.

I need to find a good manual for this motor or at least some parts diagrams.

Thanks again for your help!

EDIT: One other thing, the primer bulb for the oil has always stayed rock hard...to the point I can't physically squeeze it. If air got in the oil line, wouldn't it go soft?

 

[ob]

The constant tone from the alarm is indicating a engine overheat . The VRO has no overheat alarm. Just no oil, and low oil. My advice would be to replace the water pump if you can't verify a recent replacement of it and a thorough inspection and or replacement of the engine thermostats. If the alarm issue continues, the problem may lie with the engine temp sensor or the alarm itself.

 

[boobie]

Are you sure it's not a fuel restriction alarm ?? Find the switch on the motor, disconnect it and see if the alarm stops.

 

[jakedaawg]

^^^^this Good catch Boobie.

 

[Joe Reeves]

Your #3 post/reply (A Constant Beeping) is an indication of either having the engine overheat or encountering a fuel restriction problem.

Your engine is equipped with the S.L.O.W. feature that if a engine overheat condition is encountered, the ignition of the starboard bank would be eliminated which would drop the rpms to 2500 rpm/// and the engine performance would stay that way UNTILL the engine is shut down, then restarted which would reset the S.L.O.W. feature setting. You do not say anything about a loss of power so I suspect the fuel restriction warning. See the following:

(Fuel Anti Siphon Valve)
(J. Reeves)

Many of the later OMC V/6 engines incorporate a fuel restriction warning via a vacuum device attached to the powerhead. If the engine overheats, or if you have a fuel restriction, the warning is the same.... a steady constant beep.

NOTE... Only the V/6 & V/8 engines have the above "Fuel Restriction Warning". The warning horn will not sound on the other models.

The fact that a engine is not overheating, but the warning horn sounds off with a constant steady beep, and that the rpms drop drastically would indicate that the engine is starving for fuel due to a fuel restriction. Check the built in fuel tank where the rubber fuel line attaches to the tank fitting. That fitting is in all probability a "Anti Siphon" valve which is notorious for sticking in a semi closed position. It will be aluminum, about 2" long, and the insides of it will consist of a spring, a ball, and a ball seat. If this valve exists, remove it, knock out those inner components which will convert it to a straight through fitting, then re-install it. Hopefully that cures the problem.

The above procedure will cure a restriction problem with the anti siphon valve as stated. BUT, it may also allow fuel to drain backwards to the fuel tank when the engine is not running (siphoning backwards) due to the fact that the carburetors/fuel pump etc are higher than the fuel tank. This condition is not an absolute as the valves in the fuel primer bulb usually prevent this backwards siphoning problem. However.... if this does take place, the cure would be to install a new anti siphon valve.

NOTE: There has been cases when the output valve in the fuel primer bulb would come apart, and the inner portion of the valve would actually reverse itself and be drawn back into the primer bulb's output valve body. This in effect would create a shut off valve and result in a fuel restriction. If this is the case, you should be able to feel something laying in the bottom of the primer bulb when held horizontally.

 

[chevysam41]

...My advice would be to replace the water pump if you can't verify a recent replacement of it and a thorough inspection and or replacement of the engine thermostats...

The previous owner indicated that he replaced the water pump (I think he said it was a whole new pump) either last year or year before (I can't remember which but could find out). Although I don't usually like to take a sellers word on a boat, the tell tale is pretty solid.

Are you sure it's not a fuel restriction alarm ?? Find the switch on the motor, disconnect it and see if the alarm stops. ...

I'm not sure that it isn't. I had planned to look at it yesterday until the alternator went out on my wife's car (when it rains, it pours). Boobie, by "switch" are you referring to the fuel vacuum switch that Joe is referring to in Post #2? If so, I need to find a diagram and locate this switch.

Joe: I have not noticed any loss of power or involuntary de-throttling or loss of RPM. Checking where the fuel line connects to the tank will be tough right now. The boat is a center console and the connections are directly underneath, basically center mass of the boat. I plan to pull and replace the tank this fall anyways and would prefer to do it then, but if you really think it needs to be checked now I can. Regarding your Note: I will say is that the fuel primer bulb won't hold pressure and will never really get rock hard anyways (cheap attwood bulb that came on the boat). I have another Johnson bulb ready to go that I just haven't had a chance to install yet - any chance that could be part of the problem or is that wishful thinking? I haven't noticed anything loose in the currently installed bulb.

Thanks again for all the replies!

 

[Joe Reeves]

A dead giveaway pertaining to a fuel restriction (99% of the time) is that the engine's vacuum/suction action, pulling fuel from the tank) will cause the fuel primer bulb to deflate somewhat, flatten out so to speak. Does that take place? There is an exception.............

If the outlet valve of the fuel primer bulb comes apart, the valve components will drop into the center of the bulb BUT eventually that portion floating around in there will get drawn back into the outlet valve shell BACKWARDS which effectively creates a shut off valve. This of course creates a fuel restriction BUT has no effect on the appearance of the bulb..
**************************
The fuel vacuum switch is normally located in back of the electric starter.... has a smaller fuel line attached and also a TAN signal wire.

The problem you've encountered, according to the warning signal (constant steady beeping) is either a "Fuel Restriction" or a "Engine Overheating" one.... however if a overheating one, the engine's S.L.O.W. feature should have shorted out the starboard bank of cylinders and dropped the rpm down immediately to 2500 rpm maximum.

 

[chevysam41]

A dead giveaway pertaining to a fuel restriction (99% of the time) is that the engine's vacuum/suction action, pulling fuel from the tank) will cause the fuel primer bulb to deflate somewhat, flatten out so to speak. Does that take place? ...

Good question...to be honest I'm not sure if the primer bulb deflates under way. What I do know is that every time I have needed to pump the primer bulb/choke to start (which is sometimes the case if I stop to fish for a couple of hours then decide to move), it is always soft. Though it will firm up some after squeezing 4-5 times, it will never get "hard".

Here are my thoughts based on what I'm hearing - let me know if I'm off base here: 1) Replace fuel primer bulb before going back out. 2) If #1 doesn't fix the problem, when alarm comes back on, switch the fuel restriction alarm to off.

Going to step back for a second and ask probably a dumb question, but wanted to confirm. The alarm is a solid tone (we believe), but on the gauge, the words "no oil" are illuminated when the audible alarm is going off. Does it still make sense that this is a fuel issue?

 

[cfauvel]

Also it is not uncommon for the vacuum switch (TEE into the fuel inlet near the VRO) to simply fail and turn on early.

someone mentioned disconnecting the two wired plug for that switch to see if the horn problem goes away....

also put a vacuum gauge in its place to see the amount a vacuum at various RPMS....at idle it should be 3 inhg and at higher speeds rise to I think no more than 5 inhg.

I believe the vacuum switch will sound at 7inhg....so you can test that with a vacuum pump....Turn key to ON, attach vacuum pump to vacuum switch and draw 5 inhg (no sound), then to 7 inhg (sound)

Oh and think about another mechanic....

 

[boobie]

If I remember right the vacuum switch trips at 4 inhg. You can adjust those switches.

 

[cfauvel]

If I remember right the vacuum switch trips at 4 inhg. You can adjust those switches.

I double check mine tomorrow

 

[jakedaawg]

If I remember right the vacuum switch trips at 4 inhg. You can adjust those switches.

cfauvel

​There were two different vacuum switches with different settings.

V6/gray housing/6.5-7.5 in/Hg

V6/black housing/5-6 in/Hg

I do not recall being able to adjust these.

 

[cfauvel]

cfauvel

​There were two different vacuum switches with different settings.

V6/gray housing/6.5-7.5 in/Hg

V6/black housing/5-6 in/Hg

I do not recall being able to adjust these.

Lean something new every day.... I have the grey housing on mine....

 

[boobie]

All I can say it was some years ago that we adjusted them. We used a vacuum pump and an ohmmeter and turned the screw on top to set . 4 in/Hg was the going setting.

 

[jakedaawg]

All I can say it was some years ago that we adjusted them. We used a vacuum pump and an ohmmeter and turned the screw on top to set . 4 in/Hg was the going setting.

Wasn't that on the old crossflows or the 90* motors?

 

[boobie]

No, it was what ever motor the vacuum switch was used on. I'm mainly interested in what the OP finds out. I probably should have never brought up the vacuum switch, but it does give a warning horn !!

 

[chevysam41]

Thanks for all the replies everyone. Can anyone show me a picture of where this vacuum switch is on the motor and what it looks like? I'm having a helluva time finding diagrams.

I'll try the vacuum test tonight, assuming I can find the switch. Hopefully I have some hose that I can connect between the switch and a brake bleeder. It sounds like this test is testing the same thing as unplugging the switch when the alarm goes off under way, correct?

 

[cfauvel]

well I can only describe where it is on mine...it is TEEd into the gas inlet into the fuel pump