1998 Mariner offshore V-135 2.0 Liter Low oil alarm

I have a 1998 mariner offshore outboard with a new powerhead in 2000. Last night while on the water i got the beep beep beep of the low oil alarm at 1/2 throttle. i shut it down and checked the oil in the remote reservoir (just filled it) checked the line. Checked the reservoir in the engine (full). Started up idled fine, ran at an idle just fine in gear and even up to 1/4 throttle but soon as I pushed it more I got the low oil beep again. Came home tore oil pumpp apart, gears in like new shape so its not the nylon gear on the shaft (whew). took cap of and tripped float... that is working and is not the source of the alarm. This motor has been impeccably maintained. Put it on the muffs on the driveway and started it.. idled fine, no alarm. Started to raise idler arm and beeep beep beep, goes away as soon as I return to idle. As a side note my tach has gone off, its reading almost 3000 at idle which i know isn't right and pegs at 6000 at 1/2 throttle which again I know isn't right. that just developed this week as well. All marinas are booked till September for repairs. I understand I can premix but I don't want to 65 gallon tank I don't wanna deal with that headache especially with the fail safes in place to prevent a powerhead meltdown. Any ideas why my alarm goes at >2000 RPM but not at idle. Thank you ahead. If more information is needed please let mek now. I was supposed to hit the water tomorrow fishing but I'm afraid to until I pinpoint this problem. BTW blowing good smoke at idle so oil is getting in there. I'm at the point that I don't believe anyhting is wrong with the oil pump and this is a fault elsewhere.

Re: 1998 Mariner offshore V-135 2.0 Liter Low oil alarm

UPDATE. Tested oil bleeder and oil is flowing good. Ran it and triggered alarm at 2000 rpm systematically unplugged connections to alarm module never silenced alarm but would still silence at idle... disconnected all wires to module including wire to coil for cylinder 4 now alarms at all RPM. I'm thinking alarm module at this point. Again I systematically disconnected the white, blue white, blue, and finally green wire. Could not get alarm to stop. Any thoughts?

Re: 1998 Mariner offshore V-135 2.0 Liter Low oil alarm

The cylinder in the pump may be worn enough to not pump enough oil at higher RPMs but enough to satisfy if at the low RPMS. I would start thinking about another pump. the only other thing I can think of is a kink or debris in the line restricting the flow. Because the alarm isn,t an all the time thing i believe it,s doing it,s job and warning you.

Re: 1998 Mariner offshore V-135 2.0 Liter Low oil alarm

Unfortunately, Maxz doesn't realize that the sensor doesn't measure oil flow, only rotation.

There is a troubleshooting sequence in the manual. Apparently your oiler is working, so the trouble is one of.
1. No signal under some conditions from the switchbox.
2. No signal under some conditions from the rotation sensor
3. Short under some conditions to the tank sensor (very unlikely)
4. The alarm module itself is bad.
5. Under voltage, over voltage, or noise on the power line confusing the oil alert module.

If it's an EFI engine, water in the separator. (sensor wired in parallel to oil tank)

Disconnecting the water separator and oil tank wires will silence the alarm at all times if that's the problem. Circuit is normally open to ground. Either switch grounds it.

Disconnecting the rotation sensor (any or all of the 3 wires) will set off the alarm. The alert module looks for it's presence. To test it, when connected, there should be 12 V on one wire, ground on another, and the third toggles between about 5 volts and near ground as you rotate the engine by hand. It's about 1 or 2 pulses per rotation as I remember. You can use a piercing probe to test, just don't forget to put a little liquid electrical tape on the wound you make.

The switchbox (green) wire can be connected to any cylinder. Often moved for testing. One trick you might try is to disconnect it and run the engine. If it now beeps at idle and then silences at half throttle, the rotation sensor is bad. BTW, the orientation of the magnet is critical. Put in backward, it will not work.

The oil pump either runs or not. There is a linkage to it that varies the stroke by throttle position. It's fairly straight forward. The pump itself seldom fails, but the drive gear can fail. When the pump is off you can pull the shaft and inspect it through the mounting hole. Disassembling the pump should have been the last thing to do in troubleshooting.

Hope it helps
John

Re: 1998 Mariner offshore V-135 2.0 Liter Low oil alarm

Thank you John for your reply. as i said i examined all gears internally including the nylon and they look like Brand new. so I know the pump is working. Location of the magnet? just to clarify is there a magnet on the pump shaft itself . I believe I put it back in same position but now I want to check. Ok when I disconnected the green wire it does now alarm at idle but I didn't ramp it up at all to see if it stops. i will be sure to do that in the morning. I would love it was the sensor and not the module. Again I have a manual ordered but trying to iron things out now. Also, i'm assuming the power coming into the module should be 12V. I'll have to verify its not over voltage tomorrow as well. unfortunately Disassembling the pump was the first thing the local marina told me to do because they automatically assumed sheared nylon gear and got me afraid of the same. So i will run the disconnected green wire tomorrow and test the rotation sensor. Then I will check the voltage on the others lines. Thank you again for your help.

Brian

Re: 1998 Mariner offshore V-135 2.0 Liter Low oil alarm

oh sorry... no EFI and what did you mean by switchbox? pardon my lack of knowledge. Thank you again.

Re: 1998 Mariner offshore V-135 2.0 Liter Low oil alarm

The two majick boxes with a gazillion wires on them are called switchboxes. On other makes of engines they are sometimes called power packs.

If you probe the wires to the rotation sensor, and it's good, the magnet is right.

The magnet goes into the bushing south pole first (the end that attracts the arrow on a compass) and the plug goes over it round end out. Use a little 2-4-C to keep parts in place while you stuff it into the engine.

The white wire has 12 V to the sensor.
The blue/white wire toggles between 5V and near ground, once every 2 revolutions of the engine. It's a hall effect sensor, so it's the proximity of the magnet, not the motion that toggles it. No need to spin the engine, just turn it by hand. When I do this test, I pull the plugs, flip the kill switch down, and turn it by hand. Key has to be on for power.

FYI, the engine mounted tank is to be full to overflowing. The sensor makes as soon as the oil level begins to drop. Instructions are to idle the engine, crack the cap and let the oil fill it from the boat tank. When it overflows tighten the cap enough so it doesn't leak. Be careful about overtightening. It's like the cheap weed wacker caps, and you can crack it with hand torque.

Would be maddening, but desirable for this to be your problem, wouldn't it?

Here's a load of information on the oil injection system:

http://continuouswave.com/whaler/reference/mercuryOilInjection.html

hope it helps
John

Re: 1998 Mariner offshore V-135 2.0 Liter Low oil alarm

ok here is where i am now... no voltage meter till later today. Disconnected green wire now alarms at idle and all the way up through the range, does not stop. is the purple line going into the alarm module the power supply? i know the tan with stripe is the heat sensor. I will check that voltage as well. Thank you again for all your help... will post voltage results when i get them. Thank you.

Brian

Re: 1998 Mariner offshore V-135 2.0 Liter Low oil alarm

Purple is power after key switch (by Mercury convention)
Tan with stripe is the heat switch, and also the output of the oil alert module. Pulling to ground sounds the alarm.

Is the oil reservoir brim full?

Re: 1998 Mariner offshore V-135 2.0 Liter Low oil alarm

full up to bottom of neck but only overflowing when I crack the top of the reservoir lid... ok ran the voltmeter today... got 4.99V from blue white from crank sensor while cranking by hand... 11.9-12.2 on the white to oil pump sensor. 4-6 volts out to lid but i was also grounding to same end so when i lifted lid out it blanked to 0... should this be 12 when it is supposedly not tripped? or is this lower voltage normal out to the oil reservoir sensor. couldn't get a reading out of purple wire into module... don't know why it was bouncing so bad. again still not alarming at idle but soon as I ramp up i get alarm, oh and volts out to crank sensor still at around 12 while engine running at higher rpm. Sorry to be a bother but i tremendously appreciate your knowledge and assistance.

Re: 1998 Mariner offshore V-135 2.0 Liter Low oil alarm

BJ- follow this path exactly and it will tell you what is wrong:

Run the engine to recreate the conditions sounding the alarm. Do these tests while the engine is running and the alarm is beeping. Be careful- the flywheel is very close to your hand. Keep sleeves, watches and other objects that can catch on the flywheel away.

Once the alarm starts, I would first unplug the blue wire from the oil reservoir cap. If the alarm stops, either the oil level sensor is bad or the level is low.

Next I would disconnect the green wire going from the alarm module to the #4 coil wire terminal on the switchbox. If this stops the alarm, either the rotation sensor is bad or the pump isn't rotating.

If the alarm does not stop reconnect the green wire and unplug the white and blue/white wires to the rotation sensor. If this stops the alarm, check for no spark on #4 cylinder.

If the alarm does not stop disconnect the green, white and blue/white wires. If this stops the alarm, then either the pump is not rotating, the rotation sensor is bad, or no spark on #4 or the alarm module is bad. If the alarm still does not stop, disconnect the solid blue, blue/white, white, and green wires, if this still does not silence the alarm, then the alarm module is bad. You will single out a bad component in each step, eliminating each item as you go. You can check the rotation sensor by checking its output. Turn the key on, leave power wire connected and rotate the engine. You should get 1 pulse of 5 volts for every 2 rotations. You'll need to have the plugs pulled for this test so you can turn the engine safely and easily.

I did this exact procedure and found my module was bad. That was 3 years ago and my engine hasn't blown up since so it was correct.

UFM82

Re: 1998 Mariner offshore V-135 2.0 Liter Low oil alarm

If you disconnect the wires to the rotation sensor, it will alarm under all conditions. It looks for that.

Back to the rotation sensor. Did the 4.99V go down to near zero every couple of revolutions? It should toggle between near 5V and near 0 V as the engine is turned over. If not, the magnet might be backward, or the sensor might be bad.

Re: 1998 Mariner offshore V-135 2.0 Liter Low oil alarm

yes almost exactly as you said... every two rotations i would get 4.99 then back to 0.00. Thank you ufm but i did those tests and alarm would never stop no matter which ones i unplugged. which originally led me to believe alarm module but i want to be absolutely positive and not throw parts at this especially when they cost more than 200 a piece.

Re: 1998 Mariner offshore V-135 2.0 Liter Low oil alarm

I'm afraid we're sneaking up on a bad alarm module.

For 2 final tests, disconnect the tank sensor and operate the engine. If it not doesn't alarm, something is wrong with the tank switch or it's wiring.

For the last test, disconnect the purple power wire to the alarm, and hot wire it directly to battery voltage at the solenoid. Operate the engine. If the alarm now goes off, the alarm module is bad. If it does not, there's a fault in the ignition switch purple, or the cannon connector pin 2, or the wire from there to the purple terminal supplying the oil module.

It is theoretically possible for the rotation sensor to fail at speed, but I've never seen it. usually if you get good strong indication as you have, it's OK.

Others have chiseled into the oil alert module and found pretty shoddy electronics in it, with poor solder connections, and poor sealing. An intermittent module wouldn't be much of a surprise.

Used modules are around, often for free. They all (V6) operate the same, sometimes lead connections and color coding is different, but that's why they make solder and heat shrink.

hope it helps
John

Re: 1998 Mariner offshore V-135 2.0 Liter Low oil alarm

will perform the final two tests tonight. I will be ok spending that money on the module as long as i have pinpointed it... I can say right now that the alarm does NOT stop when i disconnect the cap sensor. as I have already tried that. just have to hotwire the purple tonight. Will update later. Again thank you for all the help.

Brian

Re: 1998 Mariner offshore V-135 2.0 Liter Low oil alarm

Check for battery over voltage if you haven't done that yet. Should be OK up to about 16V as far as the oil module is concerned. Voltage is regulated on that engine, so unless something is drastically wrong, this should check out. (translation, long shot)

Re: 1998 Mariner offshore V-135 2.0 Liter Low oil alarm

If not, the magnet might be backward, or the sensor might be bad.

Click to expand...

Around 1993 the magnet is mounted permanently in bushing so it cant be reversed.

Re: 1998 Mariner offshore V-135 2.0 Liter Low oil alarm

Faztbullet said:

Around 1993 the magnet is mounted permanently in bushing so it cant be reversed.

Click to expand...

Thanks for that info, but we've already been by that point.

yes almost exactly as you said... every two rotations i would get 4.99 then back to 0.00.

Click to expand...

Re: 1998 Mariner offshore V-135 2.0 Liter Low oil alarm

ok where do i want to check for Battery overvoltage, like which points to monitor i know for power in to the module it never exceeded 13V. ... sorry no results for last night. too much rain here. I think we have gotten close to 10 inches in the past week. will try for more tonight then off on vacation... really hoping to get back. get a module (really starting to think that is the problem) and get back on the water. Any suggestions where to start looking for one... i found them new for $220 but i know you had mentioned used before...

Re: 1998 Mariner offshore V-135 2.0 Liter Low oil alarm

Module should be able to run on 15 or even 16 volts. Just check it at the battery. If you have a dash voltage gauge and it isn't freaking out, it's probably OK.

I get em on eBay or craigs list during the winter. I just used my last one for this year on someone elses engine.

Maybe someone looking on had ditched their oil pump and has one to give you or sell you cheap. They can contact you by PM.

I think anything V6 will work. Put one off'n an EFI engine on my carb'd XR4. Just took a little cutting and splicing, nothing major.