'90 Mercury 175 warning module

[JLEHighland]

1990 Mercury 175 OB, Model No. 1175422GD / SN 0C139827 (estimate 1100 hours, all mine)<br /><br />Beeping from the oil mix warning module has been an intermittent problem for several years. This is the beep, beep beep signal, not the solid horn sound that would be triggered by the heat sensor on the powerhead. Here is some history:<br /><br />· Oil injection pump was replaced by mechanic – did not help.<br />· New batteries – no help.<br />· Cleaned the strainer in the remote oil tank to improve oil flow to the on-board tank – this helped but did not completely solve the problem.<br />· Cap on the on-board tank is new, tight and the float switch is working properly; oil level in the tank is good.<br />· In the past, the beeping would come and go during some outings; I would rev the engine in neutral or stop and re-start the engine to make it stop. On a recent trip, nothing would make it stop. All systems checked out OK, so I added oil to the fuel tank to create a 75:1 mixture as insurance, then disconnected the power lead to the warning module to stop the noise and continued operating for the day.<br />· The bearing assembly for the drive gear to the oil mix pump was recalled and redesigned at some point; this is the part that houses the magnet that is picked up by the rotational sensor; replacing this part did not solve the problem.<br /><br />Adding the extra oil to the fuel ended up fouling the plugs and I discovered that by merely cleaning the #4 plug I could get the beeping to stop! At least until the plug re-fouled. It turns out the primary voltage to the #4 coil also provides the warning module with rotational data. I suppose the fouled plug provides a ground to the ignition circuit causing a change in the input voltage to the warning module, which then sets it off.<br /><br />I’m pretty sure that replacing the plugs will help a lot, but I have to believe this is not the root problem. What is the most likely problem and how can I test for it? A weak coil? Could I move the module wire to another coil as a test? And what caused the beeping prior to the plug fouling? Any other thoughts? I’m OK with a VOA meter, but that’s about it.<br /><br />Thanks a bunch in advance,<br /><br />Jim

 

[clanton]

Re: '90 Mercury 175 warning module

Tty moving the wire to number 5. Seems like there is a voltage spec for this wire and if it exceeds the spec, sets the alarm. Try a search on www.screamandfly.com.

 

[orca]

Re: '90 Mercury 175 warning module

G'Day. There is a motion sensor attached to the oil pump, Try packing a thin washer between the motion sensor and the oil pump. This usually cures a problem that occurs in rough water.

 

[JLEHighland]

Re: '90 Mercury 175 warning module

Clanton – screamsndfly is an interesting site! Some very similar symptoms that were caused by a bad stator. Its always been sluggish out of the hole – especially bad during break-in, again with additional oil present to foul the plugs. But the alarm didn’t start going off until it had 8 or 900 hours.<br /><br />Whaley – I assume this needs to be a metallic washer. Hadn’t really noticed that it was ever related to water conditions, but its an easy fix. Any theory to go along with it?<br /><br />Appreciate the replies.

 

[orca]

Re: '90 Mercury 175 warning module

G'Day. To JLEHighlander. when these motors first came out we had a problem when running in rough water, the buzzer would sound intermittantly. We would fit a metal washer under the sensor. This seemed to fix the problem, i often wondered if the alarm would sound if the shaft stopped working. however the oiling system on these motors is very reliable, havent heard of any failures with this system. heard of one guy who heard his low oil alarm soundin and thought it was his MOBILE PHONE. Needless to say eventually his motor locked up.

 

[BassScratcher]

Re: '90 Mercury 175 warning module

I just started having a similar problem on my 93 Mariner 200 Magnum EFI. Here's the story:<br /><br />Had the boat on the lake on Sunday. Ran it for about 15 min @ 5K RPM's and it ran fine. Let the boat sit for about 1 hour. Got back in and ran at 30 MPH for about 20 minutes. When I idled down, the oil warning came on (not the temp alarm). The engine oil tank was full and the cap is 1 month old. I checked the water sensor. It was fine. I then started the motor and noticed smoke in the exhaust, so I'm confident I'm getting oil. After this I give it gas and noticed I don't have enough power to get on plane. I immediately shut it down and trolled to the ramp. Yesterday, I put a pre mixed tank on so I could start troubleshooting. First thing I noticed when I started it up in the driveway, was no alarm. I checked the oil pump output anyway. And just as I suspected, I'm getting oil. So today, I took it back to the lake. Backed off the trailer and she ran fine for 15 - 20 minutes. I idled down, shut off the motor and then cranked it back up and let it idle. The oil warning came on again and just like on Sunday, not enough power to get on plane. I could only get it up to 1600 RPM's. In neutral, she sounds great, but under load she bogs down. What could cause a power loss and oil warning alarm at the same time? And how do I go about troubleshooting? Could this be a coil problem on cyl #4? Since I am getting oil to the engine, I think the oil alarm is a result of another problem. Any suggestions are appreciated. I'm stumped.

 

[NICK JONES]

Re: '90 Mercury 175 warning module

JLE Highland and BassScratcher, did you ever sort these problems out ? I had similar problems and thought the oil pump was okay as I could see lots of blue smoke at tick over and also had an output signal from the oil pump sensor. It turns out that at low revs there is sufficient crankcase pressure on the oil reservoir to force the oil past the pump when it's not turning ! The plastic oil pump gear on the crank was partly stripped and the oil pump wasn't rotating the same as engine speed, so the oil pump sensor signal didn't match the coil signal and hence the alarm.I still get some oil pump alarms that come and go which I assume is due to an ignition fault as the boat is well down on power under load below 3000 rpm (135 Mariner v6 1987)

 

[ManlyVehicle]

Re: '90 Mercury 175 warning module

JLEHighland, I have a 1988 150XR4 (s/n 0B265041) with a similar problem. It's been irritating me now for over 6 years now. The intermittent beeping from the oil warning system seems to come and go when it feels like it, sometimes based on the sun, very often when it is first started cold.<br /><br />I've replaced the electronic module/lubalert twice, replaced the oil motion sensor and pump, metered the amount of oil being pumped, checked the oil tank sensor, and replace the stator. Bottom line is that the engine is getting oil, but still wants to beep every now and then. I "fixed" it by disabling the oil warning system by disconnecting one of the wires going to the electronic module/lubalert.<br /><br />On my engine there is both a temperature guage and warning horn, so that if oil does become a problem, I believe the engine will run hot before it actually cooks, so I am not concerned about that, and if it does cook, it deserves to for the aggravation it has caused me.

 

[NICK JONES]

Re: '90 Mercury 175 warning module

ManlyVehicle, check you have a spark on No 4 cyl during the alarm condition. No spark could be from bad outer switchbox to no.4 coil. My switchbox gave no output to No. 4 coil when cold and at other times at random. Hence the oil alarm. (Oil module uses this as a signal to compare to oil pump motion sensor).Also when you have the alarm from cold, stop motor and warm up outer switchbox with hair dryer / low temperature hot air gun and start motor again & see if alarm goes away. This gives you a warm switchbox & cold engine. If it stops the alarm then it's the switchbox.You could also then freeze spray the switchbox and see if the alarm comes back again when cold.(Cans of freeze spray from electronics suppliers). Sounds like a "dry joint" within the switchbox.

 

[ManlyVehicle]

Re: '90 Mercury 175 warning module

WOODMAN, thanks for the advice. It sounds reasonable. I will give it a try and let you know.

 

[CU2NITE]

Re: '90 Mercury 175 warning module

I have an 85 150 xr2, had the same problem with intermittent oil alarm that drove me crazy. I tested and changed every thing and still got the alarm. Then I disconected the oil system, pluged it and now I premix. No more worrys about proper oil in cylinders, or that alarm that made my heart jump evey time it went off. I asume my plastic sleve at the end of the oil pump shaft was getting worn. Good luck.<br /><br />CU<br /><br />RUNNING ENGINE WHILE LISTENING TO THE HORN WILL MAKE YOU MORN!!

 

[ManlyVehicle]

Re: '90 Mercury 175 warning module

CU2NITE, I understand the frustration and don’t blame you for mixing the fuel on your own. I may resort to that, but would prefer getting this motor/system working the way that it should, even if it is 15 years old. <br /><br />WOODMAN, I tried the diagnostics you mentioned:<br />1) Started the engine cold – the oil sensor beeped; there was NO spark to the #4 cylinder.<br />2) Stopped the engine; heated the outer switch box with a hair dryer.<br />3) Started the engine again – the oil sensor still beeped along with no spark or intermittent spark to #4 cylinder, then the beeping went away and spark became consistent on #4. This is how it very often acts; I don’t think applying the heat really affected it. <br />4) Stopped the engine and sprayed the outer switch box with freeze spray; started the engine again. Still no beeping from oil alarm; and #4 still sparking.<br />I don’t think the temperature changes on the outer switch box affected anything, but think the outer switch box may still be at fault. Besides the trigger, that is the only related part I haven’t replaced. What do you think, should I just replace the outer switch box, or do further diagnostics on the trigger? Thanks.

 

[JLEHighland]

Re: '90 Mercury 175 warning module

I’m still having the same problem. To make sure the fundamentals were right, I installed new plugs, treated the 6-month-old gas with stabilizer and topped off the tank with new gas. After a 10 minute crawl out of the harbor, during which time the beep, beep beep resumed, it had no power to go on plane. Sounded like it was running on only half its cylinders. Finally coaxed it onto 5 or 6 and the alarm stopped sounding. <br /><br />Woodman, which plastic gear was stripped? I recall the oil pump shaft on my 175 had a steel gear. Anyway, the beeps have usually been worse at lower rpm for me. Did replacing the gear and the switchbox solve your problem completely?<br /><br />ManlyVehicle, I have been leaning toward replacing the stator, but your story makes me want to re-think. How are you checking for spark on #4. Besides the trigger, have you replaced the #4 coil?

 

[JLEHighland]

Re: '90 Mercury 175 warning module

I’m still having the same problem. To make sure the fundamentals were right, I installed new plugs, treated the 6-month-old gas with stabilizer and topped off the tank with new gas. After a 10 minute crawl out of the harbor, during which time the beep, beep beep resumed, it had no power to go on plane. Sounded like it was running on only half its cylinders. Finally coaxed it onto 5 or 6 and the alarm stopped sounding. <br /><br />Woodman, which plastic gear was stripped? I recall the oil pump shaft on my 175 had a steel gear. Anyway, the beeps have usually been worse at lower rpm for me. Did replacing the gear and the switchbox solve your problem completely?<br /><br />ManlyVehicle, I have been leaning toward replacing the stator, but your story makes me want to re-think. How are you checking for spark on #4. Besides the trigger, have you replaced the #4 coil?

 

[ManlyVehicle]

Re: '90 Mercury 175 warning module

JLEHighland, for spark on #4 I used an inductive timing light. Two wires go to a 12 volt battery for power, and then a simple clip goes on whatever spark plug wire you want to check. When there was no spark on #4, I moved the clip to other wires while the engine was still running to make sure that it was isolated to #4 not giving the spark.<br /><br />Because there was still some question in my mind about whether a bad spark plug could cause some of these “faulty” signals (as you seemed to experience), after things were running as normal (no beeping and good spark on #4) I disconnected the spark plug wire from the #4 spark plug, simulating a bad plug. This did not cause any beeping to occur.<br /><br />There was also some question in my mind about whether a bad coil could cause some of these faulty signals. So I disconnected the #4 coil from the switch box. Still no beeping.<br /><br />This leads me to conclude that a bad coil or spark plug could not cause a faulty signal. That the signal monitored by the lubalert is based on what is coming out of the switchbox for #4. My understanding is that this is affected by the stator, the trigger, and anything the switchbox itself may decide to do. I know this seems contrary to your findings where cleaning the plug seemed to help to some extent; and I’m not sure how to explain that (maybe your 175 system works a little differently than my XR4 system?). <br /><br />When my stator was replaced it was giving some out-of-the-ordinary readings using an ohm meter as prescribed in the service manual. The trigger on the other had seemed to read within the normal range. So I replaced only the stator at the time (replacing the trigger involves much the same work as the stator except I think the timing can be affected). This did not correct the problem. Not sure what to tell you but I’ve heard the stator as a logical choice from others as well. It just wasn’t the solution for me. So, now, in my case, I’m leaning towards replacing the outer switch box based on what WOODMAN said, even though the diagnostics didn’t go quite as well as expected. This should be a pretty easy job (but not cheap - around $175 w/shipping for the part). The stator cost me a little more ($185 w/tax) but the flywheel had to be pulled to install it. When I replace the outer switch box I plan to run the resistance checks on both the trigger and stator again which involve disconnecting lots of wires from the switch boxes but no removal of either the trigger or stator; that might be a good thing for you to try.

 

[dogsdad]

Re: '90 Mercury 175 warning module

In the interest of learning I have studied this thread and a wiring diagram. I don't have experience yet in dealing with outboard problems, but it occurred to me that the fouling plug is not the cause of the alarm, it's another symptom. Whatever is causing the alarm to sound at the wrong times is also causing the plug to foul. Being an electronics technician, I would suspect the stator, the trigger, the switch box, and the lubalert module itself. I also note that the advance module seems to be involved in things, and the fact that power loss is associated with some of these problems might lead me there also. Hopefully something I've said makes sense!

 

[Hemlock]

Re: '90 Mercury 175 warning module

Just a thought....<br /><br />I was fishing with my uncle and in his Lund/2002 150 Opti-max and we ran low on oil, alarm sounded, filled the 1 gallon resevoir up and still had alarm going off. Got on the cell phone and figured out we had to bleed out the system. This required unscrewing a screw at the top of the resevoir with engine running, till it came out the top. Problem solved. Maybe an easy fix?

 

[JLEHighland]

Re: '90 Mercury 175 warning module

ManlyVehicle, thanks for the detail and insight. I think you’ve helped me eliminate the coil. I agree with DOGSDAD that the fouled plug is just another symptom, but why does cleaning it help eliminate the alarm? If I test by grounding the center electrode of the #4 plug and get the alarm to sound, wouldn’t this implicate the switch box? I may do WOODMAN’s hairdryer test too. May I ask where you found the stator for $185?<br /><br />HEMLOCK, the alarm can be set off by several sensors, one of which is a float switch in the on-board tank. That’s why your alarm didn’t stop until your tank was full of oil. My alarm is coming from the oil mix pump rotational sensor, which also takes a signal from the #4 coil.

 

[Fast4wrd]

Re: '90 Mercury 175 warning module

Gentlemen, could I get you to scroll down the msg list and look at my problem with the 225 Promax alarm going off at high RPM, and it quits at idle?<br /><br />Its similar to this only different motor different circumstances...ANY help will sincerely be appreciated!!

 

[ManlyVehicle]

Re: '90 Mercury 175 warning module

JLEHighland, I got my stator at a local shop for $175.00 plus $10.50 tax; but I think a comparable part could have been purchased from http://www.mercruiserparts.com/ for $137.83 plus shipping. Based on your serial number, on that site, it looks like yours is more expensive ($312.38 plus shipping - part# 398-9610A5). Good luck! <br /><br />Hemlock, for my problem I’m pretty comfortable that there is no real oil situation. I’ve checked and rechecked for that, but good thought, thanks anyway.