Mercruiser 350 Mag MPI engine Guardian reset

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markspark7

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Afternoon all

Had an issue with the gear oil supply to the bravo3 outdrive. The plastic connector that connects the gear oil pipe to the outdrive had snapped (common fault although a pig of a job to fix!)
Refitted the connector and refilled the monitor bottle but on running the engine up at sea the rev's wouldn't go above 3000 RPM doing around 12knots.
I'm assuming the engine guardian system must have kicked in but there where no alarms sounding.

Does anybody know how to reset the Guardian system or is it a Mercruiser engineer job or something that can be sorted by myself.
I have all the fault codes but no fault code reader, can anybody recommend one???

Thanks in advance:encouragement:
 
It does sound like the engine guardian has activated. There are various severity of alarm,some of them make no noise but do flash up an alarm symbol on the screen. On my previous boat with a merc 5.0 mpi with the engine guardian, as soon as you fixed whatever the problem was the error would clear and the engine would run as normal ,there was no need to manually reset anything.
 
julians said:
It does sound like the engine guardian has activated. There are various severity of alarm,some of them make no noise but do flash up an alarm symbol on the screen. On my previous boat with a merc 5.0 mpi with the engine guardian, as soon as you fixed whatever the problem was the error would clear and the engine would run as normal ,there was no need to manually reset anything.
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Which screen are you referring too??

The gear oil connector broke off dumping gear oil in the bilge this then set off an alarm and the engine went into guardian mode.
I replaced the pipe connector and refilled the oil monitor and the alarm went off however after a sea trial the guardian mode appears to still be there.
without a code reader I cant find out what the issue is.
 
markspark7 said:
Which screen are you referring too??

The gear oil connector broke off dumping gear oil in the bilge this then set off an alarm and the engine went into guardian mode.
I replaced the pipe connector and refilled the oil monitor and the alarm went off however after a sea trial the guardian mode appears to still be there.
without a code reader I cant find out what the issue is.
Click to expand...

On mine there was a small Lcd screen in the rev counter,you could scroll through various different items of data,and it had a little 'AL' symbol that would flash up there was a problem.more severe problems were accompanied by a loud beep and a text description of what was broken,but less severe issues just flashed this symbol
 
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zt260 said:
You can buy a mercruiser scan tool
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'course he can, but I for one wouldn't go that route.
Considering both their cost and their intended usage, scan tools only make sense for someone who regularly must check different engines on different boats.
But unless the OP has such need, in his boots I would definitely fit a Smartcraft display.
In fact, since he asked "which screen?", I suppose he has a boat where the builder only fitted analogue gauges.
Why some builders do that, skimping on a $150 Merc Smartcraft display, beggars belief - but that's indeed what plenty of builders do. :ambivalence:
In his boots, having a Mag 350 MPI powered boat, I would fit one of them for good, regardless of the current inconvenience.
I can't think of any mone better spent for monitoring the proper functionality of those engines.

What julians mentioned is one version of these Smartcraft instruments, where the tacho gauge is actually digital in spite of the analogue representation, and is combined with the small LCD display that he explained.
What markspark7 could do is either replace his current "traditional" tacho with one of these, or add a separate Smartcraft LCD display.
Probably the latter is what I would do, just to avoid mixing different styles between the tacho and the other existing instruments.
And IIRC, the LCD-only Smartcraft display has some additional functionalities, compared to the one integrated in the tacho.
 
The oil level sensor doesn’t give a ‘hard code’ i,e, permanent, when you restore the oil level the code/ alarm will disappear. So either the oil level sensor is faulty, the float can get gummed up with old oil, or you have a second separate fault. Whats the alarm beep frequency and interval?
Smartcraft instruments are great so long as they are programmed correctly I have commissioned dozens of new boats that either didn’t show engine data or displayed data that was invalid due to incorrect setup at the factory, as well as the instrument it also needs the Smartcraft harness’s and junction box to connect to the engine.
 
spannerman said:
The oil level sensor doesn’t give a ‘hard code’ i,e, permanent, when you restore the oil level the code/ alarm will disappear. So either the oil level sensor is faulty, the float can get gummed up with old oil, or you have a second separate fault. Whats the alarm beep frequency and interval?
Smartcraft instruments are great so long as they are programmed correctly I have commissioned dozens of new boats that either didn’t show engine data or displayed data that was invalid due to incorrect setup at the factory, as well as the instrument it also needs the Smartcraft harness’s and junction box to connect to the engine.
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It only continuous beeped one time, the drive oil reservoir was low, I had some drive oil handy but not enough to completely fill it, about 1/2 full. Does it need to be topped off?

When I got this out of storage the lower line on the raw water intake had been left on and was damaged, I didn’t notice at first and the boat ran on muffs for about 5 mins, is there a temp sensor that may have gone bad in the raw water system?
 
The oil should be to the fill line about 2/3 full, there needs to be room for the oil to expand as the drive warms up.
on your engine there may be a seawater pressure sensor, if so, its fitted on the starboard end of the servo oil cooler which sits cross the back of the engine, it is a brass fitting with wires plugged into it, it maybe that you have damaged the impellor if it didn’t get enough water when you ran it on muffs so it sees low pressure from the pump, also the sensors go bad, they tend to dry out in storage which leaves salt crystals inside which blocks the hole into the sensor.
 
spannerman said:
The oil should be to the fill line about 2/3 full, there needs to be room for the oil to expand as the drive warms up.
on your engine there may be a seawater pressure sensor, if so, its fitted on the starboard end of the servo oil cooler which sits cross the back of the engine, it is a brass fitting with wires plugged into it, it maybe that you have damaged the impellor if it didn’t get enough water when you ran it on muffs so it sees low pressure from the pump, also the sensors go bad, they tend to dry out in storage which leaves salt crystals inside which blocks the hole into the sensor.
Click to expand...

ok, I’m at the boat now, I bought some more oil and filled it more I will remove a bit for expansion. I’m in fresh water on Lake Ontario. I replaced it with a brand new impeller when the housing broke. I will take a look at the sensor, do you know what resistance it should be showing?
 
Afraid not as we always use the CMD diagnostic tool which reads off the seawater pressure in PSI. If you mean the drive oil sensor then its either open or closed, easy to check with a multimeter on the two wires coming out the bottom but the resevoir needs to be empty so you can turn it around to simulate full or empty.
 
After checking through those things I finally had a mechanic come by, hard find this time of year in Canada. We checked over everything and during water test we found that it was not advancing the timing under load. We set base timing which was 5 degrees out. Then neutral would advance to 24 degrees BTDC at 3500rpm but only 14 BTDC under load, being 10 degrees out is huge from my understanding. Regardless he thought it was the ignition module, picked one up and installed, no luck.
Actually ran worse to only 2800rpm.
 
Hi
This isn’t anything to do with the gear lube. That would stop alarming after being put right.
most common issue on these engines Is the distributor cap famous issue. Terrible things. As for the timing. You can’t set the timing on these, in the way usually done on older variants. The timing is controlled by the ecu. If it’s not been in bits since the last time she ran well. The timing couldn’t have moved. As long as the distributor has been positioned between the two marker lines on its base...with the engine of course in its correct rotation cycle...the ecu takes over from there. I’d suggest your issue is to do with a sea water temp sensor. Also one of the common issues. Iac is another that causes an alarm too.
 
Precisely, once I tested the gear lube that was just a minor issue. I goes far deeper than that.
I may as well get into it so we get the complete story.

Parts replaced so far: water intake impeller/housing, plugs, wires, rotor, cap, coil, ignition control mod, fuel filter, fuel pump, regulator, map sensor, tps, anti syphon valve.

-Compression 155-165 all cylinders
-Fuel pressure 43psi
-In base timing it was in fact out 5 degrees
-Fire arrestar cleaned
-ECM disconnected and ran in distributor mode, where it works of internal curve
 
Ellshu said:
Precisely, once I tested the gear lube that was just a minor issue. I goes far deeper than that.
I may as well get into it so we get the complete story.

Parts replaced so far: water intake impeller/housing, plugs, wires, rotor, cap, coil, ignition control mod, fuel filter, fuel pump, regulator, map sensor, tps, anti syphon valve.

-Compression 155-165 all cylinders
-Fuel pressure 43psi
-In base timing it was in fact out 5 degrees
-Fire arrestar cleaned
-ECM disconnected and ran in distributor mode, where it works of internal curve
Click to expand...
Is it popping when not going past 3000 rpm ?
 
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