Beating a Dead Horse. To Block Off or Not to Block Off Mercury Oil Injection

[Capnmoench]

I'm sorry, I know this has been beat to death, but what do you think about a 1997 2.5l 175? Was the system improved or is it still a weak link that may cause me to constantly fear the death of my rebuilt motor. I use it for fishing and never really push it. I do want dependability, but I also have a 4-stroke kicker and having an extra tank is a pain because it's always in the way. But a blown powerhead is also a pain. I don't want another one of those.

[FORBESAUTO]

At stock rpm levels it wasn't as bad. But it's still a plastic drive gear that's 20 years old. It's definantly safer to mix. If it strips its bye bye in a hurry.

[Capnmoench]

It was rebuilt last year. I'm just getting it broken in. So I don't know if that's a 20 year old gear. I wasn't the one that had the work done, but I would thing that is a wear item you would replace. I'm about out of my 50:1 break in mix, so I am at a deciding point. I have a blown 150 that has an EOI kit installed on it. The gear is stripped on it. I don't know if the EOI kit was slapped on after the gear stripped or if was run after failure, but looking at the pistons that weren't the dead one, they are pretty haggard. If my alarm system is working properly and I dump the throttle at an alarm, what are my chances of not inducing damage?

[FORBESAUTO]

If I had to guess, the gear probably didn't get changed. I honestly couldn't tell ya how much time ya have, I've never tried it . I know of a bunch of stockers that have always ran with the injection with no problems. The age of this stuff bothers me, I feel it's not worth taking the chance. Just me.

[racervboat]

dump the oil injection and your the only who can f*** it up not some piece of crap plastic gear made in china.Rebuilt many v-6s with new gear new crank drive worm gear new pump and took a crap immedieatly just cant trust the system.Would rather have a vro omc system and that's just as bad but you don't have to worry about a stripped plastic crank gear taking out the powerhead. JMHO

[flabum1017]

Get a two stroke kicker and go pre-mix

[Capnmoench]

I like the 4-stroke how it just barely sips fuel. I can probably get creative with and aux tank mounting setup. As far as the alarms, how does one bypass them but still have an overheat warning?

[tlwjkw]

won't effect over heat warnin'.. has nothin' ta do with tha oilier stuff other than usin' tha same buzzer....... you will loose tha "self check" beeps..

[phillnjack]

By going pre-mix you can be 100% sure there is lubrication in the fuel that gets to the motor.
as for the alarm.. what do you do if going full throttle in a turn to avoid someone and the alarm goes off ? switch motor off and hit someone, or
keep motor running with no oil and avoid them .
I know that easy to answer ( switch of and hit them ) but its only gonna go bad in a difficult situation, never in the drive way.

nice big re-built motor deserves her pre-mix to stay healthy.

[tripower]

Doesn't mixing happen in the VST tank? If so, I don't see how you could run out of oil as soon as the horn goes off. To me, it looks like you'd have all the fuel/oil mix in the fuel rail, fuel pump, lines, and VST already premixed. It's not a lot of fuel but surely enough to shut down safely. Am I missing something? I think lots of experts are driving home with the horn going off if everyone is losing motors to the oil injection gear

I've actually thought that the opposite was more likely. When you're idling along in a no-wake at 100:1, and then get on the throttle right after that what happens? 6000 rpm at 100:1? Sure the mix in the VST will start going up but it's going to take some time.

[phillnjack]

the alarm dont go off when the oil starts dropping off, it only goes off when NO oil at all is getting through, thats the problem.
you could of already been running with a lot less oil than you think before the alarm activates.
proof of this is in the system itself,
when idling it uses a little amount of oil and no alarm !!
you might then open up and run full throttle with still only that little amount if oil as per idle, this now causes catastrophic damage and you
are thinking you are getting plenty of oil because no alarm gone off.
you might think your getting say 50 to 1 when your only realy getting 100 to 1 or even less !!! but still no alarm activated.
and if just 1 little sensor of the alarm dont connect you do not hear the alarm and bang.

[David - WI]

Tripower has the right idea, but 100:1 is the amount of oil being added to the fuel... not the amount present in the crankcase. If you look at "oil migration" data, the oil basically stays in the crankcase at idle so there is plenty of oil available to move through the engine when you "get on the throttle". As the rpm's increase the oil moves out of the crankcase but by then the oil injection system is already adding the extra oil needed.

http://www.maximausa.com/pdf/Oil%20M...on%20Sheet.pdf

(The alarm goes off when the pump stops turning; but there would still be oil in the carbs/VST and the crankcase.)

Keep in mind that with pre-mix, you have way too much oil at idle... so you get a lot of smoke idling and when taking off from idle (mine is currently pre-mix); which might not be so great for a fishing boat.

[tlwjkw]

there is only two sensors that are really "oil related" on that motor.. low oil and rotation.. rotation is tha main concern.. if it quits you "still have oiled fuel in tha vst/carbs/lines" no mater what ratio.. in theory it should be enough ta get tha motor shut down.. here's tha gig though.. its a very iffy sensor ta start with.. then ya add tha everyday "driver".. whats that noise?... must be hot?.. might be oil? (if he's actually read some information on it).. do i shut it down instantly or do i idle back to a stop then turn it off or see if it goes away?.. now can i idle back to tha ramp or not.. guess what tha "normal guy" is gonna do?.. well it still starts and idles ok!.. several motor re builders will not put tha oilier back together on warrantied stuff jus 'cause of these types...

if ya "know tha motor history", never over heated and been well maintained and NORMAL SERVICE motor then good chance it will never be a problem.. first thing outta most mouths is "its an oilier problem".. then ya got tha fact that ya NEVER HEAR 'bout tha (probably thousands) of 'em still out there workin' jus fine.. ya gotta consider this site also.. its mostly folks tryin' ta get every last drop of performance outta they're junk and if this includes you, oilier needs ta go away no mater what............ jmo

[Capnmoench]

I do believe that you would have enough oil in the lines from the mix already going in in case of a sudden outright failure, but the problem with the VRO slowly failing and skipping a tooth, but still rotating enough to not set off the alarm is very valid. I don't know what the requirements before an alarm goes off on the rotational sensor are, but it's got to have enough buffer to run at 100:1 at a slower idle. If it's still spinning enough to and idle 100:1 at 5500 RPM, then you're talking about way less than 100:1 at those RPMs. I don't know if the engine speed logic is a factor in the alarm. I assume an older technology like this built on an even older platform would not. This is good stuff. I already have a lot more sound responses than anything I could hash up in the countless other threads I researched. Keep the info rolling in. Thanks!

[David - WI]

The difference between 100:1 and 50:1 comes from the lever on the oil pump reducing the stroke of the pump; in other words if you hold the lever on the pump you would get 50:1 at idle, too.