Options

Very dark / "additional" oil after only 15 hours

JoeStangJoeStang Member Posts: 1,122 ✭✭✭✭
So I have a brand new 2013 276 Captiva Cuddy with a 350 Mag ECT. Its ran pretty good so far with the exception of a faulty coolant temp sensor that was replaced at ~ 10 hours.

I performed the recommended 20 hour oil & filter change right on time, and I used all the right stuff - Mercury Racing fully synthetic oil and Mercury racing high capacity/efficiency filter.

At the 1st oil change I noticed the oil was pretty dark & had a fuel smell to it. I mentioned it to the dealer and he stated thats pretty normal during break-in, and to just monitor it. So I figured I'd do the 20 hour oil change and it'd improve.

Well, I have 36 hours on the engine now and the oil level has risen to significantly above the hash mark and is just about completely black. It smells of gasoline and seems pretty thin. I went on a 6 hour trip this weekend and after returning I pumped out almost a quart and it is still right at the top of the hash mark. I really dont want to pump out any more oil, as it appears its being diluted by fuel.

Now, I dont fear the "black death" as I've had cars that spun a bearing and I know what shiny metallic oil looks like. Oil pressure is appropriate at all rpms and fuel consumption is very good. I got 3.5mpg on the 6 hour trip I mentioned, and half of that time was against a 3mph current.

I assume its a simple case of fuel getting past the rings and mixing with the oil. I know its possibly normal to take more than 36 hours for the engine to be "broken in", but I am getting a little nervous with the increasing oil level and possible diluting of the oil.

What would you guys do? I am going to take a bottle of the used oil I pumped out to my dealer to make sure they know I am not ignoring anything. We only have another month or so of boating weather up here, so I planned on waiting for the next oil change to be done right at the end of the season, but do you think I should do one right now?
2013 276 Cuddy ~ 350 MAG / B3
«13

Comments

  • Options
    212rowboat212rowboat Member Posts: 2,591 ✭✭✭✭✭
    edited August 2013
    I'd be curious about how this turns out... here is why:

    Oil tainted with fuel most often happens on an MPI/EFI engine due to a hung injector, and washing the cylinders- but it is evident in fuel economy.. like, really evident.. and, it makes for a sluggish cylinder on the one being washed, which creates those dreaded pop-n-pop backfires..

    fuel mixed with oil can become a combustible liquid... If it were mine, I'd get it out of there with a quickness, saving a 10oz for independent laboratory analysis (blackstone labs) and another for Mr. Dealer's service center..

    check your fuel pressure, JTKZ13, if it's not a hung injector, it could be fuel delivery is WAY over prime because your fuel pressure isn't being regulated... the trim is based off of duty cycle (how long an injector is open) and the pressure behind it.. more pressure means more fuel.. more fuel washes cylinders when it can't burn- and that thing being a '13, isn't it a catalyst engine w/ o2 sensors?  I'm surprised it isn't running rich enough to toss codes left and right.  

    edited to add:  burning rich excess fuel will eat a catalytic converter in no time flat....
  • Options
    JoeStangJoeStang Member Posts: 1,122 ✭✭✭✭
    I should say that it seems like it takes longer than it should to fire up also. Probably 3-4 cycles of the starter to start up. I havent had any backfires, pops, or poor fuel economy.  Its been like that since day 1, and I even asked my salesguy if it was normal for it to take an extra second or two to fire up.

    Fuel mileage has actually been surprisingly good, with an average of 6-8GPH, and I really dont do much slow/idle speed cruising.

    I dont have any fuel smell from the exhaust and no audible codes (since they replaced the coolant temp sensor anyways). Either way I'm going to take the sample to the dealer and change the oil again to see if it improves at all. I guess $50 is cheap insurance that I am not running thinned out combustible oil.
    2013 276 Cuddy ~ 350 MAG / B3
  • Options
    212rowboat212rowboat Member Posts: 2,591 ✭✭✭✭✭
    I'd get a fuel pressure gauge on one of those rails... one side is ported with a schrader valve, right?  If you gotta buy new oil, while you're at the parts store pick up the gauge, it shouldn't cost you any more than $15 or so...
  • Options
    JoeStangJoeStang Member Posts: 1,122 ✭✭✭✭
    Honestly I think I'll let the dealer figure it out since its brand friggin new. I could rebuild the engine myself if I needed to, but theres a reason I bought new so I didnt have to worry about fixing it myself (for 5 years anyways).

    We'll see how serious they take it now that I know its not just from the initial break-in period.
    2013 276 Cuddy ~ 350 MAG / B3
  • Options
    212rowboat212rowboat Member Posts: 2,591 ✭✭✭✭✭
    I agree with you completely.. I'd be plenty tweaked, if I were you..
  • Options
    Robyw1Robyw1 Member Posts: 56 ✭✭
    edited August 2013
    Somewhere an injector is bleeding. If you are not running rich while underway then I bet you have an injector that is allowing all of the fuel in the rail to dump into a cylinder upon shut down. I have seen it many times. The reason it takes longer to fire up is because one or more cylinders is flooded. You will probably see a puff of black smoke just after starting the engine. Also get that oil changed again as soon as yesterday.
  • Options
    Robyw1Robyw1 Member Posts: 56 ✭✭
    If I may leave further comment, when I was trying to setup my GPS for my SmartCraft, I turned on the key so that the GPS antenna could run for 30 minutes or so to locate satellites. Immediately the SmartCraft showed 42psi of fuel pressure. 30 minutes later the fuel pressure was still 42psi. Now if an injector was bleeding off fuel when it was not running the fuel pressure would have dropped off to zero within that time. The pump would not cycle again until you either started the engine at that point, or turned the key off and turned it back on again. A typical indicator of this would be the extra time it took to start the engine because the pump has to re-prime again while you are on the starter. With that being said, I am betting that your injector is bleeding off quite rapidly. However it is possible that when the engine is running the injector may function normally.
  • Options
    212rowboat212rowboat Member Posts: 2,591 ✭✭✭✭✭
    for what it's worth, my guess would be a faulty regulator allowing too much pressure behind the injectors, and therefore providing way too much fuel during operation..

    I too have seen injectors hang.. especially ev1's, with their elongated plugs- they lost favor to ev6's which have a really small point of connection...

    image


    the pulses sent to the injector are silly short duration, and there is possibility for injectors to 'hang' during operation due to resistance (ohms) provided by the larger blade not making contact connection across its surface... I once tracked down, for a long time, a bent spade in an injector... a simple man handling of the harness and connector allowed for a bad seat, and wrecked the precision of firing those things.. who'd a thunk it? :-) 

    Piazza injectors are the way things will likely go in the future.. they use a tiny crystal that reacts instantly to juice, and allow fuel to pass when they shrink- allowing as many as four injections a cycle.. that is FAST!!

    anyway, for what it's worth, injectors (so long as there are no debris in the fuel) rarely hang, anymore.. they've got that mechanism down pat, in my opinion and for what it's worth... I can't imagine merc uses inferior injectors, and have those made by Seimens (who makes better injectors than most) mad injectors on there, no matter what the brand name is..
  • Options
    JoeStangJoeStang Member Posts: 1,122 ✭✭✭✭
    I'd actually be happy if its just a hanging injector, as my bigger concern is a compression ring that hasnt seated and is allowing unburnt fuel into the crank.

    I dont have any Smartcraft guages, but I can install one if I wanted to.

    I havent noticed even a hint of black smoke or the smell of rich exhaust at any point, but I dont have thru-hull exhaust, so its not like its right at the side of the boat. When I get out to the boat tonight I'll have my wife fire it up & see if theres any hint of smoke or unburnt gas.
    2013 276 Cuddy ~ 350 MAG / B3
  • Options
    212rowboat212rowboat Member Posts: 2,591 ✭✭✭✭✭
    Al will no doubt be along shortly... this thread strikes me as the kind he will have interest in....

    I seriously doubt a ring is your issue.. I'd bank on that.. today's engines squirt precisely the amount of fuel needed to maintain stoichiometric ratio's... especially in that it's a '13, with the CARB stuff added.. it would take a dead cylinder (which you would certainly feel) to grow oil enough oil that you would notice on 15hours engine time.. just my opinion...

    a regulator going bad, though, would double your output... a 24# injector flows in the neighborhood of 248~252cc of fuel a minute at 43.5psi, where it's rated.. the jacked up thing about injectors, though, is that they rarely follow a linear course on a chart... doubling the pressure to 87psi doesn't equate to 500ish cc's, but often to mucho more, such as 550~600cc's... the spray characteristics go haywire too far above the rating, and the mechanism starts taking abuse, which can cause an injector to blow the gate... your injectors are fresh- and like I said, 'they' have those things down pat mechanically speaking... I'd be curious to see your LTFT's and STFT's from that PCM to see what it is trying to do about trim... I'd wager you are deep in the negatives on both, as the PCM tries to adjust for too much fuel...
  • Options
    212rowboat212rowboat Member Posts: 2,591 ✭✭✭✭✭
    edited August 2013
    deleted... bad idea.. :-)
    Post edited by 212rowboat on
  • Options
    JoeStangJoeStang Member Posts: 1,122 ✭✭✭✭
    Too late, I already read it!


    2013 276 Cuddy ~ 350 MAG / B3
  • Options
    212rowboat212rowboat Member Posts: 2,591 ✭✭✭✭✭
  • Options
    Robyw1Robyw1 Member Posts: 56 ✭✭
    edited August 2013
    I mentioned the hanging injector (more like a bleeding injector) because regardless of the injector style or quality, he can't control the quality of fuel being put into the tank. I have read where some additives/stabilizers that marinas use can actually gum up when heat is applied or another type of stabilizer is mixed. I am interested in hearing the diagnoses. I piston ring is not the case here because to me it sounds like the fuel is being burned off due to the lack of a misfire, poor mileage, or codes being tripped due to a rich condition.
  • Options
    MarkBMarkB Member Posts: 3,969 ✭✭✭✭✭
    edited August 2013

    jtkz,

    You're not alone. I noticed a slight fuel smell in my oil as well just the other day.  I have a brand new 350 MAG MPI, 5.7L.  I called up Mercruiser today and they told me that it is possible for this to be a once off issue.  They said as long as the oil level doesn't change, then all is okay.

    My oil is still that golden brown when it comes out of the bottle. It has 35 hours on it since the 20 hour service was done (55 in total).  The level has not changed much, and it still appears to be thick.  There is definitely a fuel smell, not like breathing the top of the gas tank, but enough to easily notice it when you smell the dipstick. 

    Anyhow, I went out tonight, and I still noticed it when I checked my oil upon return.

    I also have a very faint knocking sound at the front of my engine, only when I'm at idle.  It's the same sound as tapping your fingernail on a desk. About 4 per second.  It seems as though it might be one of the pulleys, but I'm not sure if it is related to the oil smell.  When I accelerate the noise goes away. When I go back to idle, no knocking, but then it slowly comes back after about 3 minutes. Nothing loud or heavy, just a tapping like sound.

    I'm going to pull it out for winterization at the end of September, and the dealer can look at it. If anything needs to be fixed under warranty, it should be fairly simple.

    Boat Name: King Kong

    "Boat + Water = Fun"

  • Options
    212rowboat212rowboat Member Posts: 2,591 ✭✭✭✭✭
    edited August 2013
    I interjected the types of injectors to attempt to softly say "it's highly unlikely it's the injector"... they are usually the first item to go under fire in a EFI system, but usually, even when it is them, they are just a product of a problem, and rarely the problem itself.. folks have hard times with injectors when they start playing with them thinking it's an upgrade to change them out, when most stock injectors will handle anything you can do to an engine short of boost..

    anyway... I'm looking forward to finding out what's wrong with his rig, too.. If it were mine, I'd be pretty tweaked about a brand spanking new engine producing oil.. It isn't a reflection on Rinker, but on Q/C of Mercruiser, if there is an issue... if it is a regulator, those items follow the 'wash basin' graph of failure- meaning there is a high rate of failure early in it's service life, then a high rate at the end- but a low flat line in between... it is the weak link in this circumstance...

    but as you said, Robyw1, he can't really control the quality of fuel, and if something slipped past his 10micron fuel filter/ water separator, and hung an injector, that could certainly cause his issue.. I just think that it would manifest, if that was the case, more loudly..

    edited to add: the weirdest thing about this is even if there was a hung injector, a leak down of pressure into the combustion chamber, a silly high pressure of fuel behind the injector due to malfunctioning of regulator, or any other something something to do with the fuel systems, you would think it would be readily apparent with performance and the PCM's monitoring of the entire system...
  • Options
    MarkBMarkB Member Posts: 3,969 ✭✭✭✭✭
    Isn't it a bit scary that I have a similar problem also in a brand new MAG 350 too? Is there a QC problem? Do I hear "product recall"?

    Boat Name: King Kong

    "Boat + Water = Fun"

  • Options
    MarkBMarkB Member Posts: 3,969 ✭✭✭✭✭

    Actually one thing I wanted to bounce off the crowd with my issue is given my oil is still nice golden brown, thick and level isn't changing, is it possible I'm just running a bit rich? I haven't noticed much change in my engine performance.

    My thing is I do a lot of travel at idle, because I troll for fish. I could spend 3 hours running at 600 - 800 rpm.

    Could this cause the fuel smell in my oil? If so, should I be worried about this?

    Boat Name: King Kong

    "Boat + Water = Fun"

  • Options
    212rowboat212rowboat Member Posts: 2,591 ✭✭✭✭✭
    there are dual o2 sensors on each bank... the one forward of the catalyst is for trimming fuel almost exclusively.. it uses a filament between samples of environment- one sample from outside the pipe, one sample from within.. there will be extremely minute alterations in voltage across that filament that the PCM translates to content of oxygen.. it either adds fuel or pulls fuel to achieve proper a:f ratio, or around 14.7:1... the o2 sensor behind the catalyst is for one purpose pretty much exclusively, though it does play a tiny role in a:f too, it's main purpose is to tattle on the catalyst if it isn't improving the o2 levels- meaning, they should spike considerably higher voltage than before the catalyst..  we're talking small voltages and ohms, that account for what the PCM believes to be big changes in exhaust content..

    o2 sensors have to 'come online', which is to say they need to operate within an expected parameter before the PCM starts listening to them.. before this happens, the term used to express engine operations is 'open loop', as the key player (o2 sensor) isn't reporting yet.. Some o2 sensors are heated, some aren't.. I don't know which merc uses.. once the o2 sensor reaches operating temperature, and the engine reaches operational temperature (around 160*), the engine 'closes loop' and starts to trim fuel based on environmental conditions...

    OPEN loop operations are drafted on the PCM in 'tables'.. the 'tables' dictate the trim before temperature is achieved.. they generally operate on the side of caution, and run what would be a rich condition.. the extra fuel being introduced, as counter intuitive as it seems, will make an engine run cooler- which is it's intent.. it serves as a 'knock control', as a heavy mixture of fuel is more difficult to ignite than a lean one.. lean burns hotter and with more force- rich burns longer and cooler.. it needs higher content of o2 to burn hot... the hotter a cylinder, the more likely the process of compression is to ignite it and cause 'pre-detonation', or a hot spot in the cylinder due (most often valve seats) will ignite it and cause that same dreaded ping.. an engine doesn't want to ignite the a:f load until it is ready to ignite it.. I think my engine requests 10* advanced ignition, where as a few hot engines I've built pushed that envelope north of 40* advanced..

    Closed loop is where EFI truly shines.. it maintains nearing perfect stioch ratio's.. it's positive that 14.7:1 is best overall, where it's supposed that 13.9:1~14.3:1 is best for performance, and 15.3:1 is best for economy.. richer (cooler) is **** catalysts, leaner (hotter) is **** hard parts..

    trims are maintained in expressions of Lambda, but use %'s to show adjustments.. there are Long Term Fuel Trims (LTFT's) and Short Term Fuel Trims (STFT's).. Zero is the basis on an engines PCM that hasn't stored any environmental data in 'cursive tables'.. zero is the engineered 'mathematical' means to fuel an engine..

    STFT's will swing in positive ranges, displayed as an example: 5% stft- which means the PCM has detected a lean condition and is adding fuel.. it may be because of elevation, ambient temperature, quality of fuel, or what have you.. likewise, a rich condition will cause the PCM to 'pull' fuel, and it will be expressed in negative %'s- such as -5%.. after a while, the PCM locks the 'new' trim as it's long term fuel trim, and drafts it in the environmental tables stored within.. LTFT, for instance, at 0, and a STFT @ 5% shows an addition of 5% duty cycle to the injectors.. a LTFT of 5%, and a STFT of 5% demonstrates a 10% duty cycle to injectors... on it goes... what you want to see an engine do is 'cross zero'- if an engine is 'crossing zero' it is making tiny adjustments to both trim tables, and that means it's fine tuning.. fine tuning is good.. wide variances is NOT good.. usually, a code is tripped when an engine hits north or south of 25% LTFT, and something is amiss...

    why am I spilling all this on your screens? -----

    these PCM controlled engines are freakin' awesome for both economy and performance.. they can make adjustments 'on the fly' that a carb'd engine couldn't make even if you had a scientist with a wideband o2 gauge and tiny screwdrivers hanging out in your engine compartment adjusting that carb while underway..  but for that same wonderment, they can hide an issue, and hide it well...

    if your trims are in the double digit lambda percentages, your PCM is struggling to provide the correct trims... if it is negative, the engine is struggling to provide fuel- if it is positive, the engine is struggling to control the fuel.. you may never even know it, unless you monitor the trims........

    I'd like to see what your trims are, as well as JTKZ13's.. If the cylinders are being washed to the point your 'producing' oil, and you are reaching operational temperatures, and seeing as how both of these engines are CARB engines (catalytic and o2 monitored), it may be as simple as bad o2 sensors...
    stoichiometric
  • Options
    212rowboat212rowboat Member Posts: 2,591 ✭✭✭✭✭
    oh.. and, sorry for the wall of text... this subject interests me greatly, and I often go deep into it..
  • Options
    MarkBMarkB Member Posts: 3,969 ✭✭✭✭✭
    Drew thanks for the thesis. I read all of it.

    If we deduce what could be wrong or impossible based on my circumstances, what is/are the likely causes:

    -oil level is not changing
    -oil is still golden brown after 35 hours of use.
    -engine performance still seems fine. No major changes. Oil pressure is 40 psi at idle, 60 psi at higher rpm. It only dips to 20 psi if I am racing and then drop to idle, but then it bounces back to 40. Engine temp is steady at 175 F. Still getting 30 mph at 4000 rpm. Top speed maybe has come down a bit around 3 or 4 mph, but that could have been weather conditions.

    The only thing I'm picking up is a slight fuel smell in my oil.

    Boat Name: King Kong

    "Boat + Water = Fun"

  • Options
    212rowboat212rowboat Member Posts: 2,591 ✭✭✭✭✭
    I'd extract a few ounces of oil, in a clean container... set the container aside away from the boat.. pick it up some time later and sniff it- you may find that the smell of gas isn't gas at all, but remnants from blow-by gasses (product of combustion; consolidated combustion gasses; exhaust, basically) , which are to be expected from new engines.. even aging engines will have this present..

    it's the oils job to scrub the internals of the engine of ash, which is going all over the place inside that thing.. ash is a product of boom-boom that makes the motor go-go, and oil that stinks of ash is oil that is doing its job... the blacker the oil, the more ash it's removing (or has removed), and the more it will stanky-stank of combustion gasses..

    my thought is that if you extract the oil from the boat, and sniff it afar from engine compartment, you'll smell something different than gas, but that has some of the same sharp pungent characteristics of gas...
  • Options
    Robyw1Robyw1 Member Posts: 56 ✭✭
    I do not which o2 sensors Merc uses either but the heated ones have 3 wires.
  • Options
    MarkBMarkB Member Posts: 3,969 ✭✭✭✭✭
    So drew. Will I notice that exhaust smell more strongly of I run at idle for long durations?

    Boat Name: King Kong

    "Boat + Water = Fun"

  • Options
    212rowboat212rowboat Member Posts: 2,591 ✭✭✭✭✭
    I don't know.. I'll guess yes though.. reasoning: at idle there is no load nor demand, so the pcm can become very consistent with fuel trim.. at same time, plenty of h2o is flowing, and its not like its being circulated through an exchange so it is plenty cool, allowing the engine temp to drop to just above thermostat rating, as it sips fresh coolant (raw water) maintaining that temp...

    Hard parts with allowable tolerances don't expand, or they don't expand as they would at full engine temperature, allowing more blow by, and not allowing water to dissipate from the oil that has collected there due to condensation.. it will mix more combustion gasses and by products in the oil...

    Just a guess.. i could put my shoulder behind the other side, too, bit this side just seems stronger? :-)
  • Options
    JoeStangJoeStang Member Posts: 1,122 ✭✭✭✭
    Robyw1 said:
    I mentioned the hanging injector (more like a bleeding injector) because regardless of the injector style or quality, he can't control the quality of fuel being put into the tank. I have read where some additives/stabilizers that marinas use can actually gum up when heat is applied or another type of stabilizer is mixed. I am interested in hearing the diagnoses. I piston ring is not the case here because to me it sounds like the fuel is being burned off due to the lack of a misfire, poor mileage, or codes being tripped due to a rich condition.
    I've only ever used ethanol-free gasonline (and only have used ~ 200 gallons of gas) in the 36 hours total. No additives by me, but of course who can guarantee whats in the pump. I should note that on this current oil I have filled up at 2 separate locations, so I dont think fuel quality is part of the problem.


    I interjected the types of injectors to attempt to softly say "it's highly unlikely it's the injector"... they are usually the first item to go under fire in a EFI system, but usually, even when it is them, they are just a product of a problem, and rarely the problem itself.. folks have hard times with injectors when they start playing with them thinking it's an upgrade to change them out, when most stock injectors will handle anything you can do to an engine short of boost..

    anyway... I'm looking forward to finding out what's wrong with his rig, too.. If it were mine, I'd be pretty tweaked about a brand spanking new engine producing oil.. It isn't a reflection on Rinker, but on Q/C of Mercruiser, if there is an issue... if it is a regulator, those items follow the 'wash basin' graph of failure- meaning there is a high rate of failure early in it's service life, then a high rate at the end- but a low flat line in between... it is the weak link in this circumstance...

    but as you said, Robyw1, he can't really control the quality of fuel, and if something slipped past his 10micron fuel filter/ water separator, and hung an injector, that could certainly cause his issue.. I just think that it would manifest, if that was the case, more loudly..

    edited to add: the weirdest thing about this is even if there was a hung injector, a leak down of pressure into the combustion chamber, a silly high pressure of fuel behind the injector due to malfunctioning of regulator, or any other something something to do with the fuel systems, you would think it would be readily apparent with performance and the PCM's monitoring of the entire system...
    Yeah, I dont really think its likely an injector either. I'm starting to lean towards O2 sensors, PCM tune, or some other various sensor that is sending incorrect information to make the PCM either stay in closed loop too long, or push too much fuel in certain conditions it doesnt need to (coolant temp, oil temp, thermostat, knock sensor, fuel pressure, etc etc etc).

    Drew thanks for the small novel. Its been a long time since I learned in depth about EFI stuff (I built up a 95 Mustang Cobra), but what you wrote about makes alot of sense. My issue sounds a bit more extreme compared to you Markbellino, as my oil level is definitely rising and its VERY obvious the oil is being seriously diluted by the gasoline. Mine smells like raw fuel even after sitting in a bottle for a couple days. Not to downplay your experience so far, but I dont do much of any slow speed idling, its all 2700-3800rpm cruising to spots on the lake. I wouldnt be worried at all if my oil was still honey brown & wasnt changing level. Most oil starts to smell "used" even after a very short time. Plus, if you use the dipstick to extract like I did, you didnt get every drop of the old oil out.

    So anyways, I dropped the boat off at the dealer today. They were concerned with the condition and were taking it pretty seriously. They'll have it hooked up to the computer tomorrow and go through the sensors to see if any are out of parameter.

    Drew, as a mostly "layman" regarding intricate EFI stuff what exact questions should I ask the technician? Should I ask for a print-out of any specs to make sure they arent missing anything?
    2013 276 Cuddy ~ 350 MAG / B3
  • Options
    JoeStangJoeStang Member Posts: 1,122 ✭✭✭✭
    Also, I'm not ruling it out that I have a thermostat stuck open and not letting the engine get warm enough for closed loop and tighten up the ring tolerances a bit. Since the faulty coolant temp sensor was replaced my temp gauge hasnt even touched anything above what I assume is ~ 150-160* on the gauge. From my experience most engines like operating temp around 180* for optimal fuel mileage and performance. Plus, if the oil isnt getting above ~ 220* it wont be able to "burn off" the water and acids from the combustion process.

    Now, we all know the Faria gauge isnt the pinnacle of accuracy, but I would expect to see 175* on a 100* day and cruising at 3500rpm for extended time.

    And now that I think about it the temp sensor was replaced at about 16 hours, which was just a little before the 20 hour oil change. The original oil from the factory was nowhere near as "fuelly" smelling as the stuff in it now, so I wonder if I still have some sort of issue on the coolant sensor side......
    2013 276 Cuddy ~ 350 MAG / B3
  • Options
    212rowboat212rowboat Member Posts: 2,591 ✭✭✭✭✭
    I'd ask for a look at the fuel trims... Both long term and short term, for each bank.. like I said in my novel, :-) , the pcm can cover an issue for a long time, and it can only be seen in the trim history, which is that long term fuel trim number, and that can give you hints about what's happening...

    If the long term is double digit %'s either way, the pcm is struggling to manage fuel.. let's say the engine is rich, which is what we're believing here.. so there will be a negative number (the pcm tells you what its doing instead of a status report) ... So, if long term is negative ten percent, you've had a rich condition for a while, and to the point the pcm has adjusted the base table to curve out ten percent delivery.. if in that same circumstance (-10% ltft) AND the stft is negative double digits, the pcm is still trying to pull fuel.. the pcm is changing trims to adjust for a problem in this case.. its a manageable problem, but a problem nonetheless...

    The problem with that problem is, even though its manageable, the wiggle room for error has been reduced drastically... Let's say you have a bad regulator, which is happening because of a stuck valve.. let's say the pcm is cutting fuel to deal with the extra delivery.. let's say you're cruising at near wot, around 4500rpm and ltft+stft in double negative digits, and all of the sudden that regulator decides to regulate... Dramatically and without hesitation the engine will lean out, and you could blow it to pieces with pistons shattering or melting.. the pcm, if given the margin for error wiggle room could have adjusted for it, and with a quickness, but that margin was removed by its hidden issue.. the first you know of it other than being really diligent with maintenance and noticing gas smell in crankcase and mentioning it on a message board, is a blown to bits engine where the block isn't even salvageable..

    That was really dramatic, no? My last novel rambled, I was aiming for a thriller with this one... :-)

    Point being, the trims will tell them and you what's happening with the delivery..
  • Options
    JoeStangJoeStang Member Posts: 1,122 ✭✭✭✭
    Gotcha, I'll make sure they review the fuel trim numbers in detail and try to get a print out for my records.
    2013 276 Cuddy ~ 350 MAG / B3
  • Options
    212rowboat212rowboat Member Posts: 2,591 ✭✭✭✭✭
    jtkz13 said:
    Also, I'm not ruling it out that I have a thermostat stuck open and not letting the engine get warm enough for closed loop and tighten up the ring tolerances a bit. Since the faulty coolant temp sensor was replaced my temp gauge hasnt even touched anything above what I assume is ~ 150-160* on the gauge. From my experience most engines like operating temp around 180* for optimal fuel mileage and performance. Plus, if the oil isnt getting above ~ 220* it wont be able to "burn off" the water and acids from the combustion process.

    Now, we all know the Faria gauge isnt the pinnacle of accuracy, but I would expect to see 175* on a 100* day and cruising at 3500rpm for extended time.

    And now that I think about it the temp sensor was replaced at about 16 hours, which was just a little before the 20 hour oil change. The original oil from the factory was nowhere near as "fuelly" smelling as the stuff in it now, so I wonder if I still have some sort of issue on the coolant sensor side......
    I'm finally at a computer instead of pecking on a phone...

    ^ that is reasonable.. however, Marine engines generally use 160* 'stats, and are programmed for that.. they likely 'close' loop around that temperature, but it doesn't happen all the sudden, or at least it doesn't in automotive applications.. it will start to check through, as sensors come online, and then it will bounce open/closed a few times before it finally closes.. I ~think~ it does this to 'sample' readings in closed loop before it determines it's safe.. that is just a supposition though, and it may likely be a lot simpler than that...

    rich engines run excessively smooth.. it's almost impossible for them to pre-detonate, and because they have excess fuel present, when it ~does~ burn, it burns all the way to the bottom of the stroke, or at least deeper into the stroke than a leaner engine.. that doesn't mean it's more powerful a burn, but a smoother burn..

    not reaching operational temperatures will absolutely keep the engine in open loop, rich, disallow seating of rings, and disallow dissipation of h20 in the crankcase.. a stuck 'stat will do it with a certainty, but there is a more ominous thing that can happen too, that you've had happen already: the temperature sender soils the sheets.. what happens in that circumstance is the engine actually ~does~ reach operational temperatures, but the PCM doesn't know it, and continues to provide heavy fuel to an engine that doesn't need it.. that is when excess cylinder pressures happen, and with those, excess blow-by and production of ash which taint oil, and mucho particles in exhaust, which clog catalytic converters..
Sign In or Register to comment.