Ripped off by 100hr services???

[cormorant]

Are we being ripped off with 100hr services.

The hour meter on boats runs when the ignition is turned on and simply measures time regardless of revs or work your motor is doing. In your fancy modern cars the computer actually looks at the load revs and time to determin oil changes and service required. A mate who drives his car hard does nearly twice the services to our second car that does the same Km but gets longer relaxed country runs.

So should the 100hrs be 100hrs at 4000 revs ?? like it is for diesel plant or full electronic intergration like new cars ( trust the manufacturer) when the light comes on??

There is obviously some middle ground here as if you started you motor and did 3 hour runs at 4200 rpm where the motor is under little stress it should be OK at 100hrs however asame hours at 5200 revs and the oil or plugs may have copped a hammering. Same at troll as the plugs may well wear considerably at low revs and extra ash or combustion residue may end up in the oil?

What do others think? I'm hopeing with the price and technology of the larger motors they could start intergrating the hour data to give more favourable service hours to motors under low stress with the oils being so good these days?




Cheers

[finding_time]

Good post Cormorant!

During trolling season i rack up alot of hours, over a three day comp plus a prefish 40+ hour is very achievable of which 9 or 10 will be at 4600 the rest at 2200 rpm ! Over a summer this equates to 300+ hours or three standard services on 2 motors ( It adds up) This season on my mechanics recomendation i service at 150 hrs this saves 1 service a season. My oils particually the gear box oil is still in great condition after these easy 150 hrs so i'll be sticking with this regime next season. Over winter when it's more hard running anchor, then , more hard running i'll drop back to 100hrs again!

Ian

Talking to many poeple it seems it's the gearbox oil that's the critical oil( engine oil will easily do more hrs), i wonder how etec's go with there 300hr service ?

[littlejim]

Because if mine fails because of lack of service, I'll really be in the poo, I don't mind erring on the side of overservicing. Does it really wear less at lower revs?
But what you say is spot on from a cost/effectiveness point of view. Room there for some electronic genius to invent a rev ratio/hour meter and flog it to us.

[rig_dude]

According to the mechanics at work, if you are burning fuel there is friction and heat which breaks down the oil (in 4 strokes), the plugs are still firing (just not as much), so there is going to be engine wear.The price of a service is alot cheaper than a new donk. I am with Jim on this one, I would rather get back to the boat ramp every time. Maybe look at doing an intermediate service yourself if you are going to stretch them out.

Warwick.

[BM]

Its not the gearbox oil thats critical. In reality, everything is critical.

If you want to stretch out your service interval then the following will help:

The most important thing!! DO NOT USE STALE FUEL

1) Buy a compression tester (screw in type) so you can periodically check your comps - 10% variation max

2) Check your gear oil regularly (crack the drain screw a bit and note the colour of the oil) If theres water in there it will go milky. If its not milky, then don't worry

3) Check your oil level (both 2 and 4 stroke)

4) Check your plugs (when you do the comps). Should see a nice tan coloured insulator but most of the time it will be a tad black due to prolonged idling, low running when returning to the ramp etc. More important will be if there is mechanical damage to the plug or aluminium deposits in the plug

5) Make sure your telltale is strong

6) Make sure your gearshift is operating smoothly and easily and the throttle operates smoothly

7) Make sure your steering is smooth

8) Check the condition of your fuel lines and oil lines (where relevant) and connections for both

This is all common sense (also appears in my manual :) :)) and if you take the time to aquaint yourself with your engine then you will be doing yourself some large financial favours......

Cheers

[SunnyCoastMark]

That's all good commonsense advice BM.

Funny how you go down to any boat ramp on a Sat morning and see the results of failing to observe the aforesaid points::)

I have even been guilty of neglecting one or two of those points myself:-X


Mark

[BM]

Sadly (but truly) boat ramps could easily be renamed "amusement parks"......

Cheers and thanks :)

[MyEscape]

BM,

The question has been asked before but how long does it take for fuel to go off. I currently have a 4.35 Seajay. With a 40hp 2 stroke oil injected Yamaha and an underfloor fuel tank with a capacity of 60 litres I've got quite a range. Lots more than I probably need, as I am fishing inlets/creeks in the Mackay/Sarina region.

What actualy does stale fuel do to the motor.

Steve

[BM]

Steve,

Mercury claim fuel to begin to go stale in as little as 2 weeks. 8 weeks and fuel is regarded as stale and should not be used. Even less than this time for you boys up north with the warmer temps and higher humidity.

What stale fuel does is 2 fold. As it goes stale it loses octane which is its resistance to spontaneous combustion caused by compression. Also, some nasty oxides are formed as the fuel degrades and compounds blend with one another.

All engines are designed to operate with a particular minimum octane rating. Fuel that is below that octane rating causes detonation or "pinging" which is hard to hear in an outboard. Whats actually occuring is that as the piston rises in the cylinder and compresses the fuel charge, the degraded fuel cannot withstand as much compression and begins to ignite. The spark plug then ignites the fuel charge a short time later (fractions of seconds) and there are now two distinct flames within the combustion chamber. These flames collide which creates a shock wave. If the detontation is bad enough you can crack the tops right of pistons.

Detonated pistons usually look like someone has ben nibling away at the edges and then the whole piston top as the detonation gets worse.

So to avoid engine damage, don't use stale fuel. Toss it in your car diluted with the fuel thats in it or use it in your lawnmower.

Cheers

[PinHead]

how can petrol ignite under compression? I thought it needed a spark??

[Blackened]

how can petrol ignite under compression? I thought it needed a spark??

Greg, I'm only assuming, that as petrol looses its octane to a point, it will ignite under compression, much like diesel.

Dave

[BM]

As the fuel is compressed in the cylinder that compression creates heat in the fuel charge and the combustion chamber. Degraded fuel reaches its "autoignition" temperature more quickly than fresh fuel since its octane rating has lowered and hence its resistance to spontaneous combustion has lowered.

When the autoignition temp is reached, no spark plug is required and voila you have a diesel engine AND a spark ignition engine rolled into one! With very damaging effects.....

cheers

[PinHead]

the auto ignition temp of unleaded petrol is about 370C whereas the flash point is anything above -40C. To achieve that temp you would need some high compression pressure which, I would think, would do the most damage.

[BM]

The compression pressure isn't changing though. It remains the same as for the other cylinders. Its simply the fuel that cannot withstand the compression and ignites.

Google it and you'll find heaps on it or just open a Mercury Factory Manual and its right there in the first few pages.

Cheers

[peterbo3]

I do not think the "100 hours" is important. More important is the "or every twelve months" which is included in most handbook guidelines. If you get up say, 150 hours, which for most offshore guys is a lot seeing that many days are blowouts, there is no real drama, perhaps apart from warranty issues where manufacturers insist on a service interval of 100 hours to ensure warranty.
The big thing is to drop the leg & change the impellor or fit a new pump kit every year. Impellors, if not used, will become deformed due to pressure from the cam which enables them to pump water. Also, SS bolts & alloy will "bind" over time with subsequent removal dramas. And dropping the gearbox oil is a cheap way of ensuring that your seals are still good.
So I will spend the $$$ to have my Suzi serviced every 100 hours/yearly because the Five Year Warranty alone is worth it plus Deep Tempest midweek can be a lonely place with a suspect engine.

[littlejim]

When I asked the fuel companies how long before the fuel went off the figure was 12 months. Obviously faster in hot climates and if the tank doesn't have a lid on. Kerry didn't like this and felt that the fuel people werre lying through their teeth. However if they were trying to flog more fuel they would have said it goes off after 3 months.
Another one of those items where you make your own mind up based on the feeling in your water. (I use the 12 months figure - no disaster so far.)

[PinHead]

The compression pressure isn't changing though. It remains the same as for the other cylinders. Its simply the fuel that cannot withstand the compression and ignites.

Google it and you'll find heaps on it or just open a Mercury Factory Manual and its right there in the first few pages.

Cheers

I cannot understand how that deduction is arrived at.

using the combined gas laws: P1*V1/T1 = P2*V2/T2
which are all thermodynamic variables
we have the volume (V) remaining constant at any point in the stroke in both instances.
We want to raise the temp (t) to 350C
therefore the pressure (P) MUST increase to create the situation for the petrol to ignite.

will this pressure be greater than LPP at 14ATDC?

[ozbee]

flakes of cabon from stale fuel tend to stick on the top of the piston these remain hot enough to ignite the compressed fuel before top dead centre hence giving the effect of still compressing the piston after ignition. ouch............

[BM]

Dunno Pinhead, its been many years since I did Physics and Chemistry but I see your point from the equation.

But I do know the damage stale fuel does and why it occurs. Further into it than that I don't aspire to look. But what I have said is true and accurate and you will find it backed by mechanics the world over.

Cheers

[Seahorse]

I use my boat just about everyweekend, where possible and prob go between 30 -50 litres.
I got 107 litre tank and first stop every trip is the servo to fill up, even if it takes only $20.
I consider that i am mixing good fuel with any stale fuel.
That my theory anyway.

cheers
greg

[MyEscape]

OK some good point on the fuel issue.

I've heard of additives that can prolong the storage of fuel. Are these a help or a breakdown waiting to happen.

Steve

[skipalong]

have it coming up in 2 weeks

[lee8sec]

When I asked the fuel companies how long before the fuel went off the figure was 12 months. Obviously faster in hot climates and if the tank doesn't have a lid on. Kerry didn't like this and felt that the fuel people werre lying through their teeth. However if they were trying to flog more fuel they would have said it goes off after 3 months.
Another one of those items where you make your own mind up based on the feeling in your water. (I use the 12 months figure - no disaster so far.)

BP say 12 months in a SEALED container, 1 month in fuel tanks. Is ok if topped up with 1/3 fresh. Leigh
PS, this is for petrol. Diesel is differant.

[Noelm]

Detonation is a very common thing, espcially in older Motors, but not so much so in newer Motors (but it certainly does still happen) but with the older carby Motors (2 strokes) the fuel is being transfered to the combustion chamber all the time (as distinct from fuel Injected, where it is only "squirted" in when the Injector fires) and the timing Advance is a mechanical device (as distinct from Modern electronic) so what happens is you are working your Motor hard by too big a prop, towing a Boat home, big seas whatever the reason, you have the Throttle down to maintain speed and that moved the Timing way Advanced, compared to the actual RPM,so as the Piston comes up to the top, well before it gets there, the advanced timing, fires the Spark and the fuel load , and tries to send it back down again (backwards) but the others are still trying to come up( get what I mean?) this causes big troubles in the form of Heat, Mechanical stress and disaster is imminent, newer Technology has relieved that a bit, but has introduced a whole new set of "features" that can bring your pride and joy to a sad end. that is only a Home Handy description of what goes on, but it gives you an idea why the correct prop is essential, as is good regular maintenance.

[Noelm]

OH and BM is correct on his stale fuel symptom, it will certainly make a Diesel out of your Motor quick smart, and indeed if you have a Motor that has been badly "pinging" for a long time, you can switch off the Ignition and it will still run, it just gets that hot inside your Motor that the Pistons will glow and/or melt, and that is usually not a good thing I have found.