More on seized Mariner 2.5

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m1taylor

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Many thanks to those of you who posted replies on my seized Mariner 2.5. I didn't use coke - just kept pouring in WD40 and diesel into the cylinder where the head was off. Then in trying to undo the flywheel, the rocking of that freed the piston in the cylinder and it now moves freely! So quick question - given that the piston was stuck, should I open up the crankcase to check that the seals and bearings are ok, or quit whilst the goings good and put the head back on with a new gasket and hope that the crankcase is all ok? Also, I have a new gasket, but does it need coating with anything before putting on?

There's a note on the engine about using 100:1 - but given that it has seized under the previous owner, I am tempted to ignore that and run it at 50:1 to keep the lubrication going. I just cannot believe a small two stroke should run that lean!
 
more oil runs leaner /forums/images/graemlins/blush.gif

a good quality oil will protect a good modern motor at 100/1

kawasaki will be here in a while to confirm

cheers Joe
 
Mine said 110/1 leisure, 50/1 c0mmercial so run at the 50/1 sweet as a nut after 10 years, \I think the proof is eating the pudding !! /forums/images/graemlins/grin.gif make sure the little hole in the top of the liner is clear (If you have one) it will be on the bottom when the outboard is vetical, this smooths the bounce under compresion, so I have been told. Johnson gaskets fit as well and are 1/2 the price.
 
Hey up!
The gasket does not need coating.
So you,ve freed off the" top end",good.
If she runs ok and idles ok, the bottom end is maybe ok.
If the crank seal /main bearings have suffered the motor won,t want to"idle"/tickover. Plus will be hard to start.
Not like No. 1 Son, who can "Idle" for England even though He.s Welsh!
The oil ratio question appears regularly.
Little Suzuki, proper little eng.
The dose is as follows.
Pre mix motor.
IE motor receives a "mixture of gas/lube into the carb and is then "atomised" into the combustion chamber.
Where sits a spark plug.
Sparkey explodes from time to time. (bit like the ex Wales manager, now Blackburn Manager "Sparkey Hughes")
Now "Sparkey" has to live in an awfull enviroment.
He has to ignite and flash(oo er matron) at the right time.
This is not a problem if he is fed the right mixture of fuel and oil.
Sparkey don,t want no oil but his buddies below do!
So piston and his rings are desparate for continual lubrication (similar to all mobo owners).
Carby + His Mate --Inlet, take care of all these probs, that Sparkey finds trivual
The Lube is the critical component.
Little Suzi, fed on the correct lube will enjoy 100/1.
Doh!, What,s the correct lube?
Specifically a "premix" not an "injection" badged product.
See the other thing is, Little Suzi is only gonna run in short bursts.
Hardly get up to working temperature sometimes.
Don,t "overoil" Don,t get "well oiled"
"OIL keep a Welcome in the Hillside OIL keep a welcome in The Vales etc etc.
 
As you are that far down I would continue and remove the crank case and crank, check the rings are free on the piston, thoroughly clean everything (don't want nasty, abrasive corrosion products in the engine). There is no gasket to replace on the crankcase - just a smear of hylomar is all that is needed.

Why run the risk for the sake of ½ hour more work?

As for oil mix, it will run on 100:1 or 50:1 but as posted by others 50:1 tends to lead to oiling of the plug especially if the engine is not allowed to reach operating temp and run hard so carry a spare plug.

I tend to run my ob on around 75:1 - best of both worlds - minimal oiling of the plug and good lubrication and no worries if the measure is not so accurate.
--------------------
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"Artificial intelligence is no match for natural stupidity"
sailroom <span style="color:red">The place to auction your previously loved boatie bits</span>
 
Sorry, didn't read your previous thread so only going on this latest post. Forgive me if I'm going over ground already covered. The seals and bearings are probably OK, unless the engine was dunked in salt water, in which case the mains could well need a good rinsing, at least.
If piston was seized, it may well be scored and/or the rings/ring-lands damaged. Inspecting them would be a good idea. If damage to piston is slight (eg light scoring), it should be recoverable. Equally, bore may have been scored or contaminated with ally from piston, but this should have been apparent when you lifted the head. Again, possibly recoverable, but with months to go before you use it again I'd check it out.
If head gasket is same as Tohatsu (they made the engine) it arrives coated so just chuck it in.
As to fuel/oil mix, Tohatsu indeed specify 50:1, but 25:1 for running-in (10 hours).
 
Crikey talking to too many peeps at once! /forums/images/graemlins/blush.gif
Suzuki/mariner/mopeds/motorbikes/Go Karts.
Stroke two stroke Forum elsewhere!
Theory is the same anyway
Good Morning jimminy! /forums/images/graemlins/grin.gif
 
The trouble is, I am not it's that simple - to get to the crank you need to remove the flywheel - and that needs a special tool (puller). Or is there a simpler way to get the flywheel off?
 
If you run it light and for short periods use 100:1. If you run it long and hard, perhaps with long periods of no use 50:1 will be OK and may be better.

50:1 can lead to plug fouling if it's not run hard or hot enough, though you may find someone who can reliably recommend a hotter plug to control this. Bear in mind that most 2-stroke raw water cooled engines ar way over cooled in normal use. Some are liable to clogging of the waterways however.

Me, I use 100:1 on my Johnson (for which 50:1 is recommended). The reason is that I always have used the best spec. oil available, which has improved dramatically even over the 17 years I have had the engine. It is now on it's second pair of spark plugs, and beyond fixing a minor head gasket leak last year (when I decided to change the plugs as well), has suffered no problems what-so-ever.

Conversely, you could argue that a main area of development in TWC-III 2-stroke oils is the reduction in fouling and ash deposits. On that basis 50:1 should be no problem!

Take your pick, or better still, do as the manufacturer recommends.

NB. I always use fogging oil when laying up, or if I know I won't be using the engine for more than a month. Just run it in the rinsing trank at the boat yard, and after disconnecting the fuel line, just as I judge the fuel will run off, I give a short burst into the throat of the carb. which coats the internals of the crank-case and upper cylinder as it chokes the engine to a stop. One downside of 100:1 is the 50% reduction in protection of the internals between use.
 
On my new 3.3 the book says 50:1 but if "Quicksilver" 2T oil is used then 100:1 is claimed to be OK. Also there is a sticker saying 100:1.

My view is that 100:1 is far too lean especially when these engines tend to run at quite low throttle openings and even on tick-over for long periods. (the 3.3 has a clutch)

Of course currently I am running this particular engine on running in mix of 33:1 for the first 5litre can. The next can will be at 50:1 but I won't be going any leaner than that.

Steve Cronin
 
[ QUOTE ]
The trouble is, I am not it's that simple - to get to the crank you need to remove the flywheel - and that needs a special tool (puller). Or is there a simpler way to get the flywheel off?

[/ QUOTE ]

Pullers are quite cheap to buy and easy to use. But I'm not sure I would bother. If the engine has been dunked and the bearings have corroded, the cost of repair even diy is likely to be more than you paid for the engine. And stripping down that far will cost in gaskets etc even if nothing is wrong with the bearings.

Instead seperate the power head from the drive leg and rotate the crankshaft by hand. Can you feel any roughness? If not, dont go any further. If you can, look around for a second hand spare bottom end.

As for the seized piston, again the cost of bits will make you blanch so it eaither make do as is or look for second hand bits. If there is a bit of rust in the bore, I would use very fine wet and dry with oil to p[olish the worst of it off, clean the barrel thoroughly and then re- assemble. As long as you have reasonable compression you should be OK.

Bear in mind, old Jap 2 stroke outboards die of corrosion not worn bores etc. They're tough but basic.
 
[ QUOTE ]
My view is that 100:1 is far too lean especially when these engines tend to run at quite low throttle openings and even on tick-over for long periods

[/ QUOTE ] Surely you have got your logic thewrong way round.

100:1 (1% oil) might be ok for engines running at low revs for long periods but it would be better to use 50:1 (2% oil) if running at high speed for long periods.

Personally I would use 50:1 instead of 100:1 at all times unless plug fouling was problem which could not be overcome by using a hotter plug. So I agree that 100:1 is too little oil.
 
No.

Consider where a two stroke engine gets it's oil.

It comes in the fuel vapour which condenses onto the inner surfaces of the engine. So if you have a small amount of fuel entering the engine then you also have a small amount of oil. The engine needs a minimum amount of oil to coat it's bearings and bore areas so cut this way down and you run serious danger of the motor drying out possibly completely. Remember that when you close the throttle on a two stroke you are also cutting off it's lubrication supply. Many OMC engines use ignition retardation to go down to lower engine speeds but maintain a pre-set minimum throttle opening which ensures at least a guaranteed minimum oil intake.

Do you remember the old Saab three cylinder 2T car engines of the 70s? They had a freewheel to prevent the engines from seizing on the over-run when they would otherwise, with fixed drive and a closed throttle be starved of oil when the engine was being driven downhill by the wheels.

Two stroke technology is hit and miss unless you get into the oil injection scene but with emissions being the name of the game nowadays, it will soon all be history.

Like you I would never go below 50:1 and only that low because outboards tend to run mostly at constant speeds, whatever that speed might be. Something like a chainsaw or a brushcutter needs 25:1 because of the constant fluctuations in revs.

Steve Cronin
 
Re: More on seized Mariner 2.5 / Oil in S.Africa

That intrigued me also!!

I do seem to remember that only quite low octane petrol was generally available, but don't understand even if that is so how this relates to oil mixture. And why would S.Africa in particular be singled out? I just wonder if the manufacturer knows that 50:1 is preferable, but that S.Africa is one place unlikely to kick up a fuss about polution /forums/images/graemlins/grin.gif (try following a lorry up a hill!).

Vic
 
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