Outboard motor seizing up.....advice please....

[RobW]

Hi folks, I would really appreciate some advice on this one - so if you have had a similar problem please let me know....
I have a Mariner 5hp longshaft, 2 stroke engine as an auxiliary on our trailer sailor. Its an early 1990's model, exactly the same as the Yamaha 5hp of that decade. I have owned it since 2002, since then at least it has been well looked after and never dunked.

The problem is that if the engine is left for more than a couple of weeks it starts to seize up /gets too stiff to turn over. You have to remove the starter and put a spanner on the top of the flywheel to turn the motor over - it gradually frees up enough to use the starter pull cord and away it goes - runs perfectly and if used regularly continues to be fine.....until you leave it for a couple of weeks and we are back to square one, with a stiff motor.

I am pretty sure its a problem in the powerhead - bearing? piston rings?

The engine has had little use over the years (which may be part of the problem) and is in general very good condition.

I spoke to my local service centre about the problem who advised that the cost of the re-build would be more than the motor is worth £200+. They recommended increasing the amount of oil in the fuel mix to 40:1 and spraying in fogging oil if the engine is going to be left for more than a few days.
- My worry with this is could/will the engine let us down in a big way at some point while in use?

How difficult a job would it be to overhaul the powerhead myself and change the bearings (if thats what it is)?

Should I just face up to the fact that I need a new outboard? (Reluctant to do this as the rest of the motor is in such good nick).

Any advice on this very much appreciated.

Regards

Rob

 

[Talbot]

I would increase the oil mix and take it for a long run (tank full?) and see if that makes a difference. I dont think I would go below 50:1 as you then risk oiling up the plug and the engine stopping that way.

 

[jonathankent]

I have had exactly the same problem this week with my Evinrude (threads further down). Again, last year mine became stiff, but didn't think too much of it, and did as you do 'forced' it to turn and away I went. I have then left it in the garage since last October until now.... and now is was completely seized. Anyway, took it to be serviced and they quoted the same as you 'not economical to repair'.... so I thought that was it. So, just to have a look I decided to completely strip the engine myself and see what needed to be done. Yesterday I took everything apart and have found it not to be too bad afterall.... I have freed the pistons and will move again, so I will give it a good clean up, replace all gaskets/seals and generally give it a good going over. I am then hoping it will be all OK once again. Apart from me spending an afternoon stripping, and anticipate a day to clean and rebuild it will have only cost me less than £40 for the replacement parts. Even if it doesn't work, at least I have given it a go and could save me a lot in the long run. Personally, I can't see why it wouldn't work, afterall that is what the engineers would have done but just for a lot of money.

I would say, if it is seized and they won't repair it, then what have you got to lose by having a go yourself.... I have and am pleased I gave it a go - it might just pay off /forums/images/graemlins/smile.gif.

BTW, do you know what is/has caused it to seize? Mine had somehow got a little salt water back up the exhaust to one of the cylinders.

 

[Evadne]

I had a an old 4hp (twin) outboard for the tender, I'm not sure if it was a Mariner, but it too seized, and I donated it to some sea scouts who used it to practice taking it apart and putting it back together again. The found that there was a hole between the water jacket and one of the cylinders. There wasn't a lot of metal there, and no internal anode IIRC, so if you did't religiously run it in fresh water after every trip, corrosion occurred.

If it were mine I'd take it apart to ascertain the problem, cost the parts for the rebuild and make the decision then and there whether or not to do it. It shouldn't be difficult, the main tools needed will be a socket set, a torque wrench, mole grips and a gert big hammer. /forums/images/graemlins/smile.gif It might save you money, but it wouldn't lose you any in the long run as it's going to die sooner or later. The advice to increase the lubrication seems well meant, but personally I wouldn't continue to use a motor with a known problem, sooner or later it'll let you down.

 

[Kawasaki]

If you are a competant spanner man and don,t "rush it" a top end overhaul is no big deal.
One hurdle you will face. Zincy based aluminium forms lots of the make up of outboards. Combined with steel nuts and bolts. An unfortunate mix cos the two elements like each other so much they can be quite reluctant to part company.

Take extreme care with your nuts! Especially 10 m spanner size or less (6m thread or less) Easily severed with over zealous spannering.
If any nutty boltty bit is reluctant to budge, give a good cleaning/ wire brushing to the suckers + some luby liquid. Shock the offenders with a drift and try and apply some warmth to the surrounding area HaS rules apply!

You might think, What,s He on about big script on nuts is the guy nuts?
Thing ,is peeps bring me outboards to fix cos lots of mender types don,t like to get involved. 9 times out of 10 the fix has been aborted cos srews and nuts are all rounded off or snapped because of a lack of attention to the above!

Also check the drive shaft sleeve has not become crudded up cos that,l give the same sympton.
Basically what your playing with is a little motor bike engine with a shaft and a prop stuck on it.
One other gizmo to take care with is the starting mechanism, make a mental picture of how you dismantle that bit or you,l be baffled when the string and springy bits need to be reassembled.
Good luck!

 

[kandoma]

if you can not open it up due to corroded screws, remove the glowplug and inject a small dose of WD40 just before you store it. But be carefull with the glowplug removal and insertion. They tend to freeze up in the aluminium head.


Peter

 

[RobW]

Thanks for your reply....however...glowplug? don't think my 2 stroke petrol outboard has one?

 

[brianrunyard]

He's in Swizerland, so might be Swiss, most likely means Sparkplug.

 

[pete]

Hi
My 4hp Yam had exactly the same problem when not used for a while. turned out to be a build up of crud on top of the drive shaft spline where it enters the crank shaft
(as poster Kawasaki said). as soon as I removed the leg it was free again I cleaned all the crud out and greased it and it`s been ok since.
Pete

 

[RobW]

Hi, yes your 4hp Yam will be a very similar motor too - I will give it a try this weekend, before I start pulling the powerhead apart.

Did you need to replace any water gaskets between the leg and the powerhead?

Cheers

Rob

 

[pete]

Hi Rob
Not that I remember I certainly did not buy anything and if I did replace the gasket it would only be with one that I had made myself.
I did struggle to draw the leg off as the crud in the splines was holding it in, when I managed to removed it and had a poke around in the splined hole (in the crank shaft) there was what looked like dried alluminium crud.
I think it was expanding and pressing the shaft down thus making it tight .

Pete

 

[graham]

On some motors there are a couple of bolts that go through the bottom plate of the engine housing into the engine block.

Leave these in place ,only take out the bolts that go through the drive leg mounts.This saves trashing the expensive gasket that seals the water and oilways on the bottom of the engine block where it sits on the base plate.

The lower gasket between base plate and drive leg is not quite as crucial as there is no oil there only water and exhaust.

 

[Birdseye]

I had a similar problem on my Mariner 2 HP. It turned out that the water impellor ran in a stainless steel cup which in turn was held in the alloy leg casting. Salt water used to get between the two, cause alloy corrosion which in turn nipped up the stainless cup and made the engine hard if not impossible to turn.

The answer was to drop the lower part of the leg, remove the impellor then the cup, clean out the socket the cup sat in and then repace with a new cup.

This problem is way more likely than the top end of the engine seizing unless the engine has been misused.

 

[steve28]

your problem lies in the deflection plate under the main bearing, this can only be got at by stripping the power head off. this is common fault and i have repaired several of these motors with this problem.
The reason this happens is the salt water makes the alloy corode and binds the driveshaft, when removing the leg make sure you do it gently as the water pump and gearbox circlip suffer if the shaft is too tight.

This is the reason for this fault.

steve

 

[andy_wilson]

Hi

My 16yr old Johnson 4hp had exactly the same problem. mechanic suggested the bearing on crank-case output shaft.

My inspection (with maglite) showed signs of corrosion in cylinder. Problem was cured (for a whole season) by introducing a glug of 2 stroke oil into plug-hole and gentle working to free.

The motor would then work OK all week(end) but then be seized on next visit.

Fresh water flush made no difference.

Upping 100:1 to 50:1 made hardly any difference.

Fogging oil after each session helped a bit.

Taking cylinder head off, cleaning surfaces and re-assembly with gasket cement (used old gasket) has been a perfect cure. A small area of corrosion had tracked under the gasket from the water jacket to the cylinder allowing damp into upper cylinder.

Absolutely no other damage was apparent, and it still starts second pull, whatever the conditions.