Suzuki 4 stroke 2.5hp O/B - a caution

[Neeves]

Our neighbour has a 2.5hp Suzuki O/B, as do we. We have both found it reliable - but its much heavier than the 2 stroke, 2hp, Yamaha it replaced for us.

Our neighbour's O/B is older than ours.

If you have one and open up the top cover you will find a shiny metal plate immediately under the spark plug. It seals the valves on the top of the cylinder and the compartment is full, or at least contains, oil.

Our neighbour's shiny metal plate developed a hole, it corroded - allowing the oil to leak out. There are no spares in Oz and he is waiting for delivery from Japan, but it might be from anywhere in Asia. He has waited a week so far.

This is our O/B with the spark plug, out of focus, at the top of the picture and the top edge of the shiny metal plate and the rest of the plate underneath.


Our neighbour might have been unlucky but it would be worth keeping the plate greased, if you have this model - in case the plate is prone to corrosion.

In the UK the same O/B might be defined slightly differently, maybe simply a 2hp model.....

Jonathan

 

[harvey38]

The same outboard you need to ensure is left under compression to avoid a push rod slipping out of place and £273 bill to repair

 

[snowbird30ds]

The same outboard you need to ensure is left under compression to avoid a push rod slipping out of place and £273 bill to repair

I had a slightly sticky valve on mine and yes the pushrod dropped out next time I tried to start it, sod £273! A magnet firmly affixed to a still wire retrieved the pushrod through the oil filler hole and refitted giving the valve a good working.
I did have a so called expert (suzuki agent) look at it when it did it again and he gave me all sorts of crap about wrong fuel used and had no compression and charged me £90 for a non running engine, I took away very grumpy and opened it up myself (very simple engine) and he had no concept of cam timing, it was randomly chucked together so no wonder it wouldn't start (the timing marks are very obvious), £15 for a head gasket (other gaskets were fine just got a bead of hermetite) and an hours work and it fired up first pull and has run sweet ever since.
Suzuki agent went bust not long after, not a bad thing as a bloody cowboy, I did get a refund before they went down the pan though as I'd copied suzuki UK in on all the emails.

 

[johnalison]

I know nothing about its innards but I’ve owned both the 2 stroke 2.2 and the 4 stroke 2.5 Suzukis. Although slightly heavier, I find that carrying the 2.5 is easier because of the proper handle, even though it is a nuisance having to take care about laying it down.

 

[Neeves]

I find it bizarre that you need to lay it down on the 'tiller' with the signing telling you that it is correct - even though its all counterintuitive.

I have had no complaints - start first time, every time, does what it said on the box. It has an easily seen oil window. Its dead simple, I like the gear change (unlike the Yamaha which had no gears)

But I am beginning to wonder if I'm just lucky - or my time will come

I'm just off to grease that shiny plate!

Jonathan

 

[rotrax]

The same outboard you need to ensure is left under compression to avoid a push rod slipping out of place and £273 bill to repair

As a 55 year small engine mechanic I am interested to know how the pushrod in a simple single cylinder four stroke can be displaced by not leaving it under compression.

The only possible cause is a valve stuck open. Stuck open through bad winterising or storage.

Every time a multi cylinder pushrod engine is stopped, only one cylinder will be on or near the compression stroke. The other pushrods dont become displaced, do they?

Good information though. I have a 4HP Suzuki which I maintain myself. A displaced pushrod could be replaced on my engine in moments. But there would be no point in replacing the a displaced pushrod if a valve was stuck. The pushrod would just displace again.

I suspect your £273 repair was not for replacing the pushrod - a five minute job - but for rectifying why the pushrod displaced in the first place.

IMHO, of course.

 

[snowbird30ds]

The valves are prone to sticking if the fuel is not quite right, I'd used avgas so a bit of lead on the stem was the issue.

 

[rotrax]

The lead compounds used in heavily leaded high octane fuels were used as lubricants as well as anti-knock additives.

According to an ex collegue who worked at the ESSO Research centre just up the road from here.

 

[Steve65]

Exhaust valve stems get varbon build up on the stems, causing the ex valve to stick which breaks or throws off the pushrod....very common on these, repaired quite a few.
Corroded rocker boxes are also common on small outboards, especially Hondas. Not known one on a Suzuki tbh.
You should be able to get a used one

 

[Neeves]

I knew it would have a fancy name but be warned

the rocker box cover that had corroded - pin hole roughly dead centre, is attached to the rocker box with 4 stainless bolts that can corrode into the casting. Of the 4 bolts one was corroded almost solid - verbal report from my neighbour this afternoon.

As you would expect no protection between the stainless bolt and the casting.

The philosophy behind 4 stroke outboards is they are more environmentally responsible than polluting 2 stroke. I wonder how may 4 strokes are dumped as a result of inadequate corrosion protection.

Jonathan

 

[Steve65]

The reasoning behind this is from a manufacturers poinf of view, small outboards are disposable and have a life span of around 10 years.
Thats why British Seagull are probably the most environmentally friendly outboard...buy one and you have it for life....and probably your offsprings life too

 

[Steve65]

I had a slightly sticky valve on mine and yes the pushrod dropped out next time I tried to start it, sod £273! A magnet firmly affixed to a still wire retrieved the pushrod through the oil filler hole and refitted giving the valve a good working.
I did have a so called expert (suzuki agent) look at it when it did it again and he gave me all sorts of crap about wrong fuel used and had no compression and charged me £90 for a non running engine, I took away very grumpy and opened it up myself (very simple engine) and he had no concept of cam timing, it was randomly chucked together so no wonder it wouldn't start (the timing marks are very obvious), £15 for a head gasket (other gaskets were fine just got a bead of hermetite) and an hours work and it fired up first pull and has run sweet ever since.
Suzuki agent went bust not long after, not a bad thing as a bloody cowboy, I did get a refund before they went down the pan though as I'd copied suzuki UK in on all the emails.

Bad news for you...head gaskets are stainless sheet and reusable on this model

 

[sailaboutvic]

Regards the croddered cover , on my old Honda I GRP it and three years on it was still holding out .

 

[Steve65]

Good fix, you can always take a mould off the original and make a grp one from the mould, no more corrossion!

 

[rotrax]

I did the first service for Dylan Winter's new outboard. Dylan of KTL.

One of the things we did during the service was to remove as many fastners as was possible and apply a little diluted grease - a mix of grease and oil - to their threads.

We dont know how this might have affected the long term service life of that particular engine, a Mariner, as some scroat nicked it shortly afterwards.

 

[munster1967]

I know nothing about its innards but I’ve owned both the 2 stroke 2.2 and the 4 stroke 2.5 Suzukis. Although slightly heavier, I find that carrying the 2.5 is easier because of the proper handle, even though it is a nuisance having to take care about laying it down.

How did you find the change to the 2.5, 4 stroke. Does it perform the same as the dt2/2.2.?