Johnson 4.5HP Seahorse

[Nasher]

Hi all

Collected an engine today for the smaller Nashers Inflatable (The Nippers Revenge! ) Less than £70 on Ebay with an older 4HP Seahorse thrown in which will go straight back on.

Its a Johnson Seahorse 4.5HP Twin cylinder.

The spec far exceeds the 4HP Seahorse.
It has a twist grip throttle that includes an idle adjustment in the end with a kill button, and a 12V lighting supply. It also has a proper Forward - Neutral - Reverse gearbox.

It starts and idles really well, the tell-tale is a bit weak but I'll be replacing that anyway as a matter of course. The only other things I need to do are add a Kill cord/switch and put a cage around the prop.

Does anyone know how old it is from the pictures?
Or from the serial number B001822 - J5BECSS?

Also what fuel/oil ratio should we run it on?

Thanks

Nasher.

[Tim M]

Nasher

My first outboard was the 6hp Seahorse. I think its probably the same engine. I used to run it on 50:1 following the advice the bloke how sold it to me.

[Tim M]

Nasher.

Just found my OMC dating chart thing. The first few digits sort of make sence, according this this its a Johnson (good start) and its 5hp. After that nothing matches up. I've attached the chart for you to ponder over....

[Nos4r2]

1980 and 50:1

Watch the driveshaft as you drop the lower unit-they have a habit of staying in the powerhead. I find it easier to drop the L/U with the engine vertical-that way if the driveshaft stays up you don't get oil everywhere and the gears all stay in place so you can just pop it back in.

[Nasher]

Tim

Thanks for the info.

Nos

Thanks for the tip.

It needs a little bit of work before I'm happy to let the boys loose with it, but it won't be too long.

Nasher.

[Nasher]

This engine is turning out to be a little bit of fun before it even hits the water.

I’ve stripped and greased the tiller and twist grip throttle and added a kill switch and lanyard.

As it wasn’t pumping water very well I stripped the lower leg off to replace the impellor, only to find it was almost new. After mucking about I stripped off the exhaust side plate and cylinder head to find the waterways completely clear and two very clean pistons etc. The only exception to this is the water channels in the head being partly blocked with liquid gasket. Although this was not effecting the flow to the tell-tale hole. So the engine has obviously been rebuilt quite recently.

What I have found is that the water tube in the leg is much smaller than the hole in the top of the water pump housing, so a good proportion of the water from the pump will be spraying straight into the exhaust chamber and reducing the water pressure dramatically. That’s easily fixed with a small piece of plastic tube used as a sleeve between the two.

However the real fun is now trying to source a new head gasket, as the engine number stamped on the ID plate and core plug does not follow the correct convention for a Johnson engine. So I can’t identify the model or year of manufacture. And of course nobody keeps head gaskets in stock for small 80’s engines so I can’t even match one to the cylinder head.

Powertech have tried to help, but are not really interested in spending time phoning around for a £15 head gasket when they can sell somebody a £9K ETEC of charge somebody else £500 to service another one.
They promised to investigate and call me, but I’m really not expecting them to.

Does anyone have any ideas? Or know any helpful dealers that might know something about the older engines and be able to tell me what head gasket to source.

Nasher.

[springtide66]

Whats the guy who used to write for RIB int?? Andy .......?
He had a website, cant for the life of me think of his or its name......
but he would be your man!!

[Nos4r2]

Nasher,

it's a 1980-the CS in the serial number and the graphics type dates it to roughly that era too.

For a gasket try Redline Outboards in Abingdon (01235 521562)or Duncan Walker Outboards (0118 9478641) and quote your J5BECSS serial number rather than the plated HP.

Canalside/riverside dealers are usually a lot more helpful with small engines BTW-they make a lot of their bread and butter on them.

[hobnob]

Originally Posted by springtide66

Whats the guy who used to write for RIB int?? Andy .......?
He had a website, cant for the life of me think of his or its name......
but he would be your man!!

Andy Clarke helped me with small outboard repairs when nobody else would. He used to have the Bosuns Mate website with loads of useful info. Unfortunately he has ceased trading.

[Matt]

Was gonna recommend him too. He's got a lot of stock still in his shed I believe - if you can get in touch with him.