Tohatsu seahawk 9.8, head gasket

Nang · 03 January 2022, 20:59

Hi Ribnet

I have got hold of an old tohatsu engine that is in lovely condition I am trying to replace gaskets to get it running. I can't seem to find any parts or diagrams the manual I have doesn't provide any part numbers.

I could really just get away with a head gasket tbh, but I am having no luck at all in locating one.

Hoping someone might know if there are any old tohatsu head gaskets still out there, nothing on ebay looks like it.

The models is B18D/M 9.8A

serial number is 14351

Thanks for reading

Ribtecer · 04 January 2022, 11:31

Make one?

Nang · 04 January 2022, 11:44

Thanks for you response, Make a head gasket? I understand it would need to be made from copper. I would have to get someone to machine this for me as I don't have the tooling.

Fenlander · 04 January 2022, 15:54

Last time I remember someone asking about a Seahawk years ago Tohatsu had stopped supporting this motor with parts so you are going to have an intensive search for this with no guarantee of finding one. However to get it back running I'd buy a sheet of something like this which will be enough for several gaskets and as they are so easy to swap on your motor you might as well give it a go.

https://www.racing-planet.co.uk/gask...6#.YdRs5WDP2Uk

Nang · 04 January 2022, 15:57

Quote:

Originally Posted by Fenlander

Last time I remember someone asking about a Seahawk years ago Tohatsu had stopped supporting this motor with parts so you are going to have an intensive search for this with no guarantee of finding one. However to get it back running I'd buy a sheet of something like this which will be enough for several gaskets and as they are so easy to swap on your motor you might as well give it a go.

https://www.racing-planet.co.uk/gask...6#.YdRs5WDP2Uk

Thankyou for your response Fenlander. When I click on his url "I get page not found"

Fenlander · 04 January 2022, 15:57

Try this...

https://www.google.com/search?q=gask...hrome&ie=UTF-8

The top result.

Nang · 04 January 2022, 16:05

Quote:

Originally Posted by Fenlander

Try this...

https://www.google.com/search?q=gask...hrome&ie=UTF-8

The top result.

Thank you.

This looks very cool

I think I may be able to use the old gasket as a template and cut something out that would do the job. Its quite a basic shape, wish me luck.

Any road up, it will be a fun experiment trying.

Has any one else tried this? Would be interested in any suggestions / tips that folk might have.

paintman · 04 January 2022, 17:16

I've made many gaskets over the years for various things, but esp old British motorbikes.

In my younger days mostly out of cereal packets but later out of proper gasket paper in appropriate thicknesses. (plenty on ebay)
Use a sharp craft type knife & a pair of sharp scissors.
Steel ruler to guide the knife as a straight edge.
To make holes sharpen the end of a piece of metal tubing & tap onto the gasket paper with a hammer. I used to shoot & old rifle cartridge cases worked a treat.

Never made a metal head gasket or a compound one (metal & gasket paper combined) but for solid copper ones (BSA motorbike) annealing used ones worked.

I'm curious as to whether the metal material will work - all the head gaskets I've seen (apart from the solid type I mentioned above) have all had a solid ring (fire ring) around the cylinder so will watch with interest.

Nang · 04 January 2022, 17:19

Quote:

Originally Posted by paintman

I've made many gaskets over the years for various things, but esp old British motorbikes.

In my younger days mostly out of cereal packets but later out of proper gasket paper in appropriate thicknesses. (plenty on ebay)
Use a sharp craft type knife & a pair of sharp scissors.
Steel ruler to guide the knife as a straight edge.
To make holes sharpen the end of a piece of metal tubing & tap onto the gasket paper with a hammer. I used to shoot & old rifle cartridge cases worked a treat.

Never made a metal head gasket or a compound one (metal & gasket paper combined) but for solid copper ones (BSA motorbike) annealing used ones worked.

Thanks

I do still have the old gasket, how do you anneal something?

paintman · 04 January 2022, 17:43

Will only work with a solid gasket - as in made out of one piece of metal - and I've only done it with copper.

Uniformly heat to cherry red & allow to air cool.

There is a lot of argument about whether to dunk it in cold water after heating but I've always let them air cool.

paintman · 04 January 2022, 17:56

For paper gaskets either use the old one as a pattern or position the paper over the thing it needs to fit & rub your finger over the outline of the shape. A dirty finger works best!

Fenlander · 04 January 2022, 18:25

>>>have all had a solid ring (fire ring)

Yes I wondered about that bit but for the cost of a sheet of that gasket knowing it would make at least two I would try if it keeps the OB on the water.... even if they only last a year once the head bolts are known to be free that's half the battle.

Nang · 04 January 2022, 19:02

Quote:

Originally Posted by Fenlander

>>>have all had a solid ring (fire ring)

Yes I wondered about that bit but for the cost of a sheet of that gasket knowing it would make at least two I would try if it keeps the OB on the water.... even if they only last a year once the head bolts are known to be free that's half the battle.

I am now wondering if I can remove the 2 fire rings from the old gasket and aneal them before adding them to the homemade gasket.

Fenlander · 04 January 2022, 19:24

I'd say that was very possible and a good idea.

paintman · 04 January 2022, 19:47

Nothing to lose.

Be worth trying to find older Tohatsu dealers (google search etc) & ringing around to see if they've got any old stock knocking around.

Nang · 05 January 2022, 09:08

Quote:

Originally Posted by paintman

Nothing to lose.

Be worth trying to find older Tohatsu dealers (google search etc) & ringing around to see if they've got any old stock knocking around.

Thanks

This is my first Tohatsu project, so I don't really have any dealer contacts.

I can do a "Tohatsu dealer" search on google maps, I get quite a few but I don't know how long they have been established.

Can anyone recommend any contacts?

Limecc · 05 January 2022, 09:41

Use graphite sheet. It was used as a universal replacement for asbestos based jointing when I was in the power industry years ago. Withstands high pressures and temperatures up to 500°C, good enough for exhaust flanges as well. You'll have to use a micrometer on the old gasket to measure the needed thickness.

Graphite Gasket Sheet 280 x 280 x 3mm Exhaust Turbo/ Exhaust Charger

paintman · 05 January 2022, 10:02

Quote:

Originally Posted by Nang

Thanks

This is my first Tohatsu project, so I don't really have any dealer contacts.

I can do a "Tohatsu dealer" search on google maps, I get quite a few but I don't know how long they have been established.

Can anyone recommend any contacts?

Just ring them. Not going to cost that much for a phone call & might save you a lot of faffing about with something that doesn't work.