Cleaning the carburettor in a Tohatsu four stroke 3.5 hp outboard engine

The last in the trilogy on servicing my own outboard engine. 

If you want to see sheer elation in a man who realises he has just saved his own skin by not being murdered by 'her indoors' when he asks for a new outboard - watch to the end! 

'Her indoors', by the way, makes 'Villanelle' in 'Killing Eve' look like a wussy!

https://youtu.be/Nvh4oFx9QOk

A favourite walk

I love in a stunning part of the country with some spectacular coastal scenery. A favourite walk is from Noss Mayo across to Stoke and back along the country lanes.  The river Yealm is also a nice day sail from Plymouth Sound and many a time I have slipped alongside the bar and anchored at Cellars Beach.

Just down from The Ship pub at Noss Mayo

Across the creek - The Swan

Other side of the creek - Newton Ferrers

If I win the lottery........

Or maybe this one........

Definitely this one I think

With this possibly sat on my 'free' mooring

The hidden entrance to the Yealm pool

What I call the Yealm pool where two confluences meet

around the bend to the right and up to the photos above

Looking seaward and  the hidden beach of Wembury - our 'family' go to beach for so many years 

Looking towards outer Plymouth Sound with the Great Mewstone Island on the left and Rame Head to its right in the distance. Plymouth Sound is to the far right. 

Looking back inland to the tight bend up to Noss Mayo and Newton Ferrers

Out along the South West Coastal Footpath

Spent many a time down there fishing for ray, bass and wrasse

I spy HMS Queen Elizabeth afar

a National Trust holiday cottage - or it used to be

And then some good news....some really good news. Thanks to Paul down in Cornwall, the sheared bolt was professionally drilled out of the manifold and a heilicoil inserted.  0600 yesterday I was up and the manifold and carburettor had been reassembled by 0625!

I then used CRC 6-66 marine spray, as recommended to me by JW himself.

At 1400 yesterday, the outboard started on the very first pull of the starter cord - it has never done that before. Ticking over and accelerating in gear perfectly although I will run longer tests today. 

The mere fact that it started makes me a very, very relieved man - I would never have heard the end of it from 'the boss' if I hadn't got that engine going again!

Manifold in; throttle assembly back on and tension-ed correctly, carburettor fixed in. 

Petrol tank back on....

Busy in the garden

Although lock down has been lifted slightly and we have been up on Dartmoor cycling across the old railway lines and moorlands, we have also been spending time in the garden. We have been very blessed with good weather and also in having a large, if rather steep, garden.  Well over the last eight weeks it has had considerable TLC.

The steps to the upper garden have been replaced completely. One of the upper terrace areas has been hacked back and turned into a new bee garden. The other terrace has been turned into a wood store and later on this month a new wildlife pond will be installed on it. 

The hammock has appeared in the upper wood. The wild garlic is fading away, buttercups are in full bloom and the foxgloves are emerging. 

Now the new planting is taking place in earnest - new azaleas, a rhododendron and some peonies are on their way and we have two or three trial plots of wild meadow flowers seeded. Slow worms, frogs and toads are emerging across the wild lawn.

Catching up on a nap in the hammock listening to whispering trees, buzzing bees and the gurgle of a neighbouring stream  is a rather splendid way of ending a busy day. 

Bits and pieces of maintenance

I've spent a pleasant afternoon doing odd bits and bobs on Arwen.  Firstly, I took some 'lock down' time to decorate Arwen's galley and food box tray/lids. I was using International Toplac burgundy paint and a child's watercolour brush.  The paint was gloopy and thick and dried quickly as I put it on. I guess they pass the 'from 10' ' test. 

Welsh dragon - obviously! 

The lighthouse and figure of Drake are part of my City's logo (Discover Plymouth)

I also sorted out the anchor buddy and got rid of the silly carbine clip they put on it. Now it has shackles. I will keep it looped with the anchor and clip it on as and when needed and it can now be put on either anchor as well. 

I stole this idea shameless from Tim, another navigator owner (hope you don't mind Tim). I have put a link to his video below which shows them in action. 'Them' are simple fender clips. Up to now, I have tied the fenders to the various coaming struts and this has been untidy and also limited me in where I can place them. Now the clips just hook under the coaming edge and I can place them anywhere. 

https://www.youtube.com/watch?v=I2k1tWA8-f4&list=WL&index=207&t=36s

Cheap and cheerful made out of scrap ply

Tomorrow I will sort out what I carry on board Arwen and reconsider where I store it so that she is better balanced and trimmed. I want to try and free up one of the central locker areas for day sailing kit - food, ditty bag and foulies. I want to take weight out of the stern locker as well so that she rides better in following seas (given she has an outboard hanging off her transom!)

I will also try and work out a better rowing position and also secure the oars better so that they don't keep jumping out of the rowlocks

Postscript: 

One locker freed up for camera gear and food/drink. Rowing position wise, well in the past I have sat on the top of the centre case but this isn't working as well now that I have longer oars. However, I have discovered that kneeling astride the centre case top seems to be comfortable and might work better - so some experimentation required when I am back on the water. 

I've also managed to splice some loops into my mooring lines so that they fit over the bollards at Cotehele House (or anywhere else for that matter). It isn't the neatest splicing but they all seem secure. 

Fixing the sheared off bolt in the inlet manifold

A very, very wise man, for whom I have enormous respect,  said to me, having had a look at the two photographs below, "Take it to a small engineering shop Steve". 

I considered this wise advice and then asked what I would need to do if I wanted to try and remove it myself. I'm naturally inquisitive and curious, a life long learner and this can be both a curse and a blessing. Sometimes, I over extend my curiosity! 

The wise man came back and as always gave freely of his time and advice - simple steps on what to get and what to do. No judgement, just encouragement and sound advice. 

Another wise man reading this advice on a social media post contacted me and said "Don't do it yourself Steve". He wasn't disagreeing with the advice given originally - in fact he was endorsing it - "Don't do it Steve". Both wise men knew what could go wrong because of their extensive experience with such problems; they knew how difficult the task would be, unlike me, who had no experience and just fancied a go at it! What do they say - "a little knowledge is a dangerous thing?"

I considered both sets of advice and eventually and reluctantly came to the conclusion that the advice was, as I knew from the start, very wise and maybe, having never extracted a bolt like this one from a hole like that one before, I'd better get it done professionally. At this point, one of the wise men, who lives just over the border, offered to do it at his work place, taking on a burden which he really couldn't afford to do, given the current Covid - 19 situation and the difficulties he was facing in his own work place with shortages of staff. 

The manifold removed

Within a day of the package arriving, he had extracted the bolt but was unhappy about the threads remaining in the hole. He concluded that a helicoil would be appropriate.

I had to go look up what it was. According to Screwfix, a helicoil is.....

"a brand of threaded inserts that have been created by a coil of stainless steel wire. Made to support and create stronger threads in all metals, composites, polymers and other materials where the internal thread has been stripped or damaged. Helicoil has over 65 yrs of experience and is well known in the industry for manufacturing to the highest quality standards."

Well, there you go - you learn something new every day - I didn't even know such a thing existed. I've used thread cutters before when working on a 1965 Motorvespa 125 super (called 'Stacey') but a coiled wire insert - go figure. 

In the meantime, I consider that me breaking off the bolt is, in fact, fate intervening. The lock down ban on sailing has been lifted - I could have gone today. But, I am slightly troubled by whether it is the socially responsible thing to do or not and so the enforced wait due to my own folly has given me breathing and thinking time. It has also given me time to sit back and watch from afar how arrangements work at local marinas and what issues crop up out on the water. And perhaps, it has given me time to let the initial rush die down a little. 

It will be another two or three weeks before I have reassembled the outboard engine and tested it sufficiently that I am happy that the carburettor works perfectly and the engine won't suddenly cut out and refuse to start at some inopportune moment. If I am to go sailing, I do not want to be a burden on any rescue services or other boat users. All my equipment must be in tip top condition. I must be sharp and confident in my passage plans, risk assessments and 'what if' contingency planning. 

Paranoia! I have always suffered from advanced 'paranoia'!

In the meantime, I ought to be a little kinder to myself. I have learned heaps doing my own outboard service. Three weeks ago I couldn't do any of this:

• replace the engine oil
• flush out the engine using  a flush water pipe connector
• replace the spark plug
• check the coil starter
• replace the gear lube
• grease all moving parts
• fix the waterproof neoprene gasket on an outboard cowling
• remove the lower gear unit and the water pump housing to replace an impeller
• change the shear pin
• remove and clean a carburettor (less successfully I must admit)
• remove the petrol tank
• remove the inlet manifold
• contact the national dealership - Tohatsu UK
• discover a flaw in the outboard - a quality control issue

I may not have done it the right way and whilst the impeller and lower gear unit removal and refitting were a success - I tested it in the water tank and it worked fine - the jury is out on fitting back the manifold and getting the choke and throttle cables sorted correctly. Jury is also out on whether the cleaning of the carburettor, such as it was, has had any beneficial effect. 

There is going to be some explaining to do to the boss - if that engine doesn't start in a few weeks time!

Taking out and cleaning the carburettor from a Tohatsu four stroke 3.5 hp outboard engine

Below you will find information to help you, should you decide you want to give it a go.  There are photographs from my strip-down along with video material. Then there are two excellent blog sites where someone shows how to take the carburettor out and then how to strip it down. Between my material and these external blog sites, you should have everything you need to know. 

Taking the carburettor out of the engine compartment

The external website that shows this procedure really well is found at 

http://www.greenpanther.org/index.php/diy/31-tohatsu-carb-removal

Below is my lesser contribution and at the very end is a short video of the process as well to help you visualise what is involved at a better level.

Firstly the video: 

https://www.youtube.com/watch?v=lZTcnhgQ_eE

This is at my associated YouTube channel where you will find a playlist with the other videos in my 'servicing my outboard' series. 

Step One - remove the cowling, pull out the kill cord, have the engine in neutral. Use a 10 mm socket to unscrew the three bolts that attach the petrol tank to its plate and the engine block. Lift the tank up carefully and move it to the rear of the engine compartment and let it rest there. Watch that the brass collars in the petrol tank bolt holes don't fall out an get lost!

Step two: drain the carburettor of any fuel and likewise with the fuel pipe. To do this, place a large wad of paper towel beneath the carb and open up the drain screw so that fuel trickles out onto the paper towel. the drain screw is the bottom screw seen in the centre of the lower carb in photo above. When the fuel is drained, gently pull off the fuel hose to expose the brass pipe above the drain screw - let the fuel trickle out of this pipe. Then tuck it down out of the way. 

Step three: pull the thick black hose gently off the top of the carburettor and tuck it to one side out of the way.

Step four: Loosen that silver hex bolt on the far right hand side of this photograph and carefully lift it and the plate it holds down, out of the way. Watch out because the choke cable beneath it will suddenly spring up - so be prepared for that. You can then wriggle the silver wire out of the hole on the black plastic plate. Take plenty of photos as you go so that you know how to put things back together again afterwards. It should now look like the photograph below. 

Step five: there are a couple of other black tubes that lead from the carburettor down underneath it. These tubes exit the engine compartment beneath. You can push these tube gently back up through their holes from below, ready to gently pull out in a few minutes.

Step six: it is now time to remove the two bolts that hold the carb in place. Undo these carefully. The front air filter type unit will suddenly come loose. When you fully extract the bolts, there is a nut within this unit that may suddenly fall out - so be prepared for it. Similarly, be prepared that there are three gaskets at the other end of the carb where it joins the intake manifold pipe that may also come loose and suddenly drop into the bottom of the engine compartment. 

Step seven: in the photograph above you can see a long thick wire on the top left hand side which is bent in a couple of places and sits in a plastic plate on top of the rear end of the carb. This is the throttle control. Now that you have the carb loose in your hand, you will need to twist it almost through 90 degrees to get that wire out of its hole. At the same time, don'f forget to pull the remaining two tubes out of their holes in the base of the compartment.  If you have been successful - you should now have the carburettor in your hand and the engine compartment should be looking something like these photos below

Cleaning the carburettor

Again, Green Panther did a really good summary of how to clean the carb. I was not as successful as he/she was in cleaning mine but I put my contribution below. 

http://www.greenpanther.org/index.php/diy/127-tohatsu-3-5-hp-carburetor-part-2

You should now have the carb in your hand. I put any loose bolts in an old baking tray for safe keeping. I also put the carb in another old baking tray where I then worked on it. In this way, anything that suddenly sprung out, or fell out, was caught by the curved sides of the tray. 

Step one: I just had a good look around my unit and took photographs from all sides and angles of how the external parts were arranged. I also referred to the parts catalogue for the engine - distributed by Tohatsu so that I could get clear in my head what was what.  The link to this catalogue is below: 

http://www.rodsmarine.com/Parts%20Catalogs/TOHATSU/4-Stroke%20&%20TLDI/Parts%20Catalog%20MFS2B-2.5B-3.5B%20(2011)%20-%20(00221052-4).pdf

I cannot stress enough that this is the parts catalogue for my engine - a 2011 model. you will need to check the age and what catalogue you need for your specific engine. 

(I also have a copy of the service manual for my outboard, but I can't find the pages any more of where I found it and an internet search has proven fruitless). 

Step two: turn the carburettor upside down and you will see the square base with two screws securing it. Undo and remove the screws and carefully lift the square base off the carburettor. You should now see what is in the photo below. I soaked the bottom of the square base interior in carburettor spray cleaner for 40 minutes or so. It came up really clean. 

This was the staining of the bottom of the float bowl before carb spray cleaning. I used some Q tip cotton bud thingies to remove stubborn stains.

Step three: Warning - don't lose that rubber bung. Mine fell out easily and if you lose it - the carburettor will keep flooding (as I understand it). The central brass tube with the hole and the screwdriver slot is the main jet. You can unscrew this. Mine refused to budge, even after soaking for some time in carb spray. It is brass and you need to get the correctly fitting flat tip screwdriver blade. I almost stripped mine trying to get it out and that is why I gave up. Green Panthers site gives a much better description of how to clean this jet - remember the link is above. 

Step four: I removed the black float seen in the photograph above this one. I wanted to get at the area below it to clean it out. You need to pull/tap out the pin that holds the float in place. Don't tap it all the way out and be careful - because there is a little flaot device that hangs off it and this regulates the amount of fuel going into the carb - do not let it drop off - take plenty of photos. 

Step five: the slow air jet is the hole on the right hand side of this open chamber and again you need a flat tipped screwdriver blade of the correct size to slide down the hole to remove the jet. Mine refused to budge but I managed to get carb spray down there and I then let it drain out. I'm hoping this has done the job. if it hasn't then I will be taking the carb out again, ordering spare jets and will be taking it all apart again!!

Again, I would refer you to GreenPanthers site as he/she gives a far better breakdown of what was done.  Below is the parts diagram for the carburettor to help you. 

Reassembly was the exact reverse of taking it out. Use those photographs you took to help you reassemble it.  

Now, a very public health warning! Learn from my mistakes!

I put everything back in with no problem at all. I was able to reuse the original gaskets because I was careful in the way I disassembled the carburettor from the manifold. However, I made a schoolboy error on the the very last action of putting it back in. Posts previous to this detail that mistake. However, simply put, my very last action was to give one last half turn to one of the bolts securing the carb........and it sheared. The right hand bolt screws into a blind hole and I had over-tightened it by a half turn. 

This was the result!

This disaster meant I had to take off the manifold and send it to a kind gent down in Cornwall who offered to drill out the offending broken bolt stub using specialist equipment.  I detail how I removed the manifold, which is straight forward enough, as long as you pay due care and attention and take lots of photographs in a previous post which can be accessed here: 

https://arwensmeanderings.blogspot.com/2020/05/noooooooooo.html

And that's it. I hope this helps. Don't be put off. GreenPanther proves that removing, cleaning and reinserting the carburettor is straight forward as long as you take your time, take plenty of photographs throughout the process and have the correct tools and spares ready to hand. 

Good luck, have fun, learn loads and most importantly, enjoy. 

A reminder - the external sites of GreenPanther are found at:

http://www.greenpanther.org/index.php/diy/31-tohatsu-carb-removal

http://www.greenpanther.org/index.php/diy/127-tohatsu-3-5-hp-carburetor-part-2