Yamaha 2HP Cooling Water "Blockage"

[kyleview]

Any advice or diagrams for my 2HP Yamaha much appreciated - have been on many websites so far to get bits of help, but not all. It's such a LIGHT and superb engine I want to keep going for ever - it's now 12 years old on a 23 year old Avon on a pretty upmarket yacht, but good news is no one is likely to steal!

"Today has been really nice day in Largs, unlike last few days, also what's forecasted. Got things ready on boat to service the Yanmar engine tomorrow which I feel ok about as have done 3 times before, also have the filters, etc at hand.

Then cut the grass, followed by taking the Yamaha 2HP outboard apart in the "wheelie" to see why the cooling water will not go through it. Been a real pain for the last week as worked ok for 30 minutes when I flushed through last week, but then stopped flushing water out during the week. I know nothing about outboard engines but now have the bottom in the "wheelie" and the top part in the garage and none the wiser. After taking Google advice and poking around with wire to sort out any salt blockages and getting some silicone grease from the boat tomorrow (to seal the seals) will put together and see if I have made a difference. The impeller seems to be working ok and pumping ok (was replaced last year) so will wait and see - Ian you may have some advise here"

 

[SimonJ]

Blocked waterways in outboard

I suggest you get hold of some citric acid (it comes in crystal form) and get some into the waterways. You probably have obstructed passages in the cylinder head - salt water plus aluminium/cast iron. Also trying blowing back through the cooling water 'tell tale' - if your engine has such a thing. Usually a small black rubber tube from cylinder head.

You have to be fairly inventive to get the CA in - maybe use a small bore funnel into the tell tale outlet possibly or put engine horizontally and get it past the impeller (which you can remove). Also poke around gently with a bit of stainless wire if available.

CA is fairly benign (it is in jam) so should not hurt you or the engine! It does however 'eat' through salty/scaly deposits if left for while.

Hope this helps a little.

 

[barnaclephill]

Any advice or diagrams for my 2HP Yamaha much appreciated/QUOTE]

I've just uploaded the outboard motor repair scans from PBO to my photobucket page: http://s1136.photobucket.com/albums/n491/barnaclephill/

The Yamaha Owners' Manual for models 2b, 2c, 3a, 4a and 5c have only a very basic sketch showing where the water comes out, and nothing about the internals.
Its other advice says to warm up the engine for 3-5 minutes prior to powering away, and check that the water is coming out.
On advice to flush the motor prior to long-term storage, the motor says, "Install the outboard motor on the water tank, and fill the tank with fresh water to above the level of the anti-cavitation plate.
Shift into neutral, start the engine, and run at low speed for a few minutes.
..."

In uploading the above scans, I notice repeated reference to adding some detergent to the water, and that the salt deposits would be at the outside end of the exiting tube, rather than toward the inlet.

These days I sometimes flush my Yanmar (when warm) with some brown vinegar to clear out any calcification deposits - cheaper than Rydlime.
Hope this helps

 

[VicS]

You will find exploded diagrams at http://www.boats.net/parts/search/Yamaha/Outboard/parts.html which you may find useful in conjunction with B'phill's scans.

If the system is completely blocked chemical cleaning with a acid it unlikely to be effective because if the acid can't get through it wont be able to remove any scale.

If you think chemical cleaning might work then I'd suggest a stronger acid than citric.
Fernox DS-3 limescale remover is based an sulphamic acid and will I think be more effective. Sulphamic acid is just about the strongest of what would be termed "weak" acids. DS-3 is available from plumbers merchants and many DIY stores.

Rydlyme marine descaler may be even more effective http://rydlymemarine.co.uk/

It is however very probable that you will have to remove the cylinder head and resort to manually cleaning it if it is very heavily scaled ( use a new head gasket when reassembling !)

 

[kyleview]

Thanks for the links - proved very useful in giding me to my next steps.

 

[Talbot]

used to pull mine apart regularly to keep the passageways clear. Normally the most difficult part is seperating the power head from the shaft (if I recall corrrectly something like 6-8 bolts from underneath). there is a plate between power head and the leg. This provides access to most of the passageways below the engine. Taking the head off allows access for a screwdriver into the passageways around the cylinder. A new head gasket is good, but you can often get away without replacing it!. check the impellor is good, and is turning. Check that the brasss tube from the impellor pump housing up to the base of the engine (located on the plate mentioned earlier) is clear, poke a pin through the tell-tale, bolt it all up again, and you should be fine.

 

[CreakyDecks]

Just reiterating what has been said above. The chances are that water paths in the cylinder head are absolutely rock solid with scale and you will need to dig it out with a screwdriver. I did mine ages ago and managed to re-use the head gasket with no problem. It just comes down to luck whether you can get the head off without damaging the gasket (or whether some idiot has glued it on!) so I'd source a new one before starting but not actually buy it.

 

[2copplane]

ditto

I had the same problem with my 2hp Yam a few weeks ago. Took the head off and scraped out the channels. I reused the head gasket and everything worked fine.

 

[alahol2]

This may be of assistance.

 

[steve66]

Hi i have done dozens of these and the only effective way is to take the head off. As has been said before unless you really damage the head gasket it can be reused.
ps, i have loads of new and secondhand spares for these

 

[grafozz]

head off

After reading this thread , I was prompted to have a go at taking the head of my 2hp yamaha . It has been overheating for ages , just makes it to the beach usually . After fitting a new pump , impeller and all gaskets it still overheated .
I spent this afternoon stripping down the head and found lots of salt crystals and general muck , luckily there was a new headgasket in the spares box , then scraped and poked out all the waterways using various wires and a small drill bit at low speed, re assembled it and fired it up . The result was amazing ! water poured out of the exhaust , first time for 2 years !

three cheers for the forum ! thank you all .
gramos .

 

[kyleview]

Hi i have done dozens of these and the only effective way is to take the head off. As has been said before unless you really damage the head gasket it can be reused.
ps, i have loads of new and secondhand spares for these

Steve - where did you get the spares - can you let me know as I am having little success so far.

I have emailed and called - http://www.outboardspares.net/acatalog/Parts_for_Yamaha_-_Mariner_2A_2HP_Outboard_Models.html - three times in the last week to no avail / replies.
Also they appear to have only one of the gaskets I require:
Yamaha / Japanese Mariner 2HP 2/Stroke Outboard Exhaust Plate Base Gasket
Yamaha Part Number: 646-14623-A1
They do not seem to have this one 6A1-14613-A0
as I need one for each side of the Exhaust Plate Base.

I also think I will need a head gasket from all the other input as I need to get in from that end to sort the blockage out - and again not on their website

Thanks

 

[VicS]

Outboards Direct ( aka Oakley marine) in Brighton are good. They are Yamaha agents

Ron Hale in Portsmouth is another

You could always try the " dealer locator" on Yamaha's website http://www.yamaha-motor.eu/uk/dealer-locator/index.aspx?category=Marine Engines#cc=GB&prod=Marine Engines To find one in your own area

 

[oldharry]

Had three of them - the first one was nicked off the back of the dinghy (scumbag used bolt croppers on the padlock) So dont assume nobody is interested in 'liberating' them....

Second one - very battered and rattly and power down, but still starts first pull, and does everything it says on the box.

Third one (bought cheap thru the For sale board here) to replace the 'bag 'o nails' when it finally dies... nice and quiet but didnt like starting from cold, and then got very hot with virtually no water circulation. Took the leg off, and tried to flush it through with water. No louck, so got a large dinghy air pump, connected that to the water inlet and put some pressure on it. Blew the blockage (salt crystals) clear, and it ran perfectly. Unconvinced so I took the head off. Bad mistake - one of the head bolts sheared: wot fun! However, managed to extract it as it had broken at the very top having seized in the cylinder head, not the barrel. An extractor drew the remains out without further damage. Was I lucky? yes.

So what did I find inside? There is quite a narrow neck where the water enters the head to cool it, and that seems to be the most likely place fro a blockage. But pumpinj it up with a high volume air pump had cleared it completely.

Starting problems soon sorted by a thorough clean up of the carb using carb cleaner from local motor shop and setting up properly. Now starts third pull cold, and first pull hot.

Make sure the filter in the fuel line is clean and running free - any restrcition here can make it unstartable for a minute or two while fuel seeps through after opening the stop tap.

No 1 never spilt fuel when tilted. Nos 2 and 3 do.... no idea why?

 

[steve66]

I have a few spares i have collectoed new and used over the years including a brabd new crank bearings and conrod going cheap if anyones interested!! Sorry i have no gaskets but as yet i have never had to replace a head gasket.Exhaust / lower plate gaskets i have made myself but to be honest i have had success with just a smear of silicone over the original gasket, but make sure it literally is a smear as you can easily block up the water galleries

 

[kyleview]

Steve - a man of my own thinking - Thanks.

 

[kyleview]

More questions - 2HP Yamaha Water Circulation.

I have now taken the drive shaft away from the engine and cleaned out all the passages on both sides of the "separation" plate. Then reassembled using a silicon grease on the old gaskets. Water circulation a lot better to start with judging by what was coming out of the vent 3/4 way up the shaft, no leaks, but after 5 minutes the water venting fell away.

Then got a bit more adventurous and took the head off - the end with the plug into it. Again cleaned out, not a lot of salt, and reassembled using the old gasket, silicon grease, etc. Started up and even more water out of the vent, but after 5 minutes the amount of water venting diminished again and some smell / smoke was starting.

I have taken all the advice on this post, looked at all references, but am I missing another place I should be looking at for a blockage. I note the other end of the engine can also be taken apart, but would not think it would be that hot and needed water to cool - maybe I am mistaken and the blockage could be there?

The impeller, lower shaft pipes, etc appear to be working/clear OK as I get plenty of water venting for the first few minutes when running. Also impeller was replace just over a year ago, also pipe to impeller appears clean

Any further advice much appreciated - must be near fixing!

 

[Seajet]

I take the head off my Yam 2 & Mariner 5 every winter lay-up, never have any snags and can usually re-use the gaskets.

A pro' mechanic friend has the same engines and doesn't bother, then wonders why he gets salt blockages.

I also run the engines in fresh water at the beginning & end of the season, in the case of the 2hp sometimes mid season too, it all helps; the 2hp is 1988 vintage and going happily, great engine.

 

[steve66]

Its definately your impeller or impeller housing if you have a good flow for the first few minutes. Have you checked for any blockages for the water inlets to the water pump housing and also check if you have a seal on the pump housing and water pick up pipe.
Good luck your nearly there!!

 

[pagoda]

Its definately your impeller or impeller housing if you have a good flow for the first few minutes. Have you checked for any blockages for the water inlets to the water pump housing and also check if you have a seal on the pump housing and water pick up pipe.
Good luck your nearly there!!

Having stripped my 2hp Yam down on the pontoon once (to great amusement of everybody else) - and cleaned out the offending salty bloackages- I'd agree on the water feed tube seal comment.
When I dismounted the leg the seals on the tube crumbed away. I replaced the tube & associated seals. The tube was not expensive. Gaskets were more costly..
Since you can't run this engine in neutral -the best option is to take the prop off and run it in a bucket of fresh water until the water is warm. Replace water if need be.
Caley Marina in Inverness are pretty good at sourcing parts and posting out.

regards, Graeme