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Old 02 October 2015, 07:40   #1
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Yamaha 8hp 2 stroke water and tilting issues

Hi All

I've finally got round to checking out my 8hp Yamaha 2 stroke, purchased off eBay a few weeks ago. It starts and runs beautifully, but I am a little concerned it's not pumping water well enough. It takes around 20 seconds or so from start up to see any water, then it's a bit 'dribbly'. If you rev the engine a little, the water flow improves, but seems much less than I recall on my old Mariner 4hp I used to own, and on the Mariner 9.9 I had. I stopped the engine and then retried and it definitely seems 'hit and miss' with the amount of water flowing. I'm thinking new impeller, perhaps new pump? Any thoughts on this?

Secondly, I can't get the motor to tilt! If you grasp the cowling at the rear and pull it's absolutely solid! The knob on the side on the clamp appears to do nothing, nor does the shallow water lever.. I'm sure I'm missing something obviousl (even though I've looked in the manual!) Can anyone advise on what I'm doing wrong? I've had several outboards and I've always just grasped the cowl and pulled! (albeit sometimes having a lever to pull! )

Any advice on the above gratefully received! I can post a video of the engine running (to show the water, or lack of) if that helps!

Many thanks!

Ian
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Old 02 October 2015, 14:47   #2
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The 6/8hp two stroke are notorious for blocked telltale as instead of exiting the exhaust cooling chamber via a hose like most other larger Yamahas, it comes directly from the block into a chamber in the leg, which gradually collects debris which then blocks the telltale.

It should just tilt by lifting on the back of the cowl. Try undoing the 12mm nut a turn or two on left hand side clamp and tapping it, this often frees them up.
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Old 02 October 2015, 16:32   #3
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Quote:
Originally Posted by phantom 19 View Post
The 6/8hp two stroke are notorious for blocked telltale as instead of exiting the exhaust cooling chamber via a hose like most other larger Yamahas, it comes directly from the block into a chamber in the leg, which gradually collects debris which then blocks the telltale.

It should just tilt by lifting on the back of the cowl. Try undoing the 12mm nut a turn or two on left hand side clamp and tapping it, this often frees them up.
Thanks very much for that insight Phantom. I will have a look at those clamps tomorrow!

Regarding the tell tale blockage. Is it a matter of stripping things down? Or just poking a little strimmer line up there? Sounds like a strip down would be best. Any information on how this would be carried out?

Sorry for the further questions!

Many thanks once again for your help ..


Ian
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Old 02 October 2015, 16:45   #4
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ive got a yamaha 5 that wont pump water properly - ive had the powerhead off and cleaned all waterways, and put a brand new water pump in it and still it just dribbles out! as for tilt, do you need to put it in forward gear so that the locking mechanism lifts?
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Old 02 October 2015, 18:06   #5
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here is my yam 8hp...note the water stream from the head.

i can attest to it blocks easier than most, mines was about half what it is there when i noticed it last time out. water was hot, had to shove some wire in and all good again.

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Old 03 October 2015, 04:02   #6
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here is my yam 8hp...note the water stream from the head.

i can attest to it blocks easier than most, mines was about half what it is there when i noticed it last time out. water was hot, had to shove some wire in and all good again.

Thanks very much for that clip dubrus.. Very useful to compare. I'd say mine is chucking out about a third of that from the tell tale hole! Definitely some cleaning out required! Looks like I'm going to be busy with this one!

Festinghouse - do you fins that your 5 still runs and works OK? I obviously don't want to damage anything... The engine itself sounds so sweet..
Regarding tilt - should the Yam be in forward gear to tilt it? I'm sure the Mariners were 'tiltable' in neutral.

I'm reasonably handy with spanners (do all my own motorcycle servicing for example). Even so, would it be worth getting a marine engineer to take a look at it? I do know of a decent one.

Your thoughts gentlemen?


Many thanks once again.

Ian
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Old 03 October 2015, 04:04   #7
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Ive spent half my life as a Yamaha engineer, sometime I'd have to strip the powerhead off after customer complaints, clean everything out, then it'd be back the next week after running in sand again with same problem. You can strip it down and clean it all out, but then you risk snapping powerhead mounting bolts depending on age. Personally I'd try compressed air up it when it is running if possible. May work depending on how much accumulation there is. Sometimes is it crystallised salt that will go after some running.
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Old 03 October 2015, 04:14   #8
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Ive spent half my life as a Yamaha engineer, sometime I'd have to strip the powerhead off after customer complaints, clean everything out, then it'd be back the next week after running in sand again with same problem. You can strip it down and clean it all out, but then you risk snapping powerhead mounting bolts depending on age. Personally I'd try compressed air up it when it is running if possible. May work depending on how much accumulation there is. Sometimes is it crystallised salt that will go after some running.
Thanks Phantom - very useful info again. I'd heard about the crystallised salt issue but never having personally run engines in the salt water enviroment, I've never had an issue. Obviously the original owner I bought this from used it for coastal runs. If there is any water coming out of the hole at all, is that acceptable? I'm keen to not overheat the engine obviously!

I do have a compressor, so yes I could certainly try that tip. I need to have a good go at this again and see if I can persuade it to run.

Do you think it's unlikely to be connected to the impeller then?

Many thanks

Ian
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Old 03 October 2015, 04:27   #9
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mine seems to run just fine, but having said that its only my reserve so doesnt really get used - im now of the opinion that ive literally done all i can with it!
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Old 10 October 2015, 07:42   #10
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I thought I'd post again to report back what I've discovered with this engine..

Phantom was pretty much spot on.. - many thanks Phantom.

The cooling issue through the tell tale, was indeed a build up of salt. A careful cleaning and blasting with compressed air has resulted in much better performance. This was improved even further by replacing the impeller. I now have a good strong flow of water through the tell tale!

The tilt issue was indeed an overtight/partially seized 12mm bolt. This is also now sorted.

I'm happy to report that the engine now runs spot on!

Thanks all for your help on this one!
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