[kram]

Hi,

I have a problem which my outboard mechanic has been unable to resolve and I'm hoping someone on this forum has come across the problem and can offer some advice.

My outboard is a 1993 Yamaha 115hp CETO 2 stroke.

The last few times I've been out on the water my overheat buzzer has sounded. Last trip, the buzzer sounded after running for 10 minutes at approx 3000rpm. At that point I normally idle the motor and after approx a minute the buzzer goes off and I continue my trip.

To date the following work has been completed on the outboard:

100 hr service which included new impeller -> problem occurred on next outing.

2nd attempt to resolve included new thermostats, grommet, clean out all salt build up and associated gaskets > again problem occurred on next outing.

3rd attempt to resolve included a new water pump housing when we noticed an unusual amount of water leaking from lower unit (refer to picture) > new water pump housing didn't resolve the lower unit leak so I don't have any confidence that the problem is resolved......I'll most likely try it over the next few days and see what happens.

Please note the leak starts 10 seconds after the motor is started and the motor has noticeable steam from the exhaust after the engine warms up.

Hopefully someone can confirm that the leak is unusual and offer some advice. Thanks in advance.

Regards,
Mark

[scottcmb]

there is a tube that connects to the water pump housing when you place the gear box back onto the midsection.....this tube is the transfer of water to your powerhead from the waterpump housing.....it rises up all the way inside of the midsection to the top from the bottom.....check this for corrosion and holes....if there are holes then not enough water will get to the power head......hence the big leaking in your pic you show.......if the tube is ok...then i would look at making sure it connects to the waterpump house correctly.....it might not have slipped into the rubber grommet correctly and damaged it hense a big leak also.......the tube might have been bent out of the way of the rubber grommet it slips into and hasnt connected properly when the gearbox was reassembled....i hope this is your problem....an easy fix

[kram]

Hi Scottcmb,

Thanks for such a fast response. I was quite impressed to get something within 30 minutes of posting.

I suspect that the problem could be with the water tube as my outboard mechanic checked the rubber grommet on the water pump for damage and correct seating when the water pump housing was changed last time. (I am surprised that he didn't check the tube though...maybe he just didn't mention that)

In reference to the water tube. Is there any gotchya's before I start this work? Is it a matter of just dropping the lower unit to gain access to the tube? or is the operation more complex than that? I have a Seloc repair manual but it makes no mention how the water tube is secured to the powerhead. Maybe if you know you could comment on this.

Once again thanks. I'll be really happy if that's all it is.

Regards,
Mark

[scottcmb]

the lower gearbox is easy to remove...nothing tricky or to surprise you.....Has the poppet valve that controls water pressure been checked??
when you remove the gear box look up inside the mid section to see the tube to make sure it isnt bent out of position if it seems ok then i would suggest making up a hose than will slide tightly onto the tube that you can connect the garden hose to.
remove one of your thermostat covers and take out the thermostat....leave uncovered....with a friend turning the tap onto a gentle flow wait to see if you get water coming out where the thermostat sits (this can take a bit of time to fill the cooling jackets before water comes out depending on how hard your friend turns the tap on)....by rights if the cooling system is ok water WILL come out at the thermostat housing!!!....
If not then start your search for the leak from the bottom and work your way upwards.......i cant remember if that tube runs all the way to the bottom of the powerhead or not on your model.......but either way it needs to be checked from pump to power head.
sorry to say but looks like you might have to remove the powerhead and gearbox to find the leak in the midsection....BE VERY THOROUGH!!!
if you remove the power head may aswell check the state of the exhaust manifolds there are two of them....and check the exhaust chamber also......look for bad corrosion!
What country do you live in?

[kram]

Thanks Scottcmb, I live in Victoria, Australia.

By the sounds of it I will need to get someone to do the work.

[kram]

OK..I removed the lower gearbox...checked out the lower part of the tube which looks in good condition.

I connected a garden hose to the tube and turned on a gentle flow...soon after a stream of water came out of the telltale. Anyway I noticed that water was dripping down the tube evident from where the tube disappears into the lower part of the mid section. The motor was trimmed to near horizontal position and no water was evident at the top part of the mid section.

So to my laymens eyes, the leak seems to be related to the tube...otherwise I would detect water at the top part of the mid section....now I just have to work out whether I can get access to the top part of the tube without creating a major piece of work... (any hints would be welcome).

Once again thanks scottcmb for your help.

[scottcmb]

ARRR thought you were over this side of the world, to get to the top part of the tube the power head will have to come off sorry to say.
If you are good with the spanners in the hand then it is not a hard job at all to do yourself (a good way to get to know your motor more) and will be alot cheaper too
And also like i said before with the power head off it will be a good opportunity to check the state of the manifolds and chamber.
Im in New Zealand if you want my number for any help PM me and i will give you my number.

[kram]

How heavy is the power head? Will I need lifting device? Otherwise it does look pretty easy to do.

[scottcmb]

two people can lift it with no problem......my son and i lift V6's with no worries......but if you have access to a block and tackle hoist then that would make it much easier for reasembly......oh and while you are at it......check the condition of the shift rod by pulling it out after you remove the powerhead they have a tendancy to corrode to the point of snaping 3/4's the way down the rod......if its warn to half the thinkness of the rod....i would replace it

[kram]

My Seloc manual states that I need to remove:

electric cranking motor and relay
flame arrestor, choke and carburetors
oil injection system
Yamaha Microcomputer Ignition system + sensors and switches
CDI unit + ignition coils
flywheel and stator assembly

prior to Powerhead removal. It's sounding like quite a big job.

Can I take any shortcuts or do I need to do the lot? and reading through some of the other threads it sounds likely that a few bolts will break during the process (not sure)?

Any comment about what I can expect through a Powerhead removal?

[kram]

I think my problem is resolved.

I took the boat out with a marine mechanic this morning and like clockwork the buzzer sounded. First thing we tried was a new pair of Thermo switches. After that the overheat buzzer didn't sound anymore. No matter how hard we drove the boat.

I did check the Thermo switches myself prior and they activated at around 185F so I thought they were OK.

I guess one of them must have had an intermittent fault that could have been triggered at high speed due to vibration.

I'm just glad we finally resolved it.

[scottcmb]

did he make comment about the amount of water coming out of the lower leg?.......the photo is a bit hard to tell without seeing it up close.....glad you have it sorted

[kram]

yeah....he claims that it's normal....but I'm still a bit suspicious of this.

For now I'll just keep an eye on it and try to compare the leak to other Yamaha's.