1987 Suzuki DT100 water outlet question

[Willhuntforfood]

Hello Everyone,

Working on my boat today and have a question about the water discharge on my motor.  Can anyone tell me how much water would come out of the "tell tale" or water pilot hole?  I started the boat today in a trash can of water and nothing came out of the pilot hole, I could feel air but no water.  My other smaller outboards would have a steady stream of water but it would also be a hose and might act as a primary water discharge point.  I looked in the service manual and it showed water could flow out that pilot but most came out the middle of the prop.  Any thoughts?

Any in sight would be appreciated.

[fitz73222]

Was the gearcase fully submerged atleast past the gearcase and midsection split line? They will not pull water unless the pump is submerged or they are force fed from an ear muff flush attachment. Try again and make sure it is deep enough. Once running, hold your hand on the long flat exhaust plate on the side of the block and see if it gets hot enough that you cannot hold your hand on the plate. The water from the pump passes through the exhaust baffle first on its way to the cylinder head and thermostat. You should be able to hold your hand on the plate at all times; about 90-110 degrees. The cylinder head will get warmer to the touch; about 120-130 degrees an then cool off a little once the thermostat opens. If she heats up beyond your ability to touch the exhaust plate; time for a new water pump AND thermostat.

Dont ever start these engines without a water supply or submerged water pump or it will fry the rubber impeller in a matter of seconds.

[Willhuntforfood]

Thanks Fitz,

I thought I had it submerged enough but possibly not.  I will get a set of muffs and try it again.  I will check again tomorrow with the muffs.  I only had it running for about 20-30 seconds.

[Willhuntforfood]

I got muffs today and tried them out.  I taped off the secondary water inlet and attached the muffs to the primary inlets.  I started the motor and ran it for about 20 seconds and no water was coming out but air was.  I was told it takes a little time for the jacket to fill up with water before it starts coming out the tell tale.  Did not want to run it too long for fear of doing some or more damage.  I am going to back it into a lake later this week and fully submerge the motor and try it again.  How long should I run it without seeing water?

Thanks for all your help.

[fitz73222]

Not sure what you mean about "secondary water inlets". Usually they will start to relieve themselves pretty quickly. Do the little trick I told you about feeling that exhaust plate. If you have a "V" engine the exhaust plate is between the cylinder heads and if it is an inline engine it will be on the left or right side of the block. If shes not pumping the plate will heat up in less than a minute. No harm will come to the engine; the pump is already needing replacement anyway.

[wingtime]

20 seconds is not enough time for the water pump to get primed and fill the engine with water.    If water is shooting out of the exhaust then run it for at least a minute or so...     Also I know nothing about Zukis.... are  you sure this is a tell tale port or a exhaust relief port?

[Capt. Bob]

A couple/three questions.

Is this motor new to you (think first time starting it up)?

If not, did water ever come out before?

If it did, do you remember about +/- how much?

It sounds like you have owned it for awhile and it does have a "pisser" so maybe something has blocked the passage. Try sticking a thin wire in the tube and clearing the line. Happens on OMCs all the time or.............

Have you already tried this?

Just thoughts.

[Willhuntforfood]

Hey Guys,
First of all, sorry, the motor is a 1995 not 1987.

Cptn Bob- I just purchased this boat and motor and have not run it prior to this weekend.  I have emailed the previous owner and am going to be meeting up with him this week to make sure water came out of this or pilot hole or the just the water over flow outlet.

Fitz, I am calling it a secondary water but the service manual calls it a "sub water inlet"  

Put the boat in a lake today and ran it.  No water came out of the tell tale, felt air and saw some exhaust smoke coming out of it.  After about 2 minutes of idling, the exhaust plates were too hot to hold my hand on and then the temp light and buzzer came on the monitor gauge.

Wingtime the service manual calls this the "pilot discharge hole" and is being diagramed in the cooling system portion of the manual, i am calling it a tell tale.  

Fitz I think you are correct the pump is gone and possibly the thermostats as well.  Bummer.

[Skoot]

Hey Guys,
Fitz I think you are correct the pump is gone and possibly the thermostats as well.  Bummer.

Bummer nothing, thats an easy/regular maintenance fix...   ...Hopefully!  and if thats all it is the repair cost should be pretty low.
good luck, let us know how it turns out

[slvrlng]

Hopefully you didn't cook one of the piston tops as well. I go by the old school way of thinking when no water shows out the "telltale". I was taught that if you run the motor for more than 60 seconds without water moving through it the edges of the impeller can melt in the housing and you can cook the pistons. If an outboard is not "peeing" within 15 to 20 seconds, SHUT IT OFF!

[Willhuntforfood]

Hey Guys,

Here is what I found out.  Impeller was destroyed, see pic below.  When I removed the lower unit I had some greasy sludge on the wall of the exhaust tube, and that led me to discover that the collar on the housing around the drive shaft was broken and had a couple pieces missing so obviously the oring and oil seal were not working.  Now that I know that I have had some gear oil running through my cooling system do I need to find a way to clean that out or will it just wash out with use when the new pump is working correctly?  I assume that I would need to at least remove the thermostats and clean and test them, along with the cooling water sensor.  The lower unit oil was replaced last fall by the previous owner so when it came out it was clean.  I also wanted to replace the spark plugs and found the previous owner was using the wrong NGK plug, arrrgh!  

Not a good start to my new boat experience!

Thanks again for all your help!

[fitz73222]

The good news is you have all six blade tips. I've seen them break off in small pieces and lodge themselves up in the power head base grommet and cause overheating even with new components. Someone probably started her up without any water hooked to her and melted the pump. I`ve actually seen people do this innocently at the ramp; just to make sure it will start once they launch! The gearoil in the powerhead cooling passages will not hurt anything. It will wash out with use. In fact, when you reassemble the waterpump you need to use grease on the impeller blades as you rotate the impeller clockwise while you push down on the impeller housing until it meets the base plate. Unless someone has run the engine for an extended period while overheating; no harm has come to engine. A compression test done correctly will validate this. The normal consequence of running while overheating is piston skirt scuff, were the piston has expanded beyond design and made physical contact with the cylinder wall.

[Willhuntforfood]

Thanks Fitz,
I did have some smaller pieces of the impeller that I removed from the bottom of the main water inlet.  I have ordered a new housing with new o ring and oil seal.  I am glad to hear the oil will not cause an issue down the road.  I do know of the use of grease on the install as well.

Thanks again, you guys have all been great.  I should have the housing tomorrow and will let you all know how this turns out.

[wingtime]

Yup I agree with Fitz someone started it without any water and melted the pump.  Since this motor is new to you I personally would have replaced the pump, thermostats, poppet valve, lower unit oil, zincs or any other part on a zuki that should be replaced every season.  This way you know what you have and can maintain the motor correctly from here on out.

[fitz73222]

And I agree with Wingtime. No time like the present to get that baseline established for preventive maintenance. It is very reassuring to know when you have gone through her from cowl to prop including fuel system; turn the key and go! For $200 doing it yourself worth every penny...