9.9 Yamaha Water Blockage

Model: FT9.9ELD
My cooling issue investigation is unfolding as follows;
No water was coming out the pee hose so I replaced the impeller (is was still in good shape) confirmed there was no blockage between the intake and the pump, the water tube was clear. There was a very small piece of hard black plastic in the intake below the water pump plate. not from the impeller, looked more like the pump housing plastic. I did not replace the pump housing. as it seemed to be ok. The only spot on the pump housing the black plastic could have come from would have been at the top inside where it rides on the drive shaft. Could this cause no water going to the power head. ( The pee hose is clear of obstruction and I ran it with the thermostat housing off with the thermostat removed and no water was filling the thermostat cavity. referring to this picture: http://www.**********/parts/search/Yamaha/Outboard/1990/FT9.9ELD/CYLINDER%20CRANKCASE/parts.html
I could blow air into nipple part labeled 26 but could not blow into nipple marked 27 it was blocked. Can I check the function of the pater pump when the lower unit is off. If I submerged it how quickly would the drive shat have to spin to push water up and out the water tube? Could the efficiency be checked this way? Any help with this investigation would be helpful.

Re: 9.9 Yamaha Water Blockage

Hi
Try connecting a hose to the intake pipe with the lu removed and see how the water circulates. IF it does ok then its your lU. (dont turn the hose on to full power though)
I dont like spinning the driveshaft with a drill as you dont want to damage the splines at all but if you sort out a means of doing it that you are comfortable with even a few low rpms with a drill will show if its pumping.
If the plastic came from the outlet of the waterpump housing it could cause your problem as the water would leak out losing pressure as it entered the lower exhaust cavity

Re: 9.9 Yamaha Water Blockage

After reading some other posts on this forum, I need to re inspect the water pump housing. When I had it off I did not inspect it all that closely. I have some suspensions that the metal cartridge may have spun out of position. If it let loose maybe the positing tabs scratched up the underside of the housing leaving the trace of black plastic I found. Thanks for your tips. Using the hose will be a great way to test for a serious blockage in the power head. Hopefully I will have time tomorrow to draw some further conclusions. I probably should have purchased the entire pump kit rather than just the impeller, especially since the motor is older.

Re: 9.9 Yamaha Water Blockage

Kit is always the best as it includes the cup and wear plate along with o-rings/gasket, bolts etc., for just a few $ mores.
but it does not include the housing. That has to be purchased separately.

Re: 9.9 Yamaha Water Blockage

Took the lower unit off and the water pump parts all look fine, no visual issues. I tried to flush some water up the water tube but there seems to be some restriction. Looking in where the thermostat goes I can't get any water into this area via the water tube using the water hose. My air compressor into the water tube allows me to hear a bit of flow but very little. Removed the water tube it is clear and in good shape. I blocked off the tell tail and put the thermostat cover back on without the thermostat in place and tried to blow air into the top of the thermostat cover hoping it might clear out the restriction but no air passes out the water tube when I do this. What next, anyone have any ideas. If I take the powerhead off where would I start my investigation? I just had the powerhead off I guess the new metal gasket I just put in won't be re-useable ?

Re: 9.9 Yamaha Water Blockage

I dont have that model but sometimes those nipples have check valves in them so they may seem blocked when thats actually them operating as required, so you may want to inspect them visually for foreign material.
I suspect you will need to split the head at the cylinder head gasket and check the holes heading each way to find/clear the blockage, although you might get lucky and find when you lift the powerhead again that the offender is right there blocking the inlet into the head as parts often get caught in the first entry bend/small hole into the head.
I can recall countless times using small wirehooks to retrieve plastic impeller blades that have wedged in the first bends of seized outboards ive bought.
Ive gotten away with using those base gaskets again sometimes and other times not. Id put in a new head gasket though and torque it to spec

Re: 9.9 Yamaha Water Blockage

I puled out the water tube and while I was pulling it out I was turning it a bit and it broke in half. Once I got the second half of the water tube out I realized it was quite corroded. Maybe my issue? Once the power head was off I checked and did not find any restrictions that would stop water from at least getting into the main area where the thermostat is located. I went down to the local shop to order a new water tube and picked up a few new gaskets. While I was there I traded a case of beer for some tips from the marine mechanics while they were on their lunch break. The teck showed me a trick they use on older Yamaha kickers to cheat the salt build up issue with out investing too much money and time into old motors. The technique was done by removing the valve cover and drilling 2 holes about 5 inches deep in specific spots then tapping and using a 6mm bolt with thread sealer to cap up the renewed circulation path. After this I was able to blow air through all the passages. In the next few days I am going to re install the power head and the new water tube then try using the hose to push water through the power head, if this works, then I will change the water pump insert cartridge, outer plate cartridge, reinstall the new impeller and some new water pump gaskets, put the lower unit back on and hope one of the areas that I have been working on solves the issue. If still no luck then I will pull the head off and get more serious. I have got to the point in this project when it has become me against the outboard and my principals will force me to spend more time and money than it would cost to pick up a replacement. Come hell or high water I plan on getting one more season out of this old Yamaha. I may feel different if the fishing season approaches before my success.

Re: 9.9 Yamaha Water Blockage

Sugo said:

Removed the water tube it is clear and in good shape.

Click to expand...

Sugo said:

I puled out the water tube and while I was pulling it out I was turning it a bit and it broke in half. Once I got the second half of the water tube out I realized it was quite corroded. Maybe my issue?

Click to expand...

These 2 quotes have me wondering what the truth was

Re: 9.9 Yamaha Water Blockage

The first time I removed the water tube it appeared ok from the outside no hoes and I could blow through it without restriction. I drew a conclusion it was in good shape without a close enough inspection. The second time I removed it was when it broke, this allowed me to see the inside of the tube at the spot it broke and it was the inside that was very corroded. This observation made me look more closely at the end of the tube that enters the water pump housing and I realized that there were a few small imperfections making me wonder if it was getting a good tight connection.

Re: 9.9 Yamaha Water Blockage

was there water coming out of some places when you tried hooking water hose to the tube or was there just no water flowing anywhere at all?
Maybe gasket was blocking off the passage

Re: 9.9 Yamaha Water Blockage

So, the water pump is working correctly (replaced all the parts) and I replaced the water tube. (Tested the water pump while the lower unit was off using a drill) Concluded good water flow. Reassembled and gave it a try. Still no luck. A bit of sporadic week flow mostly hot stem. To help me better understand the circulation path in the power head I was hoping someone might have a picture of a Yamaha 9.9 with the head off. Very little water is getting into the gallery where the thermostat is located. So the restriction must be between the bottom of the power head and this thermostat gallery. While the power head was removed I could blow air up the intake hole on the bottom and most of the flow would be coming out the exhaust port and a small percentage up to the thermostat housing and out the pee hose. I don't want to remove the head only to find I still can't access my issue. Any education would aid at this point.

Re: 9.9 Yamaha Water Blockage

I figured the education factor is worth the cost of a new head gasket so I puled the head off. I cleared out most of the passages but I assume my issue is where the water is entering the water jacket. The intake on the bottom of the power head is at lest 5/16 and the passage from the intake hole to the water gallery is only about 1/8. When I blow in the intake with the compressor this 1/8 passage to the water jacket is the only place the air comes out. Are there other passages from the intake that must be blocked or should this 1/8 hole be larger. I don't know the casting layout so I am hesitant on drilling the 1/8 hole larger without an educated opinion. My 2 pictures are the intake on the bottom of the power headand the 1/8 passage to the water jacket.

Re: 9.9 Yamaha Water Blockage

Hi im currently travelling and cant see pictures but i dont think you should be drilling. A smaller hole could be a design feature to increase the waters velocity and help push the water around the water gallery. ive seen many small inlets on outboards which is why disintergating impellers often get stuck at the first squeeze entry.

Re: 9.9 Yamaha Water Blockage

Problem solved. Taking things apart helps understand how they work and makes troubleshooting much easier. Turns out my issue was not the water pump. The blockage was under the exhaust cover. The cooling path: Intake in lower leg, Water pump, water tube, intake bottom crank case, distribution via galleries under exhaust cover, cylinder walls/head/exhaust cooling ports/pee hole, thermostat, back into leg out center of prop. With more education I could have solved this with out removing anything except the exhaust cover plate and at a cost of only 2 gaskets and 30 minutes of labor. I guess I learned much more taking the long route to the solution, It also gave me a good excuse to hang out in the shop with a few pops . Here is a picture. (It's not my picture but it shows the issue I had.)



In an earlier post on this thread I described drilling the exhaust cooling passages via under the valve cover , If you are going to attempt this then be sure to do it when you have the exhaust cover plate off so that you can be sure you don't drill to far and end up drilling into the exhaust port. I also don't recommend trying this until you fully understand the exact path you are attempting to clear.

I just want to follow-up on this post and say it really helped me. I have a 2000 Yamaha F9.9 outboard that seemed to have clogged water passages from PO lack of maintenance, this picture made me open the exhaust cover and it looked very similar to the picture. Cleaned everything well and it is running much better now, thank you so much for posting this.