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Author Topic:   Yamaha 90 Water Pump Replacement

btb posted 07-30-2009 10:38 PM ET (US)
The saga continues:
I replaced the water pump impeller and the other contents of the water pump kit box (gaskets, a plate and the impeller), and put everything back together.
I ran the motor on the muffs - I ran it with the ignition off, just on the starter motor for a bit, then ran the motor for a few seconds and - no water appeared to be being pumped - nothing came out of the telltale.
I took the lower unit off again, double checked everything which all seemed ok, put it all back together again and this time ran it only on the starter motor with the plugs removed and still nothing - no water at the tell tale. I put the motor in a trash can full of water and still nothing.
So I took the whole thing apart again, disassembled the water pump, wondering if a gasket was improperly cut or something was blocking water ingress into the pump, but no, everything looked good. So I am at a loss as to what might be wrong.
Questions: 1) what does the Pilot tube do - the only thing I did not do was reconnect the pilot tube. Can that cause no water to be pumped? 2) The Seloc manual says the drive shaft oil seals must be replaced if the oil seal carrier is removed: I did remove it to replace the lower gasket - must I now replace the two oil seals?
Any idea why this thing is not pumping water? I know the waterways in the motor are clear as I ran Salt Away through it all on a fountain pump.
Help! Perplexed.
Bill, San Diego
Phil T posted 07-30-2009 10:54 PM ET (US)
Bill -
If you have a classic Yamaha 90 hp outboard (inline 3 cylinder, 2 stroke) you hook up the muffs to the lower vents, turn on the hose 3/4 and then start the motor (with the plugs) and let it idle. The water should exit the tell tale hose (starboard side) in 10-15, maybe even 20 seconds after the motor has been running. It is not instantaneous.
The hose that feeds the speedometer, if not hooked up should be plugged. Will not affect the tell tale.
Report back before doing anything else.
btb posted 07-30-2009 10:59 PM ET (US)
Hi Phil. The first time I hooked up the muffs, had the tap nice and open, lots of water going everywhere, i.e lots of water pressure at the muffs. I spun the motor for 30 seconds or more on the starter only, then ran the motor at idle for 15 or 20 seconds.
The second time I did all that, but only spun the motor on the start, but with the spark plugs removed.
After I have been fishing, I flush it at home on the muffs, and the tell tale starts peeing pretty soon into the process, say after 10 seconds of idling.
btb posted 07-30-2009 11:16 PM ET (US)
Hi again Phil. OK, I see where you may be going with this. Even with the plugs out, the starter may not spin the motor as fast as the motor idling. Maybe I switched it off too soon? Any idea if just spinning the motor on the starter with the plugs out will push water through the system? That was my assumption - but maybe I am wrong.
Bill
btb posted 07-30-2009 11:28 PM ET (US)
OK, been thinking about this some more. I didn't run a stopwatch on any of these tests of course, and I am thinking I switched the motor off more like after say 8 seconds. I doubt I ran it for anything like 20 seconds...
I DID spin the motor on the starter without any sparkplugs for at least a minute - still no water at the tell tale, but maybe that doesn't spin it fast enough to push enough water round the system. I am guessing the water pump is pretty inefficient and weak...even when brand new.
Bill
Irish Hooker posted 07-30-2009 11:56 PM ET (US)
On my 90's, one starts peeing quickly, like 10-15 secs. and the other takes 30+ secs. I did the exact same thing the first time changing the pump. Turned out I didn't let it run long enough.
IH
Tohsgib posted 07-31-2009 11:57 AM ET (US)
Running it for 20-30 seconds with no water is not going to hurt the engine. If impeller was put in backwards it might take some time to reverse it?
btb posted 07-31-2009 12:02 PM ET (US)
I double and triple checked everything - the impeller is definitely in the right way, all the water-flow holes in the gaskets are right, the impeller is definitely turning with the drive shaft - the water tube has no option but to mate with the water pump housing (there is no way to check that this connection is made right, so I was a bit reticent on the first test to run the motor very long But now I have determined that the water tube HAS to connect with the water pump body) .
I need to let it run longer, is what it sounds like... I guess just spinning the engine on the starter motor with the plugs out still isn't fast enough to make it work...???
Bill
Phil T posted 07-31-2009 01:46 PM ET (US)
The engine must be running at idle. Don't mess with the turning over without plugs. Just run the engine on the muffs.
btb posted 07-31-2009 01:48 PM ET (US)
OK, the consensus is in: run it longer. Will do...
btb posted 07-31-2009 03:36 PM ET (US)
Mere words are inadequate to describe the beauty of that powerful, confident stream of crystal clear cooling water flowing strongly from my tell tale. I think the stream started well before any real amount of seconds passed.
So everything is ok.
Thanks to all for their help, suggestions etc etc.
Onwards & Upwards!
Thanks! Bill
Ablewis posted 08-02-2009 10:21 PM ET (US)
I didn't want to highjack Bill's thread, but now that this is solved, I would like to know if the rebuild of the water pump that Bill described would be advisable for any motor of this vintage? I too have a classic Yamaha 90 hp outboard (inline 3 cylinder, 2 stroke). The flow from the tell tale is strong, but I'm thinking this might be good insurance? How much time does this repair take (I have never removed the lower unit)? Also, nobody answered Bill's question about the seals, "The Seloc manual says the drive shaft oil seals must be replaced if the oil seal carrier is removed: I did remove it to replace the lower gasket - must I now replace the two oil seals?"
Andy
btb posted 08-03-2009 10:02 AM ET (US)
Andy, I would say if nothing goes wrong the whole thing should take a couple of hours.
Surprisingly the lower unit/gearcase comes off pretty easily: separate the "pilot" tube (pitot tube?, undo the 5 bolts, and out it comes. The best way is to have the engine tilted all the way up. The drive shaft is quite long. You may want to have a helper the first time around to help you with the weight and overall cumbersome nature of the thing.
I rigged up a stand for the lower unit with a couple of saw horses and a couple of cross bits of wood to support it.
Get the kit from Yamaha. I would also get the two oil seals and the "grommet" for the water tube - these things should really come in the water pump kit.
Obviously I hit a major snag when that bolt sheared off. Another less-than-easy thing was to remove the woodruff key but in the end it came out when I heated that piece of the shaft with a heat gun and then touched an ice cube on the key itself, while my buddy levered it out. On fiddling with the woordruff key later, a small screwdriver can be inserted into the keyway at the top, behind the woodruff key, for leverage. But on mine it definitely needed the heat/cold.
Undo the 4 bolts and lift the cover off. Next remove the impeller, then the woodruff key then the plate and a gasket. Pending the answer to the question about the oil seals, and whether you have the replacement oil seals, remove or don't remove the grey pump body and the last gasket.
Use plenty of waterproof grease on everything.
While I had my lower unit off, I followed a suggestion on another thread here and used some salt-away in a bucket with a fountain pump and cycles the water through the engine using the pump connected to the water tube - maybe that did some good - who knows.
BTW, as discovered here, on our 90's there is nothing to undo on the gear selection rod, its splined.
Good luck!

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Author	Topic: Yamaha 90 Water Pump Replacement
btb	posted 07-30-2009 10:38 PM ET (US) The saga continues: I replaced the water pump impeller and the other contents of the water pump kit box (gaskets, a plate and the impeller), and put everything back together. I ran the motor on the muffs - I ran it with the ignition off, just on the starter motor for a bit, then ran the motor for a few seconds and - no water appeared to be being pumped - nothing came out of the telltale. I took the lower unit off again, double checked everything which all seemed ok, put it all back together again and this time ran it only on the starter motor with the plugs removed and still nothing - no water at the tell tale. I put the motor in a trash can full of water and still nothing. So I took the whole thing apart again, disassembled the water pump, wondering if a gasket was improperly cut or something was blocking water ingress into the pump, but no, everything looked good. So I am at a loss as to what might be wrong. Questions: 1) what does the Pilot tube do - the only thing I did not do was reconnect the pilot tube. Can that cause no water to be pumped? 2) The Seloc manual says the drive shaft oil seals must be replaced if the oil seal carrier is removed: I did remove it to replace the lower gasket - must I now replace the two oil seals? Any idea why this thing is not pumping water? I know the waterways in the motor are clear as I ran Salt Away through it all on a fountain pump. Help! Perplexed. Bill, San Diego
Phil T	posted 07-30-2009 10:54 PM ET (US) Bill - If you have a classic Yamaha 90 hp outboard (inline 3 cylinder, 2 stroke) you hook up the muffs to the lower vents, turn on the hose 3/4 and then start the motor (with the plugs) and let it idle. The water should exit the tell tale hose (starboard side) in 10-15, maybe even 20 seconds after the motor has been running. It is not instantaneous. The hose that feeds the speedometer, if not hooked up should be plugged. Will not affect the tell tale. Report back before doing anything else.
btb	posted 07-30-2009 10:59 PM ET (US) Hi Phil. The first time I hooked up the muffs, had the tap nice and open, lots of water going everywhere, i.e lots of water pressure at the muffs. I spun the motor for 30 seconds or more on the starter only, then ran the motor at idle for 15 or 20 seconds. The second time I did all that, but only spun the motor on the start, but with the spark plugs removed. After I have been fishing, I flush it at home on the muffs, and the tell tale starts peeing pretty soon into the process, say after 10 seconds of idling.
btb	posted 07-30-2009 11:16 PM ET (US) Hi again Phil. OK, I see where you may be going with this. Even with the plugs out, the starter may not spin the motor as fast as the motor idling. Maybe I switched it off too soon? Any idea if just spinning the motor on the starter with the plugs out will push water through the system? That was my assumption - but maybe I am wrong. Bill
btb	posted 07-30-2009 11:28 PM ET (US) OK, been thinking about this some more. I didn't run a stopwatch on any of these tests of course, and I am thinking I switched the motor off more like after say 8 seconds. I doubt I ran it for anything like 20 seconds... I DID spin the motor on the starter without any sparkplugs for at least a minute - still no water at the tell tale, but maybe that doesn't spin it fast enough to push enough water round the system. I am guessing the water pump is pretty inefficient and weak...even when brand new. Bill
Irish Hooker	posted 07-30-2009 11:56 PM ET (US) On my 90's, one starts peeing quickly, like 10-15 secs. and the other takes 30+ secs. I did the exact same thing the first time changing the pump. Turned out I didn't let it run long enough. IH
Tohsgib	posted 07-31-2009 11:57 AM ET (US) Running it for 20-30 seconds with no water is not going to hurt the engine. If impeller was put in backwards it might take some time to reverse it?
btb	posted 07-31-2009 12:02 PM ET (US) I double and triple checked everything - the impeller is definitely in the right way, all the water-flow holes in the gaskets are right, the impeller is definitely turning with the drive shaft - the water tube has no option but to mate with the water pump housing (there is no way to check that this connection is made right, so I was a bit reticent on the first test to run the motor very long But now I have determined that the water tube HAS to connect with the water pump body) . I need to let it run longer, is what it sounds like... I guess just spinning the engine on the starter motor with the plugs out still isn't fast enough to make it work...??? Bill
Phil T	posted 07-31-2009 01:46 PM ET (US) The engine must be running at idle. Don't mess with the turning over without plugs. Just run the engine on the muffs.
btb	posted 07-31-2009 01:48 PM ET (US) OK, the consensus is in: run it longer. Will do...
btb	posted 07-31-2009 03:36 PM ET (US) Mere words are inadequate to describe the beauty of that powerful, confident stream of crystal clear cooling water flowing strongly from my tell tale. I think the stream started well before any real amount of seconds passed. So everything is ok. Thanks to all for their help, suggestions etc etc. Onwards & Upwards! Thanks! Bill
Ablewis	posted 08-02-2009 10:21 PM ET (US) I didn't want to highjack Bill's thread, but now that this is solved, I would like to know if the rebuild of the water pump that Bill described would be advisable for any motor of this vintage? I too have a classic Yamaha 90 hp outboard (inline 3 cylinder, 2 stroke). The flow from the tell tale is strong, but I'm thinking this might be good insurance? How much time does this repair take (I have never removed the lower unit)? Also, nobody answered Bill's question about the seals, "The Seloc manual says the drive shaft oil seals must be replaced if the oil seal carrier is removed: I did remove it to replace the lower gasket - must I now replace the two oil seals?" Andy
btb	posted 08-03-2009 10:02 AM ET (US) Andy, I would say if nothing goes wrong the whole thing should take a couple of hours. Surprisingly the lower unit/gearcase comes off pretty easily: separate the "pilot" tube (pitot tube?, undo the 5 bolts, and out it comes. The best way is to have the engine tilted all the way up. The drive shaft is quite long. You may want to have a helper the first time around to help you with the weight and overall cumbersome nature of the thing. I rigged up a stand for the lower unit with a couple of saw horses and a couple of cross bits of wood to support it. Get the kit from Yamaha. I would also get the two oil seals and the "grommet" for the water tube - these things should really come in the water pump kit. Obviously I hit a major snag when that bolt sheared off. Another less-than-easy thing was to remove the woodruff key but in the end it came out when I heated that piece of the shaft with a heat gun and then touched an ice cube on the key itself, while my buddy levered it out. On fiddling with the woordruff key later, a small screwdriver can be inserted into the keyway at the top, behind the woodruff key, for leverage. But on mine it definitely needed the heat/cold. Undo the 4 bolts and lift the cover off. Next remove the impeller, then the woodruff key then the plate and a gasket. Pending the answer to the question about the oil seals, and whether you have the replacement oil seals, remove or don't remove the grey pump body and the last gasket. Use plenty of waterproof grease on everything. While I had my lower unit off, I followed a suggestion on another thread here and used some salt-away in a bucket with a fountain pump and cycles the water through the engine using the pump connected to the water tube - maybe that did some good - who knows. BTW, as discovered here, on our 90's there is nothing to undo on the gear selection rod, its splined. Good luck!