Outboard Tell Tale Stream

T

Tortuga

New member
Good evening all, my 2008 Yamaha F90 is not producing any flow through the tell tale stream out the back of the engine. It doesn’t seem to be overheating and has no alarm sounding or obvious heat. I cleared the accessible water tubes and replaced the impeller and case. Still no luck.

I’m considering compressed air through the water tubes, but don’t want to damage anything. Any concern there?

If that fails my next step is to remove the intake manifold, drop the lower unit, and gently inject water into the intake tube (that goes into the water pump housing) and track the water flow in and out of the engine and relevant components.

Any other suggestions? Many thanks!

Matt
 
Was the engine sitting in the water, or running on muffs when the telltale would not work?

What rpm was the motor at when no telltale stream?

If you can reach it easily, a quick check of the poppet valve may lead you to the problem. If it is stuck at low rpm, there may not be enough pressure to work the telltale.
 
I don't put a lot of stock in what that little stream is doing as they get clogged. It probably has a rubber line running to a port to the side of the powerhead. The first thing I have always done is run a piece of welding wire through it. Lots and lots of times, there is nothing wrong anywhere else as there was just an obstruction on the last leg.
 
Thanks for this good advice — way better than stripping down the engine to chase it. I was on muffs at about 3000 rpm and no luck. I’ll drop in the marina and see if that gives it better pickup. I’ll also try the compressed air and weed whacker string.

Any idea how long it takes for the overheat alarm to sound if it actually has a water clog? I only experienced that once while running into deep chop with my engine trimmed high — :shock: !
 
Tortuga":1kemt0ni said:
... Any idea how long it takes for the overheat alarm to sound if it actually has a water clog? I only experienced that once while running into deep chop with my engine trimmed high — :shock: !
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Depends on how clogged it is and how hard you run the engine. You could try cranking the engine with the thermostat housing open and see if you have water coming up there.
 
This might be a great time to check your thermostats as well as clearing the telltale tube. You'll get an idea of how much salt deposits built up inside the head. You may also want to run some Saltaway thru the engine after being in saltwater.
 
I routinely have the same problem with my Yamaha 80’s. Sometimes it’s a tiny spider nest (web), but mostly it’s bits of debris that get clogged at the little plastic exit port of the housing (the tell-tail pee port). That port connects to a small rubber tubing that connects to the engine. Don’t remove the port, it has a purpose, I believe it increases the backpressure of that stream to provide proper flow and pressure to the head.

Go to your local smoke shop (I know it’s weird going there when you don’t smoke) and get a pack of pipe cleaners (they’re about 5-6” long). While your engine is idling in the water, reach around and feed that pipe cleaner up that pee outlet port several inches then quickly pull it out. Sometimes it takes two times to get it to flow well. Works for me every time.

Good luck.
 
Just an update — I changed out the impeller and pump housing (which was easier than I expected) and swapped out the thermostat. Also very quick and easy. Then I unplugged the flushing tubes that were accessible and put some compressed air through. Dropped it in the marina and ran it. Pretty modest stream but getting flow. Ran the boat today for a couple hours in the chop — no heat issues, but limited water flow. Then at wash down when I was flushing the engine had a total block — but cleared the line just above the little nozzle — a salt crystal about 1 mm. Cleared that and got a strong flow. Next step will be to use Salt Away.

Question that came up: I disconnected the Yamaha flush intake (that little hose connector to flush engine) when I was running the engine in the harbor and it had a very strong flow. I assume that the water flow is up from the lower unit through the water pump into the engine block and out of the block through the tubes to the tell tale? In other words, if the water pressure at the flush intake is strong, that indicates that the water pump is working well and that water is moving through the engine? Does that make sense?

Thanks for any thoughts!

Matt
 
Yes Matt that is correct. Water is inducted thru the lower unit by the water pump impeller and is forced upward thru the entire engine head and is eventually discharged thru the exhaust system. The tell tale stream is only a small part of the cooling water discharged.
 
Schuster":gal57o7x said:
Yes Matt that is correct. Water is inducted thru the lower unit by the water pump impeller and is forced upward thru the entire engine head and is eventually discharged thru the exhaust system. The tell tale stream is only a small part of the cooling water discharged.
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The tell-tale stream on Honda engines (at least on mine) does not go through the engine block. Just shows that the pump is pumping.
 
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