Muff Flushing Mystery - Any Ideas?

[HMBJack]

I own twin 2006 F250's (TXR's) with 1,585 hours.

All year long, I have been flushing each engine with two garden hoses: 1 with muffs for 8-10 minutes after use + a 2nd hose attached to the garden hose fitting.

Just this past week, my port engine suddenly no longer has the pee water stream! This happens whether on both the muffs + garden hose fitting (engine running) or just the garden hose fitting (engine off and tilted up).

I replaced the water pump impeller (the previous one looked perfect and only had 170 hours on it). I also put a soft wire up the tell tale outlet some 12" - no clogs or restriction. I removed the black tell tale hose off the output fitting that goes through the lower housing and I can blow air up into the tell tale line with no restriction.

With the boat and engine in the water, my engine however has a strong water stream at both idle and at higher RPM's. No overheat alarms.

So... Any ideas what could suddenly cause my pee stream to stop when flushing no matter how I do it?

Might this have something to do with the poppet valve? I can't think of anything else.

Thanks,
Jack

[fairdeal]

I removed the black tell tale hose off the output fitting that goes through the lower housing and I can blow air up into the tell tale line with no restriction.

I'm not following that... "black hose through the lower housing" sounds like the speedometer.
The telltale begins at the base of the block - under the starboard head -
then runs around the bottom of the lower cowling on the port side.

The "poppet" on that engine is a particularly robust device - I would not expect it to "fail" - substantially change.

I would suggest to try "backwashing" -
push the end of the garden hose against the telltale outlet -
force water back into it.
See if that helps.

[holmen78]

I had this exact problem when I stored my boat for the winter. I had salt and debris (very likely corrosion too) between the poppet valve grommet and the aluminum in the head, and that made the grommet to expand inwards making the valve stuck a little to the grommet. Water pressure from hose through muffs with engine running could not move the valve. I have a2002 90hp 2-stroke so the poppet valve design might be very different to yours.

[HMBJack]

Yes - I'm referring to the fitting where the pee stream comes out of on the lower housing of the powerhead (not the lower unit).

I can remove that black hose easy enough and have blown air up into it but nothing changed. It does not feel restricted since I can blow into it.
I like Holmen's suggestion on the Poppet. Might I need to remove and inspect it? If so, I'm not sure how to do this. As I recall, the poppet is on the rear of the head down low and hard to reach.

In theory, if the poppet is stuck or blocked, could this cause the pee stream not to happen on muffs but normal operation while the boat is running in the water?

Here's another detail: I had two High Temperature Alarms go off on this motor while running at high speed (4,300 RPM's). Right after this condition, I experienced the no pee stream while on muffs (but okay with boat in the water). I immediately changed the impeller (earlier was fine).

So perhaps my condition points to a stuck or faulty poppet?
If so - would a good water backflush fix this?
Or should I remove and inspect the poppet?

[fairdeal]

the "poppet" ,when open, allows "an additional path" for water to flow, just below the base of the block

so if pressure is being supplied by the water pump (as in normal running)
some water can "escape" before it gets to the block

going the other way - supplying water to the garden hose flusher - perhaps it could be a factor
(although I think, a stretch)

anyway - you'll need to remove the aprons and that funny little sternmost cover :



then there is a 10mm (head) bolt holding down a little clamp -
and finally unscrew the unit with a BIG wrench (or channellocks)

[fairdeal]

link to video of "testing:

https://vimeo.com/294780454

[HMBJack]

Thank you Fairdeal! Very useful. I will report back after I inspect the poppet...

[holmen78]

Funny, that black plastic valve looks exactly like the one on my old 2-smoker.

[HMBJack]

Well... I just got back from the boat.

Removed the Poppet Valve and inspected it. Clean as a whistle and functioning like new.

I now know what my issue is not: It's not the Impeller and it's not the Poppet valve.

And I installed new T-Stats in April of this year so I don't think the lack of a pee stream on muffs is that.

Any other theories? Or should I ignore this now since the engine operates and pees just fine while in the water?

[fairdeal]

there is nothing odd per se about not seeing a telltale when flushing, but fine when running in the water -
that's normal for many people

Yes, so long as it has a telltale in "real use", that's what's really important.

what's odd in your case is, it's a recent development.
So something has changed.

Either in your water supply pressure/plumbing/hose -
or within the engine.

personally, it would drive me to investigate further.
I know you said you blew air back into the telltale -
I repeat my suggestion to do that with water; just press the end of the running hose against it.

remember, that telltale stream is a circuitous path - in and out of the fuel cooler and reg/rectifier
air can find its way through an occlusion far easier than water

[99yam40]

just remember when you have no flow the fuel cooler and rectifier are not getting the cooling it should have.

was there a motor back some time ago that had a problem with flow or maybe over heating of fuel that they found there was a tee fitting that was plugged going back into the lower part of block?

but think it was not a big F motor. maybe a 60, but I could be way off on that

[HMBJack]

Thanks guys. I'll keep trying different things.

I will do the backflush thing with water up into the pee hole tube next. That could break loose a piece of seaweed or something which may be blocking it upstream somewhere.

[99yam40]

Try hooking up the hose to power head flush and turn on the water so when you blow air or water up the TT maybe it will be pushed out somewhere else and not come right back to plug things up again.
but as he said some others have said they have trouble getting large motors to pee when on flushers

[99yam40]

thinking more about the other thread I mentioned, I believe it was a f60 that had TT water coming out when running, but did not have flow thru the fuel cooler.
so it should not have anything to do with a problem like this F250

[pstephens46]

Try hooking up the hose to power head flush and turn on the water so when you blow air or water up the TT maybe it will be pushed out somewhere else and not come right back to plug things up again.
but as he said some others have said they have trouble getting large motors to pee when on flushers

Hook garden hose directly to water tube with lower off. Not running, should be enough water to pee. Unless your water pressure really is pathetic. Should pee easily with two hoses,
on on muffs and other to flush fitting.