'94 Mercury, 40 hp, two stroke: How to ferret out impeller hunks.

[halmc]

Here's the chronology of my friend's above-referenced Mercury:

1. Once running fine engine sets up during 18 month lake drawdown.

2. Owner (a friend, no kidding) celebrates lake replentishment with a cruise, engine almost ceases to pee, steams, shuts off.

3. Starts only after cool down: same scenario as #2 after warmup.

4. Engine delivered to shop full of "professionals" Impeller replaced. Old impeller shows major hunks missing.

5. $365 later owner takes boat back on to lake: engine almost ceases to pee, steams, shuts off.

6. "professionals" are swamped this time of year, can't get to it for weeks.

7. Engine lands up in my shop.

8. I will, of course, go behind "professionals" to see if/what they buggered up by my QUESTION IS THIS:

9. QUESTION: on the seemingly safe assumption that some of the impeller hunks are lodged here and there in the egine's cooling passages, is there any easy way to flush 'em the heck out, or must every passage be inspected?

PS: this has always been a fresh water engine, its inpection plates look as if they would remove easily.

PPS: Any measure taken against the "professionals" would take longer than fixing the engine, so may we please skip that discussion.

 

[Bosunsmate]

Re: '94 Mercury, 40 hp, two stroke: How to ferret out impeller hunks.

I remove watercover gaskets/exhaust gaskets and backflush through all ports with LU dropped and a sieve underneath to see what comes out.
Ive forgotten what they a called but those cotton things on wires are handy to thread down channels too.
I wonder if it was tried in a barrel after impeller was installed
Check thermostat for blockage/opening too

 

[halmc]

Re: '94 Mercury, 40 hp, two stroke: How to ferret out impeller hunks.

I remove watercover gaskets/exhaust gaskets and backflush through all ports with LU dropped and a sieve underneath to see what comes out.
Ive forgotten what they a called but those cotton things on wires are handy to thread down channels too.
I wonder if it was tried in a barrel after impeller was installed
Check thermostat for blockage/opening too

Thank you, boats. Pipe cleaners is the word you're looking for I'll bet. How about a second question: is it plausible to think that some of the impeller is still in the engine? I mean does that really happen, cuz I have no appetite for taking all that stuff off -- but of course I will, if I must.

 

[Bosunsmate]

Re: '94 Mercury, 40 hp, two stroke: How to ferret out impeller hunks.

Pipe cleaners- yes thats right on.
To answer that question it is plausible. Ive seen them sitting just where the intake tube narrows at powerhead adaptor base
Does it not pee right from start up?

 

[halmc]

Re: '94 Mercury, 40 hp, two stroke: How to ferret out impeller hunks.

Pipe cleaners- yes thats right on.
To answer that question it is plausible. Ive seen them sitting just where the intake tube narrows at powerhead adaptor base
Does it not pee right from start up?

Won't know that until this AM when I plan to observe it on the boat and in the lake, tho I probably won't loose it from its trailer. The owner says that it initially squirted "pretty good" but slacked off.

Maybe a loose hunk lies dormant until start-up, then lodges in a tube narrowing, or other place?

Anyhow, knowing that you've seen this actually happen is a huge help. I'll remove the LU today (after a brief offering to the fresh water gods) and see whassup. I'm not confident that the new impeller was installed correctly, and wanna check that out first, then comes the water passages.

Your help is much appreciated!

 

[halmc]

Re: '94 Mercury, 40 hp, two stroke: How to ferret out impeller hunks.

Turns out this thread should have been entitled, "How to ferret out dirt dobber homesteads". The short story is dirt/mud dobbers built a nest in the tell-tale hose that prevented any flow of water through the engine. The long story would inlcude a lengthy chapter about the accumulation of water in the fuel tank which got pumped into the carburetors, which in turn, delayed the exploration of the cooling issue for the length of time it took to free the carbs and their intricate little passages of water -- and to cuss some. No -- uss lots.

No good deed goes unpunished.

PS: wasn't it clever of Mercury to use locktite on the carburetor nuts!

PPS: a lesson I seem to relearn with every motor that comes and goes is to never trust the owner to relate symptoms to you. Observe them yourself, no matter what.