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new waterpump blue smoke/exhaust out tell tale

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BACKWOODS BREAM BUSTER

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Hello everyone...im new to the forum and hoping i can find some help here...the search option did not yield any help so here it goes...1980s mercury 50hp 2 stroke thunderbolt ignition.replaced waterpump impeller and housing plus all seals and gaskets as a kit with impeller turned in correct direction with a little grease in housing and water pick up tube seated correctly.noticed old impeller chewed up in pieces after removal.took it out for testing at the dock right after replacement and fresh gas...started it up, but it took abt a minute of operation before any stream from tell tale but was good and strong once going and worked flawlessly at low idle and wot all in a total time of abt 20-30 mins.pulled her back home and was confident everything was fine for the next day of fishing...well me and the buddies docked again and of coarse i checked to see if she was still pissing just for insurance only to see blue smoke/exhaust coming out tell tale after a minute of operation again...shut it off immediatly and checked for clog in the piss tube...no clog..put her back in...same thing again...loaded up and hauled ass back home mad of coarse.ok...pulled lower unit off again to check waterpump assembly again and noticed this grayish water oil mixture along the drive shaft and around the pump housing.Removed he pump again and the top gasket under the housing was broken...replaced it...put it all back together same as above and was confident that was the problem...filled up a big tank i had with water and sat the merc inside...started up fine of coarse but only a dripple from tell tale plus the same blue smoke/exhaust...frustrated i pulled he lower unit again and thought ok maybe its clogged somewhere in the passages.rigged up the water hose to shoot up the water pick up tube into the motor bc i dont own an air compresser and after about a sec or so there was strong backpressure but still no stream of water out tell tale.so i used he hose again but this time straight into the tell tale piss hole and water went in easily and back out the other end but not out the water pick up tube seemed like out the exhaust tube or around it i also noticed water coming out around the spark plugs so water jacket seal may be busted but it did not do that with the hose up the other end...so of coarse i thought i unclogged whatever was there...put her back together and lowered the merc back in the water tank again with enough water to cover the cavitation plate...fired her up with a better stream but still not adequate enough and noticed the water was steaming as it was coming out also..so i shut it of and let it cooled abt an hr and started her up again...NO WATER AT ALL jus blue smoke/exhaust...said the hell with another lower unit tear down...i never did a compression test because the old merc fires right up so i figure it doesnt need it...id hate to take it to the shop and pay more to fix it than its worth especially if its only a simple problem that i cant seem to booger out...sorry for the long story but i figure much detail is needed...i think i can send pics if needed...PLZ sombody shine some light on the situation so i can get back to the backwoods and bust some more bream..THANKS
 
I'm having a really hard time reading this because it's such a huge single paragraph - but here goes..

I think your problem would be best described by intermittent stream of water out of the tell tale? And occasionally when this happens you see smoke instead?

Assuming I got that right. The smoke could be steam or could be exhaust, neither would be really abnormal - since the exhaust & cooling are connected together as they escape I think exhaust could momentarily find it's way there if there isn't water to take up the space.

I haven't tried it recently but with a garden hose you should be able to generate plenty of pressure to get water out of the tell tale. That test tells me most likely you got a clog.

Just for kicks though - double check to make sure the water pump impeller has been correctly mated with the key, ie so it's not spinning on the driveshaft. That is probably all set just mentioning it.

If that all seems fine and your testing indicates a clog - especially since you found the original waterpump impeller had chunks missing, most likely your tube and/or the area under the powerhead are clogged by the chunks.. I do not remember if the tube can be removed on that engine - on some it's just pressed in with a grommet and you can pull it out - that could save you some work if the tube is just clogged - most likely though if chunks made it into the tube they made their way up and out and are stuck under the powerhead - in which case you will need to pull the powerhead off. This is not a big deal provided the bolts come loose.

Jon
 
Thanks leaky for the reply...greatly appreciated...i am pretty sure it is clogged somewhere under the powerhead especially now since uv confirmed it...the water tube is removable on this motor...do i have to remove the mid section in order to remove the powerhead...i thought it was possible to see into the cooling system behind the exhaust plate but two bolts in tight spots prevented that from happening unless powerhead removal...also in order to put it back together would i need a torgue wrench...thanks again for your help
 
thanks racer one...what would the exhaust and exhaust tube have to do with the water pump and cooling system...not questioning ur knowledge but i jus like to increase my know how lol...would i be able to remove the exhaust tube and put it back on easily without a gasket or seal...do u think my problem would cause me to remove powerhead...thanks
 
BACKWOODS BREAM BUSTER said:
Did i lose all my help????
Click to expand...

I think he is saying, since the cooling water escapes via the exhaust tube, if that was clogged you could see such a problem.

Myself, within about an hour of noticing this problem I'd be shining a flashlight up there and if nothing turned up I'd be pulling the powerhead off.

Unless you've got a saltwater engine that spent it's time on a mooring and everything is really stuck, pulling the powerhead is not a big deal.

Just take your time - start with a 1/4 inch ratchet and find just the right size extension and sockets, see if things come apart easy. If they do not round up a MAP gas torch and either use air tools or hold the tools squarely and tap on them with a hammer to shock them out. Everything should come pretty easy.

Take a look around and disconnect what is needed to make the powerhead come free (ie possibly just the fuel line, battery cables, shift/throttle cable, and control harness).

You probably do not have a lifting eye, see if there are a couple open set of tapped threads on top of the powerhead - take a piece of metal and make yourself something to hook onto so you can pull it straight up with a chainfall or come-along. The powerhead on this engine is a peanut so one person could even easily lift it right off, it just is more difficult to do that with all the rigging in place.

Get it off and take a look. Hopefully it's real obvious - specifically in Merc's a few times I've found a piece of the impeller in the chamber under the powerhead.

Jon
 
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