Running Jet Pump In Trash...water Pump Problems?

[LittleRedFisherman]

I've heard for years about how you'll hate a jet when the water get trashy, I've never had a problem with that till this weekend on the Little Red River. I had to stop about 10 times in two miles to clean off my intake. Something must have sucked up in there, because it wasn't showing that it was pumping water anymore to cool the engine. It' a 25 Mercury Jet, and was wondering where I should start. Was hoping it's just the indicator, and am going to try to blow air or water back down that tube. I ran the motor some after that happened, and it didn't seem to be overheating. My duck hunting buddies used to have these problems with there mercurys running them in the woods, my Evinrude never had that problem, so I think it's a Mercury thing, and suggestions appreciated if there's something more I need to do to fix it!!

[fishinwrench]

Take a piece of wire (or weed-eater cord works great) and ram it up your pee hole.

If that doesn't clear it out and make it start pissing again you'll have to pull the thermostat housing and verify that you are getting substantial water pressure to the top of the powerhead.

If there is little to no water gushing out let me know and I'll coach you through the proper steps to refresh/repair the cooling system.

[LittleRedFisherman]

Take a piece of wire (or weed-eater cord works great) and ram it up your pee hole.

If that doesn't clear it out and make it start pissing again you'll have to pull the thermostat housing and verify that you are getting substantial water pressure to the top of the powerhead.

If there is little to no water gushing out let me know and I'll coach you through the proper steps to refresh/repair the cooling system.

Thanks fishinwrench, I was going to work on it today, but been a little under the weather as our household had caught the bug... One thing I noticed when I first started it, it would piss out for like a second or two. Got me to thinking it might be stopped up down deeper in the system. What about blowing air from an air compressor down through it?

[fishinwrench]

What about blowing air from an air compressor down through it?

Well, you can try all kinds of things but a systematic approach will get you to the heart of the problem more efficiently, and assure that there isn't more than one issue (like a worn out water pump, a partially melted water tube grommet, AND some debris clogging a cooling passageway).

Many times there are multiple causes involved with a single symptom....ESPECIALLY when dealing with jet pump equipped outboard cooling systems.

[LittleRedFisherman]

Fishinwrench? I blew around on some of the pipes the other day, and took it fishing today. When I first started it, it was pumping perfect, after about 5 minutes of running, it was pissing about half a stream. After about 10 minutes, nothing was coming out the indicator, it seemed to be clean. However, the engine to me, didn't show any sign of running hot? Where do I need to go from here, because I didn't have to run the motor no longer than 5 minutes at time today, i'm afraid to run it much longer till I know for sure it cooling properly.

[fishinwrench]

It sounds like you have some debris in the cooling passages of the block.

Pull the thermostat housing cover, remove the thermostat and spring and run it for a minute in clean water. It should blow water like crazy out of the thermo recess, and hopefully clear out most (or all) of the crap that might be blocking the narrow water passage.

If it just barely pushes water out then you'll need to drop the jet pump and inspect the water pump impeller and housing. Inspect the rubber water tube grommet in the housing, and look below the pump plate to be sure there isn't a wad of debris collected there.

If all looks good go ahead and install a fresh impeller and blow about 120psi compressed air directly up the water tube while taking note of the amount of air (and any debris) coming out of the thermostat hole. If there's any debris it will look like the crap on the bottom of your lawn mower deck....clumps of wet grass and wood debris).

Only blow from the water tube UP, don't try to force any crud back down the tube....it won't come out that way.

If it seems like you're not getting it all cleared out then the powerhead will have to be pulled so that all the cooling passages can be easily flushed out.

[LittleRedFisherman]

Ok, thanks a lot FishinWrench!! One more question, where is the thermostat housing on the 25 merc at? Sorry, i'm pretty mechanical, but i'm geared to work on John Deere and Internationals..lol

Here's a pic I took the other day, where do I go from here.. You see where I took the hose off that blows water to the indicator, it was clean as a whistle.

[fishinwrench]

Oh Lord ! Didn't realize we were dealing with a 4S until I saw the pic.

Port side of the block (above and behind the oil filter)

The thermo cover is #14 on this diagram.

http://www.crowleymarine.com/mercury-outboard/parts/11848_130.cfm

Jesus, what a rediculis amount of s#!t just to get 25 horses <shakes head & rolls eyes>

Ok, 4-stroke rant kept as short and PC as possible.

[LittleRedFisherman]

Your preaching to the choir I guess, it has run good for me, but i'm an Etec man myself. When I used to duck hunt a lot, my Merc buddies dealt with this issue a lot it seemed running though the woods and trash. My Etec has never... ever. give a minutes trouble. It's weep hole is the size of my thumb, it's like a trash pump...lol.

Anyhow, thanks, i'll look this over and see where i'm at, if it seems over my head, probably run to to Doniphan and let Fred look at it....

Edit....After looking at it, I think I got this, thanks again for the info Wrench!! You may have to go fishing with me someday!!

[fishinwrench]

No Prob. And I'd love to.