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Murphy's Law at it Again...Cooling Problem

7K views 41 replies 11 participants last post by  Un-shore 
#1 ·
Okay well I just did the water pump last night and took it out today. There is something blocking the system! The alarm went off twice today, once before I knew there was an issue and once after I thought it was solved.

It'll pee great at idle but when I get up to higher RPM, it'll plug up. Then I'll reduce RPM back to idle and it's still plugged up. The problem was first noticed after scraping through some of the bottom (negative low today) at idle and it got plugged up.

I tried the high test line trick and it temporarily worked but that didn't last long.

I got back home and pulled the lower unit. I then vacuumed, back-flushed, and anything I could think of to the LU and water pump. No help! It keeps clogging for some reason...

So...was are my options here?
 
#3 ·
Stop running it in the mud and grass
Too true SW, too true... ;)

RK, you're going to have to flush out the block.
Possibly by removing the thermostat, or the exhaust cover.
You've pushed something up into the passages,
now you've got to figure out which one is blocked.
I've used compressed air, the vacuum cleaner
pipe cleaners, weedwhacker line, and parts removal
to find and eliminate clogs. Caused not by hitting bottom,
but by running through sargassum patches offshore,
and getting chunks sucked up into the outboard.
If it's not one thing, it's another.
 
#5 ·
So I thoroughly examined the system of water flow through the block. Why did I get a 4 stroke again? One of the things I miss about the 2 stroke...SIMPLICITY!

It comes through the block (pending the thermostat), enters the "fuel cooler", and then out of the motor. ALL of these areas are very difficult to access and would probably require some major disassembling...or baby hands...

But, from what I saw, there is no reason why the back flush shouldn't have knocked it out...apparently my judgment doesn't mean anything, though.

I guess this is a project for tomorrow...if anyone wants to come over and help, let me know ;D

Keep the advice coming...and the "not running through sand/mud" is permanently noted... :mad:
 
#6 ·
So I thoroughly examined the system of water flow through the block.  Why did I get a 4 stroke again?  One of the things I miss about the 2 stroke...SIMPLICITY!

It comes through the block (pending the thermostat), enters the "fuel cooler", and then out of the motor.  ALL of these areas are very difficult to access and would probably require some major disassembling...or baby hands...

But, from what I saw, there is no reason why the back flush shouldn't have knocked it out...apparently my judgment doesn't mean anything, though.

I guess this is a project for tomorrow...if anyone wants to come over and help, let me know  ;D

Keep the advice coming...and the "not running through sand/mud" is permanently noted... :mad:
U keep fugged up everything u use... ;D ;D ;D

U need me to come over or bring the boat over and I can help u out my my time is wayy too tight! ;D ;)
 
#7 ·
Oh I forgot.....

The most common to get clogged up with mud,sand, and weeds is the thermostat.

So before u do anything....just take the thermostat out and then bolt it back in.

Then run the motor with water hose and ear muffs in idle speed.

Let me know how the motor pee without the thermostat.

If it does pee really good then it's the thermostat. If not then it's something else.

Hope this help.
 
#11 ·
I pulled the LU again and took the WP housing off. Everything looked great. Impeller looks as good as the day I took it out of the box...which just happened to be 2 days before :)

I pulled the thermostat and Shop-Vac'd in there...which I'm guessing would include the water jacket. I need to get a new gasket (which no one has, of course, so it has to be ordered) so I can test it.

I also pulled the top off the "fuel cooler" and Shop-Vac'd the passages in there (not the ones containing fuel, of course).

That's all I can think of...I don't know what else I could possibly do.

If this doesn't work, I guess I'll just have to take it in for warranty work. Hopefully they won't notice it's been "tampered" with.
 
#13 ·
RK, you better get a Saint Eligius medallion to attach to that block!
Maybe that'll exorcise the hoodoo that seems to be drawn to you... ;)
Can't hurt...might help... :D

Who's Saint Eligius? The Patron Saint of Mechanics!   :cool:
Hahaha!! I like that idea! I've tried doing things the normal way (i.e. - proper maintenance, etc.) and I'm willing to try anything!

Anyway everything is bolted back up. I put some RTV gasket maker on the thermostat cover temporarily to test it with and without the thermostat in.

I ran it sans thermostat and there was very little water pressure. Which makes sense...

I revved the RPMs up pretty high and nothing seemed to get clogged.

Then I put 'er back in the garage, unbolted everything (again!), cleaned off the thermostat, cleaned off the surfaces, reapplied the gasket maker, and bolted everything back up. Now I'm just waiting for it to dry a good bit before test #2.

Cross your fingers...
 
#14 ·
Did you know that you can cut your own gaskets?
Before gasket kits in a box, it was normal to have a roll of gasket material in the shop.
You simply made what you needed on site, no waiting on shipping or back orders.
I remember tapping gasket shapes directly from car engine parts using a ball peen hammer.

Here's a how to...

http://www.explorerforum.com/forums/showthread.php?t=240437
 
#15 ·
not to make liight of the situation but i think i know more about mercury cooling now than i ever did thanks to the trial and tribulations murphy has endured, good luck getting it squared away dude :)
 
#16 ·
Well I ran the motor with the thermostat and here are some observations I made.

First, I know why the motor started to pee intermittently or quit at high RPM on the hose...the earmuffs would slide around due to vibration! [smiley=1-doh.gif]

Second, I fixed this issue by filling up a big trash can and running the motor in there. Here I was able to get the most realistic depiction of how it would be on the water, anyway.

Unfortunately, it didn't go how I had hoped...the stream is somewhat strong but still sputters and the motor seems to be running hotter than it should. It feels as if it's running hotter than my 2 stroke. I took the RPM up pretty high (probably close to max once on accident) and ran it for 10-15 seconds a couple of times at probably around 1/2 to 3/4 of max. It started to smoke a little but stopped when it idled for a few seconds. I also noticed that the exhaust housing was fairly hot, as well. I don't like how this is looking...

I'm going to call the dealer tomorrow and hope for some "warranty" work. Hopefully they're willing to work with me...can't be affording a big bill right now. :-/
 
#17 ·
keep in mind brother that the water is recirculating so the water going in the motor is continually getting warmer the longer you run it when you run it in a garbage can unless maybe your cycling that water out with fresh cooler stuff :-? :-/
 
#18 ·
keep in mind brother that the water is recirculating so the water going in the motor is continually getting warmer the longer you run it when you run it in a garbage can unless maybe your cycling that water out with fresh cooler stuff :-? :-/
I was. I had the hose going continuously when it was running to keep cool water in there.

Anyone have any other thoughts on what this could be? The issue wasn't present until after I did the water pump job...
 
#20 ·
I'm too tired to typed this...before I was planned about going to econ river today but end up cutting trees at the house in 6am in the morning and went to the zoo for few hours with a family.


Please Please don't trottle up 3/4 turn and that's cause mis firing over reving the motor that's can caused to smoke.

Just leave it to idle to 1/4 throttle when u running at home.

I hope u can take it to the dealer tomorrow and tell them u have warrenty on the motor. Just tell them u want to have them to check out through the motor completely.

Hope everything goes well.....

U need to get back on the water than worry about the motor went wrong all the time....;D.
 
#21 ·
That's no 2 stroke for sure, looking at the parts diagrams on line.
All sorts of cooling passages, complicated, including a pressure grommet.

http://www.boats.net/parts/search/Merc2/Mercury/25%20EFI%20(3%20CYL)(4-STROKE)/0R106999%20&%20Up/Driveshaft%20Housing/parts.html
 
#22 ·
Thank you Brett for reminding me of a "grommet".

There is also a grommet at the top of the intake tube and if you took the tube out you may not have gotten it in properly and that could be pinching things.

Also that grommet is a focal point for corrosion. Use in salt water will cause corrosion to grow behind it and with time grow and squeeze the grommet closed.

Good luck at the dealer.
 
#23 ·
this issue has me wondering now about what part or the cooling system is the "bottle neck"? i have had junk get stuck at the pee hole but never in the engine itself and i have sucked up a lot of mud and trash in my days :-/
 
#24 ·
Most outboards have an intake screen to prevent large particles from getting into the block.
That screen is visible at the water inlet on the lower unit. Holes are about the same size as the whizzer tube.
Impact and vibrations can damage the screen and allow larger particles through. Usually a problem on older motors.
My biggest cooling problems over the years were blocked intakes, improperly installed o-rings or gaskets,
impeller separation from the bushing, stuck thermostats, deposits on internal  passageways caused by heat, salt water, and aluminum blocks.

The silliest reason for overheating I've ever seen, was leaving the flush muffs on, when launching.

Wasn't me! ;D
 
#25 ·
RK, having run one of those in all kinds of temps, (and even back-to-back with the 2-stroke) I can say that they run hotter than the 2-strokes. The pee stream will be hot. At times almost too hot to hold your hand under.

I never had an alarm go off, but it does run hot. I think because of the EFI system. I remember back in my old drag racing days of the early 90's mustangs they ran at 180 degrees from the factory, which is HOT! Something about the emissions....

Anyways, if you're having the alarm go off, it's one of two things: either the thermostat is the wrong temp or possibly even malfunctioning, or you have a clog.

Also, DO NOT take the way it runs on the muffs as being golden. For some reason I've never had luck doing that, and comparing it to how it runs in actual open-water conditions. Good or bad.

Have you tried a piece of weed-eater string in the pee hole? I usually carry a good length of it in every boat is it's stiff enough to get in there and root things out, but very flexible so it'll make the bends.

-T
 
#26 ·
Yeah I learned about rooting out the 'Ol peehole while rocking around in Tampa bay in the old classic ...

Motor was fine ... gunk in the Peehole ...

Ok I Can't resist how often can you say peehole on a blog ...
 
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