Hey guys,
I’ve got a few questions about some water cooling issues I’ve been seeing with my motor. It’s a 20 year old Mercury 2-stroke, and recently I’ve noticed that water is shooting out of the exhaust port (pic attached) - is this an issue, or is the part of the normal cooling process that I somehow haven’t noticed before?
Secondly, my tell-tale stream diminishes to almost nothing when I rev the engine to get on plane, and once I’m finally on plane it returns to “normal”. Any thoughts here? Wondering if I have a poppet valve issue.
Usually, with the motor in the water at normal depth, when the motor is idling, you should the exhaust outlets on the back of the motor should be spitting, not flowing. In order for more water to be coming out of those ports, you must have a restriction somewhere else in the flow path.
Re: the tell-tale slowing as RPMs increase, again, that shouldn’t happen. The water pump is directly driven by (on) the drive shaft which is splined straight in to the bottom of the motor crank shaft. If the motor is spinning faster, that pump is spinning faster. If everything is working, as RPMs go up, water pump pressure and flow go up. For the tell-tale to be slowing as RPMs increase, something weird is happening. Maybe a completely worn out pump impeller. Maybe a restriction in the flow path. Maybe both. No way to tell.
I have no good news. Until last Fall, I ran a 1995 Johnson 88spl. She died (again… for good, this time). Had to replace a piston. When I pulled the head cover plates off of her, the cooling passages were absolutely filled with crusty stuff that I assume was a mixture of salt and aluminum corrosion. I was amazed that she had actually been cooling well enough with those passages full of stuff. She was fresh water rinsed after each use religiously. I suspect any 20yr old 2-smoker that has been in salt water will have the same issues.
First suggestion - rebuild the water pump. If it is not healthy, nothing else in the cooling system matter.
Second, I have no idea where/how the thermostat(s) on that motor. But, they are regular maintenance. Do it/them.
Third, maybe do a mild acidic rinse. Vinegar or something slightly acidic in a barrel and let her run in it for a while. Then, run her in clean fresh water to get any/all acid out. Acid should be extremely dilute. There are commercial products for this trick. I’ve never tried this trick, but, the chemistry says it should move the deposits/corrosion out of the cooling passages.
Appreciate the thorough response. And yes you’re right, the exhaust port is “spitting” and not “flowing”, so I’ll assume that’s part of the normal process.
The water pump is only a year old, and I’ve never gotten any overheat alarms, so I’m assuming it’s still doing the job. Once at full throttle, the water pressure from the tell-tale is strong like it’s supposed to be. It just diminishes during the actual acceleration phase
I think you’re right though, time for an acid rinse. Thanks for the suggestions
A bad poppet will generally leak water out of the vent hole. Although, I have seen them restricted, from pieces of failed impellers, tiny shells, and other debris. Might just need cleaning?
I find all this helpful too, thanks y’all. Currently working my way over my old Mercury as well (1993 25hp) and have the foot off in the garage awaiting a water pump kit.
Getting the lower unit off for the first time in over a decade of hard saltwater use wasn’t easy. The first two 5/8" bolts turned with a ratchet just fine, third was a bear and the fourth wouldn’t budge. I hit it for a few days with PB blaster and tried a breaker bar, was afraid i was going to twist it off but it moved. I don’t have an impact wrench but that occurred to me too.
PB blaster also helped me free the lower lube screw on the foot that was giving me hell.
MD- can you clarify on blue grease, sir? I got the regular gun full of marine red, but was thinking something harder. Assume I’m gonna want a good work over with some gasohol and a wire brush beforehand too, lower is gunked with some sandy grime inside. Not sure I’m ready to try Palmer’s acid bath just yet.
Thanks again all. Sorry to sort of jack your thread, OP- last time i tried to start a topic it wouldn’t let me.
also somewhat relevant: how much heat is too much? I don’t want to put MAPP gas on something if a heat gun or my wife’s hair dryer is a good place to start.
this forum is great for my self-confidence in working on the old smoky motor, but when it comes to the 4 stroke Honda, Chris is my man.
For heat, I’ve used one of those benzomatic propane bottles/torches. Aluminum moves a lot with heat (relative to other metals). Heating an aluminum chunk that holds a steel bolt will cause a lot more expansion in the aluminum than it will in that bolt. I don’t know what the melting temp of Al is, but, I wouldn’t want to get anywhere near it.
I try to use as little heat as absolutely possible. Just enough to get the bolt to spin. How much is that? Don’t know. It is a risky dance every time.
I would NEVER put a power tool (electric or air) on a bolt stuck in an outboard. The aluminum corrosion in the bolt threads is pretty porous until you get the bolt to move. If you can get the bolt to turn without wringing the head off, if you do not work it back and forth (you try to just unscrew it), you are packing that powder up tighter and tighter in the threads. That can grab the threads and gall them at any point as the bolt comes out. I like to use a 6 sided box end wrench if I can get one on the bolt.
0a - As suggested previously by our fellow brethren, pray. Pray continuously as you work.
0b - Lubricate the worker as needed with any preferred libation.
0c - Recognize that the bolt is precious. It is beloved. To lose it will bring great strife and tragedy. Are you praying?
1 - Wire brush clean the area around the bolt head.
2 - Heat it a little. Do not heat the bolt, at all. Only heat the area around the bolt.
3 - While it is hot, spray with lose juice of your choice around the head. (I use pb blaster but have no idea if it is good/best/crap)
*** Did you stop praying? Don’t stop! ***
4 - Tap the head of the bolt pretty firmly with a hammer as it cools a little and is bathed in the juice. With each tap, you’re basically trying to push/bounce the bolt further into its hole as the area cools making little tiny (maybe microscopic) cracks in the corrosion crap that is filling the threads so the lose juice can seep in… if it can. Probably not…
5 - While it i
Since buying air powered impact wrenches…different strengths…I set it on the lowest setting…after attempts with the manual impact wrench. That would be gentle tapping to loosen the “grit” on the threads.
Also…bees wax doesn’t ignite like pb blaster does unless you have melted the pot meta/aluminum housing.
And Barbawang…(dog party organizer/Marine Biologist)…I’d help you anytime/anywhere…all you gots to do is say so.
[quote]For heat, I’ve used one of those benzomatic propane bottles/torches. Aluminum moves a lot with heat (relative to other metals). Heating an aluminum chunk that holds a steel bolt will cause a lot more expansion in the aluminum than it will in that bolt. I don’t know what the melting temp of Al is, but, I wouldn’t want to get anywhere near it.
I try to use as little heat as absolutely possible. Just enough to get the bolt to spin. How much is that? Don’t know. It is a risky dance every time.
I would NEVER put a power tool (electric or air) on a bolt stuck in an outboard. The aluminum corrosion in the bolt threads is pretty porous until you get the bolt to move. If you can get the bolt to turn without wringing the head off, if you do not work it back and forth (you try to just unscrew it), you are packing that powder up tighter and tighter in the threads. That can grab the threads and gall them at any point as the bolt comes out. I like to use a 6 sided box end wrench if I can get one on the bolt.
0a - As suggested previously by our fellow brethren, pray. Pray continuously as you work.
0b - Lubricate the worker as needed with any preferred libation.
0c - Recognize that the bolt is precious. It is beloved. To lose it will bring great strife and tragedy. Are you praying?
1 - Wire brush clean the area around the bolt head.
2 - Heat it a little. Do not heat the bolt, at all. Only heat the area around the bolt.
3 - While it is hot, spray with lose juice of your choice around the head. (I use pb blaster but have no idea if it is good/best/crap)
*** Did you stop praying? Don’t stop! ***
4 - Tap the head of the bolt pretty firmly with a hammer as it cools a little and is bathed in the juice. With each tap, you’re basically trying to push/bounce the bolt further into its hole as the area cools making little tiny (maybe microscopic) cracks in the corrosion crap that is filling the threads so the lose juice can seep in… if it can. Probably not…
5 - Whi
[quote][quote]For heat, I’ve used one of those benzomatic propane bottles/torches. Aluminum moves a lot with heat (relative to other metals). Heating an aluminum chunk that holds a steel bolt will cause a lot more expansion in the aluminum than it will in that bolt. I don’t know what the melting temp of Al is, but, I wouldn’t want to get anywhere near it.
I try to use as little heat as absolutely possible. Just enough to get the bolt to spin. How much is that? Don’t know. It is a risky dance every time.
I would NEVER put a power tool (electric or air) on a bolt stuck in an outboard. The aluminum corrosion in the bolt threads is pretty porous until you get the bolt to move. If you can get the bolt to turn without wringing the head off, if you do not work it back and forth (you try to just unscrew it), you are packing that powder up tighter and tighter in the threads. That can grab the threads and gall them at any point as the bolt comes out. I like to use a 6 sided box end wrench if I can get one on the bolt.
0a - As suggested previously by our fellow brethren, pray. Pray continuously as you work.
0b - Lubricate the worker as needed with any preferred libation.
0c - Recognize that the bolt is precious. It is beloved. To lose it will bring great strife and tragedy. Are you praying?
1 - Wire brush clean the area around the bolt head.
2 - Heat it a little. Do not heat the bolt, at all. Only heat the area around the bolt.
3 - While it is hot, spray with lose juice of your choice around the head. (I use pb blaster but have no idea if it is good/best/crap)
*** Did you stop praying? Don’t stop! ***
4 - Tap the head of the bolt pretty firmly with a hammer as it cools a little and is bathed in the juice. With each tap, you’re basically trying to push/bounce the bolt further into its hole as the area cools making little tiny (maybe microscopic) cracks in the corrosion crap that is filling the threads so the lose juice can seep in… if it can. Probably not…
Barbawang - no worries about “hijacking” the thread, I learn something from all of these scenarios so it’s always helpful in the end
Palmer - that might be one of the best posts I’ve read on this site, so I’m hoping to end up on the side of libation, prayer and celebration instead of the endless weeping. Don’t want my tears to cool down the aluminum I’m trying to heat up
Good info here. Especially on not too much heat on aluminum. You can’t see it getting red like steel and I’ve seen many a boo boo with that just right point to aluminum melting using a torch.
I love some PB blaster and use it a lot, but if you are willing to spend a bit more for something much better with “frozen/ seized” bolts get some Kroil oil. It is expensive but I give my word that is it way better than anything on the market that i’ve used. Heat your, bolt spray it heavy and let it sit a few minuets. It is also some of the best oil to use as Cutting fluid for drilling that I’ve come across. Don’t breath the smoke from it after spraying it on a heated bolt… will give you a nasty headache. Stinks too.
Only place I’ve seen it local is the Parker hyd store on the frontage road off I26 between Jedburg and Summerville.
