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Mercury Outboard Water Pump


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10-21-08, 05:25 AM   #1  
Mercury Outboard Water Pump

I just bought a 1987 Crestliner with a 1987 Mercury Black Max 175 HP Outboard. I have not had the opportunity to put it in the water yet, so I hooked up the flushout attachment just to check it out. Can someone tell me how much water should come out of the discharge (small hole at rear base of power head) when idleing.

 
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10-21-08, 04:04 PM   #2  
When you started it, did the water stream spit water a few times before you saw a solid stream? That's normal. It takes a minute or two for the water to circulate through the engine.

Feel the water after running it for a few minutes. Be careful! With the engine up to temp it will be very hot. At idle, the water flow is restricted so the engine stays up to temp. As you increase the RPMs the stream should get stronger, but don't rev it too high or you could collapse the garden hose. A few seconds without water can damage the impellor.

Since you just bought the engine, you should replace the impellor unless you know for sure that the previous owner replaced it in the last couple of seasons. It's cheap insurance versus major enginer repair due to overheating.

 
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10-21-08, 05:20 PM   #3  
I'm a firm believer in new water pump impellers. As Rick said cheap insurance, and it's easy on the mercs.

The best way to tell the condition is with a water pressure gauge and should be at least 10 psi wide open on the lake not a hose.

 
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10-23-08, 09:05 AM   #4  
Posted By: Rick Johnston When you started it, did the water stream spit water a few times before you saw a solid stream? That's normal. It takes a minute or two for the water to circulate through the engine.

Feel the water after running it for a few minutes. Be careful! With the engine up to temp it will be very hot. At idle, the water flow is restricted so the engine stays up to temp. As you increase the RPMs the stream should get stronger, but don't rev it too high or you could collapse the garden hose. A few seconds without water can damage the impellor.

Since you just bought the engine, you should replace the impellor unless you know for sure that the previous owner replaced it in the last couple of seasons. It's cheap insurance versus major enginer repair due to overheating.
Thanks for your reply. I never did get a solid stream. I did not go above idle because the manual said not to with the flushout attachment. The stream that I did get was warm so, it must be removing the heat. Thanks again for your help.

 
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10-23-08, 09:08 AM   #5  
Posted By: samuari I'm a firm believer in new water pump impellers. As Rick said cheap insurance, and it's easy on the mercs.

The best way to tell the condition is with a water pressure gauge and should be at least 10 psi wide open on the lake not a hose.
Thank you. I did plan to replace the impellor because I do not know if the previous owner did, but I assume he didn't.

 
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05-18-09, 09:23 PM   #6  
i just bought a 1972 starlite evinrude 135 hp out board motor i was cruzing around the lake about five miles an hour and noticed it was only spitting water out the exhaust not a real good stream just spitting the water that was coming out was warm to the touch is this ok or should there be more water coming out i could not get goin fast the lake was to shallow did not want to hit somethng PLEASE let me know if this is normal

 
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05-19-09, 05:37 PM   #7  
tsherrill, the water should be a solid stream, if the lake was shallow and weedy there is a chance it picked up a weed and is stuck in the outlet. Take a air nozzel from a compressor and blow back through the outlet, this will dislodge anything that may be in there. If that doesn't do it replace the waterpump impeller.

 
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05-19-09, 08:07 PM   #8  
Ok i made sure there was nothing lodged in there.. i only had it running for 5 to ten minuets is there such a thing as the hotter the motor gets the more water comes out.. i dont know much about these motors lol thanks for answering my questions.. one other thing as long as some water is coming out can the impeller still be bad i mean do they have way go out i really dont even know what an impeller is lol dont know anything about these motors just want to be sure it is cooling the way is is suspose to.. i never reved up the motor either does the water come out faster at hi rpm and not as much when idel or should it always be about the same thank you so much Todd sherrill

 
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05-20-09, 05:43 PM   #9  
Todd, the impeller is made of rubber and will wear out from sand, over time the fins will curl and the worst is running without water. Most of the time they will wear slowly and you will lose water pressure. At Idle it should be about 5 psi and at full throttle it can reach 20psi. It's splined on the driveshaft so the faster the motor spins the more volume and presure it builds. All manufactures suggest replacing them every 3 years sooner in dirty water or if the boat sits in the water.

 
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05-20-09, 05:49 PM   #10  
ok Thank you i will get it changed thanks again for all her advice

 
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05-31-09, 02:21 PM   #11  
I am having some problems with my 135 hp evinrude starflite 1972. It idels shaky and when i give it gas it trys to die unless i slowly give it gas for it to build up rpm.. runs awsome once it get to a hi rpm. Any suggestions is this the carbs or did i simpiy put to much oil in the gas i added a little more oil to a 50 to 1 ratio good that be the problem.. it never smokes so i thought i would add a little more oil to the gas and it still did not smoke. Let me know what you think thanks alot

 
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06-01-09, 06:42 PM   #12  
i pulled the spark plugs out they were pretty black looking what does that mean.

 
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06-02-09, 04:27 PM   #13  
It is usually a rich condition that can have many causes too much oil is one of them. I would put new ones in. This might take care of the low speed stumble.

 
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06-04-09, 11:35 PM   #14  
ok Thank you very much .

 
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06-05-09, 08:48 PM   #15  
You are welcome, keep us posted.

 
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06-06-09, 12:02 PM   #16  
well i got the spark plugs changed and put new gas in it and hook it up to the motor flusher and it ran great no stumbling awsome thank you again for all your help in helping me get this old boat running

 
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06-16-09, 04:37 PM   #17  
hello again i have a question that i think i know the answer to but not sure..I noticed yesterday after i put my boat back on the trailor thal the prop nut was loose i could turn it with my fingers.. but it does have a pin in the nut so it wont come all the way off it will turn a little in both directions not much thoungh is this ok or normal or should i take the pin out and re tighten the bolt then but the pin back in thanks for your help Todd

 
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06-16-09, 06:01 PM   #18  
Pull the pin and tighten the nut to about 25 ft-lbs. If it is left loose it will wear the splines.

 
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06-16-09, 08:37 PM   #19  
Ok Will do Thank You very much!! i was sure it needed to be tight but you never know so i figured i would ask.

 
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06-16-09, 09:40 PM   #20  
Ok i have one more question would sure appreciate some help with this. I have a 16ft browning tri hull fiberglass boat it is a good sized boat with a 135 hp evinrude starflite 4 cylinder motor.. I can only get about 27 mph at about 4200 rpm and when i have it wide open it sounds like it is rapped out but i dont think it is what is the top rpm for this motor and what kinda speed should i be getting.... On the motor mount it says operating range 4500 to 5000 rpm... it will not rap that high...one more thing what rpm should i not exceed when cruzin around the lake.. This is a lot of question i know but i would really like to know all this.. this boat is new to me Any advise would help thanks a lot When i have it wide open it rpm is around 4500 or a little less so i dont think i am getting all the power out of this motor.. I read some where this motor is a workhorse is this true

 
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06-17-09, 05:25 PM   #21  
I would get a different prop 1 pitch lower if it's a 19 go to a 17. What that will do is raise top rpm and give you more low end power and might give you some more speed. Think of it like being in too high of gear in a stick shift car, it just puts a big load on the motor.
Check the large auction site for a prop much cheaper than a dealer.

 
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06-17-09, 06:23 PM   #22  
Will do thank you for your advise.

 
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06-17-09, 09:36 PM   #23  
hey again my boat is hard to get started and does a little shaking and sputtering would it be in my best intrest to get the carburator reworked.. I am asking because if you think this would fix the proplem i will get it done.. a guy said he would charge me 250 to 300 to do this and a tune up should i get this done or is it a waste of money will just doing this fix my motor thanks again for all your help..

 
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06-19-09, 09:33 PM   #24  
That's kind of a judgment call, without actually seeing and hearing it I can't say. The carbed 2 strokes have a "synk and link" procedure that if it's off can cause rough running conditions.

 
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06-20-09, 04:08 PM   #25  
Ok thanks for your help i think i will go ahead and see if this fixes it worth a shot i guess

 
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06-20-09, 10:43 PM   #26  
When you get a tune up do the check this (sync and link) or adjust it or will i need to specifically tell them to check this

 
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06-21-09, 10:26 AM   #27  
I would ask to be shure it's done, also ask if you can have the compression # written on the work order. It's just something I like to see.

 
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06-21-09, 12:38 PM   #28  
Ok i will be sure to tell him i will let you know how it goes thanks for your help i apprecate it

 
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06-24-09, 08:04 PM   #29  
well i just got my boat back from the shop and took it out to the lake today and it starts really easy now thats about the only difference but thats worth a lot to me and here is the compression test 120 115 108 123 is that good.Thanks alot

 
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06-25-09, 06:37 PM   #30  
Good to hear it's starting better for you.

That compression sounds good overall, it might have a little scoring in one cyl. but nothing alarming.

 
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06-30-09, 08:35 PM   #31  
Hey i was wondering on my boat motor mount i have a rod with different places to put it in for the position of the motor for it to be father down or to move it up. I was wondering if i move the motor up or down for more speed. or is this just to keep the boat level or for planing.. i thought i heard somewhere if you move it a certian direction it would make your boat go a little faster so witch way should i move it for speed thanks for your help

 
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07-01-09, 08:16 PM   #32  
If you move it up you might pick up a MPH or 2, but it might porpus at midrange speed. All hulls handle different on my hydrostream I run it on a hydrolic jack plate so I can move it up and down. I also have a low water pickup so I can run the propshaft even with the bottom of the boat. I think I can pick up about 8 MPH from moving it up 6 inches.

So if you don't mind trying it raising it might help but I dought it will make all that much differents.

 
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07-01-09, 08:41 PM   #33  
Ok i will give it a try thank you

 
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07-08-09, 07:23 PM   #34  
1987 Mercury water pump issue

I recently had my '87 Mercury 25hp serviced with water pump repair. I do know the impeller was replaced. It gives a good flow during idle and at least up to half throttle. I did notice on the last 2 outings the stream from the "pee" hole diminished greatly to nearly nothing at full throttle. It was spitting water at best with plenty of steam. Is the pump going bad or is it possible the repair guy replaced it with a worn impeller?

 
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07-09-09, 06:39 PM   #35  
Lightning welcome to the forums. Just to let you know your question will be easier to see if you start a new post rather than adding to one.

As for your question I dought someone would not use a new impeller they are so cheap it's not worth the hassel.

I have seen the gasket under the pump housing tear and it will pump great as long as it is under water but as you get up on plain it comes out of the water and sucks air and quits pumping.

Does it quit pumping if your in neutral and rev it up? If you do this be carefull as there is no load on the engine so it will rev quick.

 
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07-13-09, 06:09 PM   #36  
I bought my boat from a individual and was curious i know this is not the subject on this site but was wondering if someone can help me out.. I have my boat registerd with parks and wildlife and as far as i know it 100 percent legal i have heard you have to have a tag on your boat trailer is this true

 
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07-13-09, 07:49 PM   #37  
Each state has it's own laws on boats and trailers.

 
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07-23-09, 06:55 PM   #38  
my outboard motor is leaking gas that is really oily i think from the carburator when i have the motor tilted up all the way it leaks on to the transom not a lot i have no idea where it is coming from really i know the fuel lines are not leaking any suggestions can it simply be leaking out the carburator and if you think this is where it is coming from is this a big deal thank you todd It is not started when it leaks like it just slowly sips out down threw the bottom of the motor down the side of the motor


Last edited by tsherrill10; 07-23-09 at 09:25 PM.
 
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07-26-09, 06:34 PM   #39  
That is normal to see fuel leaking when tilting the motor.

 
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07-26-09, 07:41 PM   #40  
hey all please help

i have a 1987 or 88 25hp merc outboard tiller model.
i am getting a good piss stream out the back, but when at top speed, i have noticed the top of my upper unit, and the cylinders are getting extremely hot.

i troll alot and at a slow troll its luke warm to almost cold. does anyone know what temp this motor should be at at full throttle.

or if anyone has any advise on why the sides of the upper housing, and the cylinders are getting so hot.

i put a new impeller in it last season.

 
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