Lower unit water pump on 1979 Marktwain 165hp

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moffitt77

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I have been told by a local mechanic ($90 per hour!) that I should replace the water pump in my lower unit every 2 years. Is that something that is necessary?
 
Don S

Don S

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Re: Lower unit water pump on 1979 Marktwain 165hp

Good suggestion if you want to avoid overheats. It's called preventive maintenance.
 
Bondo

Bondo

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Re: Lower unit water pump on 1979 Marktwain 165hp

moffitt77 said:
I have been told by a local mechanic ($90 per hour!) that I should replace the water pump in my lower unit every 2 years. Is that something that is necessary?
Click to expand...

Ayuh,.... Darn Great idea,... That's why this is a Diy site, 'n most of Us do our Own work...


Btw,.... $90. an hour is gettin' to be on the Cheap side...
 
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moffitt77

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Re: Lower unit water pump on 1979 Marktwain 165hp

Thanks for all of the replies. I am pretty handy working on cars and gotten better working on my boat, not much different. Does anyone have the service manual or steps for replacing that water pump? I am sure I can do it myself. It runs cool 140-160 when I am pulling tubers, but does get hot when we sit to switch 190-200. Or does it need replaced? It was replaced about 15 months ago.

Thanks,

Mik,
 
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haulnazz15

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Re: Lower unit water pump on 1979 Marktwain 165hp

You shouldn't see it get over 160 no matter what you're doing. My MT runs 140 all day long. Replacing the water pump/impeller takes about an hour and requires pretty much nothing but a socket wrench to remove the lower unit and water pump, an allen wrench for the fin/anode, and a slot screw driver to remove the drain plug to drain the gear lube. Easy work if you have even the slightest bit of mechanical ability.
 
ktbarrentine

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Re: Lower unit water pump on 1979 Marktwain 165hp

moffitt77 said:
Thanks for all of the replies. I am pretty handy working on cars and gotten better working on my boat, not much different. Does anyone have the service manual or steps for replacing that water pump? I am sure I can do it myself. It runs cool 140-160 when I am pulling tubers, but does get hot when we sit to switch 190-200. Or does it need replaced? It was replaced about 15 months ago.

Thanks,

Mik,
Click to expand...

Wow... my symptoms exactly. Replaced the water pump (w/ kit) and temps are good (~140) at speed and at idle (if temps go up at idle means yer flow has gone down because the impeller is not doin what it should.). Here's a good manual link for you.

https://docs.google.com/leaf?id=0B1...ODAxOS00YWZjLWFmZDgtZjMxNjQxOTkzMzUz&hl=en_GB
 
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moffitt77

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Re: Lower unit water pump on 1979 Marktwain 165hp

it never runs over 140, just noticed it shooting up when we stopped and turned the motor off to switch kids. I was pulling 2 tubers and it was 100 degrees out.
 
ktbarrentine

ktbarrentine

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Re: Lower unit water pump on 1979 Marktwain 165hp

Ok... sounds good...just keep an eye on it in the low-wake zones and when idling at the dock...that's when mine would creep up to too high. I now replace my impeller one a year while I am doing all my outdrive preventive maintenance/greasing stuff.
 
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moffitt77

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Re: Lower unit water pump on 1979 Marktwain 165hp

I replaced the impeller, back to normal temps. Thanks.
 
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