Mercruiser 3.7 Water Pump Replacement?

[Wellcraft170]

So I picked up a boat today that needs the water pump replaced according to the person I bought it from. Now, I've had this engine with all of the boats I've owned and my fathers boat has it as well, but I was curious is this different then the impeller?

 

[Scott Danforth]

there is the raw water pump and the circulating pump. the raw water pump will be in the lower unit. the circulating pump is on the motor, driven by the cam

here is an iboats thread on replacing it http://forums.iboats.com/forum/engi...pump-cam-seals-on-1982-mercruiser-470-day-one

it also covers the speedy sleeve fix needed

 

[Wellcraft170]

there is the raw water pump and the circulating pump. the raw water pump will be in the lower unit. the circulating pump is on the motor, driven by the cam

here is an iboats thread on replacing it http://forums.iboats.com/forum/engi...pump-cam-seals-on-1982-mercruiser-470-day-one

it also covers the speedy sleeve fix needed

oh okay gotcha. any idea what the circulating pump would cost to get replaced after its all said and done?

 

[Scott Danforth]

if your inquiring about taking it in somewhere to have them work on it. you have to first find someone willing to work on the 470. it wont be cheap.

guessing about $1500 in labor alone

 

[Wellcraft170]

if your inquiring about taking it in somewhere to have them work on it. you have to first find someone willing to work on the 470. it wont be cheap.

guessing about $1500 in labor alone

i actually have a family friend who's been my mechanic for over 15 years and he's worked on all of my 170's

 

[Scott Danforth]

Then I would take it to him.

 

[stonyloam]

OK, slow down a bit here. Are you SURE they were talking about the engine water pump. The ONLY reason you would have to mess with that is if it is leaking antifreeze out of the weep hole on the lower starboard side of the pump. Unless is leaking (bad cam seals) it should never "wear out". The impeller in the outdrive is no different than any other alpha 1.

 

[Scott Danforth]

Stoney, have you ever known a 470 to not wear out the cam seal surface? would be different if Mercruiser hardened the shaft, however they didnt

 

[stonyloam]

Hey Scott, yeah they all will leak eventually. The seals themselves will fail, on mine I did not use a Spedi sleeve on mine and it has held just fine for 10 years. The new seals are pretty good and sill probably work well even if the cam surface is grooved a bit. The op said the waterpump needed to be replaced, but on the 470 there is no "water pump" to replace, anyway not like in a conventional engine. There is just an impeller bolted to the end of the cam, which should last forever. The only thing that would ever need to be replaced is the cam seals, and the indicator for that is the weep hole leak. On a conventional engine the seals and bearings can fail, and then you replace the waterpump. So me being a "470 guy", when the op said it needs a new waterpump, I am thinking impeller. Yeah we think differently

 

[Wellcraft170]

Hey Scott, yeah they all will leak eventually. The seals themselves will fail, on mine I did not use a Spedi sleeve on mine and it has held just fine for 10 years. The new seals are pretty good and sill probably work well even if the cam surface is grooved a bit. The op said the waterpump needed to be replaced, but on the 470 there is no "water pump" to replace, anyway not like in a conventional engine. There is just an impeller bolted to the end of the cam, which should last forever. The only thing that would ever need to be replaced is the cam seals, and the indicator for that is the weep hole leak. On a conventional engine the seals and bearings can fail, and then you replace the waterpump. So me being a "470 guy", when the op said it needs a new waterpump, I am thinking impeller. Yeah we think differently

this makes a lot of sense. i would be a whole lot happier if it was just an impeller change.

 

[stonyloam]

Yeah an impeller is a lot easier, but the cam seals are not too bad. About $100 in parts and a few hours work if all goes smoothly (it never does). If your mechanic has worked on 470's he has probably done a few. Good luck.