Water pump impeller replacement

[gotaf7]

When servicing water pump should I change out the 2 fiber gaskets and metal plate under the water pump impeller, I have had the impeller changed every second year but have never changed those 3 parts. 1B914695

[06 SB]

No need to change out the metal plate unless it is worn or damaged. You should be changing out the other gaskets when replacing the impeller. I do mine every year which is around 75-100 hours for me.

[leonreno]

And there is a third gasket under the water pump base that should be replaced also, the base is the part that is under the two gaskets and metal plate. It comes out and there is a gasket under it. I don’t change it every time but usually every other time.

[SilverFox579]

It's helpful to also tell us what engine you have. Accessing Mercury's parts site and entering your serial number I know you have a 135, 150, or 175hp Optimax. When servicing the water pump (service interval is annually or 100hrs whichever comes first) Don recommends replacing the impeller, plate, all 3 gaskets (one either side of the plate and one below the pump base).

That said, I agree with 06SB, if the plate isn't worn, there's no need to replace it, same goes for the pump housing insert. If you can catch a fingernail in any grooves on the plate or housing insert, I would replace them.

[gotaf7]

It's helpful to also tell us what engine you have. Accessing Mercury's parts site and entering your serial number I know you have a 135, 150, or 175hp Optimax. When servicing the water pump (service interval is annually or 100hrs whichever comes first) Don recommends replacing the impeller, plate, all 3 gaskets (one either side of the plate and one below the pump base).

That said, I agree with 06SB, if the plate isn't worn, there's no need to replace it, same goes for the pump housing insert. If you can catch a fingernail in any grooves on the plate or housing insert, I would replace them.

My engine is a 150, does the pump base just pull out to access the gasket underneath?
thanks for the info.

[leonreno]

It does pull out, but it doesn’t “just” pull out. Usually have to use two screwdriver to pry it out a little by little. But there isn’t really anything holding it down. They way I do my pumps is one year I replace the whole water pump (but not the base or the gasket under it), the next year I replace the whole pump and the base too. I buy the whole pump kit for one year and then I buy the whole pump plus base kit the next year. That way when I replace the base gasket I don’t have to be gentle getting the base out, since I’m replacing it. My method is probably overkill, very seldom does the whole pump need replacing but it’s not really that expensive and I don’t won’t to have to stop a fishing trip due to overheating, my trips are infrequent enough that it makes a difference to be super sure the pumps working.

[SilverFox579]

I have never replaced the pump base, but always replace all 3 gaskets. You know the saying "been there, done that", gasket under the pump base bit me once, won't ever again. Just as leonreno said, you'll need a couple screwdrivers or something similar to get the pump base out. If I don't get sidetracked on higher priority things again, I'm doing mine today and will share pics later today or tomorrow.

[gotaf7]

Thanks guys I appreciate the info.

[leonreno]

I don’t replace the pump base because it needs to be replace but do it because it cost about $10 and I don’t have to baby the old base out.

[JOE54]

I don’t replace the pump base because it needs to be replace but do it because it cost about $10 and I don’t have to baby the old base out.

+1

[RockNBass]

Can you provide the order of the gaskets (2.5L)? I couldn't find this through a search or in the service manual. When I changed mine earlier this year I followed the same order as the ones I removed, but there was one gasket that appeared (to me at least) that could have a piece cut out because that one particular piece of the gasket did not have a matching surface to mate with once installed. FWIW I did not modify the new gasket but have wondered ever since. Thank you!

[SilverFox579]

2.5L Optimax water pump replacement

[silverbullet02]

I’ll admit I’m kinda impressed how much work some of you guys do for an impeller replacement. I can’t say I’ve had a pump base off in over 10years on any of my boats, and the last time was only because of the seals leaking. I just pull the top off, replace that gasket if it looks bad, check everything out visually, and if I don’t see anything wrong I just put a new impeller in and put it back together, heck I even use a little oil on my finger to smear inside the cap. Longest I was able to run an impeller was 5 years I think, but that was a science experiment. Now that I have water press and temp gauges I only do water pump when my gauges tell me.

[SilverFox579]

Took 20mins for me to do mine and that included taking pics for the tutorial. Recommended service interval for the Optimax is annually or 100hrs, whichever comes first, and Don always recommends impeller, plate, and all 3 gaskets when servicing the Optimax water pump. Don't know if that applies to your Super Mag so YMMV.

[leonreno]

The thing is, the hardest part of changing a pump is the removing and replacing the lower unit, the pump swap is easy, and cheap so I just always replace the whole pump so I have no worries, but I agree, it’s not always needed.