Water impeller change on a 150hp optimax?

[mattorschell]

My engine s.n is 1B274973 and my question is when I changed my water pump there is a gasket then the metal face plate and then another gasket. So a total of two gaskets and a face plate. Should there only be the gasket and the face plate? Not sure the guy who did it before me did this correctly. Just doesn’t seem the need of the gasket under the face plate. That’s how I reassembled it but just sitting here thinking and in the directions thread on this site has pictures and it only looks like one gasket in the picture. So if anyone has experience with this could you please let me know how many gaskets your had? Thanks

[Bruce2]

Gasket below face plate and gasket above face plate, not having one on the bottom of face plate could cause a no water pressure problem.

[mattorschell]

Ok. That’s how it was. The gasket below was missing a portion of the gasket and it looks like it would do the same thing again so I just cut that portion out. Hopefully that don’t affect anything. I figured it was already missing from the last gasket without a problem. It’s the portion that has no support from the lower unit housing. I could put my finger under the plate and just feel the gasket.

[SilverFox579]

There are 3 gaskets, one below the pump base and two between the plate, all 3 should be replaced every time you service the water pump. If you aren't replacing the housing, service includes impeller, plate, and 3 gaskets.

[mattorschell]

On this model there is only two gaskets and the plate.

[SilverFox579]

The 2.5L Optimax uses 3 gaskets. I have the same engine and service the water pump myself and there are 3 gaskets. If you only change two, it's because you didn't pull the pump base to access the third one.

[mattorschell]

Is the pump base under the blue part that is under the the two gaskets and plate?

[leonreno]

Yes

[mattorschell]

Yeah I did not get that deep into it.

[EuropeanAM]

Ok. That’s how it was. The gasket below was missing a portion of the gasket and it looks like it would do the same thing again so I just cut that portion out. Hopefully that don’t affect anything. I figured it was already missing from the last gasket without a problem. It’s the portion that has no support from the lower unit housing. I could put my finger under the plate and just feel the gasket.

Nope. Go buy a NEW gasket, and don't alter it.

Improper TORQUE on the nuts is the #1 cause of gasket failures.

There are actually a total of THREE gaskets (one above plate, one below plate, and one below the water pump BASE). Each is critical.

[mattorschell]

I did the water impeller change last time and I torqued it with a calibrated torque wrench so I know the torque was correct. The part of the gasket that was missing was under the plate where the water comes into the impeller. There is nothing there to keep it from tearing off again and going into the water impeller. The gasket was kept intact every where it touched the pump base and plate.

[mattorschell]

Tested today. Everything worked great.

[EuropeanAM]

If you would, pick back up somewhere in the 20+ runtime hour range, would be good to know where you're sitting for idle water pressure, and how long you can run at 2000-3500 RPM's (without incident).

[SilverFox579]

Tested today. Everything worked great.

Good to hear!

[mattorschell]

Idle was 1.8 psi and around 16 to 18 psi running

[mattorschell]

I’ll keep an eye on it.

[SilverFox579]

I usually see 4 - 5 psi at idle first time out with a new water pump and it settles to around 1.8 - 2.0 psi after an hour or two of run time. Only other water spec is WOT, anything else is just in between. For your non-ProXS 150 you'll want to see a minimum of 1psi at idle and 12+ at WOT. Pressures sound good at this point.