2000 OX66 low water pressure

Have twin '00 OX66's, in the spring I did both water pumps, new T-stats and poppets on both engines.

The starboard engine has great water pressure, running up around 20psi at cruising RPM, around 43-4400. The port engine had lower pressure from the start in the spring, around 15psi, but has recently gotten worse, and is now around 10psi at the same cruising RPM, 43-4400.

I'm not getting an overheat alarm or anything. I have noticed the port tell-tale is dribling out at idle, but there is plenty of water coming out of the exhaust pressure reliefs at idle, and it's coming out of the reliefs at a good pressure too.

The strange thing is that there is a lot of water coming out of the pressure reliefs at 4400 RPM on the port engine, and not that much at all on the starboard engine. It seems to me at that RPM there shouldn't be that much water coming from the pressure reliefs as the exhaust and cooling water all go out the prop, because there isn't that much backpressure at that RPM.

What would/could be causing this drop in water pressure on the port engine? Should there be that much water coming out of the pressure reliefs at 4400 RPM?

I was thinking that possibly the gasket on the port water pump housing might not have seated right when I did the water pumps in the spring, that gasket is a pain to get to stay in the housing when you are putting it together, even with grease to hold it in place, not sure why it's not contoured to the shape of the housing, the way OMC does it, but whatever.

I'm not sure if that would have just given me low pressure problems right off the bat or if that could have gotten worse over time though.


Thanks for any help.

Re: 2000 OX66 low water pressure

could be the gasket, doubt it. most likly the rubber dam under the plate or the poppit valve grommet.
I have never had an issue with the housing oring.

Re: 2000 OX66 low water pressure

Thanks rodbolt. WHat is the rubber dam under the plate, I will take a look at that when I pull the boat out of the water.

Do you mean you never had an issue with the housing o-ring leaking, or getting into the groove?

Thanks.

Re: 2000 OX66 low water pressure

really need a model number, all OX66 means is its an EFI 2 stroke.

Re: 2000 OX66 low water pressure

OK I'll get it when I get home. It's a '00 200hp.

Re: 2000 OX66 low water pressure

Model # is SX2O0TXRY.

What would most likely happen if the housing o-ring wasn't seated in the groove right when I tightened the housing down?

Re: 2000 OX66 low water pressure

most likly noting, wont be the first I ever took apart for maint and the last guy had left it out or cut it in half.
myself I would dissasemble the pressure valve, remove the grommet, carefully clean the grommet pocket with a scraper pick, reassemble with a new grommet and retest.
that much water out of the relieif indicates we are dumping to much water into the exhaust tube area, guess where the water the poppit valve dumps goes?
from the valve,through the tube, directly into the ex cooling chamber.