89 200HP Mariner Low Water Pressure - water pump and hoses flow fine

[tristanlee85]

Did u do the base plate with seal also ?

That seals the water pump from the gear housing? It's new as of a couple seasons ago so still in great shape.

[Merc 2.5]

OK well put in new poppit and stats and make sure everything is lined up when putting lower on and report back and let us know the out come,, you could also back flush while it's apart and make sure no blockage

[gmacrae]

Curious to know if the poppet is the issue... and what your resulting water pressures are

[Merc 2.5]

curious to know if the poppet is the issue... And what your resulting water pressures are

x 2

[tristanlee85]

I don't have the parts yet, but took the poppet and t-stats off tonight just to inspect. The t-stats looked fine as per my inspection last year. I brought them in and boiled them in water. They both opened at the same time and closed when put in cold water so I suspect those are fine. Nothing seemed out of place with the poppet, though when I did pull it completely out I did manage to find a tiny pebble in there. Otherwise, the gaskets didn't seem worn or ripped. I'll make sure to pull all the lines and put high pressure through them so ensure they aren't clogged. I'll pull the lower again tomorrow and inspect the copper tube to see if there's anything their either.

Other than that, I don't know what else it could be. Surely the lower isn't clogged with anything, but since it is pretty much sealed other than the transfer hose over to the water pump inlet, I'm not sure how much I can inspect to see if there are debris down there.

[gmacrae]

I went to re-kit my poppet a few years back and the kit I was given didn't contain the right parts. All seemed to fit well but my water pressure went thru the roof. I basically changed back to my original spring and pressure went back to normal... maybe you could jam the poppet closed or something to make sure that the system is able to provide good pressure up to the powerhead at idle, pisser working etc (without the poppet dumping it back out, if that is what's happening), to confirm there is no blockage in the block or mid etc?

[tristanlee85]

...maybe you could jam the poppet closed or something to make sure that the system is able to provide good pressure up to the powerhead at idle, pisser working etc (without the poppet dumping it back out, if that is what's happening), to confirm there is no blockage in the block or mid etc?

Could you elaborate on how I could force it to stay closed?

Just blew tons of water and air through all the lines and into the t-stat ports. No dirt or blockages.

[tristanlee85]

Well, good news, or at least an improvement. I put everything back together as-is (without the new components yet) and sealed up the poppet housing with some RTV since the new gaskets aren't here yet. At a cold idle, I was getting ~7.5psi and a decent stream from the telltale. As it got up to temp and the thermostats opened, the pressure dropped a little (5psi) and just barely a trickle from the telltale. When I gave it some RPMs, the pressure would jump up to 10 - 12psi, which must have triggered the poppet valve because as it would hit 12psi, it would drop back down to 7.5psi and then rise back up. Could be poor/old components and a not 100% seal with my RTV, but at least it is a step in the right direction. Because this was in a large tote and didn't include additional forced water due to normal speed, I suspect the pressure would still be higher under load.

[tristanlee85]

Well no dice on the new poppet valve. I think it might be the new cork gaskets it came with. When the engine is idling water is coming out that pin hole which to me indicates that the diaphragm isn't functioning correctly. Trying a thin layer of RTV in place of the cork gaskets. I wonder if the gaskets aren't fitting tightly causing it to compress against the diaphragm wrong.

Grr.

[tristanlee85]

The cork gaskets were ****. RTV worked out great. No leaks. At idle, I'm getting about 5psi. As I rev it up, it maxes out about 10psi. Revving higher will drop it back down to 5 - 7psi. When idling, temp gets up to 210° and hadn't went any higher for a good 15 minute idle. As I rev it up, the temp dropped to ~160°. Just to verify water flow, I removed the poppet valve and housing completely and let it idle. Water was gushing from the head where the water was hot and from the valve area where the water was cold.

I guess I'm just expecting pressure to be higher and idle temps lower, but I'm out of things to check.

[mn808gade]

in the lake or tote??-th