Poppet valve issue?

[bronze_back_hunter]

I do some basic electronic installs and maint stuff on about a dozen boats every winter. I had a guy bring a boat I haven’t worked on before. It’s a 98 Merc Pro Max 225. Serial number 06787301. He told me he wasn’t getting any water out of the pee hole. I asked about his last water pump service and he said about 10 yrs ago. As I imagined the impeller and gaskets were all destroyed. The Tstats had been gutted also. I replaced all the water pump parts and Tstats. Also blew out all the lines. When I started it up last night in a barrel it still would not pee any water. Would a faulty poppet cause that? I have ordered a replacement that I haven’t got yet. Just want to see if I should check anything else. Thanks!!

[EuropeanAM]

Likely 0G787301. Some of these were setup with the telltale coming from the thermostats (meaning no telltale stream until, or unless the thermostats are open).

What is the water pressure at idle?

Moving over ot the 2.5L Forum for you.

[bronze_back_hunter]

Sorry about posting in wrong forum. It does come from the Tstats but the old Tstats were wide open on it before when I first rebuilt the water pump and it still would not put any water out the telltale.

I let it idle for about 5 min after replacing the Tstats. Water Pressure was around 3 while in the barrel still no water from telltale. I removed the Poppet valve this morning before coming to work and it had a bunch of small rock and sand but no visible damage. Could it still be bad?

[EuropeanAM]

Go ahead and replace the poppet, grommet, spring, washer, diaphragm and gaskets since you pulled it out. Pretty simple device... needs to be able to seat properly, diaphragm intact, and poppet needs to be able to slide smoothly in and out of the grommet.

Inner gasket has a tendency to "hunch" up between the chambers sometimes- it's acceptable to slice that area of the cork gasket out (so it can't distort).

3 psi is acceptable at idle... pull a hose right at the thermostat and monitor there. Depending on the temp of that water- it can take 5+ minutes for the thermostats to open in cold weather.

[bronze_back_hunter]

Will do. Thanks so much Don!!!

[JaySmithRacing]

I agree +1 I build lots of 225 Pro Max motors always remember that is an inverted thermostat engine their stats are different !! I also drill a 1/16” hole in the bell of the thermostat to let air escape works for me for 20 years ....

Jay @JSRE

[bronze_back_hunter]

Installed the new kit and have water coming out of hole in poppet valve. I have took it back off checked the diaphram and screw all seems right, still have water coming out? I made sure it was correct part number. Not sure what the issue is now?

[bronze_back_hunter]

Pulled the assembly back out and compared with the old parts, only difference was gasket thickness. Put in old outer gasket and everything is good. Pumping water like it should now after tstats opened up.

[David L]

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I've experienced this same problem after servicing Poppet parts. Ended up being item 12 in the <Parts Diaghram> was not tight enough which caused water to weep out the hole as you described.

[bronze_back_hunter]

Thanks. It was plenty tight enough. Actually got worried about breaking the plastic. It is working fine now after the gasket switch.