1989 Merc 200hp water pressure/poppit question

[gss036]

I just installed a new temp sender and temp gauge and a water pressure gauge. Good news is that the temp gauge works great. Bad news, I think? Water pressure at idle to 2000 rpm is only running 4-6 LB pressure and is too low, good tell-tale stream. Running at 4000 rpm pressure is at 12# and 16# @ 5000 rpm.<br />I am assuming that the poppit valve is stuck wide open. Would my assumption be correct or is there something else wrong? The impeller was changed last year and has about 20-25 hrs on it. Also new thermostats. Any suggestion welcome.

 

[north40]

Re: 1989 Merc 200hp water pressure/poppit question

These pressures are ok. As long as you have good tell tell stream and no overheating alarm don't worry. Sounds like you have everything covered.

 

[jaybirdtx]

Re: 1989 Merc 200hp water pressure/poppit question

On the opposite side of the poppet valve there is a screened fitting that can clog. Its connected to the hose going to port thermostat.

 

[gss036]

Re: 1989 Merc 200hp water pressure/poppit question

OkieBoat, my hose to the poppit comes off the top center of the block. There is a seperate hose that crosses the top of the engine, then to a discharge port that has nothing to do with the poppit. I have a schematic showing the water flow on the 89 and later 200 Merc.<br />I don't follow you on the screened fitting that you say can clog. Could you be specife.

 

[KCLOST]

Re: 1989 Merc 200hp water pressure/poppit question

Your pressure seem a little low to me... <br /><br />Is that 4-6psi at idle just after start-up or after it has warmed up a while?<br /><br />And what was the part# for the impeller you installed last year?

 

[gss036]

Re: 1989 Merc 200hp water pressure/poppit question

The pressue is right after start up but seems about the same after running. I had a shop do the install on the impeller. I need to lean how to do my own. I was thinking in the sring about buying a whole pump and install that as it only a few dollars more and would be a lot easier.<br />What do you think about the poppit?<br />We only have the rest of this month for fishing chinook here and then closed until Jan, 06. We get Jan & Feb then closed until about July. They change it every year.

 

[KCLOST]

Re: 1989 Merc 200hp water pressure/poppit question

The poppet is diffinitely worth checking, but your WOT pressures are a bit low to me also and those pressures would be with the poppet open...<br /><br />That's why I asked about your impeller. Your year of engine may have a different pressure range than earlier models.

 

[KCLOST]

Re: 1989 Merc 200hp water pressure/poppit question

Meaning, there may not be anything wrong with it...

 

[rodbolt]

Re: 1989 Merc 200hp water pressure/poppit question

what is the specs out of your merc manual say its supposed to be ?<br /> you have a merc manual right?

 

[Bilgewiper]

Re: 1989 Merc 200hp water pressure/poppit question

I also own a '89 200hp Merc. The factory shop manual says a "minimum of 12psi @ 5500 rpm. Mine runs same as yours at idle and about 18-20psi at 6200rpm and 65mph if I remember right.

 

[gss036]

Re: 1989 Merc 200hp water pressure/poppit question

Yes Rodbolt, I do have a manual, just not enough sense to look there. Manual say 12 psi minimum @ 5500RPM. I only ran up to 5000 rpm and it jumped up to 16 psi, so that is good. It does not give low rpm reading. Sounds good to me, now to get back to my plumbing project, copper plumbing been in for 38 years and we have high PH level in our well water, so everytime I touch a shut off valve, I end up having to replace it. Done 4 so far. Kind like running in salt water.<br />Thanks for the help everyone.