Old Merc 150 pisser question

[Aquamaniac]

Seems old Mercs would not run water out the pisser until thermostats opened. Something to do with design I believe.
I have two questions:
-doesn't this create a problem at startup....not knowing for sure you have sufficient flow cooling things?
-when flushing the engine after use, will the entire system be flushed? I don't see water coming out the pisser with the muffs. It does come out pisser when running boat in the water.
Any thoughts????
Thanks!

[Fletch170]

I could be wrong here, but that is not good. My best guess is that the poppet valve is stuck open. Your engine should ALWAYS pee , at least as far as I know.....

I think you could be at risk of overheating, as you are getting inpropper circulation at low RPM? I'm no expert, but that's my take. Some of the guys on here wil chime in I'm sure.

[Fletch170]

It is my understanding that the poppet bypasses the cooling system and into the exhaust plate.

[Blue Agave]

By design the thermostat remains closed until the motor reaches normal operating temp. Completely normal on Mercs not to pee until the thermostat opens. How long are you running it on the muffs?  Long enough for the thermostats to open?  Does the over heat alarm go off when on the muffs?  Sometimes the muff can be the source of the problem.

[Fletch170]

Really? How do you know if she's pumping water?

Granted, this is my first merc, and have always had Yami's. If the yami isnt peeing as soon as it's fired, you have a problem.

[Fletch170]

Hmmm, interesting. I guess yami's have a portion of the cooling circuit "peeing" regardless if the tstats are closed.

See, I learned something today:)

[Aquamaniac]

I wondered about the muffs as well.....saw a set in WallyWorld that was a double feed. The set I am using just feeds from one side. Might make it easier to pull enough water. The impeller, poppits, thermostats, etc were done relatively recently. I don't leave it long on the muffs.....worried it might not be getting enough water. Alarm has not sounded.

[Capt. Bob]

I wondered about the muffs as well.....saw a set in WallyWorld that was a double feed. The set I am using just feeds from one side. Might make it easier to pull enough water.

I'm guessin' it's more marketing than better engineering.
Remember that the pump draws water from the cavity in the lower unit (at least on OMCs and Yamahas but I'm betting Mercs too) that fills through the water pickup vents. Unless your hose is restricting (or the muffs themselves) that flow of water, it fills very quickly. I believe it fills faster on the single feed due to less restriction.

Also, the impeller is displacing that water while running on the muffs (at idle) so you could even reduce the pressure some and it would still work fine. When the motor is in the water, the pump acts as a displacement type pushing the water through the system. At speed, the water pressure is much greater in the sump and it deflects the impeller vanes relegating the pump to a circulating type.

On my older Johnyrudes, there was no telltale. On the muffs, I would watch for the vents on the top of the lower unit to start flowing water when the T-stats opened. If you didn't see water, you checked the temp gauge and shut the motor down as it reached about 180 degrees. Out on the water, you cannot see those vents so you had to rely strictly on the temp gauge for conformation. No alarms back then.

Good luck.

[Aquamaniac]

Thanks Capt. Bob....you saved me from buying another set of muffs!

[Blue Agave]

Alarm has not sounded.

Assuming that you have a properly functioning alarm, there should not be an overheat problem. Has the impeller been replaced?  Has the upper water pump housing been replaced?  One of the more neglected parts is the water pump base, has the base been replaced?  Pull the thermostats and inspect them or replace them, pretty inexpensive and quite an easy job.  Good luck.

[Fletch170]

Went out and purchased a nice teleflex temp gauge. Now knowing my 225 offshore merc wont piss until it's warm, the temp gauge and new sender will give me a little piece of mind.

[fitz73222]

Hey Fletch,
Don't mean to bust your bubble on the temp gage but the reality is it probably won't even register past "C" on your engine. Most multi appication temp gages don't even start to move until 140 degrees, which is about 20 degrees higher than your normal operating temp. So when you get it hooked up, dont be surprised or think something is wrong because it stays on "C".

[numlaar]

Hey Fletch,
Don't mean to bust your bubble on the temp gage but the reality is it probably won't even register past "C" on your engine. Most multi appication temp gages don't even start to move until 140 degrees, which is about 20 degrees higher than your normal operating temp. So when you get it hooked up, dont be surprised or think something is wrong because it stays on "C".

I think it depends on the model of the gauge...

I run this one: 58862P Water Temperature Kit

Its specifically for outboards with a temp range of 100-220.... Mine registers through all the ranges just fine.... (145ish is where I typically run). I actually have one in each cylinder head on my V-6... so I know exactly what both sides of my engine are doing at all times. (this is in addition to the temp alarm of course).

Its well worth the money for that piece of mind for me.

[Fletch170]

I purchased The teleflex "Eclipse" model that matches the rest of the brand spankin new gauges I have. This is intended for outboard use, as mentioned, the range is 100-200 degrees.

A lil tough ti find, but i got one, and paid through the nose. But, I think it's worth it:

http://www.ebay.com/itm/181588201654?_trksid=p2060778.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

I especially like the perimeters which are as follows "Cold- Good- FU*ked"

[Blue Agave]

IMO a water pressure gauge > temp gauge. At Idle you should get 3 - 4 Ibs of pressure, if you have that the water pump is suppling water to the block.