2003 mercury 150

[askipper3]

any good feedback on this engine? I have on on the seacraft( still dont HAVE it), and he started it for me and it took lik a minute for the water to start coming out. He says the temp sensor needs to heat up. Once that happens shes spits strong. It sounds great tho. Also I jus want to know if it's reliable, i had a 2001 90 on my seafox and i nevr had a problem.

[gbf03]

Is it it a efi opti, dfi, or carb? 2 stroke or 4 stroke? I had a 2001 150 efi on my 20 sf and performed well.

[Bigshrimpin]

That's normal for 2 stroke motors with the poppet valve. The motor builds up h20 pressure and then the poppet will open.

[askipper3]

Good to know that,(wher'd ya find theh diagram?) and yes it is a 2-stroke carb, saltwater edition.

[eggsuckindog]

The Carb motors are really tough, all of them.

[Fr. Frank]

The Carb motors are really tough, all of them.

Yes, but never, never, never take out the poppet valve and run your engine like that. The poppet valve raises the water pressure in the water jacket of the engine. Without it, portions of the block & water jacket can run "dry" and overheat and warp.

[Bigshrimpin]

http://www.biggerhammer.net/mercury/
It's like cliff notes for two stroke merc engines

I got the diagram off that site, but it's right out of a service manual.

[Blue_Heron]

Good to know that,(wher'd ya find theh diagram?) and yes it is a 2-stroke carb, saltwater edition.

Also, if you look at the diagram, the teltale is downstream of the thermostats, so it won't pee until the heads heat up to operating temp and at least one of the stats opens. Both my V6 Mercs take two to three minutes to warm up and start to pee.
Dave

[Bigshrimpin]

Just to reaffirm what Fr. Frank is saying about the importance maintaining your cooling system - impeller, thermostats, and poppet valve . . . just look at the warranty statement from OCC on their rebuilds.

http://occcranks.com/warranty_info.html

*NOTE: The number one (1) journal on V-6 Mercury crankshafts is not included in the one year breakage warranty.



#1 is the cylinder that goes on the 2.5L motors . . . usually b/c of a stuck thermostat, worn impeller, or bad poppet valve.

[Blue_Heron]

#1 is the cylinder that goes on the 2.5L motors . . . usually b/c of a stuck thermostat, worn impeller, or bad poppet valve.

#1 is the cylinder that went on my '91 150 XR4. Ate a ring six months after I bought it. Had low compression only in #1 cylinder when I bought it but I took a chance 'cause the price on the boat was so good. Had the powerhead rebuilt and no problems in three years. I change the impeller every two years. Some do it every year, but my water pressure gauge still shows very good pressure after one year.

A note on the poppet valve; if it's installed incorrectly, as mine was during the powerhead rebuild, it can result in excess cooling water pressure and air in the cooling system. The poppet is basically a pressure regulator. If you look at the cooling system diagram posted by bigshrimpin, you'll see that the hose to the poppet is attached at the high point of the water jacket. When your impeller is nice and fresh, it produces about 25-30psi of pressure at speeds above idle. Because the water pickup on the lower unit sometimes picks up air, there has to be a mechanism to purge the air from the cooling system. The poppet purges the air and bleeds off excess pressure at the same time.

As it was explained to me, if the poppet diaphram is installed incorrectly, it don't bleed off pressure or air. The result is high cooling water pressure and the engine still gets hot because there's air pockets in the cooling system. Mine's fixed now, but it was a learning experience.

Disclaimer: I'm no mechanic. There are plenty of folks on this site who know more than me about this stuff. But I like to tinker and learn about how things work. If anyone sees something I've got wrong, please feel free to step in and make corrections.

Dave