2000 150hp Mercury Outboard

Hi all,
I have a quick question. I have a friend who has a 150 Merc on the back of his boat. Last time he was out the over temp alarm went off. He noticed it did seem to be pumping water like it should be, Now he wants me to check the impeller for him. Is dropping the lower unit as simple as it appears to be? From what it looks like, its just a matter of a few bolts/nuts attaching the lower unit to the leg. It appears to have electric shift judging by the solenoid attached to the shift linkage on the side of the motor. Any surprises there?

BTW, if it were mine I would have bought a manual for it, but he hasn't.

TIA

Re: 2000 150hp Mercury Outboard

Get on youtube... They have a few merc waterpump videos.

I've never did one with the electric shift thing... But my black max 150 was a cake job.... Only problem i had was getting the shift linkage back together lol

Re: 2000 150hp Mercury Outboard

I do not see any evidence that the motor is an electric shift. I never heard of a Merc with an electric shift.

Has your friend checked the poppit valve and thermostats? That motor may not have the hidden bolt under the zinc anode. Remove and install gearcase with motor in neutral.

Re: 2000 150hp Mercury Outboard

Maybe what I was looking at wasn't a switch like I thought it was. The shift cable certainly appears to be attached to via a linkage. This is what I was looking at...sorry for the crappy pics. I didn't plan on needing them. I figured I could find an exploded few of the motor online if I had the serial number. Unfortunately, I haven't found one yet.





Serial Number


I've worked on several OMC motors in the past, and a couple Merc's, but nothing this new. I couldn't see any evidence of a place to disconnect a shifting rod on the leg like most other motors I've worked on. Am I missing something?

At Chris1956, he hasn't done anything with the motor. He didn't dare to. Didn't want to screw something up.

BTW, he was idling along when the over-temp horn went off. He looked back and noticed it wasn't peeing like he thought it should. He said he didn't have any weeds or anything wrapped around the water intakes.

Thanks for all the help!

Re: 2000 150hp Mercury Outboard

Chris1956 said:

I do not see any evidence that the motor is an electric shift. I never heard of a Merc with an electric shift.

Has your friend checked the poppit valve and thermostats? That motor may not have the hidden bolt under the zinc anode. Remove and install gearcase with motor in neutral.

Click to expand...

I wasn't familiar with the poppit valve so I researched it a little bit. Now that I know its purpose & function I think it's unlikely the problem. However, the thermostat very well could be! From what I understand the thermostats can cause overheating at idle, not so much at full throttle.

Re: 2000 150hp Mercury Outboard

I have same motor. Recently posted about high temp alarm I get after running for awhile and then dropping back to idle. I haven't tested on the water yet, but I found the plastic strainer screen a bit clogged. It's located on the lower port side, the plastic nut/fitting is accessible with the lower cowling removed. Cooling water flows from the strainer via a hose to the air compressor, top port side of engine. On that air compressor is a temp sensor, at least on my Optimax 150 anyway. My motor has one sensor at No. 1 cylinder and one on compressor.

Troubleshooting guide suggests that a clogged 'cooling water strainer' can be reason for low water pressure and for hightemp alarm.

I'm hoping that's the cause of my temp alarm - maybe your pal's too.

Re: 2000 150hp Mercury Outboard

webre said:

I have same motor. Recently posted about high temp alarm I get after running for awhile and then dropping back to idle. I haven't tested on the water yet, but I found the plastic strainer screen a bit clogged. It's located on the lower port side, the plastic nut/fitting is accessible with the lower cowling removed. Cooling water flows from the strainer via a hose to the air compressor, top port side of engine. On that air compressor is a temp sensor, at least on my Optimax 150 anyway. My motor has one sensor at No. 1 cylinder and one on compressor.

Troubleshooting guide suggests that a clogged 'cooling water strainer' can be reason for low water pressure and for hightemp alarm.

I'm hoping that's the cause of my temp alarm - maybe your pal's too.

Click to expand...

Thanks! I'll keep it in mind when I go look at the motor.

Re: 2000 150hp Mercury Outboard

Well, last week we dropped the lower unit. The motor has a splinded shifter shaft that just slips into itself. Nothing I've ever seen before, but a very simple setup none-the-less. As we dropped the lower unit we tried to figure out where to disconnect the speed-o-meter tube. We saw the fitting on the top of the lower unit but we didn't have a tool to get down in there. Eventually the tube separated from the coupler on the front of the motor's leg. When we reinstalled the lower unit we didn't do anything with the speed-o-meter tube. He never had it hooked up to begin with so we said screw it.

As for the condition of the impeller and housing; everything looked fine. The impeller was a little bit dry-rotted but nothing too serious. Since we had it apart we replaced the impeller and housing anyway. After we buttoned it all up and fired up the engine, he said it pumped better than it did before. I honestly don't know. I didn't test run it before.

He didn't want to mess with the thermostats at this point. He's going to run it for awhile and see if he runs into any other problems. If so, then we'll pull them. Had it been my motor, I think I would have pulled the t-stats. I wasn't convinced the water pump was faulty. We'll see though.

Thanks for all the help on this people!

Re: 2000 150hp Mercury Outboard

Dry rot on the impeller indicates it was faulty. It had to be replaced or you would have had cooling issues. You also replaced the stainless steel wearplate and the two gaskets, right?

Re: 2000 150hp Mercury Outboard

Chris1956 said:

Dry rot on the impeller indicates it was faulty. It had to be replaced or you would have had cooling issues. You also replaced the stainless steel wearplate and the two gaskets, right?

Click to expand...

Sure did. I used everything in the kit.

Re: 2000 150hp Mercury Outboard

Ran the boat in a fishing turnament this weekend and the problem persists. Now he's going to swap the thermostats and see what happens. Apparently it wasn't the impeller. :-(