Where's the water pump on my Mercruiser?

[northernmerc]

I have a 1992 Sea Ray with a 4.3 Mercruiser that we bought new seventeen years ago. The water pump has never given trouble, and I've never touched it. I always assumed that the water pump was on the front of the engine, driven by a pulley and belt. But after looking through posts on this site, I'm wondering about this.

Can anyone tell me if this engine has a water pump on the front of the engine or is it somewhere in the leg? If it's in the leg, maybe it's time to change the impeller???

Thanks for your help.

 

[Don S]

Re: Where's the water pump on my Mercruiser?

Depends on which drive you have. And what cooling system.
A Bravo drive has the raw water pump belt driven on the engine, Alpha drives NORMALLY have the raw water pump mounted in the drive. BUT, on some occasions, they could have a belt driven pump, and possibly even both.

 

[Fun Times]

Re: Where's the water pump on my Mercruiser?

I have a 1992 Sea Ray with a 4.3 Mercruiser that we bought new seventeen years ago. The water pump has never given trouble, and I've never touched it. I always assumed that the water pump was on the front of the engine, driven by a pulley and belt. But after looking through posts on this site, I'm wondering about this.

Can anyone tell me if this engine has a water pump on the front of the engine or is it somewhere in the leg? If it's in the leg, maybe it's time to change the impeller???

Thanks for your help.

Your impeller should be between the upper & lower unit of the stern drive, See number 27 in this link so you have an idea of where it's at. http://www.mercruiserparts.com/Show...=GEAR+HOUSING+(DRIVESHAFT)(STANDARD+ROTATION)

If it's been 17 years ago then it's more then likely it's time for a full service for the engine, And the stern drive needs a service also, And that would be pulling the drive off and everything checked out and greased up. Good luck with it.

 

[cr2k]

Re: Where's the water pump on my Mercruiser?

The pump on the fromt of the engine bolted to the block is called a circulation pump. There is another pump as Don said either on the engine (usually mounted on starboard side and low) or, and most likely in the outdrive.

Separate upper and lower and it is on top of the lower around the vertical drive shaft.

This is a regular maint. item as they either wear with use or the rubber gets hard and set.

Interval should be no more than 2 years, so yes you are lucky if it is still cooling.
Also make darn sure you have all the parts to the impeller or you will have problems.

 

[northernmerc]

Re: Where's the water pump on my Mercruiser?

Thanks for the info. I'm quite sure it's an Alpha drive, so I guess it likely has a water pump in the leg.

According to the temp gauge, the motor cools well. If anything, it cools a little too well. When new, the gauge used to read at 160 or a little higher. For a number of years now, it likes to run just under 140. Even after changing the thermostat, it still runs there. Maybe it's just that the gauge isn't totally accurate?? Can anyone think of any other reasons for running cool?

Otherwise, the motor has given great service. One change of spark plugs, in addition to oil changes, has been about it for maintenance. It likely helps that the boat is trailered for each use and lives in a garage between uses.

 

[Lyle29464]

Re: Where's the water pump on my Mercruiser?

I would take this boat to a shop for a complete service. The heart of the water pump is neoprene and is way past its life. Like others have said you need to service the drive and you really need a shop to do this. They remove it and check bearings and u-joints plus the boots. A manual heat gauge will screw in the sending unit hole and tell you what is going on. I would get one. Many reasons why it reads 140. I would replace the thermostat. Check book for right one. saltwater use requires a different one.

 

[zbnutcase]

Re: Where's the water pump on my Mercruiser?

saltwater use requires a different one. Huh?? 'nutcase

 

[northernmerc]

Re: Where's the water pump on my Mercruiser?

I would take this boat to a shop for a complete service. The heart of the water pump is neoprene and is way past its life. Like others have said you need to service the drive and you really need a shop to do this. They remove it and check bearings and u-joints plus the boots. A manual heat gauge will screw in the sending unit hole and tell you what is going on. I would get one. Many reasons why it reads 140. I would replace the thermostat. Check book for right one. saltwater use requires a different one.

Thanks for the advice. Disassembly and inspection sounds like a good idea.

Most likely I would do this myself, considering the poor results I've had with the OMC dealer and their warranty work on my Johnson outboard. I ended having to redo their work and fix other things they missed. Although I've never had one of these apart, I've worked on outboards, cars, and heavy equipment for more than forty years. The manual should help me through this.

Regarding running cold, I did change the thermostat a few years ago with the correct part. Doing so made no difference, but maybe I should try that again. Last time I removed the thermostat, the two long bolts that hold down the thermostat cover seemed on the verge of snapping because of rusty threads. I did put a generous amount of lubricant on the threads before reinstalling them, so hopefully that will help them come out without snapping. Next time, I'll probably try new bolts and proper anti-seize.

I've checked the operating temp of an outboard using a hand-held laser sensor. I suppose that is an option with the 4.3. Any idea what temperature one should look for when taking a reading, lets say in the area where the intake manifold joins to the head? Or is there a better spot to take a reading?