Merc 5.7L fresh water pump issue...getting hot...best way to resolve?

[Kedwards68]

I recently purchased a 1996 Regal Commodore 292. It has dual carbureted Merc 5.7L with Alpha drives...gen 2 I believe. On the hose with water to stern and fresh water intake both motors start and idle well. I never have run the motors above 3000 rpm and above idle only for a second or two. The boat is new to me and I have let it idle for a while while checking out other systems. After a while I have had the motors get hot enough to set off the alarm. They were shut down immediately. I had a smaller Regal that would get warm on the hose on a long saltwater flush so I didn't think about it too much. I finally put it in the water and both motors got hot about the time the boat got on plane. I shut it down and was lucky enough to coast back to the dock. I'm thinking the hose pressure might have made up for impeller insufficiency. Sea-cocks were open.An impeller issue is the first thing I will check. I'm trying to find info on the removal of the freshwater pumps. The stern drive impellers I am familiar with. It looks like I can remove the whole bracket with the pump attached to it. Is this the best way to get it out? I've watched videos on it but the motor is out of the boat. I need any advice I can get on replacing the fresh water impellers with motors in boat. Also on anything I could be missing.

 

[achris]

You had both engines, equipped with belt driven raw water pumps, running from a hose at the same time? There's the problem. EACH of those pumps is more than capable of sucking more water than a hose would ever be capable of supplying. With 2 engines. .. I strongly, as I think you are, suspect you have destroyed both pumps. ..

Getting them off the engine is the same, regardless of whether the engine is in the boat or out. The videos showing how is done with the engine out is done like that for clarity. If they try to make that video with the engine in the boat, all you'd see is a guy with his hands under an engine... not so useful. .. Follow the same instruction. ...

Chris. ...

 

[alldodge]

Removing the whole pump is the easiest if you can get at them. Once out they can be repaired on the bench. Note which hose goes where and normally the bottom hose comes from the drive, but make sure to take note of position.

Once pump is apart note the direction the impeller is twisted in place, reinstall with same twist using soap. Look for grooves in the housing, if they have grooves housing may need to be replaced. Also look for grooves on the stainless wear plate

Also if pumps will be replaced with boat in the water have some rope handy to tie the intake hose up high

 

[thumpar]

Remove the pump not the bracket. They are pretty easy to get out once you figure out the best way to get at them. Remove the hoses. Remove the 4 bolts to take the pulley off the front. Then there are 3 nuts that hold the pump to the bracket. The pump can then be pulled back out of the bracket and it is loose. Fish it out of the engine bay. Do the work on the bench. Putting it back on is in reverse.

This year I got lots of practice. The first time I put it on a found an o-ring still in the package after getting it mounted. Took it off and put the o-ring in. When I remounted it I got it on upside down. 3rd time was the charm.

 

[Kedwards68]

Thanks for the help! I'm going to try to find some more videos and give it a go. The port engine has enough room that I may be able to get just the pump off the starboard I'm not too sure of. I'm not the smallest individual. That may determine how successful I am. If I decide to have the work done for me, how much should I expect to spend on the repair?

 

[alldodge]

Most charge by the hour plus parts. I would see this being a 2 hour billable job but won't take that long with a guy who's done some. Going rate in your area determines, at least 50 and up to 100 hr

 

[Bt Doctur]

The impeller in the drive will do nothing but cool the drive oil and the hose is most likely cut in half at the gimbal and is plugged/capped inside at the transom.
The engine mounted pump is the one doing all the work .These motors have fresh water cooling?

 

[Kedwards68]

They have a closed cooling system for the motors. Outdrives have their own impellers.

 

[Kedwards68]

Most charge by the hour plus parts. I would see this being a 2 hour billable job but won't take that long with a guy who's done some. Going rate in your area determines, at least 50 and up to 100 hr

Would that be 2 hours per motor or total?

 

[alldodge]

Would that be 2 hours per motor or total?

I'm guessing but yes 2 per motor. Suggest just call, I'm sure they can give you a figure

 

[kenny nunez]

Just a curious question. Is the drive pumps supplying water to the engine pumps, or as previously stated, disconnected and only cycling water to keep the drive oil cool ?
If the drive pumps are connected to the engine pumps without a “Y” connection drawing water from the bottom additionally then the engine pumps are starving and the impellers burned up and will continue to do so.

 

[Kedwards68]

Just a curious question. Is the drive pumps supplying water to the engine pumps, or as previously stated, disconnected and only cycling water to keep the drive oil cool ?
If the drive pumps are connected to the engine pumps without a “Y” connection drawing water from the bottom additionally then the engine pumps are starving and the impellers burned up and will continue to do so.

The two systems are separate. Engine pumps pull from seacocks. I'm sure the engine pump impellers are shot. My thought was that with my outrageous water pressure from my hose that the fake-a-lake feeding the engine pumps circulated enough water to keep the engines fairly cool with impellers that were already compromised.