Running slightly warm

[dozerII]

Hey guys, been pretty quiet here for a quite some time as I have had no problems, but we all know that doesn't last for too long. This was the third season for my 1976 Starcraft Mercruiser 120 since it's restoration. I have not put a lot of hours on it (about 15 in three summers) but it has been out to the lake mostly for fishing. This spring I noticed the temp was a little higher than normal in the 160 range and slowly over the summer it got up to about 185-190, once in July both the wife and I thought we smelt rubber burning, I shut it down right away and checked everything out and all looked good.
So now that it's all winterized and in the shop I pulled the outdrive to check further on the warm running issue. When I split the upper and lower, I'm a little confused by what I found. The impeller looks real crappy, the copper tube that belongs in the upper was dropped all the way down into the pump, and the upper oring on the lower drive shaft had worked it's way above the upper seal??

What do the experts say.

 

[stonyloam]

I say replace the impeller and housing with OEM parts and you should be OK. The "rubber burning" smell was probably your engine exhaust bellows overheating from lack of cooling water. Take a good look back there to look for damage. I would not be surprised if your exhaust shutters are gone or in bad shape.

 

[Bt Doctur]

The vanes are pointing in the wrong direction that would make it run warm

 

[Bondo]

Ayuh,.... Probably need a fresh rubber bushin' for the water pocket cover to better hold the copper tube in the upper,...

Heat can make 'em hard, 'n slippery,...

 

[dozerII]

I say replace the impeller and housing with OEM parts and you should be OK. The "rubber burning" smell was probably your engine exhaust bellows overheating from lack of cooling water. Take a good look back there to look for damage. I would not be surprised if your exhaust shutters are gone or in bad shape.

I will have to pull the elbow to check the shutters, I'm thinking your right on the OEM parts.

The vanes are pointing in the wrong direction that would make it run warm

It was installed correctly, I just slid it back on for the picture.

Ayuh,.... Probably need a fresh rubber bushin' for the water pocket cover to better hold the copper tube in the upper,...

Heat can make 'em hard, 'n slippery,...

Is the water pocket bushing the only thing that holds the tube up?

Thanks for the info Guys.:thumb:

 

[Bondo]

Is the water pocket bushing the only thing that holds the tube up?

Ayuh,.... Correct,....

 

[dozerII]

Ayuh,.... Correct,....

Thanks Bondo, any thoughts on what would cause the oring just below the splines on the vertical shaft to work it's way up past the seal into the upper housing??

 

[Bt Doctur]

It was installed correctly, I just slid it back on for the picture.

That needs explaining because the driveshaft turns in a clockwise direction that makes the tips point the other way
That usually happens if it was installed dry and the shaft turned to align it with the coupler.Try some soapy water or K-Y, never grease or vasoline.
Look at this link time stamp 6:54
http://www.bing.com/videos/search?q=...=0&FORM=VDFSRV

 

[stonyloam]

I think he meant that it was installed correctly ORIGINALLY, but when he put it back on for the photo he slid it on upside down

 

[Bt Doctur]

I`ll buy that for the 3 vanes in the same direction but what about the other 2 that are visable

 

[bruceb58]

Do you ever start your engine without muffs? Even for a few seconds? That impeller has gotten overheated.

 

[dozerII]

Do you ever start your engine without muffs? Even for a few seconds? That impeller has gotten overheated.

I did once last summer, was just about to start the boat, answered the phone finished the call then started the motor without turning on the water:facepalm: shut it off in about 20 seconds

 

[bruceb58]

I did once last summer, was just about to start the boat, answered the phone finished the call then started the motor without turning on the water:facepalm: shut it off in about 20 seconds

Guess what....that could have done it.

I did something just as dumb...I started the engine and lowered the drive squishing the hose and stopping the water. I replaced the impeller. Not worth getting stuck somewhere.

 

[stonyloam]

I`ll buy that for the 3 vanes in the same direction but what about the other 2 that are visable

I have no idea LOL. Unless it got really hot when run without water and took a weird set?

 

[Oshkosh1]

I don't buy the 20 seconds and your impeller's toast theory...

I decided to test it a few years ago. I had to pull my lower unit to seal it so figured I'd sacrifice the impeller in the name of research. I fired the engine up and let it run 30 seconds bone dry. Pulled the impeller and it was fine. I think it takes more like a minute or so.