3.0 mercruiser overheat

[sidingguy]

!987 Slyvan Offshore 3.0 . Motor had'nt been run since 99.Fresh gas,new points plugs etc and away it went.25 lbs oil pressure 180 190 temp on muffs. Off to the lake.After about 20 minutes easy running it got warm so back to the trailer.New water pump impeller ,old one was shot. Noticed leak under bell housing any connection with overheating?Can't see under there from inside boat .Maybye shift cable bellows?

 

[Scott Danforth]

Leak from bellhousing is either a failed bellows or a cracked block

 

[tpenfield]

Leak for the bell housing could be from a variety of places, but checking all of the bellows would be a good place to start. The only factor for the overheating issue would be if the inlet hose that attaches to the bell housing is cracked.

Seeing as how the boat has apparently sat for 18 years unused, all of the rubber pieces (bellows, hoses, etc) could be suspect.

BTW - 180-190 F degrees running on the muffs is not that great.

 

[Alumarine]

Should run at 140 whether on muffs or in the water.

 

[Grub54891]

There is a core plug inside the bellhousing. If it froze it will be pushed out. Happened to me, but not by me, like that when I got it. Easy fix if nothing else is cracked.

 

[fishrdan]

99, you need to replace all the bellows. I would do the lower shift cable at the same time (use a genuine Mercruiser/Quicksilver cable)

As for overheating, did all the pieces of the old impeller come out, or were there vanes missing? If vanes were missing, you need to find/remove them as they can restrict water flow. Freshwater or saltwater? It may be worth it to pull the manifold and riser to check for restrictions, and inspect the riser->manifold sealing surfaces.

Use a mirror or snap some pics with a smart phone, to see where the water is leaking by the bellhousing.

 

[sidingguy]

Bellows ,all in good shape only one vane broken on impeller and I found that at the time of replacement.Pulled thermostat and found it was was broken! Leak at bottom of bellhousing is wait for it ROTTEN TRANSOM!!! Bottom 3 inches is mush.Filled bilge with water and it leaked out around gimbal ring. Looks like next post will be in Restoration!