Motor damage due to overheating

[Merctrubl50]

50 hp 1972 Merc 4 cyl Thunderbolt ign.overheated when key slipped out of old impeller shaft.Was told motor is now junk but it runs with new impeller and key.Mechanic says it has water in cylinder 4 and piston and rings must be ruined there .It ran about 4 minutes overheated at 5500 RPM.(Freshwater) Engine also has pitting under back cover and ruined gasket.Runs now with new impeller and key in old worn shaft but misfires on cyl 4 What most likely was warped damaged etc?Powerhead ?Maybe only gasket(s)?Have decided not worth repairing and engine is "junk" mechanic says .Would cost much more than $1500 offered by me to fix according to mechanic. BUT IT RUNS WITH :% LEVER UP AT IDLE.in neutral(#4 misses constantly and leaks water in ). If lever is lowered it quits.Please give worst case scenario and least worse case scenario.It runs! How much could it cost for a running engine to be fixed TO NOT LEAK ? Its old however and may not be worth it because other parts may go ?

 

[Deep_Blue]

Re: Motor damage due to overheating

do you know how long you ran it with out the impeller? how did you notice it wasnt cooling?

that sucks. sorry to hear that. even more reason im buying a water flow gauge (seems worth it)

 

[denny4]

Re: Motor damage due to overheating

Waterflow guage? Hmmm? How about some info on that since its new to me.

 

[Merctrubl50]

Re: Motor damage due to overheating

GUESS IT RAN ABOUT 5 MINUTES WITHOUT IMPELLER .I noticed blue smoke arising from motor cowl as it slowed down .I touched side of motor for a split second and realized it was boiling hot and water pump must of quit . Boater.... a friendly stranger towed me back to marina about 2 miles away .Refused to accept any payment after I offered $20 even.

 

[Texasmark]

Re: Motor damage due to overheating

Similar problem on OMC 3 cyl. Stat froze shut. Was at WOT and engine froze. Investigation revealed galling of piston to cylinder wall.....little chips of alum all over inside. Cost me an overhaul with a .030 over bore, new pistons, rings etc.

That engine didn't have an OT alarm. Current engine has one and stat stuck closed, but this time I heard about it before any damage was done. Phew.

Sorry for your misfortune.

Mark