LOW COMPRESSION/1989 MERCURY

G

GOOSER

Cadet
Joined
Dec 28, 2001
Messages
15
I AM CONSIDERING THE PURCHASE OF AN 80 HP MERC 1989 VINTAGE. CURRENTLY IT CARRIES 90 LBS COMPRESSION IN CYL 1 & 3. BUT ONLY 60 LBS IN CYL 2. MECH WANTS TO HONE & RERING ALL 3. ALSO NEEDS A STATOR AND CARB REBUILD. MECH THINKS SINCE IT SAT FOR 3 YEARS THERE IS RUST ON CYL WALLS. ANYTHING ELSE NEED TO BE CHECKED BEFORE I COMMIT TO BUYING IT???
 
F

Fouled Plug

Ensign
Joined
Jun 29, 2001
Messages
935
Re: LOW COMPRESSION/1989 MERCURY

Was the test done with the motor warmed up? If so, I'd give a decarb treatment a try before tearing it apart. Sitting will cause the piston rings to stick sometimes. I'd also check the lower unit lube, look for water and/or metal shavings.
 
G

GOOSER

Cadet
Joined
Dec 28, 2001
Messages
15
Re: LOW COMPRESSION/1989 MERCURY

THE ENGINE WAS NOT WARMED AND ALL PLUGS WERE REMOVED DURING THE ENTIRE TEST. ALSO NO ADDITIVES WERE USED...
 
R

Rex

Chief Petty Officer
Joined
Aug 12, 2001
Messages
424
Re: LOW COMPRESSION/1989 MERCURY

if them want 1500 for it then take off<br />for what the repair would be.<br />I would say buy it and run it for a little bit. and i bet you will be happy with it.<br />but do not pay them what they want.<br />I'm talking about a very good price to <br />take that chance.<br />good luck<br />Rex a. Hubble
 
A

alcan

Commander
Joined
Dec 14, 2001
Messages
2,505
Re: LOW COMPRESSION/1989 MERCURY

Gooser,<br />I would check everything.From the prop to the starter rope,from the gas cap to the end of the exhaust pipe.This is an expencive habit (I mean hoby)From Your description this motor dosn't sound like it has alot going for it.Did you want a winter project? If your mechanicly inclined, wanna spend a few bucks it might work out. Good luck.
 
F

Fouled Plug

Ensign
Joined
Jun 29, 2001
Messages
935
Re: LOW COMPRESSION/1989 MERCURY

Has this motor run at all? It may be as simple as cleaning the carb and firing it up to see what you really are looking at. Do not rely on cold compression readings, especially since the motor sat for 3 years. If it has not run since, it is premature for a mechanic to be talking rebuild. If you can get it running, check the hot compression. If not, your wallet may take a real beating on this one. Best to look for a good running used motor before buying a dead one.
 
G

GOOSER

Cadet
Joined
Dec 28, 2001
Messages
15
Re: LOW COMPRESSION/1989 MERCURY

ASKING PRICE WAS ONLY 750.00 WITH A STAINLESS PROP THAT NEEDS A HUB. THE MOTOR RAN FINE(I KNOW THE OWNER) UNTIL THE STATOR WENT BAD AND HE PARKED IT. SEEMS HIS WIFE GOT THE BOAT AND HE GOT THE MOTOR IN THE DIVORCE!!!
 
O

ODDD1

Lieutenant Junior Grade
Joined
Jan 23, 2001
Messages
1,054
Re: LOW COMPRESSION/1989 MERCURY

Gooser, the last 90 hp merc [1989] i bought damaged Ipaid $250 US for it...and it had a bad cylinder.....there has been some question on this board about proper procedure on a compression test, personally I do them cold and dry...a leak is a leak, hot or cold....if you are seeing numbers under 100 psi the motor is weak....if you got one down 30 from that, its a dead hole, no arguement...
 
G

GOOSER

Cadet
Joined
Dec 28, 2001
Messages
15
Re: LOW COMPRESSION/1989 MERCURY

GOT 2ND AND 3RD OPINION FROM OTHER MECHANICS AND THEY ALL AGREED THAT IT SHOULD BE RUN TO SEE IF THE (RING) LOOSENED UP AND COMPRESSION WENT UP. ALSO RECOMMENDED SEAFOAM IN THE CYLINDERS TO CLEAN THEM UP. ANY IDEAS ABOUT WHETHER THE CRANK MAY PIT OR DO THEY USUALLY REMAIN IN GOOD SHAPE FROM STORAGE?
 
F

Fouled Plug

Ensign
Joined
Jun 29, 2001
Messages
935
Re: LOW COMPRESSION/1989 MERCURY

The condition of the crank? Depends on if the motor was fogged for storage, the environment it was in, etc. I would run it on a break in mix of 25:1 for the initial start-up, at any rate. Not that it would help if the crank was pitted, but it should be nicer to the other parts! :D Good luck!
 
G

GOOSER

Cadet
Joined
Dec 28, 2001
Messages
15
Re: LOW COMPRESSION/1989 MERCURY

GLAD I LISTENED TO ALL OF YOU SEASONED VETERANS. ANOTHER MECH AND I BROUGHT IT INTO HIS SHOP AND REMOVED THE INSPECTION COVER ON THE LEFT SIDE. THERE WAS ICE IN THE WATER JACKETS AND AS THE FLYWHEEL WAS TURNED BY HAND WATER WOULD COME OUT FROM AROUND THE BOTTOM PISTON. DON'T KNOW IF THE BLOCK WAS CRACKED OR IF THE CRANK/BEARINGS GOT RUINED BUT I WILL AVOID IT. WILL BE LOOKING FOR ANOTHER OLD ENGINE. MAY HAVE FOUND A NICE 85 EVINRUDE 70HP. ON A BOAT. I FIGURE I CAN SELL BOAT & TRAILER KEEP MOTOR AS IT RUNS VERY WELL AND WAS JUST SERVICED BY MY FRIEND...THANKS FOR SAVING ME A LOT OF MONEY...GOOSER
 
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