1985 mercruiser 170 engine froze up

bayliner09

Seaman
Joined
Aug 13, 2011
Messages
67
Hi guys was wondering if anyone could help me I was given a 1985 170 4 cylinder it supposably ran when it was parked 6 YEARS AGO I poured oil in the cylinders when I got it home changed the oil found what looks like radiator fluid in it not a lot but some and let it sit for two days tryed to turn it over by hand but it won't budge not at all any suggestions from anyone I'm afraid to tap the key and try that, should I back off the lifters I just want to get oil circulating so I can check compression for prsible head gasket leak thanks guys
 

Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,453
If you found AF in the oil then suspect it was severely overheated and popped a head gasket. AF is 50% water so it coud have damaged a piston or cylinder wall.
Is the drive attached and does it have the correct amount of oil and not water, if in doubt remove the drive .
Easiest to just remove the head and look inside.
 

Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,453
shift into fwd gear, prop will lock if turned CCW, remove rams, remove 6 nuts ans 5 washers and pull straight back and off. Sometimes you need to just raise it and drop is to break it free but be warned it may slide right off.
 

HT32BSX115

Supreme Mariner
Joined
Dec 8, 2005
Messages
10,083
I'll have to figure that out before ordering parts thanks

There's a large group of people here on iBoats that are familiar (love/hate) the 3.7L/470 engine.

If yours is frozen, you should probably either get a reman longblock, or go to another different engine. But I'll leave the suggestions to "others"

Cheers,


Rick
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
51,385
a few places common to the 3.7 for coolant to mix into the oil

head gasket and cam bearings. both common failures. the exhaust manifolds are also a failure point

if AF sat in the cylinders, etc for a while, it would have rusted the rings to the bores. this would come from the head gasket

if the manifold failed, it would lead to rusted valves, rusted rings, etc.

if it was my boat, I would yank that motor, replace with a 4.3, make new motor mount pads and be on the water shortly after.
 

bayliner09

Seaman
Joined
Aug 13, 2011
Messages
67
Found the source of the problem there was a huge crack in the exhaust manifold going to lap valves and put it back together for now I'll post results
 

QBhoy

Fleet Admiral
Joined
Mar 10, 2016
Messages
8,348
Agree with what Scott D says. Change it now, before anymore misery.
If not, perhaps get used to overheating issues. Many will disagree and say just look after it properly...jeez, speaking from experience, they are just a nightmare, unless you enjoy replacing water pump seals, perhaps shafts...if not, prepare for many many overheating issues and ruined family days out. Just remember to tell your other boating friends to take extra fuel for the tow home or back to the boat ramp ! Patience, friendship and relationships will be tested...
Hate to be negative, but it's the truth.
Replace with a 4.3 after changing the engine mounts or if you can get away with it (on a light boat), stick a 3.0 in it.
All the best.
 

bayliner09

Seaman
Joined
Aug 13, 2011
Messages
67
Thanks for the reply boys I'll look into the 4.3 how hard is it will it bolt right up after changing the mounts I've done a couple fiberglass boat floors before
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
71,310
Ayuh,... The Biggies in that swap is the new side motor mounts, 'n a exhaust y-pipe,....
 

bayliner09

Seaman
Joined
Aug 13, 2011
Messages
67
And probably waiting for a deal on a used one or shelling out 7,000 for a compleatly new one
 

bayliner09

Seaman
Joined
Aug 13, 2011
Messages
67
And probably coming up with the right deal on one or shelling out the 7,000$ for a new engin on a 30 year old boat
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
51,385
Just look on craigslist for free boats. Guaranteed to find a rotten boat with a good motor for cheap
 

bayliner09

Seaman
Joined
Aug 13, 2011
Messages
67
Just finished browsing Craigslist not a thing except a rotten boat no motor with trailer 1000$ or bay liner with a 383 stroker that overheated for 500$
 

bayliner09

Seaman
Joined
Aug 13, 2011
Messages
67
Can anyone inform me what manual Is the best I'm overwhelmed with options motor serial is A409486 and outdrive A404686 thanks
 
Top