Swapping outdrive '79 Searay 898 Mercruiser

[KingFloyd]

Hello everyone
I have a '79 Sea Ray with a 898 Mercruiser (305 Chevy engine). After a series of problems stemming from not winterizing the boat, I decided it would be cheaper to replace the outdrive rather then changing the water pump .( I tried and failed miserably, frying another water pump and suceeding in getting my gear oil to look like a light green milkshake). Anyway....:
I found a used outdrive but I would like to know if it would bolt up directly to my gimble and the spline and driveshaft would fit without any modifications. I was once told my outdrive has a 1.5 to 1 ratio, but I'm not sure. Here is what the ad for the used outdrive states:

GOOD USED OUT DRIVE THIS IS A 1.74 R OR 1.72 R IT TURNS I AND 3/4 TIMES WITH 1 TURN OF THE PROP. IT HAS CLEAN OIL AND SHIFTS GOOD. THIS IS IN GOOD WORKING CONDTION NOT NEW IT IS A 1978 ? BUT IN GOOD CONDTION FOR ITS YEAR. THIS OUT DRIVE WAS USED ON A CHEV 305 V8 MOTOR AND I WAS TOLD IT WILL ALSO WORK GREAT ON A INLINE 6 CYL CHEV MOTOR .

Can this be a perfect match?
Thanks a million for any advice

 

[Don S]

Re: Swapping outdrive '79 Searay 898 Mercruiser

No, that is not the drive you want, wrong gear ratio.

I would bet money when you changed the water pump, you never read the oem manual, never replaced and probably lost the quad ring that goes around the oil passgae between the upper and lower gear units.
Does the drive still work, and have you tried reading the OEM service manual on how to do the reapairs? You can download the manual for free in the Adults only sticky at the top of the forum.

 

[KingFloyd]

Re: Swapping outdrive '79 Searay 898 Mercruiser

Thanks Don. Would the gear ratio make that much of a difference? And is the quad ring the little o ring, sealing the oil passage on the rim of the outdrive right next to one of the bolts attaching the upper unit to the lower one?

 

[Bondo]

Re: Swapping outdrive '79 Searay 898 Mercruiser

Would the gear ratio make that much of a difference? And is the quad ring the little o ring, sealing the oil passage on the rim of the outdrive right next to one of the bolts attaching the upper unit to the lower one?

Yes,... and Yes....

 

[starsnstripers]

Re: Swapping outdrive '79 Searay 898 Mercruiser

The ratio for a Straight L-6 165hp is 1.65:1. My ratio chart to my surprise does list the 1.65:1 for the 200(305ci) v8.If you get a used drive your still going to have to replace the water pump. You may have a seal in the drive leaking also. Why dont you have it pressure tested ans find out where it's leaking and fix it? I didn't see any 1.72 or 1.74 drive, there was a 1.78 which was for a 200(292ci) L-6 and then the 1.84 for many 4cyl. and other applications.

 

[starsnstripers]

Re: Swapping outdrive '79 Searay 898 Mercruiser

Also the chart i looked at is early 70s it may be that your year 79 is a 1.50:1 i'll see what i can find.

 

[starsnstripers]

Re: Swapping outdrive '79 Searay 898 Mercruiser

Everything i find for the 898 (305) is the 1.65:1 ratio. So the drive he has is probably right. But i'd make sure if your going to buy it. He says it came from a 305 but he doesn't know ratios. And who's to say someone didn't put the wrong drive on it? Good luck

 

[betayv]

Re: Swapping outdrive '79 Searay 898 Mercruiser

hi there check this link http://mercstuff.com/

 

[jaxnjil]

Re: Swapping outdrive '79 Searay 898 Mercruiser

Thanks Don. Would the gear ratio make that much of a difference? And is the quad ring the little o ring, sealing the oil passage on the rim of the outdrive right next to one of the bolts attaching the upper unit to the lower one?

not don;sorry

yes thats where the quad ring is.
the ratio could be workable but it depends on the elevation you run at more than any other factor.

if your at sea level or not much higher; no. if your higher yes it could but need to know what your elevation is.
this info is in the manuals don has made avalible in the adults sticky.

 

[starsnstripers]

Re: Swapping outdrive '79 Searay 898 Mercruiser

What does gear ratio have to do with elevation? Maybe fuel/air ratio (carb) I'm not diagreeing just curious what the relationship would be?

 

[jaxnjil]

Re: Swapping outdrive '79 Searay 898 Mercruiser

the higher the elevation the more gear you need to stay in the range of efficient prop pitches.

more gear compensates for loss of power due to lack of air,

if you dont know this then, theres a good chance you dont have this problem

 

[KingFloyd]

Re: Swapping outdrive '79 Searay 898 Mercruiser

Thank you all for your valuable advice. I will buy the outdrive as a spare since it's very cheap, but I will try once again to put a water pump into mine. Last time I put one (last week) I fried all the rubber inside to the point that the plastic housing melted. I bought another one today( a water pump) and I discovered that in between the impeller cup ( the metal cup where the impeller sits) and the housing there is a groove. My water pump kit comes with a rubber bushing which would sit perfectly in that groove. On the manual it does not state anything about inserting that bushing. Should I put that bushing in there or will that create unnecessary friction and heat?