98 4.3 mercruiser

[Capri#dragster]

long story short I put a newer motor in my 91 Bayliner Capri an I’m in the process of switching everything over from V style belts to serpentine. I have everything else in place but I have no idea on where to mount the idler tensioner. I know it goes above and to the left of the water pump. But not sure where it bolts to. If someone could tell me what bolt holes to use on the motor itself or could take a picture of where theirs is mounted I would really appreciate it.

 

[Scott Danforth]

Welcome aboard

you will need all the belt accessories, pulleys, brackets off a 1996 or later motor. no mixing or matching because it wont work. between the 1991 motor you had and the 1998, the motor has gone thru two major re-designs.

basically the 4.3 V6 families are below (although Im a bit fuzzy on the changes from 2007 on as I havent dug into them as much)

1985 - first year of production, 2-piece RMS
1986 - 1-piece RMS
1987 - Block changes, head changes
1988-1991 - Block and head changes
1992-1995 - New block - balance shaft added, new heads
1996-2000 - Vortec heads added, Block changes, timing cover changes
2001-2007 - minor block changes
2008-later - more minor block changes
believe 2015-another revision

use the parts break down to see where everything goes.

also, you will need to change your motor mounts from the big squishy ones from the 1991 motor to the style used after 1992 (balance shaft motors)

 

[gergAlicious]

On my 2004, facing engine, top right ear goes to larger bracket that has the lift ring on top (also mounts the OD oil container and remote oil filter). Lower mount ear connects to a short bracket from power steering. Lower left attaches to block near timing cover.

 

[gergAlicious]

Here are some pics. Apparently there are two lower ears.

Here arethe bottom two connections - left to block, right to the power steering pump bracket:

Here is the upper connection:

So I was wrong in my first post. There is no connection at water pump. Just one high, and two low.

These may help also:

 

[Capri#dragster]

[No message]

 

[Capri#dragster]

The above pic is what my motor should look like when finished. That is the same belt routing that I will have. If you’ll look just above and to the left of the water pump that is my tensioner. But I have no idea where to bolt it on at. Block???? Head???? Or part of the water pump????

 

[gergAlicious]

My guess would be the front of the starboard head. There are three holes there.

 

[achris]

This implies you are using the alternator and water pump (and I suspect, starter motor, fuel pump and distributor) for the automotive donor engine. Very bad idea.

Remove everything from the donor engine until you are down to a long motor, then build it back up with the marine certified accessories from the old broke engine. ..

Chris. ....

 

[Scott Danforth]

if the 98 motor is an automotive/truck motor, Chris is correct, you would strip it down to an assembled short block with the heads off, knock out the steel core plugs, install brass, install marine head gaskets, then get a 1996 and later marine circulating pump and all the brackets from a 1996 and later marine motor along with the marine rotating electrics, etc.

you could use the brackets, v-belt setup, etc. from your 1991, however you will need 1/4" spacers for the water pump pulley, and half the brackets to get things to line up.

 

[Rick Stephens]

If you wonder why you need a marine water pump and alternator, those are pretty easy questions to answer. An automotive water pump is made to run in glycol and not plain water. They rust out literally in no time at all used on an open fresh water cooling system. The alternator in a car is not particularly protected from spark generation, a marine alternator is. A boat is a perfect fuel air bomb container in the event of a fuel leak. All it takes is one ignition source to make it go boom. A car is open at the bottom and all the fumes and leakage fall out the bottom. Don't build a bomb. Fiberglass boats burn really well.

 

[Scott Danforth]

 

[Scott Danforth]

 

[Capri#dragster]

Seems we are getting off topic. All I need to know is where to mount the tensioner. I have already completely rebuilt the motor. Just didn’t have the brackets and pulleys for the new motor. I now have those. But not sure where to bolt on the tensioner

 

[Rick Stephens]

If safety is off topic, you are in the wrong forum.

 

[Bondo]

Seems we are getting off topic.

Ayuh,..... Welcome Aboard,..... Not really off topic, as You haven't answered any of the questions 'bout the origins of yer build,....

Is it a pickup motor,..??

 

[Capri#dragster]

Yes this is a boat motor yes it came off of a boat the only thing different is that I am putting a much newer model motor and to my 91 model boat. So I had to change the whole front and over to a different belt system I already have everything to mount it on I just do not know where the tensioner belt to does anyone have a picture of their boat that can show me where the tensioner bolts onto