Merc 3.0 engine/drive alignment question

[craze1cars]

Just replaced a rotted front engine mount, and I understand the importance of using the proper tool to ensure proper engine alignment for the driveshaft. However...it would seem that the particular design of my boat makes alignment impossible anyway. Here's what I've got:<br /><br />1992 Rinker 181 with 3.0 Mercruiser Alpha 1. The only adjustable engine mount is a single front mount, the big "A" frame up by the pulleys allows typical up/down adjustment. Where I would expect to find 2 adjustable rear engine mounts near the transom for adjusting height and engine "twist" there are none...just empty mount brackets that are simply hovering several inches above the hull. This boat is designed so that the full weight of the rear of the engine is being supported by the transom itself with basically a large plate/bracket and approx 6 or 8 bolts going through the transom, with the transom sandwiched tightly between the gimbal housing and the engine. The engine is bolted tightly to this plate, which in turn is bolted tightly to the gimbal housing through the transom. There are no adjustments here.<br /><br />It would seem to me that this method would be permanantly aligned, as any movement of the engine is followed by the entire gimbal housing/outdrive AND the transom itself. If I adjust the front of the engine up or down, it'll simply twist and stress the entire transom, but I see nowhere that driveshaft alignment would change.<br /><br />Am I misinterpreting this? I see no benefit to buying an alignment tool if there is nothing to adjust. I am planning to simply adjust the front of the engine up/down as needed with the lone adjustable mount to find the most neutral position that relieves as much twisting stress from the transom as possible. Surely this isn't unique design...is there a hidden adjustment here that I can't readily see? Any other tips/thoughts would be appreciated so I can be sure to get this engine properly positioned.

 

[rabidfish]

Re: Merc 3.0 engine/drive alignment question

Yes, you are misinterpreting the issue. Good thing you posted! We can help!<br /><br />The engine mount in the rear is typical of every currently produced sterndrive, regardless of manufacturer. So is the front for the 3.0L<br /><br />The engine alingment is for (up and down) alignment. The rear mounts(as well as the fixture used to drill the holes) hold the side to side alignment in place. <br /><br />It is important to make this adjustment. The only way I know how is with the "alignment" tool.

 

[Don S]

Re: Merc 3.0 engine/drive alignment question

Along with Rabid's information, "ALL" of the parts for the rear mounts must be there and in good condition or you will not be able to get the alignment to work. Then you will be replacing couplers quite often (engine and drive pull plus a $300 plus part)<br /><br />

 

[trog100]

Re: Merc 3.0 engine/drive alignment question

BMW made an drive/engine arrangement that simply hung on the transom.. the engine was mounted in a steel tubed frame that mounted thru the transom to the gimbal housing with eight or so large bolts.. there was no alignment needed.. the rear of the engine bellhousing which contained the gimbal bearing was supported by a large rubber doughnut all part of the arrangement that bolted thru the transom to the gimbal housing.. it was all designed to be aligned when assembled..<br /><br />i can visualize what craz1cars is describing.. if the rear of the engine is bolted thru and supported by the transom and bolted straight to the gimbal housing and all clamped together it wouldnt be possible to adjust such an arrangement either.. only at the front to relieve stress on the transom..<br /><br />or has craze1cars carefully described something that dosnt exist.. ???? <br /><br />trog100

 

[craze1cars]

Re: Merc 3.0 engine/drive alignment question

Actually, I apparently described poorly. The photo provided by Don S very clearly shows what I have at the rear of my engine by the transom. I take it that these are the adjuster bolts...I thought they were rigidly mounted. I will apparently be getting my engine alignment tool and using it appropriately. So....now that I see these two bolts exist, how do they work? Do I simply turn bolt E in (down) to bring that corner of the engine up? Is there a locknut or anything here I need to be concerned with or do I just put a wrench on it and go?<br /><br />Incidentally...I'd like to say I'm a bit disappointed in my "Clymers" Mercruiser shop manual. This is one of several holes I've discovered...they don't even mention this type of adjustment. Thanks all for your help and assistance.

 

[DHPMARINE]

Re: Merc 3.0 engine/drive alignment question

The two bolts you are refering to are torqued down tight and are not adjustable.There is no reason for your 3.0 liter to be out of whack left or right.What is adjustable is the front of the engine,to align it with the outdrive.<br /><br />DHP

 

[craze1cars]

Re: Merc 3.0 engine/drive alignment question

That's what I thought...I put a wrench on 'em and both were bottomed out tight like you say, which leads me back again to my initial question...what's the point of adjusting the front bolt if everything to the rear is rigidly mounted and is going to move right along with the engine? Or are those 2 rear bolts set in rubber mounts or have space in them that allows some flex or something? If that's the case, that would explain it. Thanks again for all the tips.

 

[DHPMARINE]

Re: Merc 3.0 engine/drive alignment question

Trog100,<br /> I don't know about the BMW setup as I have yet to see one in a boat.Same thing with the Mercruiser/BMW connection.I'd love to see a Toyota setup,but that hasn't happened.<br /> Years ago Mercruiser used a Renault engine that was suspended solely by the transom,and Volvo did it for many years,until they switched to U.S. motors.<br /><br />DHP

 

[rabidfish]

Re: Merc 3.0 engine/drive alignment question

what's the point of adjusting the front bolt if everything to the rear is rigidly mounted and is going to move right along with the engine? Or are those 2 rear bolts set in rubber mounts or have space in them that allows some flex or something?

You are adjusting the front of the engine to align the coupler with the gimbal bearing. This is a vertical adjustment. The two bolts cannot support the weight of an engine, let alone one bouncing along in the water.<br /><br />If you do not ensure the coupler bore is straight with the gimbal bearing, the rubber portion of the coupler will self destruct in relatively short order. (read: removing the engine again)

 

[rabidfish]

Re: Merc 3.0 engine/drive alignment question

Trog,<br /><br />Some of the early Volvo's used a set-up like that also. (B-20 i think) It had great access to the entire engine... Even had 1 1/2 feet clearance for the bilge pump... Ah... those were the days!

 

[rodbolt]

Re: Merc 3.0 engine/drive alignment question

yep<br /> you could even remove the volvo 4cyl oil pan to weld the rust through at the drain plug without removing the engine.

 

[Don S]

Re: Merc 3.0 engine/drive alignment question

Get a Mercruiser manual. It has 4 pages of detailed instructions on how to adjust the alignment. The rear mounts are rubber, and need to be in good shape. Not sure what you are trying to adjust on the front, but there are not 2 bolts there for adjustment.<br />And it don't mean squat what BMW and Volvo did, this is how MERCRUISER does it.<br /><br />

<br /><br />

 

[rodbolt]

Re: Merc 3.0 engine/drive alignment question

ohhh Dons the picture is killing me.<br /> maybe we should write seloc and clymers tomake manuals with softer,more absorbent pages .<br /><br /> ya also have to remember we are dealing with an automotive tech. usually have long sloping forheads and wide set eyes with disproportionaly long arms

 

[craze1cars]

Re: Merc 3.0 engine/drive alignment question

hey....I resemble that remark...

 

[rabidfish]

Re: Merc 3.0 engine/drive alignment question

LMAO!...............oops... sorry JB

 

[rodbolt]

Re: Merc 3.0 engine/drive alignment question

hahahaah<br /> glad ya got some humour <br /> I worked on autos for a time. cant run them wide open without getting a ticket so I changed years ago.<br /> ya got a handle on alignment and why now? the rear mounts are rubber pressed into the "ears" on the bell housing.

 

[Don S]

Re: Merc 3.0 engine/drive alignment question

Danger Will Robinson, Danger !!!!!!!! <br /><br />

 

[rodbolt]

Re: Merc 3.0 engine/drive alignment question

hahahaahah oh my god. hahahaahah

 

[rodbolt]

Re: Merc 3.0 engine/drive alignment question

but how do you change the arm bellows?

 

[Don S]

Re: Merc 3.0 engine/drive alignment question

ARM BELLOWS?????? Thems is easy....wanna think about the crotch bellows?..............<br />Hmmmmmmmmm I had that manual here someplace.....let me look