Mercruiser coupler runout

[ivboost]

Hi guys, I have a problem, I have just put 2 new vortec 350's in my boat to replace the old 228's and because the new engines are 1 piece rear main, I bought 2 new couplers, Sierra 18-2172 to fit the newer crank pattern. I've just fitted both engines back into the boat and tried to align the gimbal bearings only to discover both couplers have runout, worst part is I'm in Australia and I bought both couplers from boater152 on US ebay. What should I do?

 

[84EdH]

Re: Mercruiser coupler runout

Hi, and welcome to the iboats forum world! First how have you come to the conclusion both couplers have runout? Not to be picky about terminology, but it is important here. Aligning the gimbal bearing is only part of the process of aligning the engine.

I don't know how much experience you have with engine alignment, but the chances of the alignment process being off is waaayyyy bigger than two new couplers having runout. Of course anything is possible.

Fill us in with some more details: your outdrive types and serial numbers, what have you done so far? gimbal bearing replace? gimbal bearing alignment, engine alignment, where are you with getting the alignment bar into coupler etc. and you know there are oem manuals available, alignment procedure, and videos all available at the head of this forum in the adults only section.

BTW, once you get all this right, your boat is going to fly!~

 

[ivboost]

Re: Mercruiser coupler runout

I have a shaft from a outdrive with the uni mounts machined off and where the gimbal bearing runs it has been machined down by 1/8 it has been taped up the end so I can screw a long bolt in it so I can pull it out. Now what is happening as I turn the motor over 90 degrees at a time, the shaft is pressed hard against on side of the bearing, as I rotate the engine by 90 degrees further the pressure of the shaft onto the bearings moves around 90 degrees further, indicating the coupler is on the ****... One is not to bad in and out by hand on all quarters, keep in mind it has Been machined by 1/8 the other is not good at all.....

Drives are alpha one, new bearings and have been aligned with a standard drive shaft, I have a few

Can't wait to get her back in the water it is a bertram 28 flybridge

 

[84EdH]

Re: Mercruiser coupler runout

Lots of thoughts: first, if your makeshift alignment bar is machined down 1/8 where it fits through the gimbal bearing, the bearing may not be set 100%. Next, I am not sure how you set the gimbal with any amount of force with just a long bolt tapped in. at any rate, I would first try to adjust the "set" on the gimbal bearing and see if I get any improvement.

Next, I would re-suspend the front of the motor, with rear mounts torqued, and be super careful about getting each front mount lower nut holding same weight, then turn carefully each nut the same from then on with any up/down adjustment.

Once I got the bar in/out as smooth as I could, I would test at 12:00, then 180, to 6:00 and try to even out just the up and down as best as possible. then start with 90 degree checks. as a last restort, you can loosen the front mounts to the stringers and try a tiny bit of leverage to get the front of engine to move sideways, even 1/16th might help. I have done this using a bar and a wedge shaped block of wood to hold the engine while I tested align bar again. then torque down, and final check alignment. my last thought would be a "runout" coupler. good luck!

 

[alldodge]

Re: Mercruiser coupler runout

Sounds to me like an incorrect matting issue between the crankshaft, flywheel and coupler. Did you do anything to make sure everything matted flush?

 

[84EdH]

Re: Mercruiser coupler runout

Dodge, I don't follow. besides bolting it all together, what else is there to mate?

 

[alldodge]

Re: Mercruiser coupler runout

There is also a possibility you should have changed out the flywheel and used coupler 861523A9
Engine Coupler Assembly for Mercruiser 861523A9 18311A17 - Sierra 18-2412 - iboats

 

[alldodge]

Re: Mercruiser coupler runout

Dodge, I don't follow. besides bolting it all together, what else is there to mate?

The OP is going from a 228 (305 cuin) to a new 5.7 cuin. The 305 used two different couplers between 1982 and 1984. I'm guessing since the pervious Sierra 18-2172 part was used is bolted to the crankshaft. The Vortex engines bolt to the outside of the flywheel.

 

[84EdH]

Re: Mercruiser coupler runout

yeah, I just presumed using the conversion coupler, bolted to the crankshaft was all there was too it. Not that I've seen all coupler style, but I have never seen the one you listed above. My experience was either crank mounted or triangular coupler to outside of flywheel

 

[alldodge]

Re: Mercruiser coupler runout

The new ones look like the above but not always. Probably should have shown this one
Engine Coupler Kit for Mercruiser 18643A7 - Sierra 18-2175 - iboats

which is the other type used on the 228 Mercs

 

[84EdH]

Re: Mercruiser coupler runout

Aaah I see now

 

[ivboost]

Re: Mercruiser coupler runout

I firstly checked the alignment of the gimbal bearings today with a genuine mercruiser tool and can confirm both bearings are aligned so I removed the engines and couplers today held them in the lathe and mic'd them, both are way out of center, so I require new couplers

I'm running 12 3/4 flywheels with the vortec motors because I reused the flywheel cover and transom plate from the 81 model 228's and that's what they were using. I also have 2 new marine starters to suit that size flywheel so it made sence to go that way. The flywheels and couplers all mounted very neatly, new studs, new vortec 12 3/4 inch flywheels and new couplers al bolted nicely together.

One a side note, the late 3.0 4 cylinder mercruiser uses a 12 3/4 inch flywheel, can I use a coupler off that motor to give me a option between the two different couplers as the late vortec motors use a 14 inch flywheel. Part no. Sierra 18-2321

Please put forward your opinion thanks

 

[ivboost]

Re: Mercruiser coupler runout

18643a7 is to be used with a 14" flywheel

 

[alldodge]

Re: Mercruiser coupler runout

Merc coupler 12632A7 is for a 12 3/4 flywheel but I'm not sure it will bolt up to your flywheel bolt pattern. Sure is bad and very rare to find two 76850A2 bad couplers in one place, unless someone is selling rejects. Sorry but I just don't know for sure.

 

[ITestBoats]

Re: Mercruiser coupler runout

Sounds to me like an incorrect matting issue between the crankshaft, flywheel and coupler. Did you do anything to make sure everything matted flush?

I would be interested what IVBoost finally did to solve his issue. I personally have seen some "questionable" coupler run-out issues.

 

[alldodge]

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