Mercruiser Bravo alignment problem

Andy_Sydney

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Mar 18, 2014
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11
Hi,

I have 2 X Bravo II sterndrives attached to Mercruiser 4.2TD engines. The boat is a Sea Ray 290 SFB. I have been renovating it for the past 2 years. Both engines have been rebuilt from the crank up. Both Bravo Sterndrives and housings were removed, bead blasted and epoxy coated. I re-fitted them as per the instructions in the manual and lowered the engines in.
The port engine aligned fine and the alignment tool slides in and out easily. The starboard alignment is way out.

When the two mounting bolts are out I can reach around and feel the gaps between the flywheel housing and the transom plate. The starboard mount is a lot higher and I can actually turn the fiber washer in the gap with my fingers. The engine sits firm on the port mount. Both front mounts are set to the minimum adjustment.I have tried all combinations with the front mounts. I have also tried aligning the new gimble bearing.

I have attached 2 pictures, one shows the perfectly aligned engine the other shows the visibly off engine. Both pictures look directly at the splines inside the coupler with the crank center hole centered

My question is:

Is it possible that the inner transom plate is wrongly aligned? It would seem to be the only explanation

Many thanks in advance
Andy
 

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Bondo

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Re: Mercruiser Bravo alignment problem

Ayuh,... Welcome Aboard,... Did ya get the rear motor mount stack of bits, 'n pieces in the right order, 'n All the bits,..??
 

Andy_Sydney

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Re: Mercruiser Bravo alignment problem

Hi thanks for the quick reply, when i stripped it all down there was only a fiber washer between the engine mount and the inner transom plate. I put it back in the same way but I have ordered new bolt kits and they come with this spring washer that I have been reading about. Any idea if it is possible to mis-align the inner transom plate?
 

alldodge

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Re: Mercruiser Bravo alignment problem

Hi thanks for the quick reply, when i stripped it all down there was only a fiber washer between the engine mount and the inner transom plate. I put it back in the same way but I have ordered new bolt kits and they come with this spring washer that I have been reading about. Any idea if it is possible to mis-align the inner transom plate?

:welcome: to iboats Andy

Here is an image of the setup from Service Manual 22

4.2 Diesel.jpg
 

Andy_Sydney

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Mar 18, 2014
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Re: Mercruiser Bravo alignment problem

Thanks for the warm welcome and responses guys!
I'm picking up the new bolt kit complete with spring washers today and will test with the springs in place.

One thing I did read about was the design change:

design_change.jpg
Link

My engines are both 1993 D254 models. I got hold of a broken 1997 D4.2 for spares which is almost identical. I'm wondering if I got the flywheel casings mixed up and fitted the newer one to this problem engine. I have a horrible feeling that I'm going to need to haul it back out and re-align the transom plate. I'll try it with these washers before I do anything else.

1897994_10152091605347893_1982924856_n.jpg
 

alldodge

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Re: Mercruiser Bravo alignment problem

Thanks for the warm welcome and responses guys!
I'm picking up the new bolt kit complete with spring washers today and will test with the springs in place.

One thing I did read about was the design change:

View attachment 226011
Link

My engines are both 1993 D254 models. I got hold of a broken 1997 D4.2 for spares which is almost identical. I'm wondering if I got the flywheel casings mixed up and fitted the newer one to this problem engine. I have a horrible feeling that I'm going to need to haul it back out and re-align the transom plate. I'll try it with these washers before I do anything else.

View attachment 226013

I'm guessing that you should have the old style which use the spring washer. If the bolt is tightened without the spring washer the rubber mount is stressed and can fail. As in your bulletin, check the serial number. The new style started at serial number 0M660000
 

Bt Doctur

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Aug 29, 2004
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19,093
Re: Mercruiser Bravo alignment problem

The way you can tell is the old style bushings are smooth and the new style bushings are knurled. Considering the rear mounts are now too low, i suspect you need the doublewound spring to correct it.
 

Andy_Sydney

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Mar 18, 2014
Messages
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Re: Mercruiser Bravo alignment problem

My engines are OD00.... so they should be the old mounts. Tried the new spring washers with it, now its about 1/2 inch too high :grumpy: I think I may have got the casings mixed up and fitted the newer style. Doh!

I'm going to haul it out again this weekend and make sure that the inner transom plate is square on the bolts and fit the other flywheel casing to the engine. Interesting that the port engine didn't have any of these spring washers, I fitted it back in the same way (without them) and it lined up perfectly. Alignment tool slides in and out very smoothly with two fingers. Will update when progress is made.

Thanks guys!
 

Fun Times

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Re: Mercruiser Bravo alignment problem

Is it possible that the inner transom plate is wrongly aligned? It would seem to be the only explanation

I'm wondering if I got the flywheel casings mixed up and fitted the newer one to this problem engine. I have a horrible feeling that I'm going to need to haul it back out and re-align the transom plate. I'll try it with these washers before I do anything else.
When you say mixed up, are you saying you had new flywheel casings/housing too? as in brand new or off the 1997 engine?

1993 and 97 should be the same fit/type/style etc. flywheel housing.

As for the inner transom plate, Can't think of a way to mess that up really.

See page 23 and 37+, http://www.boatfix.com/merc/Install/gas/86419602.pdf

Also check to see if the rear motor mounts have started to slide out/moved from the flywheel housing.

If so you may need new rear mounts. Item #23, http://www.mercruiserparts.com/Show...bnbr=100&bdesc=FLYWHEEL+HOUSING+(STERN+DRIVE)
 

Andy_Sydney

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Joined
Mar 18, 2014
Messages
11
Re: Mercruiser Bravo alignment problem

Hi Guys,

Thanks for the replies! I had the engine craned out again last weekend. As soon as it came out I could see what BT Doctur meant by the 'knurled' mounts, these were very different from the 'flat' mounts on the other bell housing. It turned out that I had fitted the housing from the donor 2007 D4.2 engine (sorry Fun Times, I wrongly said it was a 1997 in an earlier post). Anyway, changed the housings over, straightened up the transom plate. It moved about 15mm or 1/2" at the top when all of the mounting bolts were loosened. Top holes were slightly oversized and it was offset to the left. I lowered the engine back in after light pushing and shoving got the bolts to line up with the mounts. I tightened everything and as soon as I tried the alignment tool it slipped straight in :D It needed a little adjustment on the front mounts to get it really smooth. I am very pleased but do feel a bit stupid for making such an obvious error.

I'd like to thank everyone on here for their help, I'm a step closer to getting back out on the water!!
 
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