# inboard engine alignment?



## wave warrior (Oct 2, 2005)

looking at a 24' inboard, owner says it may need engine/tranny aligned...what does that take/cost?? only have owned I/O and outboards...any other thing to consider please chime in!!!


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## Dfrenzy (Dec 18, 2008)

These sites may help you. http://www.marinemechanic.com/nrfpt_dir/inboard_alignment.htm http://www.elberts.com/faq.htm#q20

Prices vary but most often will run around $150.00 Per engine depending on how long it takes. I will try to answer any questions you may have.


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## capt j-rod (Feb 14, 2008)

I have done this numerous times. Start by asking the famous question... Why is it out of allignment? Rotten motor mounts (glass, not actual bolt-on mount) or stringers is usually the culprit. Either way, a more accurate way of describing shaft allignment is motor relocation. Un bolt the shaft from the tail of the tranny and slide it back about 1/4" to start. have someone spin the prop and take a spacer to see how far out you actually are. Loosen all four motor mounts and use large pry bars to manipulate the engine around the shaft. Check the gap all the way around being sure to spin the prop. When all is well tighten it up and check it again.I use feeler gauges to dial it in as close as possible. Before doing this you may need to replace the cutlass in the strut, and all of the packing around the shaft. If they are worn, you will struggle to et it to allign properly. Like the opening sentence reads, I suspect if there is movement, there might be soft fiberglass in the hull. Good Luck!


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## Hook N Book (Apr 7, 2004)

I have an I/O so i'm not sure if this helps or not. My owners maunal recommends having/checking engine alignment every 100 hours. The last time I had done, I had the impeller replaced alos...total was less then $200 at a boat/marine dealer.


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## CarpetBagger (Sep 21, 2009)

Tranny bolts to engine, coupler and prop shaft to tranny, so if its an alignment issue its the engine you are going to worry about.

Fairly easy job, but time consuming, you gota make sure your motor mounts are in good shape...Hose em down with some good penetrating oil and let em sit for a day or so if you are skeptical...

What you are most worried about is the coupler to tranny alignment. From there its just a matter of your shaft being straight. You need to take the coupler apart from the tranny and see what happens...it will probaly move slightly, and you then need to move your motor accordingly. You can use a feeler gauge to get the spacing right between the coupler and the tranny face. Sometimes its a matter of left to right and also a matter of up and down...its hard to say.

Good way to check the alignment prior to doing anything is to put the drive in neutral. Hose down the shaft with WD40 on the strut. Go on the outside and try to spin the prop...If it hangs up or becomes harder to push in the rotation, you need to align the motor. If it spins smoothly with no hangups it could be just a prop tuning you need.

My motor needed aligned when I got it, and a buddy of mine helped me out greatly. Learned a lot in the process. Its a couple man job getting it right...


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## Benboat (Jan 20, 2008)

Engine alignment is critical for an inboard boat. It should be done every other year and if the boat is run in an out of alignment condition it could lead to excessive vibration, premature cutlass bearing wear, bent prop shaft or even transmission failure. The tolerance is within .003 thousandths measured with a feeler gauge. The boat should also be in the water in its natural state when doing the alignment. I have seen alignment change 1/4" between when the boat is on land and when it is in the water due to hull flex. Motor mounts should be checked for excessive play and replaced if needed. The alignment being checked, as stated by CarpetBagger, is between the prop shaft coupler and transmission output flange. Checking the alignment is fairly easy and just a matter of splitting the coupling and measuring the gap with a feeler gauge. Doing the alignment could take several hours if it is off, especially if the motor mounts are hard to get to. The idea is to have the engine aligned with the prop shaft when it is centered in the cutlass bearing in the strut and hopefully the shaft tube in the bottom of the boat. This job is best left to an experienced technician who has the right "feel" as it can be a bit of an art.


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## CarpetBagger (Sep 21, 2009)

Ive never seen one out a 1/4" when done in water vs on land...This might be a possibility if you have a poorly supported boat sitting on jackstands, but a boat suported on the stringers by a trailer generally puts the hull into a fairly normal state of flex. Not to mention it makes spinning the shaft a heck of a lot easier...lol


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