Engine mounts

[SparklePlenty]

My 2016 25SC has 160 engine hours. A pre-season check found all four engine mounts loose- one so loose it could be turned with a finger. Although I have never noticed any vibration, the bolt that holds the exhaust support was broken, probably from slight vibration. All bolts are tightened and I will be tuned in to any vibration on a short cruise this weekend. I hope the alignment has not been compromised. As I understand, loose engine mount bolts are not unusual on Ranger Tugs.

 

[Andrew Custis]

Hello,

Thank you for sharing. Engine mounts settle in over time as the rubber softens and it’s not unusual to check the torque on these. This is something to check as well as alignments to keep up on the maintenance.

Thank you for sharing.

 

[Bosn Mate]

Andrew:

Do you have torque specs on the engine mounts bolts and alignment procedures for my R29-S? If, not, where can I get them?

Thanks!

Mike

 

[Andrew Custis]

Hello Mike,

These are actually listed in the Volvo installation and technical manuals for the engine. I’ll see if Tim can post these tomorrow for you.

Best regards,

 

[Bosn Mate]

Thanks Andrew!

 

[BB marine]

A preventative maintenance checking mounting lag screws and motor mount adjusting nuts for tightness should be done at pre-delivery, 50 hr check, and once a year. If a nut is found loose it is a good idea to check alignment. If the mounting nuts are tightened properly after alignment the nuts should not come loose. If the Lag screws are tightened and installed properly (Straight hole drilled in the engine stringer, right size hole drilled in the stringer, properly sealed hole with lag screw) the lag screw should not come loose. Unfortunately this isn't always done hence the need to check them. Because of the tight quarters in the compartment torquing is not really achievable at least in my C26 and many other boats that I have worked on. I use the term tighten it Milwright tight, as tight as you can get it. I use 2 different wrenches to tighten them properly 1) straight end and 45 degree opposite end and 2) 90 degree open end wrench.( Always back up the bottom nut) I have them in a tool box on the boat. I can post the size later (metric) "The bottom nut needs to be backed up when tightening the top nut".





As you can see from this illustration the only cause of the nuts loosening is not tightened properly. The last person that did alignment didn't tighten them properly. The mount settling or mount fatigue will not cause the mount nuts to loosen.

Alignment procedures are in general the same for all straight inboards google inboard engine alignment to get the procedure.
Proper alignment will put less strain on the mounts, less wear on packing and cutlass bearing and reduce wear on transmission components. Also give a much smoother operation through out all operating ranges of the engine.

 

[YukonRon]

I use a paint pen to put a line across each nut, bolt and mount assembly for a quick visual check if anything moves.

 

[Chimo]

I use a paint pen to put a line across each nut, bolt and mount assembly for a quick visual check if anything moves.

Our R25SC had the nuts marked from the factory.

 

[knotflying]

Check the bottom nuts also. I found one of my bottom nuts moved down a quarter inch. The top nut was in the tightened position, so technically there was no support below. My point is always check both nuts and don't assume everything is okay if the top nut looks correct.