21ec engine mounts

[Pilotnavigator]

I check the engine area every week or so, one the last day of our summer cruise I noticed that the starboard forward engine mount was loose. The bolts had backed out of the deck. These are lag bolts into something that I am not sure about. What should be done to keep this from happening? And any special info on tightening them! Also should this have messed up the shaft Alighnment?
Thanks
John

 

[Capt’nKarl]

John. That’s a real puzzler. I’m not sure why it happened but I’d retighten the bolt, which Im sure you’ve already done, to see if it loosens again. The engine mounts are subject to a lot of vibration. Have you had the engine in low RPMs for an extended time? Low RPMs cause more vibration on the mounts. What type of engine and how many hours? I’ve got a 3YM30 Yanmar with about 500 hours on it but have not had this issue.
Karl

 

[Pilotnavigator]

Volvo with 350 hours. The mount is attached with lag screws not bolts. Not a lot of low idle running. Will wait to see if there is any factory ideas them will apply some sealant and reinstall the two screws.

 

[Newf]

One of mine came loose at around 500hrs so I just tightened it down again and snugged up the other 3. (Volvo Penta as well) I've put an additional 1200 hrs on and no other looseness noted.

 

[Pilotnavigator]

Glad to hear this is not unique will reinstall with some 4200 and tighten down. I thought them were bolts and not screws. That was the second surprise after seeing them loose.

 

[GA-Midnight Cruise]

Check your engine mount to make sure it is good. You may be transferring vibration from a failed mount to the screw. I'll share with you my addiction and preface that my self indulged sport is not for your average boater. I also operate in remote locations. These are lag screws and likely in wooden rail beds believe it or not. You can use 4200 to secure them. That's a poor man's remedy but works as long at your beds don't have rot. I run R-21 Classics in an activity I call, "Hair Boating". Its an adrenaline, habit form of boating in under powered and under sized circumstances in inlets and bars that pushes the envelope. I'm a certified junkie. I pull the engine, shave down the rail beds to compensate for the 1/4" aluminum plate that I install then glass back over in place. Tap the machine bolts for the mounts into the plate and you have a solid ABYC attachment. Then re-align the shaft. You don't want an engine shifting in it's bed when your in an 8' trough. I really like the R21 classics. It challenges the fundamentals of piloting skills with a hi degree of adrenaline. I do operate solo and am geared for possible swims and loss of a watercraft. When you are at the bottom of a trough, there is not much mast left in the pic back on shore and it is pretty outrageous. It's freak boating on steroids. Keep an eye on those bolts and identify root cause for them backing out.

GA-Midnight Cruise

 

[Newf]

"Check your engine mount to make sure it is good. You may be transferring vibration from a failed mount to the screw"

Not to derail from the original topic of looseness but do the rubber mounts themselves fail often? I read an article somewhere suggesting that these engine mounts be replaced every 4 to 5 years if you are putting 250-300hrs per year on your engine. I've just had a closer look at mind because of this thread and there appears to some separation in the rubber to steel bond and cracks in the rubber on one of them. They appear to be solid when trying to "rock" each location but I intend to remove one for a closer inspection on the bench. I was just wondering if anyone has replaced them after 4-5 years? They are quite pricey at $170 US each but cheap when compared to other failures that could occur from faulty mounts.

 

[Newf]

Removed mounts for closer inspection. All 4 had some degree of cracking and fatigue in the rubber but the rear starboard side was in poor condition so they are in need of replacement to prevent damage to other components. Photos in album.

 

[Newf]

Glad to hear this is not unique will reinstall with some 4200 and tighten down. I thought them were bolts and not screws. That was the second surprise after seeing them loose.

New mounts on order and hopefully will be in early next week. Noted above is the use of 4200. (Not familiar with the product) As I will be removing all of the lag bolts to install new mounts would this be a good product to use or is there another product that would provide some addition strength to the lag bolts/wood connection given that this will be the second time that I have removed them. Would I just squeeze this in to fill the holes prior to installing the bolts or just coat the lag bolts prior to installation. Thanks in advance for any assistance.

 

[Pilotnavigator]

The idea using the 3m 4200 was to seal the hole around the lag screws to keep any water that might get in the cockpit from getting at the wood that is in the engine stringers. So all you would need to do is put a bead around the screw and insert them. My mounts looked ok. But during commissioning the engine had to be lifted up with another shim to align the shaft. This meant The existing lags on had about one inch of purchase. I installed longer screws. If you replace all the mounts you will need to have the shaft realigned.

 

[Newf]

The idea using the 3m 4200 was to seal the hole around the lag screws to keep any water that might get in the cockpit from getting at the wood that is in the engine stringers. So all you would need to do is put a bead around the screw and insert them. My mounts looked ok. But during commissioning the engine had to be lifted up with another shim to align the shaft. This meant The existing lags on had about one inch of purchase. I installed longer screws. If you replace all the mounts you will need to have the shaft realigned.

Thanks Pilotnavigator. Yes I will definitely have to realign the shaft. I intend to remove and replace one at a time using the existing height measurement at each location. This should put me in the ballpark of where I should be and hopefully the final alignment will only be some fine tuning.

 

[Pilotnavigator]

Sounds like a good plan! For anyone’s future reference, where did you get the mounts?

 

[Newf]

Sounds like a good plan! For anyone’s future reference, where did you get the mounts?

I ordered them through Port Boathouse, Port Alberni, Vancouver Island. This is the dealer that I bought the boat from but you could order them from any Volvo-Penta dealer. Not cheap, list price--$230.00 Cdn each and this is just the mounts, does not include the hardware that goes with it,,,studs, nuts, washers etc. (I'll reuse these stainless fasteners) Part # for the mounts is 3888806.

Got them come yesterday so will swap out today and hopefully the shaft alignment goes OK.

The Dealers mechanical staff was surprised that they were starting to fail, as they had not seen this before with this engine in the R21-EC's. I believe it's due to all of the hours at low idle since the engine runs a lot smoother at crusing speeds than it does at trolling speeds of 900RPM's or less.

 

[Pilotnavigator]

Mine ok fine, I have around 350 hours but very little at idle. But nice to have the part number when and if they need doing.
All the best with yours.
John

 

[Newf]

Mine ok fine, I have around 350 hours but very little at idle. But nice to have the part number when and if they need doing.
All the best with yours.
John

Hi John, A little bit of info for you should your lag bolt loosen off in the front starboard mount again. I striped the material in the front hole of the same mount location during my reinstallation. This was the same location where the lag bolt had loosened off at 500hrs so it probably was damaged at that time. Anyway, I found that the lag bolts screw into a block of "something" probably wood that is coated with fiberglas. It is approximately 1" thick, which is not a lot of material considering the amount of vibration in the engine. This block is visible with light and mirror through the front access hole in the deck. You can drill out the holes in this mount location and install thru bolts with nuts and washers underneath making it a much stronger connection. (Would have to remove the throttle cable if you do not have a 10" or longer drill bit.) This is the fix I now have to do on mine. You can access all 4 bolts in the front mounts through this hole in the deck although you would have to remove alternator and engine mount bracket on the Port side if you wanted to install thru bolt there. It's good to know that it can be done if you had too.

Shaft realignment went fairly well. A little time consuming and a little congested there to play with the feeler gauges but doable.

 

[Pilotnavigator]

Thanks, good advice and information on the mounts. I do have a very long 3/8 drill bit that I could use. Will keep in mind if they loosen again. The other alternative is to drill out larger, fill with thickened epoxy and re drill for the lags.