Loose Engine mounts

Post by **mhanna** » Fri Sep 12, 2008 4:39 pm

The other day while checking various things I noticed that the starboard front engine mount (tranny mount) was loose. When I say loose what I mean is I got 4 full turns on it before it got tight. I also checked the starboard rear mount and got 3/4 of a turn. The port sides where tight.
I am guessing that when under load the starboard side of the engine tries to lift ? It makes sense from having a a counter clockwise prop rotation (viewed from the back).
I will be watching this more closely but am wondering if anyone else has had this problem ? It is a large lock nut and should not do this..

Matt

ps- I am glad I carry a BIG adjustable with me...

Post by **Carl** » Fri Sep 12, 2008 5:51 pm

I am by no means an expert, but after finding what you did, you might want to consider having your drive shaft checked for alignment. If not properly done you could be doing some damage.

Post by **RobS** » Sat Sep 13, 2008 6:36 am

Nice avatar - did you hire a professional photographer for that one.

I'll help you out with a check of your engine alignment. I don't think there would have been any reason for Dicksons to have loosened the mounts when they had the boat for the valve work and other servicing was there? I don't recall everything they did...

Hopefully you did not feel any vibrations. Want prompted you to check them?

Post by **Mariner** » Sun Sep 14, 2008 10:20 am

On our Camano I once noticed that two engine mount nuts had managed to work themselves all the way off the stud and fallen into the bilge. I have no idea how long it was like that, but I would imagine it was quite some time. There was no odd vibration or anything. The engine stayed right where it was supposed to. I replaced the nuts and added backing nuts on top of them to lock them in. That solved the problem.

Post by **mhanna** » Sun Sep 14, 2008 3:22 pm

After speaking to RobS, I checked on those mounts again. There are 2 nuts under the tranny mount plate, those should be used for leveling out the motor. I assumed (you know what they say) that the top large nut was the only one loose when I tightened it. Today I loosened the large top nut just to see if those 2 nuts were tight. Wrong..... they are supposed to lock against each other to stay put. Well they were at the bottom of the thread and I could turn them by hand.
I will have to do an alignment, good thing Rob did it already and knows how

!!!

Matt

Post by **RobS** » Sun Sep 14, 2008 5:59 pm

Matt,
I'm good for Tuesday night. Give me a buzz or shoot me an email.

Post by **Russell** » Mon Sep 15, 2008 11:42 am

It would be appreciated if you could post a description of how to check the shaft alignment on the engine box models. I have done it on sailboats but this reversing transmission is a mystery to me. Thanks.

Post by **Denis** » Mon Sep 15, 2008 11:58 am

Loosen /remove the four bolts that clamp the two flanges together on the rear of the transmission. Separate the flanges a little then push them together again with a .002 guage in-between. Check all around for the same clearance. Then rotate the prop shaft and check again. If you need to make an adjustment, use the two mounts that hold the transmission, you can usually get the movement needed with these two mounts. After completing the adjustment make sure you tighten the snubbing nuts on the mounts and the bolts on the flange. D.

Post by **mhanna** » Mon Sep 22, 2008 9:46 pm

As Denis said, you need to loosen the 4 bolts on the flange (see red) and put feeler gauge in all the way around. There is no absolute value, it just needs to be the same.

Mine was off alot and unfortunately needed to be moved left to right, those adjustment bolts mostly do up and down. I needed to loosen the engine mounting pads and move the engine left and right.
RobS came over to help me finalize it and we were able to get it right on the money. It really does help to have 2 people doing this job as one can check the gauge and the other can move the bolts.

There is alot of talk about making this alignment perfect, I have Comptans marine diesel book and he states that if you can rotate the shaft by hand and you do not feel it binding then its probably alright.

I will say its an easy job to check it, its another thing to adjust it.

Matt

Post by **Mariner** » Tue Sep 23, 2008 1:33 pm

Would using a nyloc nut as the "stopper" nut, reduce the tendency to work loose?

Post by **Russell** » Tue Sep 23, 2008 3:42 pm

Thanks for posting that information. I was thinking I had to get to something under the engine. This is a whole lot easier but as you said, getting it adjusted is still tricky.

Post by **RobS** » Tue Sep 23, 2008 5:55 pm

With two people and two feeler gauges it's not bad at all. Alone, it would be real PIA. Before I arrived Matt had already checked to make sure the tranny flange and coupler flange were true and he also corrected the gross (visual) misalignment.

I reinstalled the 4 coupler bolts leaving them slightly loose. I placed a feeler gauge at the 12:00 position and then with the other gauge took measurements at the 3, 6 and 9 positions. Matt then worked the adjustments on the engine mounts accordingly until I had exactly the same reading at 3, 6 and 9 to match the gauge that I set in place at the 12:00 position. Once the 4 positions were all the same Matt tightened down the locking nuts and I continued to take the measurements all around the flange while he did so to be sure nothing moved. Then, most importantly, Matt bought dinner and beer

Post by **Yearwood** » Thu Oct 02, 2008 4:55 pm

This port got me to thinking that I had not checked engine mounts in years and we do have an intermittent vibration on our Yanmar at idle speeds. A quick look indicated that the engine had shifted from the builder's marks on the port side. One mechanic said the we needed new engine mounts. Anyone with a similar problem? Checking further ... stay tuned.

Post by **RobS** » Thu Oct 02, 2008 5:09 pm

Did he say why you needed new engine mounts? Are they corroded so bad that they are no longer adjustable? Have any pics you can post?

If they are corroded, depending on how bad, they can be sprayed, cleaned, lubed, etc. and you should be able to free them up enough to make them usable. If they are needed they cost approx. $125 a pc to buy....

Post by **Yearwood** » Thu Oct 02, 2008 5:29 pm

He was speaking of the rubber mounts being collapsed. I noticed that the engine had shifted off the builder's marks. I only had a few minutes yesterday and will look further in the morning. Probably not possible to get a camera in at the angle needed to see the rubber. There is no corrosion of the steel to speak of for I have cleaned them in the past and repainted.

Thanks.

Albin Owners Group

Albin Owners Group

Loose Engine mounts

Loose Engine mounts