Completely seized nut on engine mount

[captlloyd]

Grab the engine and try to move it side to side, if there is movement replace the mount. An engine that size is not big so if the mount is shot you will be able to move it. Penetrating fluid is not going to hurt that mount, just clean it off after you are done with some spray brake cleaner. That nut should come loose with a half inch breaker bar after soaking the nut.

[Scaramanga F25]

It is time to replace the4 mounts.

[conchaway]

Did you actually Pay $500 for work not done? If so, would you like to purchase a kadibbling pin for a low low $250.00 ?

[JOHNMARDALL]

IMHO, and having looked at your photograph, replacing just one engine mount would not be a satisfactory or long-lived repair - mounts start to lose their flexibility after about ten years. I assume your engine has two lifting eyes - how much space is above them? If there's enough room to hang a manual chain hoist on an eye bolt (temporary or permanent depending on location of top nut), cutting through the stem of the rusted mount. undoing the nuts on the other mounts, unbolting the drive flange, disconnecting the control cable and wiring harness, then lifting the engine and swinging it forward onto 4x4 bunks using a second chain hoist hanging on a beam across the companion way is a relatively simple operation. Of course, given the weight of any diesel engine, you're going to be sure not to have any body parts under it while it's suspended. Now you can work comfortably, installing a new set of mounts, cleaning up the beds and checking the stuffing box and shaft bearings (there may only be one at the outer end of the shaft log). I know this sounds awful, and it is a big job, but my guess it that you're going to end up doing it this way, on the first or second attempt.


Good luck, please come back to me at jmardall@comcast.net for discussion, and consider buying the book Replacing your Boat's Engine by Mike Westin ( full disclosure - I translated it from the original Swedish and edited it, but have no continuing commercial interest of any kind). It covers every aspect of engine work in a small boat with a lot of photographs and can really help in thinking through a project like yours.

Good luck
John Mardall
Vetus Maxwell Boat Equipment

[Stu Jackson]

Often unmentioned when discussing moving an engine is the exhaust riser!!! A not-untrivial piece...

[Dymaxion]

My choice would be four new mounts, of correct stiffness for your engine. Two fresh softer ones and and two as hard as the hobs of hell and you'll get a rocking horse motion that may hurt the shaft coupling after a time.

[NYSail]

Replace the mounts...... take the nits off the top (or cut in the rusty case) do one at a time so you can replicate height and position. I used a bottle jack to lift each corner at a time..... fairly easy.

Good luck
Greg

[Stu Jackson]

You may not need to buy a jack if you can borrow one from your car. Good luck.

[Shoalcove]

I’ve always lifted my engine from above as per John Mardall’s post. I’ve been lucky enough to borrow a chainfall from a friend or the yard. The worst part of the job is usually getting started in my experience! There is a ton of info online and good books available to help. I’d replace one at a time so that if it takes longer than you thought, you can lower the engine back on the mounts and come back later to finish. If you remove all the mounts at once you might not have that option.
Good luck!

[boatnerd]

Bushings, Inc. is in Michigan and have been making these mounts forever. Call them to confirm what you have. Speak with Ben S and he'll give you exact details as to hardness(durometer), bolt size, profile etc. to match yours. The profile height is very important. Measure and look at their drawings to be sure you clear the engine brackets. They will also give you a better price than others but more importantly send an extra lock nuts if you request. They often come with only two nuts.
If you remove your engine brackets, which makes it much easier consider changing lock washers on the bolts to the block and be sure to torque to spec so they don't vibrate loose. They're on there quite tight.

[nic26]

Originally Posted by matthidinger

No, I haven't ordered a new mount as of yet. I guess I was optimistic that the threads might be saved.

Someone else asked if I plan to just replace the whole mount and I am hesitant to do that because my engine is completely enclosed under the cockpit floor, so I'm not really sure what technique I would use to lift it up and swap the mounts. Any ideas most welcome.

A very flat car jack is a good help. Find one on a scrap yard for cars.

[wtmf]

I was going to say transmission fluid but saw that with acetone and think that is better.

[IMACSS]

Matt. Lots of good advice here with a few good options to consider so I guess the best is the one that works for you. The following is how I would consider approaching it:
1. Firstly, get some datum measurement for the height etc. It might be reassuring to know how far you have moved every thing etc.
2. You have provided a good pic of the mount and support bracket but it really doesn't show how much room you have for access to the beast. This may ultimately be a good reason to choose one method over others.
3. Seems to me that it would be better to replace the old with a new mount but . . (see 2 above)
4. That top nut may never undo without a good heat source which is often the absolute best method of "undoing" rusted nuts IMO
5. If 4 is not going to work for you then a Dremel with a cut-off wheel to produce a deep cut in the nut in line with the centre of the threaded bolt trying to get as close to the bolt threads as possible.
6. At this point a cold chisel and hammer should quickly separate the nut from the bolt . . . . BUT at this point it will become obvious why replacing the mount was the best answer as you now have to clean the upper, rusted threaded section of the bolt.
7. Not sure if a Die-nut will fit into the U-shaped mounting bracket but if so it might make the job easier although this will possibly cost upwards of $30.00
8. We have to assume that the nut below the mounting bracket is serviceable, otherwise I think that we have just blown the budget and wasted our time etc Matt.
9. At this point I would be going back to No. 3 and shaking my head while uttering a few choice words at myself.
10. The next question may possibly be how to jack up the motor to replace the engine mount but I feel more info and possibly pics are needed to answer this.

Apologies if you are not amused at my "dribble" here Matt but it may still help to arrive at the best solution etc etc

[JOHNMARDALL]

One more suggestion: The existing height of the engine bearers above the beds is a rough guide to start the alignment process, but only that, as the old mounts will have compressed and the engine-gearbox assembly may have shifted over time, or even not been ever correctly aligned. Assuming that there is no bearing at the inboard end of the shaft log, you will need to center the shaft in the log, and then make the alignment at the interface between the driven flange on the shaft and the drive flange of the gearbox. Tools required: at a minimum feeler gauges, but the pro's use an index gauge and a sighting laser. The goal is to get the flange faces parallel and on the same center. If you've got enough room for the prop to move back an inch or two, this may be a good time to insert a flexible coupling at the shaft - gearbox interface, not as a substitute for careful alignment, but to reduce vibration as the engine twitches on its now flexible mounts.


All the best
John Mardall
Vetus Maxwell Boat Equipment

[fugujohn]

Short money, and if you want to save what you already have, try this. I have stories about how well this works, but I will not bore you here. If you can put out aprox $34 you will have this setup for years to come. Here is what you do: Take the tourch, and get the nut hot. It does not need to be cherry red, but it does need to be HOT. Get her hot, put the beeswax on the head of the nut and let it melt around the bolt for a second or two. Have your socket ready to go, and take the nut off. You will be AMAZED as how easy the nut will break free. All you have really done is lube the nut/bolt interface. This works. Good luck, and contact me if you want to hear boring stories, or need further information. Here is a parts list: 14oz map gas from Home Depot is 12 bucks. Torch tip is 17.00. Walmart 2oz of Bee's wax $5.50