Broken engine mount stud

[Hydro Therapy]

Well I noticed this today and assigned it to the top of the winter list. Not sure when it broke but it would of been sometime this season. When not running the stud sits a bit off center. When running and engaged in gear it lines up perfectly.

I did a search for Westerbeke 12C Two engine mounts and struck out. I haven’t called the factory yet. Does anyone know if the stud can be replaced or do I need a new mount?

 

[Michael Davis]

Does anyone know if the stud can be replaced

I've never tried that but it looks like a lock nut on top of the mount. See if it will come off. Depending on their age I would replace all.

 

[LeslieTroyer]

Doubt individual studs can be replaced. The big offset indicates it was really stressed incorrectly and you need a good alignment.

Les

 

[JimInPB]

5 minutes with a stick welder & I think I would have that fixed. They make some really cute little 110vac powered inverter welders these days. The darn things are the size of a lunch box.

 

[Hydro Therapy]

I thought about having it welded. I may if I can’t find the original replacement. I’ve searched the internet but haven’t found it. In a few weeks she will be on the hard. I will reach out to Westerbeke if I can’t find it.

 

[BrianRobin]

5 minutes with a stick welder & I think I would have that fixed. They make some really cute little 110vac powered inverter welders these days. The darn things are the size of a lunch box.

As a welder, I wouldn't do it, the amount of heat needed do that job would at least break the bond on the rubber mount.

 

[uralite]

Try PYI , I got all new ones. They ask engine weight, max hp at rpm . I pulled one and measured hole distance etc. I did not know my original manufacturer of mounts. See website. They are good. Then call and the sales guys are super helpful. Shipping was crazy fast. You’ll have to do engine alignment anyway. I had to buy large washers, but lock washers and nuts were included

 

[CharlieSea]

For a temporary repair, get a coupling nut in the size of the stud. Use permanent red Loctite to fix it. It does appear that the stud broke from a shear force. An alignment is indicated.

 

[JimInPB]

As a welder, I wouldn't do it, the amount of heat needed do that job would at least break the bond on the rubber mount.

I disagree. I think that there is plenty of room to place a heat sink under the localized heat affected area of the fillet. I would cover the surrounding area with wet cloth, wrap the lower 2/3 of the exposed stud with more wet cloth, then hit it with a 1/8" 6010 or 6011 rod. If I was concerned about heat migration, I might spray below the welded area with a little water after the glow subsides.

 

[dLj]

I don't know if those are high strength bolts. If they are, forget about welding them.

dj

 

[JimInPB]

Why would you forget about welding high strength bolts?

 

[JimInPB]

If I were to replace the mount, I think that I would consider changing all the mounts as a set. If one stud fatigued off, then the rest may be on their way.

 

[dLj]

Why would you forget about welding high strength bolts?

To keep the answer at a high level here is a summary type answer to your question.

Grade 8 bolts have a UTS of 150ksi, grade 5 120ksi ( assuming 1" or less bolt diameter). The plain carbon alloy required for both of these has a carbon content of 0.28 to 0.55% placing these bolts into a medium carbon type steel. If these are high strength stainless steel bolts they are likely a 400 series martensitic alloy. Whie the composition is different, the following discussion still applies.

First you would need an alloy appropriate filler rod. That's a big subject.

Then you have the problem of the HAZ - heat affected zone. The HAZ will contain a region of untempered martensite that is hard and quite brittle. Unless you heat treat this, you will find your welded bolt will snap off quite easily right next to your well.

In order to make a high strength bolt even close to it's original design requirements would require a full heat treatment for the entire bolt. Simply not a practical option in this case.

dj

 

[LeslieTroyer]

Mounts are expensive, but you’ve stressed one past the breaking point, what shape do you think the others are in?? Do it right and replace all 4 and realign so you don’t stress the studs.

 

[jssailem]

I love reading engineering speak in the morning.

 

[BrianRobin]

I love reading engineering speak in the morning.

I was waiting for this

 

[markwbird]

Just replace the mount already. Boats are expensive. Embrace it. Look yourself in the mirror with a candle and the lights off and repeat: "boats are expensive".

 

[Hydro Therapy]

I’m definitely going to replace the broken one, possibly all 4. Take a better look at the rears when it’s on the hard.

Markwbird, I’m not sure what led u to believe I wasn’t going to replace it. I realize boats are expensive. I’ve owned more boats then cars.

 

[markwbird]

I think it was the question: " Does anyone know if the stud can be replaced or do I need a new mount?"

 

[Hydro Therapy]

Thanks for the clarification. Your contribution has been very helpful.