Stuck rear engine mount bolt

[RaggedEdge]

Originally Posted by formula 382 sr-1

You can cut the heads off and put heat to it and the rubber motor mount will melt then you can press in a new motor mount in. Be careful boats & gas dont react to well to heat .

I don't believe the rear mount (inner transom assembly) has a rubber insert. Just the bolt with a series of washers / spacers. I believe the runabout style front mounts do have a rubber insert, but can't believe any perf boat builder would use these instead of the solid cradle style.

Back to the liquid wrench, heat and the big hammer.

[RaggedEdge]

Originally Posted by ThirdBird

Nothing holds like a good crossthread!!!

Saves on the Lock-tite!

[axapowell]

Originally Posted by RaggedEdge

I don't believe the rear mount (inner transom assembly) has a rubber insert. Just the bolt with a series of washers / spacers. I believe the runabout style front mounts do have a rubber insert, but can't believe any perf boat builder would use these instead of the solid cradle style.

Back to the liquid wrench, heat and the big hammer.

The bushing that is pressed in the rear transom assembly does have a rubber/ fiber insert with a steel bushing. The nuts are real soft too, aluminum if I'm not mistaken. Dissimilar metals between the nut and bolt, just corroded.

Dave

Part #2 - 88791A1 --MOUNT, Rubber / 88791T This Part is No Longer Available

[RaggedEdge]

Originally Posted by axapowell

The bushing that is pressed in the rear transom assembly does have a rubber/ fiber insert with a steel bushing. The nuts are real soft too, aluminum if I'm not mistaken. Dissimilar metals between the nut and bolt, just corroded.

Dave

Part #2 - 88791A1 --MOUNT, Rubber / 88791T This Part is No Longer Available

I follow you here but doesn't the bolt thread into the inner transom plate? Your pic looks like the bellhousing side of the equation. Isn't the rear mount bolt a shoulder bolt that threads into the inner transom plate only passing thru the rubber part? Maybe it's different on the HP transom assembly, not sure, all mine have been the HP versions.

[axapowell]

Originally Posted by RaggedEdge

I follow you here but doesn't the bolt thread into the inner transom plate? Your pic looks like the bellhousing side of the equation. Isn't the rear mount bolt a shoulder bolt that threads into the inner transom plate only passing thru the rubber part? Maybe it's different on the HP transom assembly, not sure, all mine have been the HP versions.

On all of the rear engine mounts (both HP and Non) the bolt (with the washer) just goes thru the bushing on the bell housing, then the fiber washer is sandwiched between the bell housing and the inner transom assembly, then at the bottom of the inner transom, there is a cage cast in the transom assembly which the aluminum nut is housed in.

Dave

[axapowell]

You may try to get in there with a dremel tool and cut the nut off. I'm sure it's tight, but if you can get in vertically and "slit the nut" it might loosen up. Just a thought if you are out of ideas.

We had to modify a transom assembly on my buddies boat last year because the casting had been stripped out from use of an impact gun to tighten these bolts! Follow the specs when re-installing and a little anti-sieze insn't a bad thing!

Dave

[Rippem]

Originally Posted by axapowell

On all of the rear engine mounts (both HP and Non) the bolt (with the washer) just goes thru the bushing on the bell housing, then the fiber washer is sandwiched between the bell housing and the inner transom assembly, then at the bottom of the inner transom, there is a cage cast in the transom assembly which the aluminum nut is housed in.

Dave

yup

[RaggedEdge]

Originally Posted by axapowell

On all of the rear engine mounts (both HP and Non) the bolt (with the washer) just goes thru the bushing on the bell housing, then the fiber washer is sandwiched between the bell housing and the inner transom assembly, then at the bottom of the inner transom, there is a cage cast in the transom assembly which the aluminum nut is housed in.

Dave

Essentially where I was going, burning out the rubber mount is not going to free it up, that is not where it would be bound up and the rubber is not in the inner transom plate.

I have attempted to not visit these parts often over the years, so I'll admit my knowledge here is pretty basic. Though I have had the miss-fortune of being up close and personal with them a few times. I'd be real happy if I never have to see them again!

[axapowell]

Without seeing it it is hard to tell what is frozen. The "bushing" is pressed into the bellhousing. Metal outer ring, rubber layer, then another metal bushing to house the bolt. Could be bound up against the bushing that is housing the bolt. Make sense?

Dave

[ThirdBird]

Originally Posted by axapowell

Without seeing it it is hard to tell what is frozen. The "bushing" is pressed into the bellhousing. Metal outer ring, rubber layer, then another metal bushing to house the bolt. Could be bound up against the bushing that is housing the bolt. Make sense?

Dave

Nah, you were right before Dave. Its the galvanic reaction of the dissimilar metals (steel bolt into an aluminum nut). Corroded-up. I like the Dremell idea, get a groove cut in that nut and it'll break open like a peanut. I've often wondered why they use aluminum nuts anyway, what's the purpose of that material choice?