Just in the process of removing my 454s from my 272, i'm having a real problem with one of the rear engine mount bolts that locate through the bell housing and into the transom plate. It's absolutely jammed solid. Tried an impact wrench and huge extension bar but it just wont budge. All the others came out no problem. contemplating grinding the head off but there isn't much room down the back of the motor!

Any ideas on how i can undo it would be appreciated??

Cheers
Steve

I had the same problem with a 502 years ago, I threaded a rope through the mount, and lifted the mount off the bolt with the aid of Poole Boat Parks fork lift truck.

try some wd-40 on the under side of the mount and bolt threads if you can get to them, be careful cutting the head off the bolt it may be hung up inside the mount itself. also you may want to try a long extension and a breaker bar before you put an impact wrench on it.

Good advice from Past Due. I would have thought that would be step one before even asking on here.

If you cut the head off the bolt, and it is stuck that bad, you will for sure be into a new inner transom plate. Might try heat just in case someone did the red lock-tite deal. Have you checked the other mount bolts for evidence of lock-tite? Normal cautions as to the use of open flames in an engine compartment would apply here!

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 .

Soak it at the threaded area with WD-40 or PB Blaster. Let it sit for a day to get in there. Before you try to remove it, use a bar or similar item and pound the top of the bolt to send vibrations thru it to loosen it up. Those bolts are made of aluminum so it is probably just stuck. Also the longer the extension you use, the greater you reduce the actual torque at the socket due to the bar twisting. Try to use as short an extension as possible.

Good luck to you, I've been there! I had this same problem on a Scarab a while back. I wound up borrowing my friends 3/4 drive impact that he uses to service his dumptrucks. It got loose thank god, but did wreck the mount.

Thanks for the comments guys. have tried a mix of extensions and bars but it wont budge. The others came out no problem at all and no evidence of loc-tite. have soaked it in WD40 and given it some good knocks with impact wrench but trying to be careful not to round the edges off the head. have a firend coming round with a 1" truck impact wrench so will see if that will shift it. will let you know how it goes.

Get some heat on it. You don't need much just a little bit and it will start to come out.

Nothing holds like a good crossthread!!!