Mercruiser 3.0 litre Rear Engine Bolts

[Me and My Capri]

I'm trying to lift a 1990 model Mercruiser 3.0 litre and am having trouble removing the rear engine bolts. I've torqued on them with some major foot pounds and they seem to have a spring loaded effect then stop and won't budge. The Merc manual says to lift the engine slightly with a hoist first. Is this the key to getting those bolts to free up. Tey almost feel like they have a twist lock style to them. What am I doing wrong???? Any help would be appreciated.

 

[Bondo]

Re: Mercruiser 3.0 litre Rear Engine Bolts

Ayuh,.......

You already have the Outdrive off,.....Right,..??

What have you done with the Front mount so far,..??

Do you have a Hoist,..??

 

[Me and My Capri]

Re: Mercruiser 3.0 litre Rear Engine Bolts

The front mount has been lossened off, the outdrive removed, everything else disconnected and ready to lift. The only holdback are the rear bolts but I'm afraid to really torque on them. The 2 manuals I have say nothing particular about them in removing them. Like I said I've put some major force on them and they still won't budge??? No corrosion apparent anywhere?

 

[Don S]

Re: Mercruiser 3.0 litre Rear Engine Bolts

Get a big 1/2" breaker bar on an extension to a 3/4" socket on the bolt head and turn it till it comes loose. I have have had to burn off the head of the bolt and burn the rubber out of the mount to get the engine out. Then with the motor out of the way, have room to heat the area around the bolt thru the inner transom shield. You do have to be careful not to overheat and melt the aluminum.
PS, propane torches don't work at all, you need the real thing Oxy/Act

 

[Bondo]

Re: Mercruiser 3.0 litre Rear Engine Bolts

Get a big 1/2" breaker bar on an extension to a 3/4" socket on the bolt head and turn it till it comes loose.
PS, propane torches don't work at all, you need the real thing Oxy/Act

Ayuh,......

With a Long enough piece of pipe,.....
The Bolt will come,.... Or the socket will Break.......

If it's the latter,.... Then it's time for the Blue-Tip Wrench........

 

[JustJason]

Re: Mercruiser 3.0 litre Rear Engine Bolts

if you have the tools and you can get at it, an impact gun may work better. The hammering action of the tool will often spin a bolt free that a breaker bar would snap.

 

[gentner8]

Re: Mercruiser 3.0 litre Rear Engine Bolts

In my automotive wrenching, I have found heating the bolt and the spraying pb blaster yielded good results. You can see the fluid sucking into the threads. Hopefully this helps. Doing this a couple of times then waiting overnight often works for me. Good luck!

 

[Bt Doctur]

Re: Mercruiser 3.0 litre Rear Engine Bolts

gent, mercruisers are a bit different. the bolts in question most likely have
corroded to the sleeves in the rubber mounts because of the "spring back" you describe.if you can`t undo them with a breaker bar and pipe, you`ll need to cut the head off, heat the rear mounts,remove the motor , remove the remaining bolt material .

 

[Me and My Capri]

Re: Mercruiser 3.0 litre Rear Engine Bolts

Thanks for all the assistance guys. I borrowed a 2 ft section of pipe from a neighbour and put some heat on the bolts and they finally broke loose. I managed to melt one of the rubber bushings in the process but at least the engine's out. Strippped it down and the block and head are sitting in the machine shop getting reworked. The plan is to get it back together for July 1!!!

Thanks again for all your help!