manifold bolts

[blacktrain]

I have a 1993 merc. cruiser 4.3L I have to replace the manifold on one side and I am afraid of breaking the bolts. I have applied quite a bit of pressure to the point I am afraid they might break off, so I quit before I snapped one off. Any suggestions? I appreciate anyone's help. Thanks...

 

[achris]

Often a sharp hit with a hammer can loosen a stuck screw.

If that doesn't work drill the heads off the bolts and slide the manifold off the (now) studs, then work on them with the manifold out of the way. This only works if you have clearance to slide the manifold. Make sure you have before drilling the heads off.

Chris...

 

[Rick Stephens]

Once you get to studs with Chris's method, you can apply significant heat (red hot) to the stuck bolt, expanding it and breaking loose any rust. Then it will come out much easier. Note that stud sockets are much safer and cheap to purchase than grabbing with vicegrips.

 

[Lou C]

If you can run the engine on the hose try warming it up first; that might help.

 

[blacktrain]

Thanks everyone, I appreciate all your help. Never thought about grinding off the bolt heads and removing the manifold for better access to the bolt stud. Thanks again everyone.

 

[jhande]

Before removing the bolt heads, I'd try...
Run the motor to warm it up then tap the bolt heads with a hammer as if trying to drive them into the manifolds.
If the bolts are near an edge of the manifolds using a MAP gas torch to heat the head near the bolt location can help.
Last resort grind bolt heads off. Then use above to remove the studs.

Good luck!

 

[Scott06]

Thanks everyone, I appreciate all your help. Never thought about grinding off the bolt heads and removing the manifold for better access to the bolt stud. Thanks again everyone.

I've done it on old cars, grind head off, heat and pipe wrench on the remnants of the bolts. Ricks comment of stud remover is definitely better ..

Be patient with the heat especially if you are using a small propane or mapp torch. If you break it of clean with the head you will end up yanking the head to drill and tap it