Stubborn cylinder block ('77 gs750)

[erch]

So I made a winter project out of yanking my '77 apart to check the cams, valves and pistons, do a nice cleaning job and replace all the (probably original) gaskets.

Got a little lazy after I had checked the cylinder heads and let the thing sit for about 4 months. The garage isn't heated and I wasn't about to freeze to finish the job.

Cut ahead to last week, I try to get the cylinder block off and it won't budge. Reference my clymer (old original one mind you) to make sure I didn't miss anything. Rotated the crank thinking maybe the pistons seized sitting for those months, they move fine. Tapped away with a wooden block/rubber mallet contraption for about 3 hours, nothing. Got out a hair dryer with an extension cord thinking in the 8 degree (32 f) weather maybe everything had contracted, didn't get it very hot but still nothing.

The only thing I can think of to explain why this thing is still hanging on so hard is that the previous owner had the thing up north and had an aircraft/motorcycle mechanic patch a bunch of the cylinder head gasket with gasket maker, maybe he did something really stupid to the base gasket.

Any ideas?

 

[Nessism]

When those old gaskets petrify after 33 years they are a real bear to break loose.

I applaud you for not getting all heavy handed and bashing on the cylinder smashing fins. My suggestion is to look closely at the bottom of the cylinder for any possible pry points. Failing finding any, you can sometimes pry on the locations with the vertical fin support cast in joining the fins together.

One other thing you could try is making a wood or plastic wedge and driving that in between the parts. Use something soft that won't mar the metal.

Hope this helps and good luck.

 

[Detroit Diesel Man]

When I pulled my motor apart last fall it was the same thing..really reaaly tough to get the cylinders off...just alot of careful prying..working the cylinders back and forth..turns out once they came off the cylinder studs were corroded to the fins..the thing sat for 10 years with not being started..plus with humidity etc etc..just corroded where the studs came through the cylinder.


DDM

 

[erch]

What do you think about getting some liquid wrench and maybe some acetone into the gasket to see if it penetrates and eases things up? The oil's drained but the general consensus seems to be never to use that stuff on anything you ever want to seal again.

 

[Guest]

I'd use heat from a propane torch and not a hairdryer.

 

[Russ' GS1000E]

A stuck gasket is one problem.

Cruded-up studs is another....
I recently learned that cylinder removal would have been 10 times easier if I had started by removing the middle 4 studs entirely. This is the area that cruds up and keeps the cylinder from sliding off easy.

 

[erch]

A stuck gasket is one problem.

Cruded-up studs is another....
I recently learned that cylinder removal would have been 10 times easier if I had started by removing the middle 4 studs entirely. This is the area that cruds up and keeps the cylinder from sliding off easy.

Do elaborate. How would I go about removing the studs? Doesn't look like it's covered in my Clymer. I have been practically drowning them in WD-40 for a couple days to see if I could free up the corrosion.


I'm fairly certain at this point that it's corroded studs hanging on. From the look of the gasket that I can see (and I leaks I had before), the thing should practically be dust at this point. I've been working away with the WD-40, trying to get it to soak into the gasket before taking some more swings with the rubber mallet but I've been at this for days now.

edit: and I did wind up finding our propane torch. Gave that a go too with no results.

 

[erch]

good news!


Looks like I'm past the breaking point: got some wooden wedges in under some of the vertical fin supports and that was enough to release the suction long enough for the gasket to break.

Block's up about 2mm at the moment. Carefully working it back and forth till it frees up.

 

[erch]

Yup, Corroded inner 4 studs. Gasket was in about 8 different pieces, no wonder I was leaking.

 

[Russ' GS1000E]

erch,

I loosened the 4 center studs by double-nutting at the top. (Nessim tip)
Leave them in the cyl, but out of the base.
This will reduce the crud that gets dumped into the bottom end when you lift the cylinder.