1973 Eldorado - Cap over cylinder head bolt will not move

[Odradek]

Wanting to retorque the cylinder heads on my 1973 Eldorado, but I’ve hit a problem.
The cap that screws down over the top (recessed) bolt, seems to be seized.
Part number 95980120.
And this is on both cylinders.

Bought a new 26mm spanner, and removed the fuel tank now, to try and get more leverage than a socket, but neither of them will move at all.

Has anyone encountered this before ?

I resorted to hitting a breaker bar with a large rubber mallet, but have now given up, in fear of damaging something.

[Mor]

I'd get some heat onto it, blowtorch or heat gun. Is the socket a 6 point or 12 point? A 6 point socket will be far less likely to slip and round it.
The rubber mallet will be absorbing the impact when you're hitting the breaker bar, try a nice heavy hammer if it still needs a shock to move it.

[nc43bsa]

Heat, 6pt socket, air gun.

[n3303j]

Grind the socket face flush to eliminate the lead in angle. The object is to bear 100% on that narrow hex head to lessen the chance of deforming it. Combine the flat faced socket with an impact wrench and you are probably there.

You might also try giving the offending plug a sharp rap directly on top with a steel hammer. Object being to compress the sealing washer and move the plug laterally in the threaded bore. This stands a good chance of freeing it up for removal.

[Odradek]

Thanks for all the replies.
It's a 6 point socket, but yes, grinding the edge off it would give it more grip on the narrow nut.
Think I'll have to put it all off for another day though.
Simple jobs turning complicated.

[Dukedesmo]

Agree with above; heat, air gun and grinding the lead-in off the face of the socket.


I have a Ducati 916, the rear wheelnut requires a 46mm socket and it needs to be tight, problem is that the nut has a very thin hex surface such that a normal socket only grips on a small amount so tends to slip off which can not only damage the nut but also cause injury whilst you're torquing it up so I have ground the socket flat - much better.

[guzzisteve]

If you have to I have used breaker bar 1/2" and a pipe slid on it. +1 on the socket grind.

[TOMB]

When you finally get those coverable bolts out. Replace them with  a T3 PART same thread pitch, but it now uses an Allen wretch works. Fine.  When I had my El Dorado works perfect and it seals with an old ring instead of a flat aluminum washer.
TOMB

[Antietam Classic Cycle]

When you finally get those coverable bolts out. Replace them with  a T3 PART same thread pitch, but it now uses an Allen wretch works. Fine.  When I had my El Dorado works perfect and it seals with an old ring instead of a flat aluminum washer.
TOMB

I do the exact opposite - replace the socket head caps with the Loopframe hex head version. The socket head ones are soft and can strip out, always seem to be seized into place.

[pehayes]

Common issue.  Use shock rather than brute twisting torque.  Air gun is best as it delivers both repeatedly.  I've had the internal hex version stick the same way so I'm not convinced that is any better.  The internal  hex version is better for sealing since it uses a compressed o-ring.  But the o-rings get brittle with heat cycles so be prepared to replace every now and then.

Patrick Hayes
Fremont CA

[bmc5733946]

My advice is to smack it very hard right on top with a hammer. Have done it many times with both types of bolts the internal and external hex heads. I usually hit the end of my allen socket for the internal hex ones. Go ahead and hit it pretty hard see if it won't come loose, make several tries if necessary.

Brian

[wirespokes]

 author=pehayes
Common issue.  Use shock rather than brute twisting torque.  Air gun is best as it delivers both repeatedly.  I've had the internal hex version stick the same way so I'm not convinced that is any better.  The internal  hex version is better for sealing since it uses a compressed o-ring.  But the o-rings get brittle with heat cycles so be prepared to replace every now and then.


 A hard hit isn't necessary. The trick, as with rusty fasteners, is heat/cold cycles, penetrating fluid and vibration. The trick is that tapping on the fastener makes it vibrate. It will vibrate at a different frequency than the surrounding metal, breaking it loose. That will also allow the lube to seep in.

Also, even though it seems counterproductive, twist the fastener both directions, tighten, loosen. and use a metal hammer on the wrench - the vibrations help, not a rubber or plastic mallet. Just yesterday I had to remove a bleeder from a brake caliper and had to do all of these exact same things to get it out.

Patience is the key - knowing that although it feels like you're making no progress, this is the route to success.

[Odradek]

Success at last.

Thanks for all the suggestions.

I ground off the edge of the 26mm socket to get a better grip on the nut, and then bought a new, longer breaker bar.



A few heavy bangs on the nut with a metal drift and then some steady pressure on the breaker bar and the right one eventually started to move.
The one on the left cylinder was tougher, but I got it off too.

Think I should invest in two new caps before putting it all back together.

Thanks again.

[Antietam Classic Cycle]

It goes without saying... use anti-seize on the threads.