Snapped head stud!!!!!!!!!!

gas1man · Jan 10, 2016

Any ideas as to why when putting the head back on to the barrel it will not go all the way down.

It comes up about 5mm short and as a consequence I have snapped a head stud bolt right off. :shock:
Is it possibly because of a thin layer of hylomar used as a sealer??????
Any info will help thanks.

J & P

rlepecha · Jan 10, 2016

Doubt its the sealer, did you check the barrel would fit in the head prior to assembly? Wonder if its a dodgy barrel or head (assuming one of them is new?)

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jonboylaw · Jan 10, 2016

Any clues as to what you have been doing ? What changes were made with the head being off ? Any chance you put a longer crank in but forgot to get the correct barrels/Pistons? 5mm is a huge amount of change with out explanation.

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gas1man · Jan 10, 2016

Absolutely no changes , head off cleaned up , new valves only and then the attempted replacement.
Any other ideas?

J & P

rlepecha · Jan 11, 2016

Have you got the under barrel deflector pieces fitted? If so, are they in a position that means they stop the head sliding over the barrel properly?
Sounds silly but I've done it before, forgetting that the tabs sit into the fins on the barrels so can't slide post fitting.

Other than that, what about pushrod tubes.. Are they the same as before? if new, is one slightly too long? Are they seated correctly as you fit the barrel? I presume you are using new seals, is there a dodgy seal on there?

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Trikky2 · Jan 12, 2016

Unless the stud was faulty I can't see how it would snap without exceeding the specified torque?

Never over tighten or you will distort the head or case or both.

You must remove the head and find out why it's not seating. It should seat all the way without the need to use the head nuts when the pushrod tubes are not installed.