20 replies to this topic

[leroy26]

will a cyl head gasket leak for a few mins after a new ones been put on till the copper heats up and bonds?

[03jkirk]

shouldnt do if surfaces are flat and it is torqued down correctly

[Cooperman]

No.

[bmcecosse]

Where is the leak? Were both surfaces spotlessly clean? Gasket coated with a thin film of grease?

[leroy26]

not done it yet! just seeing what to expect

[bmcecosse]

Good grief......think positive !

[leroy26]

why?? i own a mini!!! like itll ever go right!

[Chance]

Done two gaskets on mine now :) just cleaned up faces, I was happy if there was no high spots
Put it on with no grease or anything, torque it down as per Haynes and been fine both times :)

[coopdog]

mine leaked like a ******* :L
think the head warped on mine

[Ryang556]

If it leaks then something's not right!

[Spitz]

I've been told to put it through a heat cycle or two ( drive a number of miles ) and re-torque the head ( in sequence )

[tiger99]

Correct, give it a few heat cycles and retorque. You can also do it again after maybe 20 to 50 heat cycles if it makes you feel better.

When torquing or retorquing make sure that the threads are oiled, so you really get maximum tension in the studs. Initial torquing, nip up in 3 stages, to 20, 40 and then 50, and make the final bit one continuous movement, so there is no error due to stiction.

Retorquing, loosen one nut at a time, and take it up in one continuous movement to 50.

[dklawson]

so there is no error due to stiction.

Tiger, I know we've touched on this before, but what type of engineering have you been involved in? Stiction is a term I seldom hear outside of mechanical engineering circles and specifically applications with dynamic and static conditions such as air cylinders.

Very true, you want to apply the torque in a slow, steady movement to avoid stiction when making these critical settings.

As for grease on head gaskets? I have never used grease. On un-coated gaskets I have used a copper filled gasket spray. On coated gaskets (like some of the Payen's) I use nothing as the shiny black coating is basically a pre-applied sealant.

[tiger99]

Doug, I am mainly in electronics, but some of my early work was in precision servo systems, where stiction was a right pain, as with your air cylinders, except that the drive was by DC torque motor and recirculating ball screw. I also used to assemble some of the mechanisms myself, so learned quite a lot about that side of things from the mechanical guys. I have also used hydraulic servos for the motion part of a driving simulator, sort of like a very cut down flight simulator.

I also find that when your job involves lots of one-offs, as it did for some years, you need to study a lot, and acquire knowledge of various odball areas of technology. I can't retain all the acquired knowledge of course, some things I may not have done for 30 years, and I would need a quick refresher from maybe Wikipedia to get up to speed again.

Nowadays I am mostly in control and safety systems for nuclear powerplants, and the only mechanical details I get involved in are things like arranging for cabinets to be securely bolted together so they will withstand earthquakes.

Alan

[leroy26]

so i need to let it idle for 10 mins two or three times then undo one nut at a time then retorque to 45lb/ft
( the minisport bolts state that they are 42lb/ft)