blown head gasket

Post by **aupickup** » Sun May 06, 2007 9:13 pm

blew the head gasket today, had to travel about 10 miles, would i have done any damage.
i have taken the head off and it is blown betwen 3 and 4
pistons seem ok , bores are nice and shiny and not scored and no lip at the top
do i have to take the tappet chest covers off when i replace the push rods

any one got a head gasket they could let me buy i am in eastbourne tho

Post by **wanderinstar** » Sun May 06, 2007 9:21 pm

You shouldn't have to take tappet covers off.
if you are in Eastbourne give ESM a ring you will have gasket next day.

Post by **bmcecosse** » Mon May 07, 2007 7:20 am

Any Autoparts place will give you a head gasket - just ask for 998 Mini gasket. But driving it like that for 10 miles was NOT a good idea - may well have erroded the head and/or block. Clean it all up - then check with a straight edge (steel rule or back edge of a hacksaw blade) across the area. When the heads off - you may as well grind in the valves. When taking out pushrods you must shake them to make sure they don't pull the cam followers ('tappets') out of the block. If that happens, then indeed you need to take the side covers off.

Post by **aupickup** » Mon May 07, 2007 9:23 am

cleaned areas up and all is good with a steel rule across the bores and all ok on head

have also checked
across diagonally and all is ok

now i have been having trouble with mayonase inside the oil filler gap, was or could this have been the start of the gasket blowing

this was a reconditioned engine, but i did notice also when undoing the head nuts that the back nuts did not take as much to undo than the front ones, so maybe the reconditioners did not torque them up the same

ah well back to suppliers again

thanks bmc

Post by **IslipMinor** » Mon May 07, 2007 9:56 am

Aupickup,

Don't forget to re-torque the head nuts once the engine is warm, and then again after 500 miles.

Post by **aupickup** » Mon May 07, 2007 9:59 am

ah ok
so torgue when cold, then run engine up to temp, then retorque, and then again after 500 miles

Post by **IslipMinor** » Mon May 07, 2007 10:09 am

Yes, and the tappets three times as well! That's when having the starting handle is really useful.

Post by **aupickup** » Mon May 07, 2007 10:13 am

thanks richard

Post by **Dominic** » Mon May 07, 2007 10:44 am

That's when having the starting handle is really useful

That's what the starting handle is for!

Post by **aupickup** » Mon May 07, 2007 12:00 pm

thats ok cos i got 3 of them

Post by **bigginger** » Mon May 07, 2007 2:35 pm

Dominic wrote: That's what the starting handle is for!

Quite handy for starting the car too, I find...

Post by **aupickup** » Mon May 07, 2007 2:40 pm

i use a key for starting the van

Post by **bigginger** » Mon May 07, 2007 3:21 pm

But still kinda useful when. say, the battery's nearly dead

Post by **bmcecosse** » Mon May 07, 2007 3:25 pm

Good idea to oil the threads of the head studs - and place thick washers under the nuts. BMC used to call this the 'Competition Head Washer Set' - but that's all it was - thick washers. These allow the nut to clamp down rather better - less friction as they turn. Then of course there is the matter of what torque to use - 44 ft lbf should be ok. Latest Minis etc are rated to 50 - but they have special studs fitted, although they still screw into the same old block!

Post by **IslipMinor** » Mon May 07, 2007 4:26 pm

The BMC Manual says 40 lbf. ft. for the head stud nuts (25 lbf. ft. for the 4 rocker shaft pedestal nuts, which are 5/16" UNF). Some of the later studs are higher tensile and need to be torqued to 50 lbf. ft., but at this torque the standard studs will either stretch (losing clamping force on the gasket) or risk stripping and have to be replaced.

The washers also need to be harder, as well as thicker, or the nut will chew up the face of the washer. Oiling is definitely a good idea.

Post by **aupickup** » Mon May 07, 2007 4:31 pm

will stick with what the manual says thanks

Post by **bmcecosse** » Tue May 08, 2007 7:37 am

Aye - but the later manuals for other A series engines advise higher and higher torques eventually up to the 50 ft lbf of the Minis. Indeed - the latest studs have a little 'Y' on the tip - and these are the ones that can go to 50. But 44 is ok on standard Minor studs. As ever - do this in small stages, round and round the head slowly cranking up the torque. I've had no problems using standard thick washers. By the sound of your description some of the nuts were not fully tightened before - and that was probably what caused the problem.

Post by **rayofleamington** » Tue May 08, 2007 3:41 pm

but the later manuals for other A series engines advise higher and higher torques

when the stud materials were changed, the torques were changed - Higher spec materials need more torque for the same elastic travel.
Oling threads will put the stud into more tension (if less torque is used overcoming the thread friction, more is converted into tension so the stud will be inder more stress). Therefore the correct specified torque in a workshop manual relates to dry threads unless specified otherwise.

Post by **aupickup** » Tue May 08, 2007 8:59 pm

on some of the nuts, the ones that came from insude the rocker cover ( for the head nuts) have a combined washer with the nut, shall i put these back on or change them for nuts and seperate washers

Post by **les** » Tue May 08, 2007 10:31 pm

. Therefore the correct specified torque in a workshop manual relates to dry threads unless specified otherwise

In fact I think there is a different value for 'wet' torque, not that I know what it is in this case!