My 53MM blows a gasket

[ian.mcdougall]

Hi All
Thursday my 53 MM decided to blow a head gasket, driving along fine after picking up my daughter and her 3 friends when it started to sound like I had a severe case of pinking, got steadily worse, losing power, had to tell passengers to walk rest of way home 10 mins walk, limped home with noise steam and horrible smells, still I had oil pressure though. It gave up the ghost and came to a halt, lifted bonnet steam coming out of split in bottom hose, pushed it last few hundred yards home with sons help. Later in evening started car, it started to run if a little rough, no horrible noises with oil pressure, so hope no bottom end problems.
Stripped head off today, was suprised to see no carbon build up, gave crowns of pistons a light rub and can read writting.So finally I come to the point, since pistons have STD + .040 does this mean it has been rebored to 40 thou

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gasket blown on NO 4 piston

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cylinder head

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lack of coke build-up

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and finally markings on piston crown

[mike.perry]

Hopefully that was a one off failure. It has gone between the piston and water passage which would explain the steam. It might be worth checking the head is flat and hasn't lifted in the corner.
There is a lot of carbon build up and it looks like traces of burnt oil. Is the engine using oil?
There are some rubbish head gaskets on the market, yours was a good one with all the water passage holes and the outside edge hemmed over. I have had gaskets that would not even fit over the studs properly.
+.040 is a 40 thou rebore. The bores will go out to +1.5 mm = +.063, just a case of finding the right size pistons.
You think you've got probems, my ends have gone and the engine is already out to +.060. Still I can always get it sleaved

[ian.mcdougall]

Hi all
I am putting back the head and the stud between the valves on no 2 cylinder is pulling out of the head, would it be a case of the threads on the stud rusted away, or the threads in head rusted away. It appears that the stud at the front of the engine has a larger thread in the head end of the stud than the top of the stud, could this have beeen helicoiled or rethreaded with a stud machined with a larger thread into the head, does anyone know can the block be helicoiled

Edited with pictures of the problem

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The stud with damaged thread note short length of stud it goes over inlets and is into the water jacket so not a lot of length can be used

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No thread in head can it be helicoiled

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front stud appears to be larger in the head is it made with a larger thread on the bottom and the head threaded to suit or would a helicoil look like this when installed
Any suggestions or tips or experience of similar problem gratefully received

Ian

[mike.perry]

You can get the block helicoiled. Remember it is a metric thread, M10.
The threads should be the same on both ends of the stud although the nut end thread is longer than the block end. You could always use an M10 bolt instead of a stud if your stud is knackered