I have no doubt that the cylinder head needs to come off. But the
metallic rattle is another thing altogether. I have an MGA that
sometimes makes a subtle metallic ringing noise that comes from the same
area that you mention. It sounds as though some little man is smacking
two hammers together down inside the engine. My best guess is that it
is wear in the wrist pin of piston number four. In your case, if it is
truly a rattle, and not a ringing noise, it may be actually be a worn
piston that "rattles" in its bore. The tach wiggle is curious, though.
Whatever it is, you may want to consider pulling the engine and doing
the whole thing..... Please let me know what you find.
1966 Morris Traveller
1964 Porsche 356C
On Fri, 7 Feb 1997 11:23:00 +0000 Phillips Kevin
>Dear MG Cognoscenti,
>I have an engine problem that I would like to get some input from the
>Car `74 B 18V engine - bit smokey but runs OK.
>Problem is a rather metallic intermittent rattle from the bowels of
>It comes from the No. 4 Cylinder (distributor) end of the engine and
>slipping gears or metal to metal contact of some sort. OUCH !
>The engine runs OK otherwise and does not drop revs or lose power when
>appears. It lasts maybe 30 seconds and then stops, it can reappear
>between one or five minutes but it's not at regular intervals.
>The noise is accompanied by the rev counter swinging wildly although
>speed always remains constant ??????
>Needless to say the car is in the garage and is not coming out again
>is fixed !
>Some other points of note -
>1. The engine oil was contaminated with water prior to Christmas which
> was condensation, but it worsened (even after an oil change) and so
> thinking head gasket..
>2. The car had also started to smoke a lot more just prior to the
>3. If the engine was started and warmed and then switched off, when
> a cloud of white smoke appears from the exhaust and the engine runs
> 10 seconds then is fine. (water ? head gasket ?)
>4. Compression test with plugs out shows higher compression than the
>last test I
> did 6 months ago when the engine was fine ??? 1=150 2=155 3=160
> about 5 psi on each cyl from previous test. This is why I thought
> was not head gasket when it first appeared.
>I am taking the engine out next week to sort the head gasket and
>new oil seals on the valves and to detain the engine bay - so this
>problem can hopefully be fixed whilst the job is underway.
>Any help, suggestions, prayers would be most gratefully accepted.
>Kevin `74 MGB