Knocking when warm

[bmcecosse]

As long as the gasket is for the 1098 - not for the 1275 engine ? If so - crack on - you've got an hour to get it changed .......

[LordAnthony]

It is - it was incorrectly ordered "just in case" for my other car in the days before I realised it was a 1275!
Sadly the kaput car is 13 miles away on my Mum's driveway or I'd be sitting here lapping away now.

[LordAnthony]

Took the head off today - The head gasket had blown between 3 and 4 and had a broken exhaust valve spring on 4.
Would one have caused the other to occur do you think?
For what it's worth, I've attached a pic of the cylinders in case anyone can see anything odd.
Is there anything else I should do whilst the head is off? It has a new bypass hose with shiny jubilee clips already.[frame][/frame]

[bmcecosse]

Pistons 2 and 3 look remarkably clean! You need to clean all the block top - ideally unscrew all the studs - countersink the stud holes slightly - and clean the whole surface but without rubbing it locally if you see what I mean ! I use the square end of a 12" steel rule - something like that - no rubbing with emery! Then refit the studs - make sure the bypass is NOT a corrugated one. On the head -same as block for the head face - best to examine the valves closely after cleaning them (spin in electric drill) - and grind in ALL the valves very carefully. And no - the broken spring wouldn't cause this.
This is where a spare head is really handy - you could be back on the road right away - and sort out the original head at your leisure!

[LordAnthony]

Right you are. A spare head would indeed be handy.
Thanks for all the help. I'd be lost without this forum.

[chickenjohn]

The pipe from the vacuum advance on the distributor is missing, or did you take it off with the carb?

[LordAnthony]

Well spotted! That was me - it was a copper one and was in the way rather.

[Declan_Burns]

Minispares sell a silicone by-pass hose which is supposed to be fit and forget. I fitted it on mine and have had no problems with it.
http://www.minispares.com/Product.aspx? ... 313&title=
Regards
Declan

[MarkyB]

A picture of the old head gasket would be interesting.

[bmcecosse]

You obviously haven't 'forgotten ' the bypass hose then Declan............after fitting it.

[Declan_Burns]

I will remember it for a long time and especially taking out the old short bypass stub and fitting a longer stainless steel one.

[Kevin]

Minispares sell a silicone by-pass hose which is supposed to be fit and forget. I fitted it on mine and have had no problems with it.
http://www.minispares.com/Product.aspx? ... 313&title=
Regards
Declan

Much cheaper and almost as long lasting is a small piece of the correct heater hose.

[LordAnthony]

Photos![frame]Blown gasket:[/frame][frame][/frame][frame]Overly Pitted? [/frame][frame]Broken spring:[/frame]

[MarkyB]

Amazing the compression test was so balanced with that chunk missing from the gasket!

[bmcecosse]

I do think you need a new exhaust valve - and a spring........

[LordAnthony]

It is odd isn't it? That's why I thought that perhaps the broken spring could have had something to do with it. But I don't see how. Either that or I did the something horribly wrong with the test but I don't think I did.

I've got a whole new set of exhaust valves and a spring on order.

Is it best to clear out all the oil ways with something before I put it back together?

[bmcecosse]

Just squirt some oil through from an oil can. The broken spring may have contributed to that bad valve - if it allowed it to 'float'. It likely be quite a job to grind in the valves - I assume you don't have a spare head ? And - if one spring broke like that - the rest are likely to be the same age and have had the same service life....... I would have fitted all new........ When the new spring arrives - line up all the springs on a flat surface - side by side - and compare their length with the new one.. I don't think you will like what you see.

[LordAnthony]

Bah! After buying new valves and springs I've just noticed that the head has a crack between 3 and 4!! It's just visible in the photo above. That'll teach me.
I'm on the look out for a replacement head if anyone has one?

[bmcecosse]

Oooh yes - I see the mark - most unusual........It must have seriously overheated at some time ? Good chance to fit an upgraded head! But there are some 12G202 heads on ebay - although a 295 is an improvement - the real way forward is a 940........
http://cgi.ebay.co.uk/A30-A35-A40-Minor ... 19bd9d1aeb
http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... :MEBIDX:IT
4 x 940 heads! http://cgi.ebay.co.uk/MIni-1275-Austin- ... 3f015dc70d

[metalmagpie]

Big ends are a lot more of a rattle than mains and you can "play" them by varying the engine load at fairly constant revs. The latter is/are a deep distressing thump and are worse a low revs. and the rear can be felt in the clutch when bad. Small ends are a lighter tap and are worse at light load as the revs rise.
Hope that makes sense, one has to experience them to recognize them and I have had known them all, to my sadness and expense at times.