Knocking when warm

[bmcecosse]

No - the compression test would have shown that. Although low - they are all ~ equal!

[LordAnthony]

Could it be a symptom of a worn clutch driven-plate?
Also, I noticed that the car slightly lurches a bit when slowing down in gear. Is this what's called clutch-judder and could it be related?
Sorry for all the basic questions. This is the first time I've had to deal with any of this.

[chickenjohn]

Left field thought......

If the oil pressure is fine, could the knocking not be another cause?? With the lurching etc, what about perished engine and or gearbox mounts? Decades of oil leaks can over time soften the rubber leading to the engine moving and possibly knocking.

I agree with BMC though, run the engine, even if it does have problems, just don't thrash it and it will be fine for a long while yet! A series engines can soldier on for ages with faults that would cripple lesser engines.

[bmcecosse]

It's not just the exhaust banging against the body ??

[chickenjohn]

Good point, BMC there was a batch of dodgy exhausts a few years ago. i struggled to get the one on my traveller not to keep bashing the cross member.

Could be that. Luckily they seem to have improved the exhaust design now in two pieces and fits better.

Could the knocking also be a missing engine steady bar/ cracked mount, the noise is the fan blades slapping into the radiator!!

[LordAnthony]

Engine mounts are present and correct as is the steady bar and gear-box metal cord thingy.
Haven't had a chance to drive it today for required length of time to induce the problem but I'll be going to work in it tomorrow (yipee.....) so will keep a look out.

[bmcecosse]

Is this the car you have for sale - or another one ??

[LordAnthony]

This is another one!
I've got 3; 2 saloons and a Traveller.
Limited funds and lack of off-street parking dicate that 2 must go.
This one with the knocking has a lovely Newton Commericla interior - purchased from this board a few months ago - so I'm going to use the money from the others to fund the upkeep of this one.

[bmcecosse]

Sounds like a good plan.......

[LordAnthony]

well, I'm at the side of the road waiting to be picked up by recovery vehicle!
Engine suddenly lost power, sounded like a tractor, started smoking and had to be pushed to side of the road. bah.

[LordAnthony]

Just got towed home. The Recovery man had a listen and thought that it sounded like the head gasket.
My compression test results the other day seemed fairly even - can head gasketss fail this quickly?
Could the gasket have blown on all 4 cylinders equally?
I'll find out I suppose when I take the head off, but likely to be next weekend now.

[MarkyB]

Presumably the blow starts off too small to affect the engine running at all, even at tickover.

The one I saw that was causing a knock was between cylinders 2 and 3, it was about a quarter of an inch piece missing.

There was one being replaced at the MOT that had an inch and a half gone .

Once it starts to go, very hot gasses are are going to be forced through a small space and will certainly be attacking the gasket further.

[bmcecosse]

Always carry a spare head gasket - then you can sort it out yourself. An hour does it!

[LordAnthony]

Ah, if it's an hour for someone who knows what they're doing then I think that's roughly a morning for me. Not including the time to visit the motor factor for bits I don't have.
If it is the head gasket, what would be the cause of the noise? Is it air being forced out of the head? Pistons knocking on something?

[bmcecosse]

No - just explosion in one cylinder escaping into the next. The 'hour' was for you - it would take me much less!

[chickenjohn]

Hopefully thats what the noise was! the head gasket gradually failing.

I would actually spend more than an hour and while the head is off, grind the valves seats in and fit new exhaust valve oil seals. Clean all the carbon off the head as well.

[bmcecosse]

Of course - and so would I - except at the roadside! Have in the past changed head gasket on racing Mini in less than 30 mins...... The longest part is resetting the valve gaps.

[LordAnthony]

Well, whilst the head is off I may as well go the whole hog.
I notice on the ESM site that there are 2 types of oil seal - "Spring" and "o ring" http://morrisminorspares.co.uk/shop/adv ... valve+stem
Can either be used? Is one better than the other?
Should I get new valves whilst I'm at it?

[bmcecosse]

Remind me - is this a 1098 engine ? Yes - you should grind in the valves - and fit new oil seals to the valve stems - correct for a 1098 is the O ring seal. You 'can' fit the cup type seal - but they may not stay in place on the inlet guide for long. You will only need new valves if the old valves are ruined.

[LordAnthony]

It is indeed a 1098.
Would you believe it! I've just checked my spares department, alright then "utility room", and I would appear to have some o rings and a head gasket in stock.