15 replies to this topic

[Minidude7]

OK, as from many of my previous posts I undertook a head gasket replacement to my 998 Mini due to overheating, run on and oil pressure irregularities I then put it all back together and it ran from the word go with a rattle despite having all the correct clearences.

 

I today removed a non firing spark plug to find it crush against the node and the when looking inside discovered this;

 

 

 

The damage is mainly to port 1 but there is some light damage is number 2. What could have caused this? this was not on there when i put the head on and there was nothing left in there... Piston Ring?? If it worth repairing or taking out the engine for a reconditioned-new one. This is not the original engine so wouldnt be an issue.

 

PLEASE HELP!!

[jaydee]

Piston rings are too soft for such damage, anyway:

Do pistons have side movement?

Do pistons how up-down play if you gently press them?

 

 

The head can be saved, but its still not cost effective these day, i'd keep everything as a spare engine, and fit the recon unit.

These studs will need a bit tapping here and there to make them straight, and please use a proper bypass hose, not the concertina type.

[Minidude7]

the pistons didnt seem to have any real movement, there was slight scuffing to the top of the bore, nothing else... i'm thinking of outing the engine now... I know purists dont like it but what is the problem with the concertina hose??

[Gremlin]

Have you got an airfilter?

[Dan]

I know purists dont like it but what is the problem with the concertina hose??

It not about being a purist, concertina hoses are designed as an emergency repair. Look how thin it is, and it has lots of sharp bends primed to fail. From the factory this would have been a piece of normal hose and why shouldn't it be? That hose is part of the system and works at the same pressure and temperature as the rest and works under the same vibration. Would you replace the other hoses with something that thin?

[Dusky]

Intrested in what has happened to be honest

This isn't normal if you didn't do anything else than changing headgasket..

[klivins]

what could have caused this? some debris in manifold when assembling? 

[Sheikh Pip]

I'd say you may well have dropped metal bits of one kind or another into the induction system as you were putting the head on!  I doubt a piece of piston ring would have escaped and done damage in both cylinders.

[mini13]

what colour are the plugs?

 

I'm wondering if a lean mix has caused the end to come off the plug  and cause that damage, could also tie in with the overheating...

 

maybe an airleak on the manifold gasket that feeds 1 & 2...

[Minidude7]

Ok... Understand now about concertina hoses... Your right...

I want to know too!! Was sooooo careful when reassembling and am certain there were no pieces of anything inside the engine before the head went back on... None of the spark plugs are broken only bent closed and I do have an air filter on...

Still can't work out what would have caused this... Valves are entirely unscathed it's literally the piston top and underneath of head... The car is full of bodge jobs so may be another that's caused the issue..

Would everyone recommend outing the engine or repairing the piston and new head!?!?

[grumpy dad]

Hi

you say

( I then put it all back together and it ran from the word go with a rattle despite having all the correct clearences.)

you should have stoped  and sorted it 

my guess is you left some thing in there 

 

now if you look at the pic 

I think no 2 exhaust valve is not shut 

maby bent 

number 1 looks very bad 

I would replace the piston rings at least 

and the head 

when you get the piston out 

you might find you need a rebore

[Earwax]

Something was banging around in one. if you look closely the V of the inverted heart shape of the chamber has been cracked off,, whether this started it or was a result it is unclear... i would be stripping the head to see what is behind those valves , if bent etc ( as above)  interesting though , it was obviously big enough to not get sucked out straight away , so where is it????

[tiger99]

Just about possible that the big ends or little ends are failing, or maybe the big end bolts are loose, so the pistons have been hitting the head. In any case, I think the engine has to come out, although the cause may be something very different.

 

I once had a smashed piston, and gudgeon pin through the cylinder wall, cranksahft bent, and entire engine scrap, in an Opel Rekord (utterly horrid car, my next one had to be yet another Mini!), and there was a broken piece of unidentifiable metal in the wreckage, which never got in there due to anything I did, so such things do happen. Curiously a valve head had been broken off for some time, as the stump was black, but that did not account for the foreign object. It may be that in this case you will never find the true cause, but at least everything is inspectable, and replaceable at reasonable cost, so I recommend a full strip and examine.

[Minidude7]

big end gone... Was smashing inside of head.... Looking for replacement now... Thanks!!

[Gremlin]

big end gone... Was smashing inside of head.... Looking for replacement now... Thanks!!

How did some of the big end to be smashing the head?!