Agreed but I would say that's pretty conclusive as I got crank pressure, an oily plug and no compression so I'm guessing something has given internally.

I wonder if faulty head gasket could cause these symptoms? Wishful thinking but fingers crossed none the less.

i had a crack in cilinder 3 , had the same problem

Before you remove the head (and destroy the evidence!) I would put some oil in that number three cylinder and repeat the compression test.

If that gives you a reasonable compression pressure, then you will know that it is a failed piston and/or rings.

When you are low on compression due to a faulty valve (or even a severely blown HG) the plug in the effected cylinder will still tend to oil up, as there is no pressure above the piston and it will start to pump oil.

To have a zero reading on a cylinder is a bit drastic, but it is still worth checking out thoroughly, as once the head is 'off', if you are still unable to see a problem, then you are left guessing at the probable cause.

Regards.

If you are getting zero compression then my money would be on either a dropped valve or a melted piston

i had a crack in cilinder 3 , had the same problem

Cracked piston?

Before you remove the head (and destroy the evidence!) I would put some oil in that number three cylinder and repeat the compression test.

If that gives you a reasonable compression pressure, then you will know that it is a failed piston and/or rings.

When you are low on compression due to a faulty valve (or even a severely blown HG) the plug in the effected cylinder will still tend to oil up, as there is no pressure above the piston and it will start to pump oil.

To have a zero reading on a cylinder is a bit drastic, but it is still worth checking out thoroughly, as once the head is 'off', if you are still unable to see a problem, then you are left guessing at the probable cause.

Regards.

Yes it's quite bad but it must be severe as it turns over the same whether there is a spark plug fitted or not.

I'll try the oil test, see how I get on, I'll report back and you'll have to tell me what you think.

If you are getting zero compression then my money would be on either a dropped valve or a melted piston

How would a valve be dead? Steam seal?

I don't even know how I could have got the engine hot enough to melt a piston, not heard it pink once, but I'm not ruling it out either.

You can burn valves out, but that wouldn't really explain crankcase pressure

Yeah good point actually, that pretty much rules out out a fucked valve

But a broken valve would cause lack of/no compression lol.

But that wouldn't chuck pressure out of the oil breather. I'd say the chances of the two issues (no compression/high crank case pressure) not being connected is extremely slim

its shagged.

end thread

But that wouldn't chuck pressure out of the oil breather. I'd say the chances of the two issues (no compression/high crank case pressure) not being connected is extremely slim

Never said they were man haha I was making your point valid although not relevant to this particular issue last time in nice to you!

Piston melted - end of speculation.

It's marked the bore slightly, can it be re-honed or is the engine scrap? The scoring isn't deep but is noticeable obviously.

Cheers

i had a crack in cilinder 3 , had the same problem

Cracked piston?

no a crack in the cilinder wall

Was you aiming for MikeyMPG

Piston melted - end of speculation.

It's marked the bore slightly, can it be re-honed or is the engine scrap? The scoring isn't deep but is noticeable obviously.

Cheers

you can rebore to 77mm max oem is 76.5mm , best way is a new block

But that wouldn't chuck pressure out of the oil breather. I'd say the chances of the two issues (no compression/high crank case pressure) not being connected is extremely slim

Never said they were man haha I was making your point valid although not relevant to this particular issue last time in nice to you!

I thought you were so how saying that it could still be a valve, my bad xx

I'm always good to You Guy, even stopped you going down the M6 the wrong way

Wouldn't be so bad if that was the first time I've done it. managed to head towards London while making my way back from a meet up near bagginton airport once

Bless you!

its shagged.

end thread

Piston melted - end of speculation.

It's marked the bore slightly, can it be re-honed or is the engine scrap? The scoring isn't deep but is noticeable obviously.

Cheers

see! told you. arent i good!

This is interesting.

I've got scoring on the cylinder walls. But it's not really scoring though, not deep. Can still clearly see the honing marks, and the scores just remove the honing marks.

Found a chip on cylinder one, but it's covered in carbon which I assumed meant it'd been there a while. Will fill the bores with petrol tomorrow and see the outcome. It's scrapped now though; bless her. :(

I can't even see how this could've happened...

I've not once heard the engine pinking so I don't see how detonation could've caused it. Plus, if it got hot to the point of melting pistons, wouldn't I have seen something on my coolant temp gauge?

The only other suggestion was oil starvation caused it to get hot... But again, never have I heard any knocking or tapping. Really odd!!

Lean?

Mine was lean top end due to wrong needles.

Which cylinder was it? This is the second time I've done it, due to aiming for max economy, but whilst it was number three this time, last time the water pump had a damaged impeller and the melted piston was on cylinder four (which naturally runs hottest due to the other three cylinders getting the coolant first). The plastic impeller was damaged by a rogue bit of the rear coolant pipe.

Both times the damage was only on the far thrust side of the crown. Last time it holed behind the rings where the crown went badly. This time it didn't puncture the piston, only melted the crown a little. It's possible the upsquirters helped this time, but they couldn't save the block which is scored. I don't think a hone will save it, so it's new block time.

This is the main reason i bought a wideband gauge, engine protection!