Engine screwed!
 

Had a car (Fiat :D ) in work with a misfire; ECU reckoned it was no.4. It was, spark plug fouled. So assumed it was a ignition fault (coil pack, or ECU is quite prone on these). Anyhoo swapped coil pack and plug over with the adjacent cylinder just to rule them out and see if the misfire moved to a different cylinder. Engine still misfired, but needed to be driven to to assertain which cylinder was causing it.

Drove it, then the misfire cleared, drove a bit futher, just to make sure it was ok. It was. Came back to workshop, tidied a few bits and bobs and went to park the car up ouside whilst awaiting the go ahead to change the plugs and coil pack. Then the engine made an almighty clatter which sounded like a piston hitting a valve - I switched off straight away.

After some head scratching, checking camshaft timing, dropped/sticky valves. Did a compression check which was fine. Fired it up again...all quiet, it ran like that for 30seconds before the death rattle came back. Switched off, rotated engine by hand again and this time found a tight spot when cylinder 1 and 4 were at TDC. Got mini snake camera out to have a look doen the bore and found fresh dents.

So off with the head: Erm... yeah, how did that get in there (see Phips self-taping screw in pics below). Owner drove it over 50miles with the misfire too :eek:

Most of that was with teh screw stuck behind the inlet valve, until it finally broke in half...and teh threaded bit intermittantly stuck on the head or piston, which is why it sometimes would go quiet, then it would dislodge again and make a racket!

Fooking hell, so the question has to be asked, just how did a self tapping screw end up in the engines internals?

Nice imprints of the screw in the piston crown!!

Is that a screw or a spring

So....new piston?

Nah, he said it was a Fiat, might as well scrap it :D

How on earth did it find it's way in there? Through the air intake? Is the air filter intact?

Someone's dropped it in and thought it would be OK.

Its one of the screws that holds the cover on the air filter housing (the filter housing is like the ones found on old cars with carburetors....remember them? :D ).

My guess is someone used the housing as a tool tray whilst changing the filter and left one of the screws inside it. Over time its bounced its way around until it found its way into the intake!

Rods not bent. Valve is straight (amazingly - it never made contact with the piston). Valve seat appears to be undamaged (even more amazingly - the metal in the screw must be softer than the metal in the valve seat ). So that just leaves the imprints in the head and piston.

If it were a decent car, a new piston and some head work would be needed. But its a old Punto worth about £1500...so its just going have the burrs filed off the imprints, quick skim and a new head gasket. Not ideal, but it'll live to fight another day. :)

This is one of those stories that you always hear of (dropping stuff into the inlet), but none of us have ever actually experienced. And there's some old duffers in this workshop too!

You would have hoped that the screws could have found there way through the exhaust valves and out of the engine.

Oldest trick in the book Ali, bumping up the price in true mechanic style :D

To quote a true mechanic: "it was running ok when it left the workshop" :lol1:

It was. B@stard thing f**ked up on the car park with me driving it :o...There's me slap bang in the middle of the car park with an engine that sounding like it just expired. God that felt awkward. :lol1:

I was changing the plugs in my mk2 950 fiesta, don't know how I did it but managed to smash all the ceramic off one plug and it all fell in the down the plug hole!
What did I do? Well it was quite simple, bang the new plugs in and start it up.
Crunch crunch crunch, then it ran lovely.:luxhello:

Don't think I'd do it now though, was young and fearless then.:D

I was once asked to look at a Mitsubishi L200 which had just had the HG replaced at the main stealer. It had a horrid knock which the stealer had denied was there. I took the head off as it was obvious where the noise was coming from & I found a 12mm nut. The head & piston were well & truly trashed just like the main stealers reputation.

Love the title :D

When my eldest snapped the cambelt on his MkI Clio I had to replace one bent valve.

It had made some indentation into the piston, but as above, an old car, it was ground and emeried until it had no rough edges and is still running around town.

Nail on head.