alcazar

iTrader: (2)

Only a 1.2, and belongs to my eldest.

Luckily he wasn't going fast when it went, and now we (I) have taken the head off and the valves out, we have two bent exhaust valves, and 3 pistons with marks, one about 1.5mm deep.

The valve that touched the other piston seems to be OK, I ran it up in a lathe to check, and it runs true.

After replacing the bent valves, does anyone not think we'll get away with the piston marks? Should I polish them out?

TIA.

Alcazar

LG John

Eh, the car won't run with a 1.5mm scratch in a piston!! I doubt it would run with even the more general scoring on the others. Sounds like new pistons to me but then I'm not expert.

The Mini Daddy

it will run you fool after about 2 minutes of running the scratch in the piston will carbon up and disapear

god, SAXO DRIVERS

LG John

Ease up mate, I said I'm no expert! And for the record I've had a 275bhp scooby and two Peugeot 406 V6s (one of which blew up!) since my saxo all those years ago so don't be so quick to judge!

Big Col

are the valve guides OK?

The Mini Daddy

had

so what you drive now?

LG John

On the 2nd 406 and the first one is in bits at the garage. Thinking of switching the engines as the bodywork on the 1st one is nicer.

Carl2

I'd expect it to run with the scratch, but it could have side effects depending on the scratch. It will a) very minutely lower compression on that cylinder b) if it has any sharp edges they may glow red hot and lead to det, so remove them.
More importantly in my opinion, that piston has obviously had a fair old knock, has doing so caused it to catch the cylinder wall and damage the skirt or wall? Definately worth checking out in my opinion.

alcazar

iTrader: (2)

The scratches are sort of moon shaped indentations in the piston crowns.

He defo can't afford a complete rebuild, so I thought of polishing out the marks with a Dremel and plenty of grease to protect the bores.
Valve guides are OK, AFAICS, and they'll get new oil seals of course along with all new gaskets.

What REALLY got to me, apart from the tight clearancers to remove amost eveything, was the number of non-reusable clips on pipes that Renault use.:

Whatever happened to the good old Jubilee clip?

Alcazar

MGJohn

alcazar,

What you describe in your 16.56 posting is the first course of action I would take. Then drive car carefully for a few miles being ever watchful and listen for signs that all is or is not well. Sounds like your valves took the main damage forces, not the pistons and rods. You can check for bore marks etc. Chances are it will be OK. In event it is not, rather than new pistons, easier to source a good used power unit.

Most car manufacturers use self-destruct on removal hose clips or fasteners for those smaller fuel lines and hoses. I think you need a special type of pliers to remove them without damage. Those on my old MG Montego Turbos I can now remove with minimal/nil damage using good condition pliers. Mind you, I ruined a good few before I sussed how to remove and recycle them. It's not a case of being a skinflint, but when you need new ones, the spares dept is closed or will have to get some in tomorrow! .... and you need them NOW to finish the job.

THE M25 FLYER

If its only light marking on the piston crowns then there is nothing to worry about,(if it failed at low speed then no worries)in all the years of repairing engines after a cambelt failure i never found the need to replace pistons,even on diesel stuff that had let go on the motorway.
What i would advise is to carefully check to see why the cam belt failed,paying attention to the belt tensioner assemby and waterpump (if cambelt driven) making sure they are free to turn and without any wear/freeplay on thier bearings. also make sure the belt is not getting contaminated by engine oil.
Finally i suggest using a genuine head gasket and replacing the cyl head bolts if they are the stretch type as most are these days........

Dream Weaver

Cambelt snapped on our old Clio 1.2 - it only had 58k miles on it as well.

Ours only bent 2 valves, but we had them all replaced anyway - local garage did the rebuild for us for £230.