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Hi there, this is my first post and some advice and help would be extremely appreciated. I have an na 1.6l mx5. The car is running a 1.8l stroker kit, hks cams and gears, extractors, apexi intake and an apexi safc controller unit. Now recentley, as i was driving along, one of the cylinders started dying. I pulled over into a servo straight away and as i was pulling in there was a loud ticking sound. I had the car towed home.
It seems one of the valves is stuck open and ive had my mechanic check it out and he has confirmed this. Now the oil pressure, engine temp and oil temp were all perfect when this happened so im lucky in that sense. The oil was new at the time. The head needs to come off and whatever is broken will be replace, the head shaved, crack tested, valves re-seated pretty much reconditioned. Would anyone know what the chances are that the valve has damaged the piston?
The valve has hit the top of the piston, the engine has been compression tested and at some points it had full compression and at others it had no compression at all. If there are marks on the top of the piston, is this alright as long as it hasnt cracked anything? Im hoping as there was full compression at some points, the piston is ok. Also would anyone recommend somewhere that may have mx5 experience to do this kind of repair?
Im new to the mx5 scene so any help and advice would be extremely appreciated, thank you.

The B6 motor is usually a non-interference design, but it probably isn't with your cams and pistons...

Probably won't be able to assess damage until you have the head removed. I would wait til then to decide. You don't want to rebuild the bottom end if you don't have to...

If you tell us your location we can help more with advice on where to go.

Thank you. Sorry i forgot to mention where im from, im located in mill park in melbourne, its in the northern suburbs.

Pistons are generally stronger than valves.

If you have had valve/piston contact, your valve, guide, etc. will be stuffed but the piston/rod may well be OK.

As Matty has pointed out, pop the head off before you get too deep into the analysis.

I'm sure the Melbourne folks can recommend someone competent with multi-cam engines.

Thanks for the feedback, im hoping that is the case, most places i have spoken to believe that the damage would be to the valve and not the piston. I am no expert when it comes to motors, i know the basics. Would it be difficult to remove the head myself? If i set up a table and remove each part and lay it out in order on the table, would it be very difficult or should i just get it done professionaly? If i could remove the head, i could just take it myself somewhere to get recoed.

enzosRus,

It is prety simple to remove the head but by the sound of it, it may well be past your ability to replace it.
You need to align the timing marks on the over head cams gears and torque the head bolts in the correct order and to the correct pressure during replacement.
If you feel that this isn't possible then the only way to go is to take it to a mechanic to do it for you.

Plus you say it's a stroker kit so who knows what mods might have been done which the mechanic would need to know about.

I must say I was a little surprised at the strength comparo- valves can get bent fairly easily but pistons are alloy and can be damaged fairly easily as well. Anyway Tony at Fulltech seems to have a very good reputation (03) 9888 7499 ( Alfadog gave him a big rap recently) The age of your engine and condition of bores etc needs to be assessed and maybe the head needs to go back on to check compression - and I also suggest not trying to do this yourself- you need facilities and knowledge which does take some time to pickup- even a thing like measuring a bore for wear is very tricky.PS your own mechanic may be able to handle this work - you will have to talk to him to assess a confidence level.

I was a little surprised at the strength comparo- valves can get bent fairly easily but pistons are alloy and can be damaged fairly easily as well

I'm basing my suggestion on the damage done after the cam belt let go in a Peugeot 405 Mi16 I once had.

It proved conclusively that it was an interference engine. Many valves dead. All Pistons fine. When I expressed concern over the pistons, the engine shop made the simple comment that it was unusual to see piston damage. Head damage was more common.

Not extensive experience I admit, but relevant none the less.

adam's point taken- the evidence is sound - I guess it is more about shape being the weak point.

Thanks for your help and comments, i will give fulltech a call during the week. I'm hoping its just valve damage. I spoke to a friends dad who used to do this kind of head and mechanical work and he believes it'll only be valve damage and that he has only ever seen one case where it damaged the piston and it was because the valve snapped. I think i'll be leaving it to the professionals to fix though. Its just gonna end up costing me more then i can afford lol, guess ill have to save up, hard to get to work though! I pulled over as soon as i noticed the problem so hopefully not too much damage has been done.

i'd also suggest nissco in bayswater for your engine work.

I gave both nissco and fulltech a call and they were both very helpful so thanks guys for letting me know about them. When i explained exactly what had and hadnt happened to the guy at nissco, he even said that he believed the head may not need to come off and it may have something to do with the cams and lifters, expecially because they are aftermarket. Im not getting my hopes up but it sounds promising. Ill have to call them both next week and decide who im going to go with. Anyway, heres a picture of my car...

Good enzo for the feedback-

Nice flares !