New Pistons

[Krian]

Hey

Checked my sparkies late last night and found a small problem - the core of the spark plugs is the colour of normal plugs in the haynes manual but the rest is covered in a dry black compound.

I reckon its just because the engine is old and hasn't had too much TLC, but rather than just getting a new engine for it i'm planning on stripping it down, putting in new pistons and rebuilding it.

So I was wondering if anyone knows what kinda prices I can expect for new pistons? Should I just see if I can get standard pistons from nissan? Or if its not gonna be a massive additional cost should I look at a cylinder block and pistons that can handle NOS? It'll save me a bit of cash should I decide to instal nitrous later

Cheers

 

[Turtle]

Hello,

I would be interested in seeing some photographs of your spark plugs if possible, since mine have this blackness as talked about in...

http://www.micra.org.uk/t8204-leakingburning-oil.html

That thread

Cheers

 

[Krian]

I took some pictures but they're not too clear - having just tried to start the car I think I may have fubared one em anyway, or at least not put it back in correctly. The engines really juddery and sounds very rough, so i'm wondering if its only firing on three cylinders.

I'll take out the plug I think is wrong in a mo and try and get some decent pictures, they do look pretty similar to the plugs in your car tho.

 

[Krian]

Just re-read meh first note and realised i'd left something out Shoulda also mentioned that i'm gonna look into getting the cylinder block rebored, if the damage isnt too severe.

Plus I wanted to make sure that i'm actually getting this right and haven't gone off with completely the wrong idea!

 

[Fordy]

iirc you can get the 1.2 bored out quite a bit

 

[Andrew]

Boring out an engine is a very expensive way of gaining power. It is a lot of work and parts.

If you are just rebuilding, it is likely that all you will need is new piston rings. Rebuilding an MA engine will cost a lot compared to the price of a new engine.

 

[Ed]

Sounds like your sparkplugs had carbon on them. If so this is TOTALLY NORMAL. Sounds like you may be about to take on alot of work for no reason!

 

[Turtle]

Well i'd like to see some pics really... pretty difficult to take clear photos I found but im sure you'll manage :wasntme:

I'd like to think my engine is perfectly healthy with a worn rocker cover gasket, but im just an optimist.

 

[detox]

yer i would like to know were you can get new pistons (custom size) and stronger

 

[Krian]

Well the exhaust was smoking a bit, hence I thought burning oil and considering the mileage, prolly because the cylinder bores where worn - I thought this was fairly common around the 100k mark? Specially if you have a red-line happy driver.

Having said that, following the oil change, fuel filter change and new oil filter it wasn't smoking today.... I'm gonna stick some new NGK plugs in either tomorrow or saturday, then after a couple of hundred miles i'll whip em out and have a look. If it doesnt start smoking again and theres no oil on the plugs then i'll leave it up to the MOT man in jan

 

[Fordy]

what colour was the smoke?

 

[Krian]

bluey-white, whilst the engine was warming up i tried holding tissue paper up to the exhaust and i'd get some kind of liquid hitting it, however it was clear so i think thats more likely to be a rich mixture on the choke.

Theres nothing coming out once the car was warmed up, just a bit of smoke.

 

[bobsp16]

bluey-white, whilst the engine was warming up i tried holding tissue paper up to the exhaust and i'd get some kind of liquid hitting it, however it was clear so i think thats more likely to be a rich mixture on the choke.

Theres nothing coming out once the car was warmed up, just a bit of smoke.

the best way to tell if your ring have gone is take your plugs out bring each piston nearly to tdc shine a torch in and look around the edge of the piston if its black after a run then the rings have gone.plus try a compression leak test

For the road i wouldn't bother reboring to 0.50 no need,pistons are £245 a set with rings and about £100 for the rebore £65 for big and mains shells,you will be pushing near £500 for a bottem end rebuild with a full gasket set..
I have rebuilt ma12/ma10many time for racers and using same standard pistons homed out new rings, shells and gaskets and i charge £300 for a bottem end and £400 for a full engine,,,