cooperjohn

this is the slap i have in my pistons, it doesnt knock when running when its cold or hot ,but should i be doing something about this, i took the engine out to change the head gaskets.
my car is a 1998 version 4 sti but i dont think the engine is the one it was born with, i was told that these pistons are forged but unless i take the engine apart i will never know ???? could anyone advise?
http://www.youtube.com/watch?v=F2H_13231-8

cooperjohn

can anyone help with this?

merlin24

iTrader: (1)

The pistons are Version 1~2 'dog bone' pistons - cant tell if they are Cast or Forged unless you look at the underside of the piston crown.
Crosshatching underside of the crown will indicate a Cast Piston - smooth underside with HF 1/2/3 markings will indicate Forged.

Looks like it needs a rebuild/boring to the next oversize to cure you piston slap.

Mick

cooperjohn

thanks for your reply, if they turn out to be forged will it be ok to run, it ran lovly befor with no knocks bangs when cold or hot, didnt use any oil either?

TonyBurns

iTrader: (3)

Luckily for you, engine tuner is just down the road

Tony

cooperjohn

yea but he wants 3k to do a forged build, it didnt knock or bang or use oil,it had good compression too, only reason ive takin it out is because it was presueeising, and drinking lots and lots of coolant, more than likly a blown cracked head as the hg were metal and looked ok.

i just need to find out if that much play is gonna meane itle more than likly go pop soon or not.

Shaks-STI

iTrader: (7)

i think there is excessive play there and that kind of play will make you open the engine again very soon.

happydude303

iTrader: (1)

to be far if you have done it your self then then put it back together and see what happes and save some money in the mean time .ps i had loaud piston slap for a few years on my subaru before i then forged it and it was fine, but seen as you have open it up with head gasket problems it might be wise to change the bearings

merlin24

iTrader: (1)

Even if they are forged pistons and they measure up ok, your bores will probably be showing excessive wear,taper and ovality (hence the piston slap) so it will need boring to the next oversize which means new pistons.

You might find a good used standard size block to drop your pistons into but chances of that are pretty remote tbh.
As mentioned above - if your in as far as splitting the crancases to de-glaze the bores, then its prudent to check the big ends and mains for wear.

Mick

cooperjohn

it has a rely sharp shiny crank il upload photo in mo and its obvious its been apart, the guy i baught it from did say it had been rebuilt with new crank and shells and to be fair the bottom end is sweet, just worried the hell outa me seing how much play is there, if the pistons turn out to be forged does that change anything with respect to the play (i.e forgred pistons expanding ect)

happydude303

iTrader: (1)

if the pistons did not slap when the engine was warm then id just put it back together at the end of the day its only cost you a new set of gaskets it may last for a few more years as piston slap is not the end of the world as long as it goes once warm and you let it warm up over a peroid of time or you could find a good donner block as above mention

rapid.STI

iTrader: (5)

My thoughts exactly, Just build it back up as is. There's a saying that goes " If it aint broke then dont fix it"

Wayne.

cooperjohn

thanks everyone, i did check the underneath of the pistons they are very smooth with no cross hatch markings so im gueising they are forged .

cooperjohn

thats the crank does that look like something it would come from the factory with, the edges are razor sharp to???