The Head Gasket in my 89 st162 has just gone and it now clunks when turned over, which I believe it a piston hitting the bore. Was deciding to have the engine redone and advised to have new pistons and rings put in. Does anyone know if I should go 20 thou over or 40 thou?. Also the head would be machined, was wondering if I should be just skimmed flat or shaved by a certain amount to increase compression 20, 40 or 60 thou?. Thanks in advance.
Clunking is not head gasket, rather a bearing or hitting valves? 20thou is best, more if the bore is badly f/d, always use new rings/pistons if you are over 150 000km Skim the head and block to achieve flatness only, any more and you'll have compression problems like me and forced to run on 98 RON
It clunks and does not start, was told by my local Toyota Dealer Head mechanic who checked out the car the other day that because it badly overheated and since it has not been driven in al least a week there would also be a lack of lubrication to the cylinders and there would a cylinder locking up against the bore, was going to have the bore machined and new pistons anyway. Would boring to 40thou be ok or is this to much or getting to close to the limit and water jackets?
No, I have 80thou pistons fitted the last 3yrs running at 11.5-1 without any gasket or block problems. There is an issue with overheated motors, the heads tend to soften and warp badly. (Alu loses it's strength at over 180degC) Best to have the head hardness tested and see if it's warped. Let your engine builder open it up and decide what's best, you can buy new gaskets, tensioners, belts, pumps, clutch etc in the meantime. If your headgasket was gone you'd have water out the exhaust or air/oil in the radiator, this sounds like you broke some rings or cracked a piston or damaged a small end. If you want more compression a better option is to use gen2 GE pistons which are similar to those fitted on our GT models. My build thread is full of hints and tips for anyone wanting to re-build a GE
Where would I or my mechanic be able to find 3sge gen2 pistons in Australia? Are they oversized or same circumference as the gen1 pistons?
All 3S motors have an 86mm bore as standard, the difference between the generations is in the compression height. You said your mechanic worked for Toyota, can they not still get factory replacement oversize pistons? If not, talk to Road and Track in QLD, they're the local S-motor guru's and they should be able to get anything you need. Cheers Matt
Spares shops can order just about anything for you and most piston makers can supply them. A cheap example - Teikin, ITM, New Era, NPR If you check their sites you will find many types of pistons for the 3S motors
