ps.

spelling in the above post is correct when an appropriate 'ello 'ello policeman franglais accent is used

hmm, we have a bore gauge kit in work which happens to be locked away in the bosses office. Considering there not bothered about leaving 600mm mijityo (excuse spelling) digital calipers lying around then that bore gauge kit must be abit pricey lol As for diy work, most days my machining tolerances drop to 0.01mm with hole diametres at a H7 tolerance. But as you state i may be lucky with bore wear. Best thing to do then is to pull out the pistons and get those bores measured. If they are big enough i maybe able to go forged with a decent hone or if still tight just a light hone and standard refit. I will come back to you with some sizes in the week. Fingers crossed theres no cracks and a nice round bore size

Right ive just pulled out the pistons. Heres some pics, theres abit of scoring to the sides but no big damage. Bores feel smooth. Bringing the bore gauge home from work tomorrow so i can get some sizes then. Let me know your opinions... Thanks

Pic #1 Looks like it needs new rings - there appears to be signs of lots of oil passing the scraper rings - looks like lots of oil between it and #2 compression ring. It also looks like both compression rings are weak allowing oil into the combustion area. Appears to be advancing into the black death TBH

Pic #2 looks like the top compression ring is struggling as there's lots of carbon build up between the two compression rings

#3 and#4 look reasonable. #4 might be showing signs of oil control ring failure

However one thing I see is that all the compression rings look to have dirty edges. This suggests to me they're not sealing well on the bore which should give them a continuous polishing

It's also hard to tell from side on pictures but all the rings look to be almost flust with the piston which would be a sign of wear. You want one side of the ring something like 1mm proud of the piston when the other side is flush

I wonder if the bores are a bit oval and it's picked up the rings when hot and rotated them so that the oval of the ring doesn't match the oval of the bore. You'd see this as two clean looking points on the rings with the dirty edge between them


Overall I have to say it's looking tired and ready for some love
You need the bore measurements to decide what to do next IMO

Always a bit difficult to tell with photos, but the piston skirts look like they may have picked up a touch on the bore walls - i.e. mild heat seize. Could be a trick of the light, but the vertical scores seem quite marked.

Agree with Steve about the rings not sticking out much. Are they stuck in the pistons or do they move freely ?

_________________
If at first you don't suck seed, try drier grain.

p.s.

just taken a pic of a piston from a 185 bottom end I'm stripping as a comparison. (unknown condition, HG failure plus piston tops show signs of foreign objects so possible turbo failure in the past.

I've also taken some measurements (cheapo digital vernier) Re. a conversation the other evening about pistons not being cylindrical - just going off topic a bit. Reflects the tops getting hotter than the bottom, plus the bottom end expanding more in the direction of the gudgeon pin.

_________________
If at first you don't suck seed, try drier grain.

Not directly related to tango's pics but the piston conversation on Friday night. JEMS pulled the file on my engine and confirmed that each cylinder bore on my new block had to be honed to get a consistent clearance for my 86mm CP forged pistons. The amount of machining on each bore was different to get the required working clearance to cope with the higher temperatures running high boost. My new TTE crank was also ground to get greater clearances to cope with higher boost levels and temps. The amount ground on each journal was different.

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Don
GT4DC Chairman
1994 Toyota Celica GT-Four ST205WRC JDM 269bhp @ 0.9bar
1994 Toyota Celica GT-Four Special GT 590bhp @ 1.8bar
1989 Van Diemen RF88/89 Formula Ford 1600
2008 Nissan Patrol GU 3.0L ZD30DDTi 154bhp

@ two_OH_five

Thanks for the help and info.

Your opinion varies on each cylinder, are the bores likely to have worn different?

The rings are flush all the way around.

Yeah agreed, she needs some love now.

@ Chris-de-bear

When the engine 'went' the starter motor struggled to turn the engine over... ''mild heat seize'' ?? The vertical scores are pritty deep. I can catch my nail in them. Also the rings are solid. Although i havent used a tool yet to try and prize them loose.

@ TrackToyFour

You mention fitting forged pistons... Was the block brand new? 86mm is standard size correct? So did you only hone the bores and then fit them? Is it running well? Ive decided no matter what the bores turn out like i wont be spending out on cast thats for sure! If todays measurements come in nice and round, hopefully a decent hone (with tips please ) will give some JE, Wisco, CP pistons a nice home... (yet to discuss piston choice).


After observing other posts ive decided to refit the original rods. But the bearing sizes have got me abit


Cheers guys!

Heat seize is where the piston expands until it is a tight fit in the bore - normally results in badly scuffed piston sides and stuck rings. Quite common in my old karting days if the mixture got a tad weak. Mild was when you didn't go off backwards into the tyre wall with back wheels locked.

If the engine ran short of coolant, have a thorough check for cracks in the bore walls - especially left hand side of No.1 (looking from front of car) where the water pump pushes water into the block and No. 2 & 3 bores.

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If at first you don't suck seed, try drier grain.

hard to turn over and overheat = bad news

If you are very very lucky the rings have seized in the pistons with some micro welding and may free off. How does the ring end gap look? If it's wide you're knackred

IMO given all that's happened prepare for a long off road period and a rebuild. If the rings unseize the engine might go again to keep you mobile while rebuilding another replacement

Ah, i used to race in tkm class! Also abit of senior rotax and 125 open gearbox. Never travelled to much though, clay pigeon and dunkerswell were the only ones. You cant beat a gearbox kart on that dunkerswell straight And as it happens i seized the gearbox kart due to no coolant. That put me into the tyres backwards.

The ring end gaps are really small, dont worry ive just brought a 1999 red toyota avensis cdx. Shes a beauty, £200 and it even came with free insulation tape to hold the wing mirror on

Right off out to get some measurements now.

Ok here i go,

All bores are the same, Measuring 85.96 consistantly at mid height. At the top of each cylinder i read 85.98 Its not all of a sudden but slowly tapers out. Ovalarity varies by +-0.03 at the worst bits, i seem to notice a pattern that the front to back of the cylinders are longer than the sideway measurements on all four.

I eagerly await the news...

No cracks or scares. Very light vertical marks. Cant really feel them.

block sounds promising then. you could rehone and rering for not much money assuming the pistons haven't suffered hugely


or you could go large

I really want to by the forgies now. Almost set on it. Im not going for 1000bhp, just want to have a reliable engine which i dont have to worry about turning the boost up or fitting a bigger turbo on etc. £550 on some pistons seems feasable. So a nice hone and then some wossner 86mm pistons from fensport will be ok? As for rod bearings... What do i need to measure?

Worth checking the state of big end & main bearings before spending money. Easy job to whip the sump off and use plastigauge / visual inspection. If the clearances are too large then you'll need to measure the crank to see if it's servicable.



do you mean front/back of the car is longer or front/back of the engine ?
I'd expect front/back of car.

_________________
If at first you don't suck seed, try drier grain.