Score marks in bore ---> Broken ring??

[solberg Fan]

Ive just taken my head of my 4k as i intended to skim the head to get more compression. One of the bores has score marks and im not sure what it really means. It was rebuilt over 2500km ago and has had a pretty hard life, altho more than half the KMs would account for normal driving.






Im not sure if the marks were there when it was rebuilt (It was honed and built by a profesional)....
Im probly going to put it out and check it anyway but id love to hear what you guys/girls view.

Thanks.

[Adydas]

Did you put the head on or them, if so its possible they scored the bore building didnt tell you and just built it anyway ???

Non the less could be alot of things, regardless of it been some crap in the engine via filter, or the ring it wont change what lies ahead future wise.

[big_boy]

more than likey a bronen top ring dew to how high up the marks go

did you run it in propley if its just been rebilt

& were the piston channels done before it got new rings

[big_boy]

if you get a very fine wire run it down the side of the rings & check them

rembour to round it off first tho

[solberg Fan]

I put the head on Adydas, but your probly right as im going to pull it apart anyway.

I folowed the engine builders instructions when running it in. Piston channels as in ring groves in the piston?? Im sure they would have been cleaned when the new rings went in. If not I would be pissed off! They should know what there doing....

[big_boy]

yeah same thing

they sometimes need more than a clean tho offen they need to be turned out square again as the were to a angle & when you put new hard rings in they twist them

[andyztouring]

Looks like its been badly overheated.Overheating causes scoring like that,or rings where not gapped when fitted.Only one way to fix,rebore and new oversize pistons.

[badidas]

or another block and resize to suit your pistons

[solberg Fan]

Thanks andyztouring,
Its never had over heating problems and has never been over 93 deg C on the temp gauge as I keep a good eye on it. I cant belive there has ever been an air lock as the 4ks are easy to bleed and definatly couldnt have been a blockage in the cooloing. Thanks for all the input, the engines out and it will be apart by tonight.

Steve

[solberg Fan]

or another block and resize to suit your pistons

I have another block with standard bore's with after market rods and pistons but pistons are unfortunatly worn.... replaceing them was going to cost me $1000!

Ill see what I can do with this engine and see what options I have.

Steve

[andyztouring]

A rebore and new pistons can be reasonably cheap,I did a 3VZ-FE (3 litre v6) for about $650 2 years ago(rebored not shaft grind),that included new pistons ,rings ,gugdeons,machining,deck top of block,fitting conrods to new pistons and supplying big end bearings.I reassembled the engine.Shop around for prices ,you can be surprised at the differences in prices.

[solberg Fan]

Unfortunatly I cant rebore this block as I need to keep it under 1300cc.
Anyway pistons out and no broken ring! Im going to put it back together. Just found out it has A R P rod bolts and am trying to find the tourque settings.... The rods are a modified version of the 4AGZE. The ARP web site recomends 40 ft lb but standard there only 52Nm (11.7 foot pound). Are my calculations completly wrong??

EDIT: Ooops, was using the wrong conversion numbers. 40 lb-ft equals 54Nm. Sweet.

[crispy'86]

maybe they tried honing the scores out, or you could give it a hone to clean up the marks

[andyztouring]

Are the pistons the right size? If the scoring was not there before rebuild,it sounds if the pistons are too tight(they expand when hot,causing scores),I would get a engine reconditioner to measure everything before reassembly.

[solberg Fan]

I dont know enough yet to hone the block my self. To be honest its only a relativly cheep car and im not going to spend to much on it. I know this may make a few people cringe (sp?) but at this stage im thinking the engine builders may have done the best they could have with the engine I gave them.

Thanks for every ones help

Steve

[solberg Fan]

Are the pistons the right size? If the scoring was not there before rebuild,it sounds if the pistons are too tight(they expand when hot,causing scores),I would get a engine reconditioner to measure everything before reassembly.

Thanks Andy, I did check that out before and the piston has no marks on the skirt or around the crown in relationship to the score marks in the bore.

The only thing that I can think of is that the marks were there when the engine was first reasembled.

[ke25sr]

if you rebuild another 1 make sure you get Chrome rings. I have never broken 1 or seen 1 broken.
Im sure they can break but the crap iron type that every one puts back in k engines are a waste of time they break so easy.

there not dare either.

[andyztouring]

Chrome rings can be very difficult to bed in,many cars that used them from the factory often burned gallons of oil or had poor compression.If you are breaking rings you are being too rough fitting them or not gapping them when fitting.I`ve done many rerings and have not yet broken a ring.(And removed chrome rings from 1 car-A MITSUBISHI Heap of shit!!!)

[Dell'Orto]

What pistons are you using in there?

[solberg Fan]

This block has Ross 322 pistons (made by Denco??). From what ive been told there fairly cheep. My other engine has Arie's in it, much better quality.

Im going to take the engine in to some one on monday and get another opinion from them. If its no problem with new bearings and rings I may go ahead and do it. Have to learn some time ahy? Ill look into chrome rings Ke25sr.

Cheers all