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Piston rings- original or not?
Posted: Wed Jul 20, 2011 2:29 pm
by Tweety
Can someone tell me the disadvantages of non original piston rings on an EA81.?
I've been told that they dont "lock" in place like original ones and therefore slowly rotate which means every now and then the gaps line up and a small amount of oil passes giving a puff of smoke.
Posted: Wed Jul 20, 2011 9:54 pm
by FROG
My ej22 rebuild aftermarket rings had the tabs on them cant remember the brand name sorry (sphincter tightening experience fitting them for me
:shock::roll:)
You can get both types, Im sure the ones without the tabs are made to suit aftermarket pistons I think ! And from memory there are two different ring groove widths on two of the three ring grooves !
Im quite sure I can get the tabbed variety are you going standard or oversize?
Posted: Wed Jul 20, 2011 10:03 pm
by Tweety
I've purchased a EA81 engine from a Subaru mechanic that appears to be an honest older bloke. He told me the engine was recoed by him 80,000kms ago. I would assume a Subie mechanic wouldnt do such a job unless it was done correctly.
He told me he used aftermarket rings that dont lock in place, meaning they rotate and you will get a small puff of smoke every month or two when the gaps line up.
That was the basis of my question. So I am not seeking parts just a query on the differences. original rings must cost some...
Posted: Wed Jul 20, 2011 10:29 pm
by FROG
Okay Tweety
yes that sounds most likely and the also the reason Subaru designed them this way
genuine prices are being lowered in a lot of areas lately .although I'm not sure EA parts are included
I'll have a look when I get a free minute
Posted: Wed Jul 20, 2011 10:42 pm
by steptoe
The rings in mine are Grant at 40 thou or 1.0mm oversize and listed for Volvo, never had a puff-a-smoke other than the FSM indicated hard right sloped turns via PCV system
Posted: Wed Jul 20, 2011 11:08 pm
by FROG
boxer is prone to do it when all the ring gaps line up at the bottom
Posted: Wed Jul 20, 2011 11:23 pm
by Tweety
that makes sense.
I assume it isnt something to worry about.
Posted: Thu Jul 21, 2011 6:19 am
by littlewhiteute
Only the oil ring expander has a tab and the corresponding groove has a peg, like "pegged rings" in a two stroke.
The compression rings are free to rotate.
Posted: Thu Jul 21, 2011 8:48 am
by steptoe
Genuine pistons may have the two stroke ring stop but my after markets never have. I have always had to set the positions of the gaps as I fit.
Posted: Thu Jul 21, 2011 10:27 am
by Tweety
right Gary....and is there any difference form original to after market??
Posted: Thu Jul 21, 2011 6:54 pm
by littlewhiteute
I used a set of Hastings rings in my last EA81 rebuild (for James), same as factory rings.
Posted: Thu Jul 21, 2011 7:17 pm
by FROG
thats them ! Hastings and same here they had the tangs on them - ej22 though
Posted: Thu Jul 21, 2011 8:57 pm
by Tweety
Thanks everyone. Very interesting these Subarus I'm beginning to like them.
Posted: Fri Jul 22, 2011 4:30 am
by discopotato03
The reason those pins are there are correctly to stop the oil rings from turning .
Subapoos being flat have some oil off the bores run down and collect in the lower side of the cylinders when shut down . If the rings did line up , even given the gaps should be small , the oil gets into the chambers and burns and you'd imagine at the worst possible for emissions phase - cold start .
Early EA82Ts don't have them , later ones do or at leat my 87 Spider Vortex one does .
A .