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how bad is this compression ?
Posted: Sat Nov 12, 2005 11:38 pm
by Acca Dacca
Did a compression pressure check this arvo and well I'm a little concerned.
Results were from the front cylinder to the back.
psi - kPa
143 - 990
132 - 910
129 - 895
123 - 850
From a manual I have it says it should be 199 psi with the limit being 170, with a maximum 14.2 variance between them. The variance is fine but I'm just worried that they fall so low below what it's supposed to be.
The engines done 217,500 km and is an 89 and was for some time running on only 3 cylinders. Is it on the way out or just showing it's age ?
Posted: Sun Nov 13, 2005 9:08 am
by Spike_Sierra
yeah thats getting pretty low, mines around 160.. ahh the days when it was 180
Posted: Mon Nov 14, 2005 12:27 am
by derelict_frog
Hate to think how bad mine would of been at 315K, it had pretty low compression, new rebuild roxxors!
Posted: Mon Nov 14, 2005 4:37 pm
by CHOPS1
derelict_frog wrote:Hate to think how bad mine would of been at 315K, it had pretty low compression, new rebuild roxxors!
So you had your 1.3 rebuilt and it rocks?
how does it go now ?
Chop
Posted: Mon Nov 14, 2005 9:41 pm
by derelict_frog
Yea its nice as, on road with 31-32s it isnt terribly fast uphills but u catch back up on the down hills lol, offroad the power is enough to spin the wheels ne time u want..
But yea the main improvment was onroad uphill, u can stay in the same gear for much longer..
Posted: Mon Nov 14, 2005 10:31 pm
by CHOPS1
Thats what i like to hear! mine is struggling up hills and on the flat with 30" tyres. mines done 235 000 kms, be interesting to see what compression mine is at? i think my stepdads got a compression tester.
Chop
Posted: Mon Nov 14, 2005 11:15 pm
by Crawford
does a rebuild fix the compression?
i thought if the compression was shit that meant you needed a new engine... and you couldnt rebuild..
and you could only rebuild engines that the compression is still acceptable for
i must be wrong?
Posted: Tue Nov 15, 2005 8:21 am
by ZOOK60
Crawford wrote:does a rebuild fix the compression?
i thought if the compression was shit that meant you needed a new engine... and you couldnt rebuild..
and you could only rebuild engines that the compression is still acceptable for
i must be wrong?
sorry dude but you are very wrong
Posted: Tue Nov 15, 2005 9:31 am
by Spike_Sierra
compression gets bad usually from worn piston rings and vavle stem seals, both are replaced in a rebuild.
Posted: Tue Nov 15, 2005 12:02 pm
by derelict_frog
Also an upgraded exhaust system can help uphills a bit, i have extractors and 2" tube, so that would add some top end power.. but never driven one with standard zorst around so could really compare...
Posted: Tue Nov 15, 2005 8:18 pm
by zookjedi
Spike_Sierra wrote:compression gets bad usually from worn piston rings and vavle stem seals, both are replaced in a rebuild.
not so much valve stem seals (they stop oil going down the valve stem into the bore) they can be a cause of a smokey engine though
out of the three engines ive got they all need rebores and than of course bigger pistons and rings , if your bore is ok (no lip on top) you should hone the bore when putting in new rings otherwise the rings won't bed in properly and course lower compression and oil usage .
the valve seats can also be a cause of low compression if they are not fully seating in which case you'll either need to lap the valves or have them reground.