Suck, Squish, Bang, Blow ring lands!

[LEMHEAD16]

Well I have been having problems with smoking for awhile now and car seems to run with a little less power than after I first went FI. Tonight I pulled out the compression tester and here is what I found. Test done at operating temp and WOT with all plugs out.

1 1202 1353 1254 120

After adding some PB Blaster to each cylinder

1 1502 1483 1254 130

I am assuming it is the ring lands. The car still runs just fine other than a little low vacuum and slightly rough idle. I am not losing any coolant so I don't think it is head gasket problem. The funny thing is it ran quiet before the compression test but after I did the test there is a loud tapping coming from the engine. I hope it will last a couple more weeks until some thigns settle down for me. I just opened a new business and I can't really take any time off for repairs and I just sold my daily driver. Good thing Spring is coming and I have a bicycle.

I think I am correct on this one but I would like to hear what you guys think. Another Stock KA bits the dust but, You gotta pay to play!

[pr240sx]

Before1 1202 1353 1254 120After1 1502 1483 1254 130

1,2 and 4. worn rings3 headgasket or valve stick open or bent

Anyway, you need to open the engine to repair.Also, dont use light oil (like PB blaster next time) use engine oil

[12valveturbo]

Is this sohc or dohc? check the breather and see if smoke(blowby) comes out when you rev it.

[emperor_lunchbox]

does the breather trick work with DOHC and SOHC?

[LEMHEAD16]

No smoke from the breather. It doesn't even really feel liek much air is coming out of the breather. Waht does that mean.

[12valveturbo]

Well on sohc when the ringlands go you get pressure out of the breather.It blows air past the rings and up the front cover and into the valvecover.

[12valveturbo]

Is it sohc or dohc? and what kind of noise are you hearing?

[LEMHEAD16]

SOHC. There are not really any noises now . right after I did the compression test there was a tapping sound coming from the back of the engine. I couldn't tell if it was coming from head or block but, it is gone now. This engine has always had a hard miss at idle. I am thinking maybe it has something to do with the head. Would bad valve seals cause low compression?

[Chezedik]

Well on sohc when the ringlands go you get pressure out of the breather.It blows air past the rings and up the front cover and into the valvecover.

In ANY engine this will be true, and so yes, it will work with DOHC as well.

EDIT: I wonder if the noise was the light oil?....
Modified by Chezedik at 6:24 PM 3/17/2006

[LEMHEAD16]

So I know I ahve low compression or maybe it is a bad gauge. You would think that the car would run bad with bad ring lands but, it seems to run pretty smooth and the smoke comes and goes. I need a leak down tester I guess.

The car idles rough for about the first 45 seconds it is started cold and then it smooths out??

[12valveturbo]

Yea a leak down tester would tell you more. I would try not to beat on it too bad until you know bevause if it is ringlands they will heat up more than the rest of the pistons(less mass) and that could lead to preignition.

[Edub1]

Make sure your readings are accurate. I believe the FSM calls for 150psi min with no more than 15psi difference.

Bottom line, if those numbers are true, you'll have to rebuild. Just doing the head or lower half on an old tired motor doesn't make any sense.

[Chezedik]

Did you test with the throttle open? Also, if you have broken ringlands, I say romp the crap out of it. After all, anything work doing is worth doing right.

[LEMHEAD16]

Did you test with the throttle open? Also, if you have broken ringlands, I say romp the crap out of it. After all, anything work doing is worth doing right.

I AM WITH YOU. I want some broken parts!!

[nissanfanatic]

Hmm... Have you ever had the engine apart for timing work or anything..??

And does the engine smoke..???

[LEMHEAD16]

never had the engine apart. It smokes but only in boost. I was thinking it was the turbo seals but then i did the comp test and got bad results. It still runs very strong to me.

[Iamjohnhayes]

a leakdown test will tell you where you are losing the compression. if you hear air out the exhaust its exhast valves and intake = intake valves but also dont forget to check your radiator / overflow for bubbles which would mean headgasket.

[12valveturbo]

If it is your ringlands and you beat on it it will prolly blow the headgasket and maybe warp the head.