I was on the autobahn today and at part throttle at 8 lbs boost it started sputtering. # 2 is dead with ZERO compression. There was no smoke, so I'm thinking the exhaust valve. Wouldn't a holed piston make some smoke? Or?
I was on the autobahn today and at part throttle at 8 lbs boost it started sputtering. # 2 is dead with ZERO compression. There was no smoke, so I'm thinking the exhaust valve. Wouldn't a holed piston make some smoke? Or?
[SIGPIC][/SIGPIC][FONT=Comic Sans MS]'91 Shadow convertible 2.5 auto, three core RP IC, S60/.48 stg 1, ported two-piece intake/52mm TB, Menegon +1 swirl, 88 turbo cam, Venolias, Crower rods, TU deep sump pan, ported exhaust, 3" from SV to TP, Hughes TC, Peloquin diff, DSS L5 driveshafts, Shelgame cal, Koni struts/shocks. [/FONT]
I would think that a hole in a piston would have been a bit more than some sputtering. What's the compression in the other three?
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135 - 140 across. The rings haven't completely broken in yet in the engine, so there is a bit of oil around the threads on the plug. I guess I can just pull the oil filler cap while it's idling and check for blow by.
A machine shop here in Germany really screwed up the valve job and the valve faces are thin. I'm kind of expecting part of the exhaust valve to be gone. This is happening at a really bad time, because I'm getting ready to ship the car back to the states next month. Awkward. Emmission test is going to be a challenge on three cylinders, so it looks like it's coming apart again before it ships.
Last edited by John B; 07-26-2014 at 03:00 PM.
[SIGPIC][/SIGPIC][FONT=Comic Sans MS]'91 Shadow convertible 2.5 auto, three core RP IC, S60/.48 stg 1, ported two-piece intake/52mm TB, Menegon +1 swirl, 88 turbo cam, Venolias, Crower rods, TU deep sump pan, ported exhaust, 3" from SV to TP, Hughes TC, Peloquin diff, DSS L5 driveshafts, Shelgame cal, Koni struts/shocks. [/FONT]
Take the spark plugs out, crank #2 to TDC, and see if you can peek in there with a flashlight. If you broke a valve you should be able to see a fair amount of physical damage to the face of the piston. Good chance you'll have damage to the spark plug too, although you'd have seen that when you did the compression test.
Did you lose any oil? I detonated my Daytona's engine a few years ago, lost all compression in #4, lost 3 quarts of oil within 15 miles, and shattered the intake valve seat. Hopefully you're not in the same boat.
No, no oil loss, but I only had to drive about 12 miles back to the house. I have a fresh head that I can put on. I just wish I had a bore scope to peek in there with before I pull the head. I tried shining a flashlight in there, and I didn't see any visible damage, but I can't really see much. The plug wasn't damaged.
[SIGPIC][/SIGPIC][FONT=Comic Sans MS]'91 Shadow convertible 2.5 auto, three core RP IC, S60/.48 stg 1, ported two-piece intake/52mm TB, Menegon +1 swirl, 88 turbo cam, Venolias, Crower rods, TU deep sump pan, ported exhaust, 3" from SV to TP, Hughes TC, Peloquin diff, DSS L5 driveshafts, Shelgame cal, Koni struts/shocks. [/FONT]
Hmm. That could be a tuliped valve then. Been there too. Valves cut too thin cause the face to pull in, which prevents it from seating. With no collateral damage, I'm betting that's what happened. You won't know until you get the head off.
rocker arm fall off and holding the valve open or not opening a valve?
i was thinking the same thing, sounds like a rocker got kicked off a valve.
I checked the rockers and for a stuck valve, all OK. I pulled the filler cap at idle and there is almost no discernible blowby, I used a stethoscope and can hear no unusual sounds, but it is spitting oil out of the exhaust at idle. ??
[SIGPIC][/SIGPIC][FONT=Comic Sans MS]'91 Shadow convertible 2.5 auto, three core RP IC, S60/.48 stg 1, ported two-piece intake/52mm TB, Menegon +1 swirl, 88 turbo cam, Venolias, Crower rods, TU deep sump pan, ported exhaust, 3" from SV to TP, Hughes TC, Peloquin diff, DSS L5 driveshafts, Shelgame cal, Koni struts/shocks. [/FONT]
I think a leak down test would tell the tale.
It has zero compression.Originally Posted by cordes
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It has zero compression.
[SIGPIC][/SIGPIC][FONT=Comic Sans MS]'91 Shadow convertible 2.5 auto, three core RP IC, S60/.48 stg 1, ported two-piece intake/52mm TB, Menegon +1 swirl, 88 turbo cam, Venolias, Crower rods, TU deep sump pan, ported exhaust, 3" from SV to TP, Hughes TC, Peloquin diff, DSS L5 driveshafts, Shelgame cal, Koni struts/shocks. [/FONT]
Which is why a leak down tester would hopefully tell where all the air is rushing to rather than making compression in the cylinder. Although the smart money is definitely on the valves since you stated there was an issue with them previously and you can't see a big hole in the piston.
^^ yea do that. if you pressurize the cylinder you'll figure out where the air is escaping, exhaust = exhaust valve. intake = intake valve ect.. its a very simple thing to do most people are not aware of in my experience. you can make an adapter out of a old spark plug, hose and a airline fitting.
1988 Lancer Shelby 2.2TII 1989 Shadow ES 2.5TI 1992 Lebaron Sedan 3.0Auto 1993 Acclaim 2.5TI-A520 Hoard parts now!
+1 to this. Put that piston at top dead center, hook compressed air to where the spark plug threads in via an adapter, see where the air comes out! Hole in piston = air comes out of crankcase, no compression but leakdown test passes means intake valve not opening, air comes out of radiator = blown headgasket.
id say if there was ZERO compression, then deff a spit rocker, even with a burnt valve, or hole in piston, ive got some comp readings before. if no air can get in, how can it make any compression? money is on the intake valve, pretty easy to pull the valve cover and check... and its usually because the lifter took a poop...
Thanks for all the tips. I'm pulling it down this weekend and facing the ugly facts, whatever they turn out to be. Have any of you used ITM rings? I think they are cast iron rings.
Last edited by John B; 07-28-2014 at 10:55 AM.
[SIGPIC][/SIGPIC][FONT=Comic Sans MS]'91 Shadow convertible 2.5 auto, three core RP IC, S60/.48 stg 1, ported two-piece intake/52mm TB, Menegon +1 swirl, 88 turbo cam, Venolias, Crower rods, TU deep sump pan, ported exhaust, 3" from SV to TP, Hughes TC, Peloquin diff, DSS L5 driveshafts, Shelgame cal, Koni struts/shocks. [/FONT]
Ha, never thought of it that way.
couldnt head gasket be totally blown out around #2, venting compression into the oil passages, and oil into the chamber/exhaust?
are all your head bolts tight?
Possible sure. Nothing surprises me anymore. i have head studs and a cometic gasket. Many, many years ago a friend of mine had a 41 Ford v8 that developed a dead miss. we finally pulled the heads, and one piston was missing the crown. The skirt and rings were perfectly intact and just quietly running up and down in the cylinder, but the piston top had broken up and fallen down into the pan.
[SIGPIC][/SIGPIC][FONT=Comic Sans MS]'91 Shadow convertible 2.5 auto, three core RP IC, S60/.48 stg 1, ported two-piece intake/52mm TB, Menegon +1 swirl, 88 turbo cam, Venolias, Crower rods, TU deep sump pan, ported exhaust, 3" from SV to TP, Hughes TC, Peloquin diff, DSS L5 driveshafts, Shelgame cal, Koni struts/shocks. [/FONT]
i just had a vehicle come in today with ZERO compression, ecotec chevy caviler, compression was 68-56-47-0, when i pulled the valve cover the timing chain was broken, the only cyl that had ZERO compression was the one with no intake or exhaust flow escaping... even the ones that had valves open made some sort of compression.
i have never gotten to check the compression on a vehicle with a missing piston crown, but i have with large holes from detonation to foreign objects, and they still made compression. my SC still made 92 psi of compression and the 4th cyl head gasket was so bad that i could watch each firing event purge from the radiator fill, and it literally looked like a steam engine.
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