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Registered
Join Date: Jan 2021
Posts: 1
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-0-,nada,none compression
Hey Guys
Fired up my ‘87 930 after it had sat for about 3 months and it has a miss. So changed plug’s and wire’s and the miss was still there. Did a compression check and all cylinders checked with 105-115# except for #2. Gauge would not move from zero on 3-4 checks. Double checked Gauge and it is good,no leaks on test hose all O rings in place. Double checked #5 and got the same reading as before (110#). So …going to do a leak down on #2 tomorrow and hopefully get some idea where to go next. Is there a possibility that a intake/exhaust valve has stuck open from sitting? Any ideas or guidance would be greatly appreciated. Thank You Guys! |
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01-09-2022, 04:10 PM
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Registered
Join Date: Jul 2011
Location: Marietta, GA
Posts: 1,045
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That sucks. Leak down will give you a better idea. Anything is possible but i'd pull off the valve cover and take a look, may have a broken rocker or something.
Good luck J
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John~ 2003 996 Turbo... 128K Daily-ish 2000 Accord V6... 275K - 65K motor/trans now given new life! |
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01-09-2022, 06:52 PM
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Join Date: Mar 2019
Posts: 1,609
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Leakdown test, as suggested, and listen for where the air is leaking. Intake, exhaust, or crankcase. That'll give you a better idea. And borescope that cylinder it with a camera if you happen to have one.
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01-10-2022, 03:48 AM
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Join Date: Oct 2006
Location: MYR S.C.
Posts: 17,321
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probably carbon holding exhaust open.
you can check the valve adjustment, which I would do anyway. (not that it changed while sitting).
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86 930 94kmiles [_  _] RUNNING:[__] NOT RUNNING: ____77 911S widebody: SOLD88 BMW 325is 200K+ SOLD 03 BMW 330CI 220K:: [_ _] RUNNING: [__] NOT RUNNING:01 suburban 330K:: [_ _] RUNNING: [__] NOT RUNNING:RACE CAR:: sold |
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01-10-2022, 06:13 AM
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Yes - you should be able to see the problem with the LHS valve covers off. Maybe a stuck valve. Even with a bit of carbon on the seat I would think you would register some compression. Low(er) , but some. If it is simply a valve that is not moving as you turn it over by hand (plugs out), a bit of CRC over it and a gentle tap may free it. Hard to think it is a piston problem - which really leaves you with the valves. Maybe carbon on the valve stem.
Alan
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83 SC, 82 930 (track) - Stock except for RarlyL8 race headers, RarlyL8 Zork, K27-7006, 22/28 T bars, 007 Fuel head, short 3&4 gears, NGK AFR, Greddy EBC (on the slippery slope), Wevo engine mounts, ERP rear camber adjust and mono balls, Tarret front monoball camber adjust, Elgin cams, 38mm ported heads, 964 IC. 380rwhp @ 0.8bar Apart from above, bone stock:-) |
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01-12-2022, 03:17 PM
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