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Aurel's Avatar
 
Join Date: Nov 2001
Location: Middlessex county, MA
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Gurgling noise at acceleration

Here is the situation: freshly top-end rebuilt 78SC, with ~ 400 miles on it. Since yesterday, I started hearing a popping noise on the right side during WOT acceleration. It almost sounds like back-firing, but less frank. More like a gurgling noise. It sounds combustion related. I am thinking incomplete combustion, or cylinder-head leak. I haven`t noticed a loss of power. What worries me is only one bank of cylinders seems to be doing it. I just hope nothing is going loose in there...Opinions appreciated.

Aurel

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1978 SC Targa, DC15 cams, 9.3:1 cr, backdated heat, sport exhaust https://1978sctarga.car.blog/
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Old 07-22-2008, 04:35 AM
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First, check that all spark plug wires and terminals are firmly seated--especially on the plugs. Your symptoms may be from something serious or very simple. I had the exact same problem which turned out to be bad (read old) Beru connectors. I replaced the wire set and the engine runs smooth as silk. Good luck and report your findings.

BTW, Beru connectors (especially old ones) can be notorious for bench testing as good, but failing during use. If you check resistance and it meets specs, try tapping the connector while testing. I discovered 3 out of 6 connectors lost continuity when tapped. Yes, they were 35 years old.
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Last edited by ossiblue; 07-22-2008 at 07:35 AM..
Old 07-22-2008, 06:26 AM
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I`ll look into that. My connectors are about 5 yr old aftermarket. Yes, it could be a spark plug not firing well at higher rpms...good idea.

Aurel
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1978 SC Targa, DC15 cams, 9.3:1 cr, backdated heat, sport exhaust https://1978sctarga.car.blog/
2014 Cayenne platinum edition
2008 Benz C300 (wife’s)
2010 Honda Civic LX (daughter’s)
Old 07-22-2008, 06:38 AM
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Your valves aren't too tite are they?
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Old 07-22-2008, 06:43 AM
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Quote:
Originally Posted by Aurel View Post
I`ll look into that. My connectors are about 5 yr old aftermarket. Yes, it could be a spark plug not firing well at higher rpms...good idea.

Aurel
Do the "water mist in a dark garage" test on right side. Left, too, while you're misting.
Old 07-22-2008, 08:10 AM
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Also, if it really IS gurgleing, it could be air in the oil line on the right side.
Old 07-22-2008, 08:38 AM
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Quote:
Originally Posted by cgarr View Post
Your valves aren't too tite are they?
I set them all at 0.04 when I did the rebuild, and it was fine initially. I could see them getting looser, but tighter would not happen by itself.

Aurel

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1978 SC Targa, DC15 cams, 9.3:1 cr, backdated heat, sport exhaust https://1978sctarga.car.blog/
2014 Cayenne platinum edition
2008 Benz C300 (wife’s)
2010 Honda Civic LX (daughter’s)
Old 07-22-2008, 09:00 AM
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