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Sparks from the engine! 700 1989

Greetings everyone!
It's been a few years since I've posted or read thru. My brick has behaved so well ... up until now.

The new development is a clacking noise around the 2nd cylinder. My wife stopped using the car after I heard the noise. Initially, it sounded like the oil was low - but worse. I didn't have time until this weekend to REALLY look at it. It was dusky out and after turning it over, I saw sparks in the exhaust manifold side of the engine! Not consistantly but definitely there. I checked the plugs and wires for damage or looseness. Nothing really out of the ordinary.

Fired it up again...the sparks don't appear to be electrical in nature. Almost like they are being jettisoned outward not arcing.

Could I have a busted valve?? The engine runs OK, not missing. If it weren't for the clacking sound, it would be normal.

Thanks for any advice or suggestions!
Cisco
1989 740 Turbo, 192K miles.
--
1989 740 Turbo Wagon, 172K; 1990 740 Turbo Sedan, 165K








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Sparks from the engine! 700 1989

The usual quickie test is done in the pitch dark. With the engine running, lift the hood. If you have positioned the car so that the under-hood area is in pitch black dark, look at the ignition wires. Leaky wires will have little blue flickers here and there as the high (40,000) volts escapes failing wires. Oviously check #2 extra varefully.

Look also for leaks of exhaust around where the exhaust manifold bolts onto the head. Seems unexpected but I have heard such a leak sound like a click.

While that plug may be firing OK at lower speeds, as compression pressures the voltage must be higher to continue to fire.

The sound. Can you tell if it seems deep from the bottom of the engine or up at the top? At idle, does it click at half the engine speed? That would point to a valve problem.

Do the after-dark tests and post back.

Good Luck,

Bob

:>)








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Sparks from the engine! 700 1989

It sounds more from the top than the bottom of the engine. I had considered a leaky manifold and there was a loose nut...last one near #4. I didn't check them all (since the motor was warm) but will. . . as for your other suggestions, too.

Thanks for replying.
--
1989 740 Turbo Wagon, 172K; 1990 740 Turbo Sedan, 165K








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Sparks from the engine! 700 1989



I agree with Bob 100%. Sparks almost have to be a problem with either the plugs or the wires. If you don't know the age of the parts, replace them. Bosch or NGK plugs, Bougicord wires.

As for the sound, we too had a loud mystery clicking/ticking/clacking sound in our 1991 740. Very strange timing, seemed to slow for the bottom end, not rattly enough for the top end. I thought it was a bad or poorly adjusted valve... with 300K miles on it, very possible... until I read somewhere that bad exhaust manifold gaskets can cause a funny ticking sound. A superficial examination showed the exhaust gaskets in not the greatest shape. I figured it was worth a try, so I got new gaskets, pulled the manifold off to find the gaskets were truly toast. We're talking a millimeter or two left between the outside and inside. I replaced everything with new gaskets, and the car runs and sounds like new again!

If you do get new gaskets, avoid ScanTech. I'd say Elring or dealership band only.

Good luck!
-Ryan

--

Athens, Ohio
1987 245 DL 314k, Dog-mobile
1990 245 DL 134k M47, E-codes, GT Sway Bars
1991 745 GL 295k, Regina, 23/21mm Turbo Sway Bars
Buckeye Volvo Club







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