spark plug well seal - Alfa Romeo Bulletin Board & Forums

 
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post #1 of 14 (permalink) Old 03-16-2017, 04:59 PM Thread Starter
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spark plug well seal

My son said one of our Alfas, 1993 164L 217,000 miles, was running rough one morning. It actually stalled pulling into a parking space. I thought it might be fouled spark plug(s) which has happened before. I removed #3 and #2 plugs because they were the worst in the past, but they looked pretty good. When I went to remove #1 plug I found that the spark plug well was FULL of oil. Earlier I noticed oil dripping under the car in the area of the power steering pump. Could a leaky spark plug well seal leak enough to allow oil to drip onto the ground? Could a spark plug well full of oil cause the plug wire to short out and make the engine run rough?
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post #2 of 14 (permalink) Old 03-16-2017, 05:59 PM
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My guess is 2 separate issues. Wouldn't a full spark well overflow toward the back. A leaking c seal might leak in the area of the power steering pump.
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post #3 of 14 (permalink) Old 03-16-2017, 06:18 PM
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Oils conduct electricity minimally under normal conditions, which makes them useful as insulators. The extent of electrical conductivity depends on the concentration of impurities, so if the oil is very very dirty, yes, it might cause a miss, but it is not likely.

I've run Alfa engines, both 4 and V6, where a plug well was full of oil and the plug did not miss. I suspect at least one of the plug wells in my 91S has oil in it, IIR, and it runs just fine. Bought a set of those seals, but have never changed them. I've never worried about it much, but if it gets to be a bad leak, then I bother to fix it, esp if it is only on the easy front bank. The rear bank? Only if it is really bad.

I'd be more worried about oil getting close to the timing belt more than anything else.

Del

Seattle

89 Milano (wife's daily driver since 1989, Shankle Sport)
91 164S (my daily driver since 1994)
94 164LS (~Q) (trip Alfa since 2000)
72 Morgan 27 (water time since 1976)

previously owned since 1964:

62 Morris MiniMinor 850, 67 Austin 1275 Cooper S (Downton 3/4 race), 64 Giulia Sprint GT (1st red one made), 72 Fiat 128 Sedan, 75 Alfetta Sedan, 78 Alfetta Sedan, 78 GTV, 81 GTV6, 86 GTV6
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post #4 of 14 (permalink) Old 03-22-2017, 04:51 PM Thread Starter
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Why are the spark plug well seals football shaped? They barely seal at the tips. Why aren't they round?
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post #5 of 14 (permalink) Old 03-22-2017, 05:36 PM
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Because for some reason the tops of the plug wells are cast in that shape. The corresponding holes in the valve covers are round. The reason may have to do with thermal expansion of the cast plug wells, they are ineffect free standing towers rising from the combustion chambers.

1991 Alfa Romeo 164L 5 spd
White on grey leather 230K km, owned from new
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post #6 of 14 (permalink) Old 03-22-2017, 08:13 PM
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it would be nice if they were more positively kept in place. I glue them down first, otherwise they tend to slip aside sometimes, and leak. Sometimes they leak anyway. I don't usually get too excited about it, as it doesn't usually cause the engine to run rough if that happens.

Del

Seattle

89 Milano (wife's daily driver since 1989, Shankle Sport)
91 164S (my daily driver since 1994)
94 164LS (~Q) (trip Alfa since 2000)
72 Morgan 27 (water time since 1976)

previously owned since 1964:

62 Morris MiniMinor 850, 67 Austin 1275 Cooper S (Downton 3/4 race), 64 Giulia Sprint GT (1st red one made), 72 Fiat 128 Sedan, 75 Alfetta Sedan, 78 Alfetta Sedan, 78 GTV, 81 GTV6, 86 GTV6
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post #7 of 14 (permalink) Old 03-22-2017, 09:46 PM
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Because usually the oil that leaks in the well doesn't get past the insulator. If it does, it will short out and miss fire.
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post #8 of 14 (permalink) Old 03-22-2017, 10:25 PM
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I'm not sure that happens, as the oil is usually a reasonable dielectric, unless really heavily contaminated with metallic/chemical impurities, usually not a problem with reasonably changed engine oil.

In the past, I've accidentally run Alfas with oil covering the plugs to the wire, and never had a problem. Yes, a mess to clean up, as you have to try to soak up much of the oil so that you don't get too much running down into the cylinder.

Out of curiosity, what condition is the 72 Berlina? I don't remember now, saw it only from a distance. And the other one?

Del

Seattle

89 Milano (wife's daily driver since 1989, Shankle Sport)
91 164S (my daily driver since 1994)
94 164LS (~Q) (trip Alfa since 2000)
72 Morgan 27 (water time since 1976)

previously owned since 1964:

62 Morris MiniMinor 850, 67 Austin 1275 Cooper S (Downton 3/4 race), 64 Giulia Sprint GT (1st red one made), 72 Fiat 128 Sedan, 75 Alfetta Sedan, 78 Alfetta Sedan, 78 GTV, 81 GTV6, 86 GTV6
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post #9 of 14 (permalink) Old 03-23-2017, 01:04 AM
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There's a big difference in the ability of of different oils to conduct electricity. Transformer oil is specifically formulated so it won't conduct unless the voltage is very high. Engine oil is a different matter. It's formulated to keep contaminates in suspension with no regard for conductivity. Metals are used in additives used in engine oil and of course there's carbon, a a product of combustion. I suspect at coil voltages of 30,000 volts would push currant through engine oil.
My 1972 Berlina is rough. There's evidence it was painted in the early '80. The good areas are badly oxidized and faded. The bad areas have surface rust. One area behind the right rear door is rotted through. I'm quite surprised how good it looks underneath. Lots of surface rust, but the floors and rockers are solid. The interior is average for its age. Not trashed, not pristine. The seat have been redone long ago in a velor reminiscent of '70 NA plush style. Overall, a driver. Interesting, it's the oldest documented 2L Berlina in North America, but has the wrong 2L....The engine is an 84 L Jetronic
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post #10 of 14 (permalink) Old 03-23-2017, 07:10 AM
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I have had no luck at getting all six seals to seal at the same time. I buy new seals and I have tried installing them dry and also with a little sealant on the underside. I currently have a high level of oil in #4. Before I last changed them it was #2 & #5 that leaked. I do not have a misfiring problem and I have a Crane Hi-6 ignition with an MSD blaster coil and plugs gapped at .040" - a high voltage setup. Oil is Shell Rotella-T plus Rislone ZDDP additive.

Ed Prytherch
79 Spider
85 GTV6 3L
76 Suzuki GT500

A little government and a little luck are necessary in life, but only a fool trusts either of them. - P.J. O'Rourke
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post #11 of 14 (permalink) Old 03-23-2017, 07:21 AM
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The design is unsound. The effectiveness of the spark plug seals is dependent on the exact effective thickness of the valve cover gasket. There must be a trick to this though because the seals on my engine never leak a drop. Mechanic installed each time.

Apparently, the oil inside the plug wells can cause thermal stress on the ceramic plug insulator. It is unlikely to short the plug to ground, that's a long way from the electrode to the metal plug body.

If you've ever made drinking glasses from old wine bottles you'll understand the problem. Fill the wine bottle to the desired final depth of the drinking glass then plunge a hot metal bar (poker, heavy bolt or similar) into the oil. Presto, a neat level fracture will split the bottle at the level of the surface of the oil.

1991 Alfa Romeo 164L 5 spd
White on grey leather 230K km, owned from new
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post #12 of 14 (permalink) Old 03-23-2017, 09:29 AM
Del
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The 1750 Berlina my friend had, was painted silver, and ended up with a 2 liter and limited slip diff from a Spider. He had finally sold it to someone on the Peninsula, Port Angeles I guess. Don't know where it went from there.

Other than that, It's weird just how Alfa never made those plug well seals more positive through the decades, considering...

guess they just couldn't be bothered.

Del

Seattle

89 Milano (wife's daily driver since 1989, Shankle Sport)
91 164S (my daily driver since 1994)
94 164LS (~Q) (trip Alfa since 2000)
72 Morgan 27 (water time since 1976)

previously owned since 1964:

62 Morris MiniMinor 850, 67 Austin 1275 Cooper S (Downton 3/4 race), 64 Giulia Sprint GT (1st red one made), 72 Fiat 128 Sedan, 75 Alfetta Sedan, 78 Alfetta Sedan, 78 GTV, 81 GTV6, 86 GTV6

Last edited by Del; 03-24-2017 at 11:44 AM.
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post #13 of 14 (permalink) Old 03-24-2017, 09:05 AM
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Quote:
The design is unsound. The effectiveness of the spark plug seals is dependent on the exact effective thickness of the valve cover gasket. There must be a trick to this though because the seals on my engine never leak a drop. Mechanic installed each time.
That may be my problem. I have a reusable gasket that has been reused many times, each time with a little sealant. I will try again with a stock gasket.
Thanks!

Ed Prytherch
79 Spider
85 GTV6 3L
76 Suzuki GT500

A little government and a little luck are necessary in life, but only a fool trusts either of them. - P.J. O'Rourke
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post #14 of 14 (permalink) Old 04-12-2017, 04:49 AM Thread Starter
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I replaced the spark plug well seals on the right side and it appears to have stopped the oil leak. If the flooded plug well was not shorting the plug, I also found that the alternator belt was slipping and the battery was weak which may have caused low voltage resulting in the "computer" to cut out and causing the rough running, it seems to be running well now.
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