valve gasket+ leaky spark plug tubes

I have a general question about newer spark plug locations, and how some cars have them now located "under" the valve cover..

I was comparing my wife's 4-cyl Mitsubishi vs our 6-cyl Jeep. The local shop said that the valve gasket was leaking on the Mitsu, and also the spark plug "tubes" were getting oil and fouling a plug - hence the "Service Engine" light.

So - when did this all change - I can't get a mental picture of how this all fits together..... "spark plug tubes" getting oil ?

tnx for any insight, photos, or diagrams you can point me at..

Reply to
ps56k
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A bit of a dealership snow job, IMHO.

Possibly bad plugs, wires, or other ignition issue could set the CEL, but what DTC codes are you getting?

All *what* change? Plugs in valve covers have been around since at least the 1950s.

Like in the commercial "Got Milk?" I guess! Maybe the tubes are fillign with oil and that's causing a problem.

Reply to
PeterD

Just did some more digging - and comparing my jeep to her mitsubishi - Here's the diagram for the jeep - the coil rail is bolted to the block, with the plugs underneath...

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I just went and looked under the Mitsu hood. It appears that the plugs are located "thru" the valve cover (new to me) and look very different than what I'm used to seeing.. even comparing to the jeep.

The Mitsu has them on top - just behind the OIL knob. There are 4 round rubber boots - and every other one has a small "black box" on it, and daisy chained to another cylinder. Left to right - 1 & 4 connected together, and 2 & 3 connected together.

Opened the Oil cap and looked inside at the #1 position and it appears to have a "tube" for the spark plug - sort of like a missle silo....

Just had never seen this scenario before...

Reply to
ps56k

I've seen several with variations on this theme - plug is at the bottom of a well in the valve cover (or other part). Seeing it once is one time to many, too. My daughter "forgot" to tighten the oil cap on a Nissan 4WD pickup and blew oil all over the engine compartment - enough to get about an inch down 3 - 4 of the plug wells which are a good 4 inches deep or more. Same problem and it was a flaming bitch to get those plugs out when they (and/or the plug wires) finally failed. Baked on oil and the mess they made of the plug boots meant having to use a long screwdriver to peal the gunk off the plugs before I could even hammer a socket in place to get them out. Did one to show her how, then sat back and drank beer while she did the others. For some reason, she is very careful to tighten the oil cap anymore....

Reply to
Will Honea

I've seen several with variations on this theme - plug is at the bottom of a well in the valve cover (or other part). Seeing it once is one time to many, too. My daughter "forgot" to tighten the oil cap on a Nissan 4WD pickup and blew oil all over the engine compartment - enough to get about an inch down 3 - 4 of the plug wells which are a good 4 inches deep or more. Same problem and it was a flaming bitch to get those plugs out when they (and/or the plug wires) finally failed. Baked on oil and the mess they made of the plug boots meant having to use a long screwdriver to peal the gunk off the plugs before I could even hammer a socket in place to get them out. Did one to show her how, then sat back and drank beer while she did the others. For some reason, she is very careful to tighten the oil cap anymore....

Reply to
Will Honea

You guys must be really young. Where were you the first time Chrystler put a hemi in a car?

Reply to
Old Crow

Well, as I said, this has been used for years, at least since the

1950s in some engines (oddly, many from Chrysler!)

I guess if you didn't grow up working on those vintage vehicles, you may not have seen them however.

The 'chaining' (connecting two plugs together) is common in distributor-less ignition systems, both plugs fire the same time but the cylinder on the exhaust cycle really doesn't do anything.

You want bizzare: the Dodge Hemi 5.7: plugs in tubes as you describe.

16 plugs, two per cylinder. Eight coils, one per cylinder. Coils are wired so that each coil fires two cylinders--a failure of a coil won't stop the engine (nice reduncancy) but will affect performance to a certain extent.

Of course, tune-ups with 16 plugs are a tad more expensive!

Reply to
PeterD

Going, "Wow, what an engine..."

The Desoto Hemi!

Reply to
PeterD

Right. 331 cubic inches and 750 pounds of cast iron fed with a 2 barrel.

Reply to
RoyJ

Hell, the front bumper weighed almost as much, too...

Reply to
PeterD

Even the 4.0 straight 6 has enough of a well to catch oil but it doesn't for all the way around. I don't recall the 68 Charger I had with the hemi being that much of a pain to get at - seems to me it was a reasonably wide hole. But that was (shudder) 30 years ago...

Reply to
Will Honea

BTW - thanks for the education...

Here's a photo of the TWO spark plug wires used...

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The long part goes down the tube to connect to the plug, with the rubber boot at the top sticking out of the valve cover. The short end merely connects to the "black box" over at the "peer" spark plug. So, instead of having 4 plug wires, there are actually only 2.

After my Saab also had some kind of "rail ignition" system, I gave up trying to poke around & follow things.... until now.

Reply to
ps56k

Yep, and with two small (by today's standards) WCFB four barrels, hot cam (for the era), 9.5: CR and cast header exhaust, it was also the first engine by an American manufacturerr to make 1Hp. / Cu. In. ... a year before Chevy

Budd

Reply to
C.L. Budd Cochran

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