Spark plugs covered in oil - how screwed am I?

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SlantedMark4

SlantedMark4

'74 Valiant 225 /6
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It all started like a month ago when my Valiant (225 Slant Six, 1974 model year), misfired badly. It stalled 4 times in less than a mile of driving. I was lucky to be near home.
I've started the car like a week later again without any issues but replaced the ballast resistor because it was a bit crumbly. I've barely touched the car since but yesterday I thought I should check the spark plugs to be sure these are not the cause for the misfire and holy ****, I've never seen spark plugs to be this oily. I have removed all the spark plugs and spark plug tubes, cleaned everything (the spark plug tube seals are rock hard btw) and scratched the carbon off the electrode, just the normal work you do... I then let it run for like 5 minutes, let it cool down and the spark plugs are a little oily already again.

It has some excessive oil consumption but I thought it was a loose connection on the oil cooler to cause that but now I think it is burning the oil...
There are no weird sounds, only the famous lifter tick. No weird knocking or anything else and the idle is smooth. The valve cover is a bit wet on top but not much. Throttle response is fine and I don't hear weird noises when I rev the engine. There is no smoke coming from the exhaust. I can't say if there is a power loss because I've driven my Valiant for just around 1400 miles.

I think compression testing is the first thing to do, right? It looks like the piston rings or valve seats / valve stem seals are bad.
I've read it is possible for a valve gasket to leak into the spark plugs and causes misfires but in a Slant Six? The spark plugs are at the side of the block, not in the valve cover? This is btw the first time I work on a slant...

The spark plugs from cylinder 4 to 6 were the worst. The one on the green towel is from cylinder 6 (closest to the firewall/bulkhead).

IMG_20240625_173227.jpg


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How Much oil do you use per 1000 miles?
Blue smoke on startup?
Pull valve cover and look at your valve seals. V8’s have neoprene umbrellas, not sure about/6’s. They get old they harden and bust up to pieces from heat cycling.

Compression test will tell you if you have a real problem, followed by a leak down test will give you a good idea what the problem is.
 
In addition to what has been said about the plug tubes, etc, make certain that something hasn't happened to "wash" the rings. Maybe the carb needle seat stuck and flooded it bad, maybe the FUEL PUMP is leaking gas into the pan.

I would get good plugs in it, make sure it seems to be running OK, go for a long enough drive and at speed to get it fully warmed up and then monitor the plugs and oil level
 
Install new plugs, remove crush rings if they have them on heads with tubes. NGK3459/ZFR5N is a good plug for these. Any seals that are hard must be replaced. They are no longer seals but leakers.
I hear tht a good source for info on these is @slantsixdan
 
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This ^^^^^^ is first on your to-do list. You can't use crush washers on drool tubes, and hard seals are no seals. Start there, it might solve your problems.
 
ch1ll said:
How Much oil do you use per 1000 miles?
Blue smoke on startup?
Pull valve cover and look at your valve seals. V8’s have neoprene umbrellas, not sure about/6’s. They get old they harden and bust up to pieces from heat cycling.

Compression test will tell you if you have a real problem, followed by a leak down test will give you a good idea what the problem is.
Click to expand...
Prob valve seals to look at
 
ch1ll said:
How Much oil do you use per 1000 miles?
Blue smoke on startup?
Pull valve cover and look at your valve seals. V8’s have neoprene umbrellas, not sure about/6’s. They get old they harden and bust up to pieces from heat cycling.

Compression test will tell you if you have a real problem, followed by a leak down test will give you a good idea what the problem is.
Click to expand...
As I said, I drove it like 1400 miles, poured in like a liter of oil already and now the oil level is below "low" already.

IMG_20240625_170138.jpg


No, there is no smoke at all. Maybe a tiny cloud the second after startup but nothing special.
I go try what the other guys said and see if it helped. I really really hope the piston rings are fine ...
 
MoparLeo said:
Install new plugs, remove crush rings if they have them on heads with tubes. NGK3459/ZFR5N is a good plug for these. Any seals that are hard must be replaced. They are no longer seals but leakers.
I hear tht a good source for info on these is @slantsixdan
Click to expand...
Thank you very much for your informations! I'm gonna see if i can get these plugs asap. But a question: Why do I have to remove the rings?
 
When you have tubes, the tube acts as the plug seal.
If you don't remove the crush sleeve, it will leak because it can't seal to the aluminum tube, only a steel/iron seat.
Like double gasketing an oil filter, a big leak.
If your oil was burning you would have a lot od blue smoke, fuel will smoke black. No smoke ? no oil/fuel burning.
 
MoparLeo said:
When you have tubes, the tube acts as the plug seal.
If you don't remove the crush sleeve, it will leak because it can't seal to the aluminum tube, only a steel/iron seat.
Like double gasketing an oil filter, a big leak.
If your oil was burning you would have a lot od blue smoke, fuel will smoke black. No smoke ? no oil/fuel burning.
Click to expand...
But where would go the oil instead? I'ts not a small amount that simply disappears...
 
Dunno about you guys, but a quart of oil loss in 1400 miles isn't all that bad. I burn more than that in my worn out slant, and I'm not driving a fog machine.
 
Hard to tell from the pictures, granted the plugs are oily but the electrode looks to be covered with soot.
 
halfafish said:
Dunno about you guys, but a quart of oil loss in 1400 miles isn't all that bad. I burn more than that in my worn out slant, and I'm not driving a fog machine.
Click to expand...

Agreed, a quart/1,000-1,500 miles isn't that bad for an original high-mileage engine from the 1970s.
 
The firing end of the plug looks fine. The outside of the plug is oily because you need to cut the washers off the plugs. The drool tubes act as the washers on those heads. When you leave the washers on, they can leak. Not always, but they can. Also, Chrysler came out with a service bulletin I believe in 1963 saying you should not use the washers with the drool tubes, because it did not allow the plug to enter far enough into the chamber with the washer on. It probably wouldn't hurt to replace the droop tube seals, too.
 
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