Wet oily spark plugs - Rolls-Royce and Bentley Forums
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post #1 of 26 (permalink) Old 11-29-2019, 07:54 PM Thread Starter
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Wet oily spark plugs

Hello
Recently my car has been suffering from a misfire ,I changed all the spark plugs and now she is running fine .
I noticed that all the old plugs were wet dark oily

Any suggestions

Thanks Alec
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Silver Shadow 2 1978
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post #2 of 26 (permalink) Old 11-29-2019, 08:38 PM
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Wet oily plugs is a condition that can be traced to a few things, over rich mixture and more than likely worn valve guides and deteriorated valve stem seals allowing oil to actually seep into the cylinder.

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post #3 of 26 (permalink) Old 11-29-2019, 09:00 PM Thread Starter
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Hello Wraithman

Thankyou for the reply

I'm able to check the mixture myself however checking for worn valve guides and deteriorated valve stem seals may will be beyond my capabilities

I will check to see what's involved

Would worn gaskets cause a similar problem?

If the valve stem seals have deteriorated would you get excessive white smoke from the exhaust?


Thanks Alec

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Last edited by Alexander Hoar; 11-29-2019 at 09:09 PM.
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post #4 of 26 (permalink) Old 11-29-2019, 09:09 PM
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How much do you drive the car, and how long/far when you do?


In vehicles of this vintage, if all of the trips are short and the car never has a chance to really heat up (and I mean really reach peak operating temperature for extended periods of time - say at least an hour, preferably two or more) you can get quite a bit of carbon buildup and it doesn't take much oil (and unburnt fuel) to create a wet surface.


The old phrase regarding "burning off the carbon" has its basis in fact. Not that you couldn't have some underlying issue, but you may not if all you take is very short trips.

Brian

The opposite of a correct statement is a false statement. But the opposite of a profound truth may well be another profound truth.
~ Niels Bohr


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post #5 of 26 (permalink) Old 11-29-2019, 09:26 PM Thread Starter
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Hello Brian

You are spot,You have discribed my driving habits of late

The car has only been out for short trips ,maybe 20 minutes

Also with the constant rain here in the UK .The car has spent more time parked up ,weeks at a time between taking her out for short trips

Hopefully the lack of use is the culprit as you suggest

Thankyou Alec

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post #6 of 26 (permalink) Old 11-29-2019, 10:47 PM
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Brian is on point. Driving habit has a lot to do with plug condition. Plugs can actually tell a lot about the motor condition. Oil that weeps down valve guides and past seals will burn off and appear blue out of the exhaust whereas coolant or transmission fluid sucked up past a bad modulator valve will be white....and the plugs will generally not be black and oily, but if you are driving for short periods there is a water component in the form of condensation that will build within the exhaust system and eventually burn off with a good run at operating temp. You will usually see drops of water dripping from the exhaust when first started.

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post #7 of 26 (permalink) Old 11-29-2019, 10:49 PM
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Alec,


Take her out for a 2 hour drive at highway speeds, then check them again after the car has cooled down. You'll still probably have "dark" as that never quite goes away entirely but I'll bet you have "and dry."


Also, as a side note, if you haven't checked and cleaned your flame trap in recent times take the time to do so.



Compared to modern cars (and the SS-II was not modern, when compared against the technology common on other marques for years - including fuel injection for one) even when they were new. RR was a very late adopter of "the new" on the whole. I never understood how the braking/hydraulic system got past "the old guard" when it did, but once it did it was kept for a very long time, well past the end of the SYs.

Brian

The opposite of a correct statement is a false statement. But the opposite of a profound truth may well be another profound truth.
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post #8 of 26 (permalink) Old 11-30-2019, 05:19 AM
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Hi Alec do you have the correct plugs in? Carburetor cars have hotter plugs to burn off the soot that injection cars don't need.
The lower the number the hotter the plugs.
4 for carbs 5 for injection (NGK)
Mike

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post #9 of 26 (permalink) Old 11-30-2019, 02:28 PM Thread Starter
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Thank you Wraithman for the explanation I'm very grateful ,my engine oil levels and coolant level are normally very good

I do see water droplets at the end of the exhaust on start up and ,white smoke which I always assumed was condensation but wasn't totally sure so you have reassured me there thank you


Thanks Brian

I will take her out for a good run hopefully soon if the rain stops

I cleaned the flame trap only last month ,I have this down for periodical cleaning now based on your advice you gave me from another post I made some years back

Hello Mike

I have NGK BPR5E which after much research thought were the correct type for my car ,So you are suggesting I have the wrong type ?

Thanks Alec

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post #10 of 26 (permalink) Old 11-30-2019, 05:45 PM
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Hi Alec, is your car carburetor or Fi ?
Mike

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