My Father in law’s Saturn sedan (1996-7?) started making a terrible racket, so he stopped driving it. I wanted to check it out, so after hearing the noise for myself (definitely in the engine), I took a peek under the hood. First thing I pulled was the first sparkplug boot, and lo and behold, it was covered in oil. The others were ok.
So what am I facing here? Worst case, engine rebuild? Or can we replace the possibly broken sparkplug? Might there be a piece of plug floating around damaging the cylinder and valves?
Research indicates that the oil in the spark plug area means that the rings and/or valve stem seals have failed. Would I have to take off the valve cover to check the extent of the damage?
I’d do a compression test or have one done on all pistons and go from there. Oil on a plug may indicate a serious problem on that piston but best to be sure. Other things can cause that symptom - a bad spark plug wire for instance. If all compressions are good, might be minor. If you have a real low compression on a piston, migh be bad (broken piston, broken rings, other bad things).
You need to understand that the “business end” of the spark plug is inside the cylinder. The part that is externally exposed when it’s installed is quite a different thing. The phrase “the spark plug area” is useless in discussing this unless it’s made quite clear which part of the plug(s) we’re talking about.
I assume that you have not removed the plug.
When the spark plug boot and the external portion of the plug are oil-covered, the culprit is a leaking valve cover gasket. It does not affect the operation of the plug, says nothing about the condition of the plug, and has no relation to any noise. It will deteriorate the boot and plug wire in time.
All concerns about pistons, rings, valves, valve stem seals, plug damage, etc., are premature unless you’ve seen evidence of such on the firing portion (inside the cylinder) of the plug. They have nothing to do with oil on the external (where the plug boot goes) portion of the plug.
I assume the engine oil level is not seriously low.
The noise is almost certainly from the timing chain and related parts (sprockets, guides, tensioners). Google on “Saturn timing chain noise” and I bet you’ll find tons of info on this unfortunately too common problem.
Gary, thanks for the assurance. I was talking about the top end, not the ignition end. With all the racket going on, we were worried about valve damage. Would a leaking valve cover gasket only affect a single spark plug boot, or should all of them be affected?
Depends where it’s leaking. It could affect any or all.
While valve damage is not out of the question, timing chain problems are far more common. Still, oil leakage from the valve cover doesn’t relate to either problem.
I just recalled that Saturn engines are prone to some noise in the valve train, usually when the oil isn’t up to snuff. If the noise seems to be coming from that area, change the oil and see if that helps. Be sure to use the right viscosity (I’m pretty sure it’s 5W30, but check the oil filler cap or owner’s manual) and fill it to the proper level.
My in-laws’ oil change habits are horrendous. Along the lines of “Just top it off when it’s low.” At this point, can an oil change even help? It probably couldn’t hurt. Would it help if I got a sound file of the noise?
Also, he noted a loss of power just before the noise started. Would that be related?
Poor oil change maintenance can certainly be a significant factor in the failure of timing chain-related parts, among other things. An oil change won’t help a timing chain problem. It could help with a valve lifter noise problem.
It’s questionable if my hearing a sound file would lead to a definitive conclusion – noises can be hard to evaluate even when one is there at the vehicle – but it can’t hurt to give it a try.
Loss of power could be a result of the timing chain jumping some teeth.
I don’t think that there is enough information here to make a diagnosis. ‘A terrible racket’ could be anything from a squeal to a tump to a rattle and could be caused by anything from low oil level to a broken connecting rod which could cost thousands to replace.
The oil on the sparkplug implies that there is either a leak at the valve cover gasket, a clogged PVC valve, or something of the sort, but these aren’t directly causing the racket. It might be that the engine is low on oil, which would cause a constant rattling noise (like rain on a tin roof, except higher in pitch.) You might want to check the oil and change it if it’s low. If the noise is still there, then it might be time to take the car to a mechanic for an estimate.