2007 Nissan Versa DOHC. It’s been thru a lot, but I like to keep it alive.
At 112K miles, I replaced spark plugs, coils and valve cover gasket including ring gaskets around spark plugs. I did this proactively, it wasn’t having any running issue. Used high-rated parts on all, and torqued all bolts to spec on install. It was the first replacement of these parts on the car.
At that time, I noticed that at least a couple (maybe more) of the spark plug wells had been accumulating some oil, but the car had been running fine despite this.
By the way, replacing the plugs in a Versa is a big PITA because you have to remove the manifold. Ditto for cleaning or replacing the fuel injectors.
Now at 125K miles I got a P0302 code, misfire 2nd cylinder. I figure “fuel injector’s clogged” so I do the same manifold removal in order to clean the injectors. In the process, I notice that the plug wells have oil in them AGAIN ALREADY. Cylinder 2 and 4 have a bit on oil there, but cylinder 3 (which never has had any misfire problem) has quite a bit more. Cylinder 1 well was completely dry. If I’m recalling right, I think the pattern of seepage is approx the same as when I “fixed” it 13K miles ago.
The seems like a design issue with the gasket and valve cover. Is there any way to put on valve cover gaskets to prevent this seepage into the plug wells? Or should I even really worry about it much? The oil consumption of the car is actually pretty low, and the cylinder with the most obvious seepage has never had a problem firing.
Hi Tester, Thx for reply. I proactively replaced PCV valve at 112K miles, along with plugs and valve gasket. Questions: How would PCV valve be related to seepage in plug wells? (Pardon my ignorance of what PCV actually does!) Would malfunction of PCV system result in check-engine code? If so, haven’t seen that.
This allows crankcase gases to be routed back into the engine to be burned.
If any part of this system becomes restricted, such as the PCV valve or the hose, crankcase gases can build pressure can force oil past seals and gaskets.
A problem with the PCV system doesn’t usually cause the Check Engine light to turn on.
No experience w/Versa, but correct (i.e. factory service manual) valve cover gasket replacement procedure on my Corolla requires more than just new gaskets. Must also place some gasket sealer material (like Permatex form-a-gasket) in certain leak-prone spots, cleaning the areas first of oils/solvents. I learned the hard way that if I don’t do that, I’ll get some oil leaks. On Corolla the leaks seem to go down the side/front/rear of the engine, not into the spark plug wells. Suggest to secure factory service manual procedure instructions.
It’s a good idea for a diy’er to check that from time to time even without any symptoms. Very easy to do on both of my vehicles, less than 5 minutes, so I check it pretty much any time I’m doing any engine compartment servicing.
Thanks for replies. I checked PCV hose–no obstructions. Took PCV valve out and shook it–it makes a clicking sound as it should. Can’t run the car right now to do vacuum test, since manifold is off, but from lack of obstructions, seems probable that there would be a vacuum. (Someone correct me if I’m wrong.)
I do recall using extra gasket-seater goo when I replaced valve cover gasket at 112K-- I suppose the best thing next time is to just use more of that goo around the spark plugs that are getting the oil seepage.
I did notice that no one tried answered my last question:
Should I even really worry about it (the seepage) much? The oil consumption of the car is actually pretty low, and the cylinder under the most obvious seepage has never had a problem firing.
Remove valve cover and inspect the flatness (especially around the bolt holes). If not really flat, then you want to get them as flat as possible. There are a few ways to do this. Then remove all old gasket material on head and cover. Add new gasket. I do like to use a gasket sealer that helps to keep the gasket in place as I align the cover to the head. When tightening the bolts, do a few turns on each bolt rotating around the head or follow the cross pattern that’s used when bolting down a head. Keep repeating until at bolt specs.
Well, Mike has still raised an interesting point. My valve cover is the thing I did NOT replace at 112K miles, and as Tester points out, it’s made of plastic. Could it be that such plastic covers become less rigid–or even can warp–with age? If so, I might take a gamble at getting a new one. It’d prob set me back $175 or so.
It’s obviously a very small and gradual leak in three of the four plug wells (but especially plug 3). It does not leak anywhere along the outside edge. The car has low oil usage. I’m thinking now that perhaps the plastic valve cover might get “soft” with age around the plugs. Anyone have any experience like that?
The leak is presumably a little oil getting past those 4 circles in the gasket pattern, then into the spark plug wells. It seems like a new gasket would stop that from happening. You’d have to carefully clean the areas that the gasket seats, both top side and bottom side. I use a high-tak Permatex spray gasket sealant for that sort of application where the gasket is flimsy and easily dislodged as the cover is installed. As long as the cover measures flat, not warped, and not cracked, I wouldn’t expect a replacement cover to be of any help. It’s important when installing the cover to tighten the fasteners in rounds of increasing tightness. The first round, just finger tight. The second round, about halfway to full tightness. In other words don’t tighten the first fastener to fully tight, then the second to fully tight, that will warp the cover. And don’t try to solve a leak by tightening the fasteners beyond their prescribed torque spec. Be careful reading the torque spec. For something like that, it is often listed in inch-pounds, rather than foot pounds. 24 inch pounds is much less tight than 24 foot pounds.
I’m not sure what adverse effect, if any, oil accumulations would have in the spark plug wells. Seems like as long as the oil was only touching the bottom outside surface of the spark plug, well below the tip, and not any electrical insulating boots, wouldn’t cause much trouble.
Hi George–thanks for ideas. You must be right about the oil accumulations not interfering unless too high. Also, the seal of the coils around the plug seems firm enough to be perhaps oil-resistant. If oil got to the inside of the coil stems at high enough level, would that just cause lack of spark, or could it be a fire danger?
Regarding gasket, the prob is that I did basically all you suggest just 13K miles ago, using gasket-seating goo and carefully following reinstall procedure with proper order and torque, but the same prob is already happening again. If gasket were indeed dislocated, leak would be much more copious, I think. Obviously the original parts were having the same problem too (when I changed the gasket at 112K). So I can’t think of anything else that makes sense besides the cover. It’s certainly a common denominator at least. Perhaps a past PVC blockage caused excess pressure, warping the plastic cover just a smidge (I do recall switching out the PVC valve once and not hearing the old one properly click when shaken). If the cover was slightly warped up in the middle, enough for oil to seep slowly into the wells, then even when I put the new gasket and PVC valve in, the same seepage could happen again. That would explain the current seepage.
I just don’t know how strong the plastic valve covers are over time and wear. Even just a little warpage in the middle would do it, I’m sure.
To answer your question, the oil will not have any effect on the spark plugs, no matter the level. Oil is a dielectric, that is it is an insulator, in thick film. It takes a very high voltage to are through oil, much more than to arc through air, so you wont see a short circuit from the oil.
In thin film, that is where two pieces of conductor coated in oil or immersed in oil touch, it will conduct. Before I retired, I worked in a distribution transformer plant. Oil is used to insulate the coils, but all the connections are also under oil.
This is really interesting information, Keith. I suppose this means that I might not worry about oil in the plug wells too much, as long as the amount is not a lot.
If oil contaminates the electrical connection at the top of the spark plug, that could cause some grief. It might not be worth worrying about, don’t know. You could do the experiment, smear some oil on that connection on one of the plugs, see if causes misfires.
