99 Infiniti i30, oil in spark plug hole?

Is the oil on the connector side of the plug, or on the inside of the cylinder at the business end? If its just in outside of the hole, then you need to replace the rubber ring on the bottom of the valve cover that seals the tube around the plug.

If it is the front side of the engine, its pretty easy and you can do it yourself for about $50 in parts (new valve cover gasket, new tube gaskets, new rubber washers on the bolts). Just take the vavle cover off and do it.

If it is the back side, its more work because the intake plenum has to come off to expose the valve cover & involves a fair amount of removing stuff. You might not want to tackle the back side if you're not too mechanically adept.

If it took you 2 hours to do the plugs on this car, which is usually a 10-15 minute job, you probably don't want to tackle the valve covers.

If its just oil on the outside of the plug its not serious at all and you can safely ignore it for a long time.

No.

Okay, it's not actually oil in the cylinder. If it were oil in the cylinder, you'd have a white deposit. If it's actual wet oil, it's probably on the outside of the cylinder and getting on the plugs when you pull them.

Yes, these are the valve cover gaskets, and I agree that this is probably the problem. It's an easy thing to replace and you can do it yourself without too much trouble. This car is new enough that there's a lot of crap covering the engine that you'll have to get out of the way and that is most of the time involved.

That could also be the case, but you don't know until you pull the valve covers.

Yes.

Not very, because it's not getting into the cylinder. It could be a problem the next time you pull a plug, though... it could dribble oil into the cylinder and lock it up if it's severe. So next time you change the plugs, swab out around the plugs with a paper towel.

You can ignore it for a good long while until you find another engine problem.

No, but it could just be the tires that are on the car. Could be a bearing on the way out too. Without hearing it, I can't tell, but I'd assume the tires at least look like they are in good shape if you didn't notice anything wrong when you balanced them. Rotate them and see if the noise changes.

--scott

Ok, I called the local Infiniti dealer and got a price quote for $100 labor to change the front valve cover gasket as well as the 3 spark plug holes, with parts its about $135, which includes a loaner car and car wash. So took it there and had it replaced.

The car drives very well now other than the subtle noise on 70+ mph highway speed. On regular street level driving I don't hear it at all.

It sounds like the rear wheel out of balance, the interval of the sound *seems* to change with the speed of the car. It sounds like it's coming from under the car. It's not obvious.

But it cannot be the wheel balance. It was like this with the old tires. And is the same with the new tire. All 4 tires are road force balanced on a GSP9700. The steering wheel is quite smooth at high way speeds.

I'll take it to a shop to have them look at it in a few weeks. What could be the cause? Worn out struct? Transmission? Should I have the transmission fluid changed to see if it improves things? (was replaced

Thanks!

Raymond

It's probably not the tires, although it kind of sounds like the rears are out of balance.

Initially, the rear tires are pretty new, the front tires are more worn out (30% left?) The previous owner replaced the rears but not the front since the front still has a bit of life left. I noticed a nail in the front, so I decided to replace the front 2 tires and have the shop balance all 4 using Hunter GSP9700 road force machine ($60 normally). So now the new tires are in the back, the original back ones are in the front.

The steering wheels at highway speed is pretty smooth, this is why I think it should not be the wheels.

But if it's not the wheels it probably is something more serious. :( My 99 Maxima does not have this noise at any speed.

Comparing to the maxima, the Infiniti's engine seems a bit louder and deeper. Has a very subtle humming/vibration when I accelerate from a stop. After the spark plug, oil, and air filter change, I think it's a bit better, but still there. It's not a big deal and I can live with it. I am just curious why the engine sounds different from my Maxima which is basically the same car.

Raymond

One of the differences (besides front & rear sheet metal) between the I30 and Maxima is that the I30 supposedly has different, more aggressive, engine control tuning. It might be that. But then again -- until recently, I had two I30s in the immediate family, a 96 and a 97. The engines sounded ever so slightly different between them as well.

Btw. If you need anything else done to the car, take it to Nissan. Its mechanically identical to the Maxima and they will work on it for a lower hourly rate.

Ah, that could explain the difference in sound. I was under the impression they are identical except some cosmetic differences.

Great, thanks!

Raymond

I had the car looked at by a mechanic. After test driving on the highway, he said the sound is coming from the rear bearings (since I told him the tires are new and same sound before/after). He tried to drive in a circle to see if he can detect which side it is coming from, seems to be coming from the left side.

He said I could still drive this for a bit until the sympton becomes more severe and more irretating. His quote is on the high side, about $900 to replace both sides. I called around, the dealer wants $605 for both sides, and another place, rated decently on yelp, quoted me $520 for both sides.

Will I be doing any harm if I wait a while before fixing the problem? Will this cause other problems in the car if the sympton becomes more severe? Right now it is a little bit annoying on the highway, but otherwise the car drives fine in the city.

What would be the cause for the failing of the wheel bearings? bad tires? bad alignment? flat tires?

Thanks.

Raymond

Bearing failures give me the willies. I would address it immediately, personally.

Aside from the consequent damage from the wheel flying off, not really.

Bearings are wear items.... they wear out and you need to replace them now and then. I don't know how much mileage you have on this, but if you are past 100,000 miles, it's a thing to look out for. Getting stuck in mud or water and submerging your wheel hub is a recipe for bearing failure, and road salt can sometimes accelerate it, but it's just one of those things that happens.

--scott

Haha, ok.

The place that quoted me $260 just called me back and said the mechanics determined it was the left side. The right side is fine. Let's see how good the fix went, I'll find out tonight!

This car has 70K on it. So if there is a problem, this type of noise is the first sign right? I'll be sure to watch out for it. I hate to have the wheels fall off. ;)

Raymond

Ok, so they replaced the left "Rear Wheel bearing and hub assembly", using OEM parts as they claimed.

Unfortunately the noise seems to be more pronounced!! The noise is slightly different, instead of fast "hohohoho" type of noise, it's more of a slower grinding/humming type of noise. It's now noticible on fast local streets.

My first reaction was, damn, I should've have them replaced both of the rear bearing. It must be the other side.

I test drove the car on the freeway with my wife in the back seat, and she said it's coming from the left side, the side they replaced the bearing!!

Either they did a s***ty job on the bearing (the shop has been around for a while and is quite reputable), or it's the other bearing making noise, or it's something else.

I am going to go back tomorrow to have them test drive it to see what it is. God damn it, maybe the previous owner got into an accident that carfax didn't show.

Raymond

Not likely. If it were in an accident, any residual damages should be found upon diagnosis.

Let us know what happens.

The technician and I test drove the car. The noise is slightly different from before. The frequency is less. I sat in the back seat, but can't quite tell whether it's from the left side or the right side. It still exists on neutral so the tech said it's not the transmission and likely the other wheel bearing.

The tech said the rear wheel bearing comes in as a package, so it's pretty simple to install and not a lot can go wrong (with the left one they put in). He put it up on the 'air machine' and spin the wheel, rotated the tires, and said the noise is consistently coming from the rear right side.

Going to bring it in tomorrow to have them replace the other bearing..

Raymond

This all sounds like deja-vue.

I'll relate two experiences from my i30t. Maybe one of them will help.

1. We started hearing rattling/clunking noises that from within the car sounded like it was coming from the rear, probably left rear. Various mechanics all had diagnoses that involved replacing various rear suspension components and one even wanted to re-weld the sub-frame in the back. Turned out to be the upper right front (yes RIGHT FRONT) strut mount was blown out. The unibody on that car is particularly good at transmitting noises around so you can't tell where they are coming from.

1. About 50k miles later it started making a wheel bearing noise. It sounded like a wheel bearing to me. Every mechanic who looked at it agreed

- had to be a bearing. Finding it was another story. To diagnose a bad bearing on an I30 (or Maxima - they are the same car), the axle has to be under load before it will make any noise, so once you get it on the rack to look at it, it won't make any noise & many techs will just guess based on luck or experience. After several different opinions, we decided it must be the left front wheel bearing and had it replaced. The sound was unchanged and the diagnosis was that the new bearing must be bad. On a whim (and many thanks to the mechanic who suggested it), and since we had two I30's with matching wheels at the time, we took one of the wheels off the other car and started rotating it around on the noisy car. The problem was a tire. As soon as the offending wheel was removed from the car, the noise was gone.

Bottom line. Don't limit yourself to what you think it has to be on this car. You might have better luck if you get a second opinion from a Nissan garage. They have seen a lot more of these under the Maxima skin.

Ok I bite the bullet and have them replace the other wheel bearing in the back. The noise seems to be gone now from my 15 minute drive from the autoshop to work today! I am going to test more on the highway this weekend but looks like this is it! Phew!

The tech said the left (1st one they replaced), the wheels did wobble a bit once they lift the car. Could the bad bearings explain why the previous owners went through so many tires (7 total) in such short mileage (69k)? Those were cheap tires but still...

Raymond

Bad bearings can chew up tires easily. Now that your bearings are good have it aligned.

This all sounds like somebody did something to this car before you got it (or the tech was just trying to feed you a line to justify replacing the wrong bearing).

I've got over 120,000 miles on one of these and 150,000 on the other one and nothing wobbles. Of course, if the bearings were loose enough to wobble, it would eat tires and the noise would be horrendous.

I changed the plugs myself at 110k using NGK PFR5G-11 (turns out the coils failed, so it also has 6 new coils). Air filter was changed

Just did another drain and fill on the transmission today using Nissan ATF fluid at a local shop. The prior one was a month (1600 miles) ago. So now I have 2 drain/fill done which should've replaced half of the fluid. Hope it works better!

I was using OD I believe. Usually it works reasonably well. It might have been just the hill is a bit steep. We did drive down highway-1 in California a few weeks ago, it was winding with some hills but seemed all right now that I think about it.

I've been pondering about whether to also do an engine oil change before the 2k miles trip. The prior one was 1500 miles ago and I put in full synthetic mobile1 10w30. I did go on 2 long trips about 500 miles each afterwards. Changing the oil would give me the peace of mind, but seems a bit wasteful. The synthetic should still be very good after 1500 miles right? even if some of the miles are all day long trips.

In case you are wondering, I am being extra catious because I've never been on a trip that long. need to do 1100 miles in 2 days and back 5 days later, with a full load. ;)

Raymond

Cars love those long trips. There is far less stress on the various components and systems because everything gets to full operating temperatures and pressures and get to run steady-state for a long time. The impurities/crud that builds up in the oil and other places gets burned off or boiled off and in general everything is better for the experience.

When you are doing mostly highway miles, you fall into the "normal" usage category (unless its death valley), which on this car means 7500 mile oil changes ("severe" usage calls for 3750 mile changes). I would not even think about changing Mobil 1 with as few miles as you have on it. It should be good for at least the 7500 miles normal interval, and probably more.