piston rings

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After feeling vibrations while driving, I decided to check the spark plugs on my Maxima. It turned out that one of the plugs was covered in engine oil. I brought it to a mechanic and he said that mostly likely it's the piston ring that needs to be replaced. The job would cost around $1,500 because it will involve a lot of labor hours. He also said that I can keep on driving it until it quits. Any suggestions?

posted by  xilef

Not a lot of comfort with that one.

The oil's getting past the piston to the plug somehow and it's the ring's job to stop that. Replacing a ring involves removing cylinder head and oil pan which on some cars (I don't know he Maxima) means taking the motor out of the car.

It also involves specialty tools. You can do it yourself but it's a lot of work and time consuming. If you drive it without. I'd expect the plug to get gunked up regularly and that leads to the vibration you felt. You are in effect driving minus one cylinder as the oil stops the plug from igniting the fuel.

I don't know of a quick easy (dirty) fix for that. Maybe others do.

posted by  HighWayMan

check it thus... get a compression tester of some description (you can get cheep ones made of plastic, acuracy dont realy matter)... pull the plugs out..test the compression on all cylinders...note if ones down on the others. inject some oil down the plug hole (just a good tablespoon)..check the comprssion on that cylinder.. if its now better its the rings (the oil forming a tempory seal) if its the same then its the valve stems/seals.

posted by  sidecar_jon

I've actually done compression tests. All cylinders registered at normal.

posted by  xilef

is it burning a lot of oil?.....if compressions Ok maybe its comming down the valve stems..which is cheeper to fix...probably

posted by  sidecar_jon

its probibly cheaper to swap the engine lot less :2cents:

posted by  cinqyg

ignor it..run it..it'll probably go on for years...just make sure u put oil in it.

posted by  sidecar_jon

Hello, each piston has 3 rings, 2 compression rings towards the top and one oil ring just above the piston skirt. While the compression rings may be good you may have a bad oil ring, bad ring landing or yes, a bad valve stem seal. Valve stem seals get hard as they are rubber and shrink up allowing oil to seep past them. Usually a bad valve stem seal can be easily determined on initial start up. Some of the oil (returning to the pan) seeps past the valve stem seal when you cut the car off and accumulates on top of the valve, when the valve opens it gets in the chamber. This gets burned out when you first start the car, thus you get a lot of oil smoke on intial start up and it seems to clear up somewhat after a minute. In any case, if you go to the auto parts store and ask them for an "anti-fouler" they will give you a small metal tubular looking object with threads inside one end and threads on the outside of the other end. Inset this into the spark plug hole then screw your spark plug into that. It has a small hole in one end which allows the spark to travel into the chamber to ignite the air/fuel mixture while keeping large oil deposits from fouling the plug. It's not a sure fix, but it will help until you can determine the exact cause. Hope this helps.

posted by  MsSnapon

OK, that's good. But did you pour oil into the cylinder that has supposedly got bad ring(s) and checked if it made a difference?

P.S: $1,500 to replace rings on one piston? Tell him where to go.

posted by  DodgeRida67

Since all cylinders registered at normal compression what would I gain by pouring a table spoon of oil into the cylinder? I thought it was only if one of the cylinders had a wrong compression reading. Also, I've checked the oil level and it turned out to be pretty low, so it's seems like it's burning a lot of oil. Does that help determine if the problem is in the ring or the valves? I don't see any smoke when I start the car. Thanx for all of your responses.

posted by  xilef

look for a blue tint. have you checked to see if you have any water in your oil. try putting some crach spray on your head (well not on your head but the cyclinder head) see if there are any cracking which could lead the channels to be leaking.

posted by  cinqyg

You are not running a monograde oil are you? You may just need to go a little higher viscousity mulitgrade (mineral or synthetic).

posted by  Wally

If all of the cylinders read normal (probably between 150 and 175 psig and no more than about 15 psig variation between cylinders if the maxima compression ratios are similar to my Altimas) your problem is not rings, My gut feeling is valve stem seals. This may or may not be easy depending on the car and cylinder head design.

posted by  tbaxleyjr


posted by  Wally

Good point - shoould be checked anytine one is trouble shooting a drivability, idle, or oil consumption problem

posted by  tbaxleyjr

Very useful posts and advice.
Just came across this website and find it very useful for those of us who want to learn about cars and how they work (& why they occasionally don't!).

I just recently took my car (95 Nissan Sentra) to get some exhaust work done at a local shop.
In an unfortunate coincidence, when I went to pick it up, it wouldn't start.
I watched as the mechanics tested the battery and sparkplugs, and eventually left as they continued to struggle to figure out what was wrong.
Later they told me they thought it might be the timing chain, but that turned out to be ok too.
However, today they told me that it was just two things:
1) a bad sparkplug, and
2) a degraded piston ring.
The mechanic sounded like he was a doctor telling a patient he has cancer.
Is my car living on borrowed time?
Should I spend the money fixing this, or would I be better off driving it until I can afford to fix it (or buy a new car)?

Thanks in advance for any response or advice,

posted by  candrews

You aren't really giving any substantial facts, just annunciation of someone else's diagnosis. Why do you consider it a coincidence that you have exhaust wrok done and the engine suddenly won't start. I'm a little rusty on my linear regression, but I would suspect a correlation between the two would be close to unity.

You should get another opinion from someone who has the diagnostic equipment to test thoroughly.

As a DIY mechanic you would as a minimum conduct a compression test. Then whack a vacuum gauge on the manifold and diagnose the needle action.

Now I know everyone can read the internet and they rabbit on how pouring some oil down the bores for a wet compression test and if the pressure rises the rings are shot or worn, but that is not necessarly true. Let me tell you straight up that your rings and bore wear may be quite acceptable and that a wet test can also seal poorly seating valves.

So my advice to you is to buy a cheap vacuum gauge and see what is going on, before you decide whether to let the engine die a natural death or give heaps of money to a profiteer for five hours work and some cheap rings.

posted by  Wally

I am having a very similar problem with my truck burning oil and smoking when I start it up in the morning. I have a 1993 mazda b2600i 4x4 truck with just at 200,000 miles on it. One other problem I have is that many times when I go to accelerate suddenly it "putters" or bogs down. It is like it gets too much gas. If I slowly give it gas and gradually increase speed it does better but I really have to get the Rpms up before switching gears or it starts to bog down. I noticed the last spark plug tends to get a lot of oil build up on it so I clean it or replace it frequently. That does not seem to help the problem though. Does this sound like a bad valve stem seal or something else?


posted by  tenn_tazz26

This is a two year old thread that you've revived when you should have started a new one. None the less... :doh:

The problem you're experiencing is a common one with that engine. Although nothing beats performing a proper diagnosis, your engine commonly has rings that become stuck in the piston due to a poor combination of operating temperature and metalurgy. If that is the problem with your engine, the only way to fix is is to re-ring it. Be aware that parts are fairly expensive for your engine and GOOD used engines are too.

posted by  vwhobo

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