Question about car with stuck Piston Ring

[good2go]

Hey guys, i'm new to the site, and it looks like a great place to find valuable information.

I have a question. I know this site is more for classic cars but this is just a general auto question mostly.

I have a chance to buy a 1994 Mazda Precidia MX3, 4cylinder, in mint shape, for $1000 canadian.

Problem is he says one of the rings is stuck and it smokes while it runs, but otherwise runs "OK".

It was his daughters car, so obviously driven easy, and it hasnt been on the road for a year and half.

Why would the rings stick? I'm thinking cause of carbon build up? He said it might just need a good run or worst case scenario new rings.

What do you think? and is there ways to unstick rings without taking the pistons out? Maybe dumping some oil down the cylinder holes or something? Any tricks? Thanks- Neil

 

[eljefino]

If you pull all the spark plugs you can confirm if one cylinder goes through more oil than the rest of them. A compression test will help too; sometimes an oil control ring can go bad but the compression rings will still be good-- this is obviously better than if that hole has much worse compression.

You can sometimes free 'em up with marvel mystery oil, seafoam, Mobil 1, diesel-rated HD oil, or a combination of the above. MMO and seafoam piston soaks (dribbled in thru spark plug hole) are popular on saturns with sticky rings. If this car's inline-4 is "level" WRT the piston tops the soak will get all sides. If you buy a quart/liter of MMO about 3/4 of the bottle will be left over after the soak; dump this in the crankcase.

Of course the current owner or his mechanic could just be guessing about why the car is going through oil-- it could be valve seals or even a leak. You wouldn't know for sure until you took the motor apart, then you could fix it "right".

 

[MONKEYMAN]

Here is more details on the piston soak that some of the Saturn owner's try:

http://www.saturnfans.com/forums/showthread.php?t=23676&highlight=mmo+soak

I am using Auto-RX right now on my Saturn. Have not done the piston soak. My understanding is that a piston soak/s work some time. Auto-RX will clean things in a more thorough way, at least that is what I am hoping.

 

[good2go]

hey guys, well i'm going to go look at the car in a couple hours, but i dont think he will be there for me to hear it run, so i'll just give it a look over to see what kind of shape its in.

but if i do go to look at it again, what would it run like if one of the rings is stuck, and what would it run like if it had cracked rings and a broken piston skirt?

what do u think about this car? its $1000 considering one in good shape running good goes for like $3500.

how would i know whether its just a stuck ring or cracked rings? by listening? driving? pulling the plugs?

what are the chances i could unstick this ring?

thanks,

 

[SWS]

I don't know anything about this engine or how to diagnose the problem, but as was said in an earlier post, "be careful". Assuming that this is the only thing wrong with it, and you can buy the car for $2500 less than the going rate, then you need to consider if you are willing to perform an engine rebuild with the "savings". If this car needs to be placed in immediate service, and needs to be dependable, then those are factors that you need to consider now, given this problem. I assume that you will not be able to "tinker" with it (piston soak, etc) before you buy it, but perhaps you can take it to a mechanic familiar with this model to get his diagnosis.

Don't fall in love with a car - just look at the advantages and disadvantages clearly and make your decision. Best wishes!

 

[cryptokid]

ill go into more detail then for you.
when i had one of these engines crack a ring it had low compression on the faulty cylinder. it was around 40psi. it turns out the ring was cracked in 3 places! and looking through the sparky hole with a borescope showed tonnes of vertical scratches and a loss of cross hatching on the cylinder wall. i *think* the broken ends of the ring was scratching the cylinder. the 3 remaining cylinders had no vertical scratches and still showed factory crosshatching.

these are the clues you can use to look for cracked ring. vertical scratches, low compression, oil comsumption and combustion chamber deposits in excess of the other 3 cylinders, smoking.

for a stuck ring its basically all the same symptoms but without the vertical scratches.


the good news is that to pull a piston on that engine its real easy. you can remove the cylinder head, intake manifold and exhaust manifold all as 1 piece.
the oil pan comes off once the downpipe is removed.

 

[good2go]

hmmmm. i dont know what to do. i have a alittle less than a yaer before it has to go on the road, but i dont want to have to rebuild the motor. i am pretty mechanically inclined but dont know much about 4-strokes or how hard it would be to rebuild it.

i was just hoping it was a stuck ring that can be "un-stuck" over a period of time by the soakings etc....

i dont know what to do?

 

[darkdan]

It's a mazda B series engine so the thing is almost bullet proof.

I'd just auto-rx it and enjoy the well priced car.

 

[eljefino]

If you have a year to tinker I'd get it and do some learning! Worst case is you could pawn it off on someone else for the same $$$ or take the loss.

 

[good2go]

well, i looked at the car, didnt get to hear it run there was nobody there, but the thing is spotless. no rust, no air bubbles in the tint, interior was spotless, all armouralled, no rips in the seat, had the full gauge cluster.

now i'm really confused, lol. if it was rough i would have my mind made up already but no that its in such good shape?

well the guy did say it was a stuck piston ring not a cracked piston ring, maybe thats a thumbs up?

wonder what the chances are of it being a stuck ring over a cracked ring? and what the chances would be of getting it unstuck? i priced out the MMO, 7.99. not bad. wouldnt that be a cheap fix! does this work every time? the soaking and stuff? or is it pretty rare that it would unstick a ring??

thanks guys i really appricate all your comments and input!!

 

[darkdan]

I don't know about where you are, but around here a decent mileage b6 engine (1.6L I-4 with 88 horsepower) costs anywhere from $100 to $300.

So even if the engine is totally shot, it takes about 6 to 10 hours of a DIYer to change out the engine on that car.

So if the $8 MMO or the $25 AutoRX doesn't work (due to physical damage) for another $300 you can have a 60k mile engine.

$1300 isn't all that bad for a car that gets 30ish mpg.

 

[Motorbike]

If the ring took a hit during an overheat situation it will never come back .

I'd do a soak right through the spark plug hole with original Berryman B-12 . Possibly a series of soaks .

One can get 8 total 4 cylinder engine soaks for 2 bucks and this works very well on the Saturn engines .

Ask member Chris for details on how he was advised to do it and his results if inclined to pursue more info on this way of getting it done .

 

[good2go]

well, i was just thinking, i'm going to call the guy tonite and find out when the ring stuck, and how he knows its the ring that stuck. then see what he says.

but until then, i was thinking, if i did get the car and it was indeed the ring that was stuck,

1) i can do the MMO like 300 times because the car isnt going anywhere,

but, if i do the auto-rx thing, it says to drive it for 1500miles with the stuff in there, although, well, this car is going to be in my driveway for about 10months, but i will be moving it around abit and starting it everyday and once in a while taking it up and down the road.

what do u think? would i be able to use the auto-rx? does the car have to be putting on the miles or can it just be sitting in the driveway?

thanks- Neil

 

[Rickey]

Addressing the possiability of a cracked skirt: If a piston has a cracked or broken off skirt there will likely be a lot of piston slap and the associated noises that go with it. Grounding the plug on the suspect cylinder would decrease or eliminate the noise. A damaged piston skirt can commly be caused by overheating, overreving,detonation,or lack of lubrication. I am wondering about mileage. You might also look for possible signs of recent cooling system trouble such as new radiator,water pump etc. I realize you you still may not have seen it run, but I am also wondering about blowby. If it smokes with no blowby this would possibly point to valve guides,oil rings,or oil somehow being sucked into the intake. Hope this is helpful... Rickey.

 

[phordguy]

You need to do a compression check before you buy it no doubt and run a leak down if possible. Those two tests will tell you if what's suspect, also the condition of the plugs will tell you a lot of what's going on in there. I've read here on BITOG that marvel's is mostly kerosene so you could fill the affected cylider with a lot of kerosene and let it do its thing and turn it over by hand. I wouldn't crank it with kerosene in the oil, but a few hand cranks of the crankshaft with a big socket wrench and repeated applications of solvent should go a long way if its a frozen ring due to carbon. Then keep doing compression tests until it gets better. Strong solvent such as B12, seafoam and good 'ole kerosene is much faster than auto-rx no doubt especially if you aren't driving the car much. Find an old retired and hopefully honest mechanic. Get him to go over and check the car out, his wisdom will be the best $$$ ever spent on engine problems. Look before you leap! Hindsight is always 20/20.

 

[good2go]

ok, thanks for the advice. i called him but isnt there until tommorow morning, so i will get ahold of him after school tommorow.

question.

1) what is blowby and how do i look for it?
2) what should the sparkplugs look like on the effected cylinder?
3) how low should compression be on the effected cylinder. i mean if 120 is good it should be around 80 or something? thanks.

 

[Chris142]

When a ring breaks it will cut grooves in the cyl wall. The only repair is to bore all 4 cylinders or sleve the bad one.... both are pretty expensive options.

Look and see if you can get one of those used low milage engines from Japan for this car. usually they run under $400

 

[Rickey]

1) what is blowby and how do i look for it?
Blowby is combustion byproducts escaping past poorly sealing compression rings into the crankcase area. If you can temporarily pull the pcv valve while the engine is running observation of blowby (or it's absence) can be made. This would be in the form of a smokelike puffing emission from the engine, not the pcv valve. Or you could just pull the dipstick with the engine running. I am somewhat hesitant about suggesting removing the dipstick or especially the oil filler cap while the engine is running as some engine designs will spatter you with oil when this is done. Referring to my earlier post: If it smokes with no blowby that would probably mean that the compression rings are ok Hope this helps. Rickey.

 

[cryptokid]

i seen that engine with what appears to be a stuck ring, turned out to be cracked rings and a broke piston skirt.
be carefull.

 

[Leo]

Always could give AutoRX a go, if you dont want to try the combustion chamber soak.