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Discussion Starter #1 (Edited)
My 2002 Corolla 1.8L "check engine light" came on and the code was P0302. That code is for intermittent fire on cylinder #2. The engine runs very rough when started cold. The #2 spark plug was fouled with carbon on several checks so the injector and coil was switched around hoping to ID the cause of the problem. I took the car to my mechanic since the correct diagnosis of this problem is over my head. He is of the opinion that either the #2 cylinder rings are stuck due to hard varnish or broken rings. This engine came down with the "disappearing oil" problem so at 139,000 I pulled the rings and all four were stuck due to hard varnish. The cylinders were cleaned and the rings were replaced and the was only using one quart of oil every 3,000 miles. Now at 182,000 the #2 cylinder has developed this problem.


Since I don't want to pull the head again etc., I have two questions.

1. If I drop the oil pan, can the #2 PISTON be removed from the bottom of the engine. (I realize pushing the PISTON back up though the block will be difficult or impossible.)

2. Does anyone know of another cause for this problem?
 

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1. No, because you need to remove pistons, not cylinders

2. No


Did you drill the pistons’ oil-drain holes larger and added a couple extras per piston while you had it apart last time?
 

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Discussion Starter #3
OOOPS! Right! I want to remove the #2 piston down thru the oil sump, check the rings to see of they are stuck due to hard varnish and then reinstall the piston up thru the oil sump. Is that possible?


I removed all four pistons, all four had stuck rings due to the build up of hard varnish. I cleaned them, punched out the varnish in the oil drain holes and then drilled 4 more oil drain holes in the third ring groove. All the holes are the same size and I tried to space them equidistant around the piston.



I was careful not to break any rings when I installed then on the piston and then when pushing the piston down into the block.



Considering all of that I'm having a hard time believing my #2 cylinder is dead due to stuck rings or broken rings on the piston.



Any more helpful info?
 

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No way to pull pistons out bottom because crank is in way.

what was state of cylinder's cross-hatching? did you ball-hone?
did you use break-in oil? what kind of break-in procedure?
What kind of oil have you used after break-in?

Do compression-test, no need to debate who's guess is better.
 

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Discussion Starter #5
The cylinder walls were glazed so I used a flexible honing tool, not the one with balls, and got what I think was a pretty good cross-hatch on then. Then I reinstalled the pistons using 10W3O, drove it for 500 miles, rarely went over 50mph, changed the oil to 5W20 Mobil 1. All of that was at 139,000 miles and now it's at 183,000 and only developed this dead cylinder about 2 months ago.



I'm going to use my shop air, do a leak down test, and listen for escaping air. If I have a hiss from the intake or exhaust valves I can handle that. But if it's leaking air past the rings....I'm done with wasting money on this engine.

Thanks for all your help.
Jon
 

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Could also be valve-stem seals leaking oil into #2.

Difficult to separate cause & effect at times. In cases like this with already stuck rings, you're only measuring effects after-the-fact. Clogged rings could be caused leaky valve-stem seals dripping oil into cylinder. Or broken rings could be caused by clogged injector leading to lean AFR and pinging/detonation. I've actually pulled out pistons with rings shattered into 10+ pieces due to detonation.

Or clog rings may be caused by improper break-in (you're supposed to break in engines HARD, this is not some '50s GM product made with square pistons), thus they never sealed. As evidenced by high 1-qt usage per 3k-miles. Should be less than 0.25-qt per 5k-miles after rebuild.


So at this point, we can measure to find symptoms (effect). Leakdown will most likely 100% for sure indicate leaky rings. But it will require lots more inspection and testing to determine WHY they are clogged (the actual problem and cause).
 

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Discussion Starter #7
Everything you just relayed to me tells me I've got to get rid of this car! This is way, way, beyond my skill level and at my age, 75, I just don't have the stamina to repair it nor the money.

Thanks for all the info!
JON
 

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You're most welcome! Yeah, sometimes, it does become more hassle than it's worth. You can sell car as-is and pick up a 2003+ without ring-issue for not much difference. Good luck! :hi:
 

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before taking apart the engine again it might just be a misfire for that cylinder. Swap the injectors from a good cylinder and see if the problem code moves to the new cylinder
 

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And in this System you seeing Burnt oil out of tail pipe the smell of burnt oil etc the rear right of rear end is black? anything to smell or see?
 

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Discussion Starter #11
Doc,
I've already swapped injectors around and also the coil. No matter what I did, the code P0302 came back which is an intermittent misfire in cylinder 2.

Thanks for the tip anyway. It helps to know I was doing something right.

Teejon
 

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Discussion Starter #12
Yo Mr. Dee!
The engine is not smoking out the tail pipe, I don't smell any oil or smoke from the exhaust, and there is not burnt oil or black exhaust gas build up above the tail pipe either.



This car is weird. The engine light stays on no matter what I've done so far and though it runs rough when the engine is cold and started up but once it warms up it settles down to 625 rpm at idle and has done so since I bought it new.


Could the engine be hitting on all four cylinders once warmed up? I only ask because it seems to me if it's only hitting on 3 cylinders all the time the rpm should be higher. What think ye?
Teejon
 

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Everything you just relayed to me tells me I've got to get rid of this car! This is way, way, beyond my skill level and at my age, 75, I just don't have the stamina to repair it nor the money.

Thanks for all the info!
JON

If everything else is in good order (interior, no rust, etc.) a DIY'er would probably be happy to buy it off you.
 

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No way to pull pistons out bottom because crank is in way.

.

Off-topic, maybe. But since you mentioned it.....

Local Toyota guru shop, when asked about addressing oil consumption issue,
suggested only rings/bearings. Pushed back on suggestion that pistons be
updated. Is crank removal so arduous that piston updating should be avoided?
 

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To remove crank, entire engine and transmission have to removed from car. Add +20hrs to job, but that's completely not necessary.

That shop must not be familiar with this model.
Cause of problem is design flaw in pistons with too small of drain holes and not enough of them.
Effect or result of this flaw is insufficiently oil-drain rate from pistons, leading to burnt oil and clogged rings.

By only replacing rings, you are not fixing actual problems, just dealing with symptoms. Leaving design flaw unresolved. Replaced brand-new rings will last 20-40k miles and they'll clogged again. Repeat over and over again every 20-40K miles.

Here's part they missed that showed they're not competent shop: pistons have to be removed anyway to replace piston rings!!! Why not replace pistons with upgraded 2003+ designs or drill out existing ones? Only costs $100 or 15-minutes. And pistons are removed from TOP of engine, leaving crank alone. Here's summary of procedure:

- remove cylinder head (might as well replace valve-stem seals while it's out)
- drop oil-pan
- remove con-rod caps
- pull pistons out top of block
- R&R pistons, install new rings
- measure head and block for flatness, R&R as necessary
- hone cylinders if necessary
- push new pistons back down block
- install con-rod caps with new bearings
- install oil-pan
- install head


That's it!!! Can be done in single day (10-20hrs) if you've got power tools and good music. And you'll have brand-new engne that'll go another 200K-miles easily since you've replaced all the wear surfaces.
 

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You make me smile and you make me sad.

Pistons removed from top of engine?
So you unbolt them and then suck them from atop?
So this local shop is simply just clueless?

This local shop has nothing but stellar reviews.
That makes me sad.

I have yet to confirm that my oil consumption is from rings
and not PCV, well, at this time in its life.

Should I confirm that it is indeed nothing simple,
are you possibly in a position to do the work or know of a
competent shop in the East Bay?

You know, I never expected to be rich, but if I could bottle you...
 

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I only recently moved up here from Santa Barbara couple years ago, so don't know about shops in area. I still send my engine-work to shops in Santa Barbara. Even then, i do all assembly work myself. I just tell shops i want "fully-radiused valve seats with 0.010 contact on exhaust and 0.015 on intake". Or " bore and sleeve block to fit these pistons with 0.025 clearance". I really don't trust anyone to put it together.

Heh, heh... what I’ve done before is barn-raising events! Get a couple people together, bring their toolbox over. Order some pizzas and car’s done in no time!

Did have some trouble one time where we met in centralized location and kid brought his car over from Santa Cruz. Got it all apart in one day and then he lost interest in putting it back together and just left it in other guy’s garage for weeks.

Do compression test next.
 
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