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Old 10-04-2009, 07:46 PM   #1
cboss
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Default Elusive P0172 code fixed, now new problem and the Saga continues !

Once again I am tackling a big problem.

To make a long story short, the story began a year ago when I purchased a 1996 Saturn SL2 w/ 175K miles on it. I spent about 6 month tracking down the cause of the P0172 code (running rich), which turned out to be the timing chain was off one tooth on the exhaust cam. Did a timing chain job and for the last few months the car has been running great and I have been getting nearly 40 mpg.

You can read the original story here:

http://www.saturnfans.com/forums/sho...76#post1346276

Even though the P0172 problem was solved, in the process of diagnosing the problem cylinder #3 was a bit lower in compression (about 160 psi) and seemed to be the worse in burning oil. The other cylinders seemed fine.

The only real problem I have been having since then is the terrible oil consumption (about 1 qt in 200 miles). I just kept topping off the oil and all was fine ....

Until today !

I drove about 200 miles yesterday and today I drove about 35 miles, spent most of the day and then driving home on the interstate (has some big hills), the SES came on and was blinking. When I was going up the hills the SES came on and going down it went off. The car was drivable, but progressively got worse.

I made it home and by the time I got home the engine was running terrible. I watched the temp and it was fine so no overheating and the oil had been kept up to level.

Once home, the car could barely idle and then started to smoke pretty bad if I gave it some gas.

The OBD-II scanner showed a code P0303 (misfire on cylinder #3).

My gut feeling was, rather than something electronic, it was mechanical so I immediately did a compression test (let it cool down for about an hour).

3 cylinders were about 180 psi or greater (dry and somewhat cooled down) and as expected cylinder #3 (the trouble one) was only about 45 psi.

It engine rebuild time now, so I am doing an inframe rebuild.

The head (read previous discussion) appeared to have been replaced by previous owner (I bought it from a small dealer who bought it from the auto auction system). It was clean as a whistle when I first pulled the CAM cover, when I got the car. While it is possible a valve died in cylinder #3, I am assuming the head is good, so hoping its just the rings.

The spark plug in cylinder #3 was terrible gunked up with crud (burned oil), while the other 3 plugs were clean, so likely cylinder #3 has been the worse oil burned for some time which would indicate very poor condition of its rings.

Also the engine smoked a lot today when I gave it some gas while idling, liking burning oil terribly, so that also sounds like rings.

The timing chain is a new kit and if the head is good like I hope, I may be able to get away with just a ring job.

This afternoon I started the tear down. I have most everything off, so I can start pulling off the timing chain cover tommorrow and then work on pulling the head. I have the top engine mount off, CAM cover off, AC disconnected from mounts and slide over (still connected to hoses), PS disconnected (hoses still connected), fan belt off, pully off and tensioner off. Crankshaft pully has been loosened (bolt off) and is ready to come off.

As before I will document all the steps I take in this thread until finished and any help will be appreciated.

Probably the first questions will deal with taking the head (a new endeavor for me) off. Also what to look for to inspect the head, even though I am hoping it is fine since has been replaced, it is still good to inspect it thoroughly.

Any special tools going to be needed for pulling the head (and putting it back on) and reringing the pistons ?

If in good condition are the pistons usually reusable or should one replace them ?

More questions will be forth coming as I get deeper into the tear down.

This is new territory for me, so help will be appreciated.
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Old 10-04-2009, 08:29 PM   #2
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Default Re: Elusive P0172 code fixed, now new problem and the Saga continues !

CBOSS IS BACK!

I can actually say I looked forward to your other saga. Kinda of glad you solved it, but kinda of miss the interesting problem and the troubleshooting you did.
The only special thngs (off the top of my head) would be a good torque wrench, piston ring compressor, and cylinder hone.
While tou are down there, throw in a new oil pump just for reassurance, and of course new bearings. You should be able to reuse the pistons if they look to be in pristine condition. But if they have any scoring marks on them think hard before you reuse them. I bet some one around here has a netter set from a project that may be worth considering.
Best of luck - I look forward to THIS thread!.
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Old 10-04-2009, 09:59 PM   #3
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Default Re: Elusive P0172 code fixed, now new problem and the Saga continues !

The determining factor in what to do with teh cylinders is a function of the condition. eyeball will not work. Clean the carbon off of the top of the bore with a scotch brite. Then run a fingernail up under the ridge area Keep the nail parallel to the cylinder wall. If you can hook a fingernail then its rebore time.

Once the head is off turn it over and fill all 4 chambers with naphtha. If it leaks out then you have another problem.

If there is no ridge then you can install new rings and go. You will need about 5 or 6 passes with a 320 grit ball hone though.

Don't forget to drill drain back holes in the pistons.
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Old 10-05-2009, 09:14 AM   #4
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Default Re: Elusive P0172 code fixed, now new problem and the Saga continues !

OldNuc,

What is a Ball Hone ?

Got a photo of one ?

I have seen cylinder hones which you use with a drill (have 3 stones on them which rotate).

Also I need a run down of what has to be removed before pulling the head.

I am in the process of taking everything off necessary to remove the timing chain cover, like I did when doing the timing chain job. What else will I need to remove/disconnect before taking the head off ?

Can I leave the exhaust and intake manifolds on the head when I take it off ?
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Old 10-06-2009, 01:33 AM   #5
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Default Re: Elusive P0172 code fixed, now new problem and the Saga continues !

Here is the info on ball hones: http://www.brushresearch.com/index.php

You can leave the intake on but take off the throttle body. Take the exhaust loose at the head and leave the rest of it intact and untouched except for the bracket under the engine. It will drop out of the way, usually.
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Old 10-07-2009, 09:24 AM   #6
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Default Re: Elusive P0172 code fixed, now new problem and the Saga continues !

Note: This is a 1996 SL2

Since Cylinder #3 has only 45 psi compression and is also the source of the misfire (code P0303), it is obviously the problem cylinder so what I see after the teardown should be noticable in Cylinder #3 (and it is).

Here is a short version of the teardown process:
(the order actually done may not be in this order)

Before starting disconnect Battery.

(1) Removed the CAM cover
(2) Drain the oil and the coolant (disconnect the thermostat and drain to get coolant out of block too)
(3) Take tension off fan belt and remove and then remove the tensioner and pully on timing cover
(4) Disconnected the AC compressor brackets (don't touch the AC hose lines though) and pull the compressor as far forwrad as possible and tie it down.
(5) Disconnect power steering pump (leave hoses alone)
(6) Put wood block under lower engine mount (dogbone) and remove bolt on Crank pully and remove pully and remove top engine mount.
(7) remove timing chain cover
(8) Set the CAMs to lock position with a 3/16 drill bit in each CAM gears set hole. Remove timing chain parts (start with tensioner, then guides and then chain). Turn the crankshaft (there is a flat on it so you can put wrench) to 90 degrees right side (3 oclock position) to lower all pistons to safe position.

I decided to remove the exhaust manifold since it makes sliding the head off easier later, but left the intake manifold on.

There is a bunch of small things that need to be done next such as:

- disconnect wires to EGR, MAP, Fuel injectors, TPS, AIC, etc.
- I pulled the fuel rail, which makes disconnecting the fuel lines easier (especially the return line) and gives easier access to back side of engine
- removed vacuum lines to FPS, etc.
- disconnected accelerator cable
- removed bracket to intake manifold (one under it) and one on EGR side
- disconnected heater (coolant) hoses to intake (there are 2)

I have done more, but will end this post with some photos
Attached Images
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File Type: jpg job07.jpg (83.0 KB, 342 views)
File Type: jpg job08.jpg (84.3 KB, 345 views)
File Type: jpg job09.jpg (85.9 KB, 404 views)
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Old 10-07-2009, 09:33 AM   #7
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Default Re: Elusive P0172 code fixed, now new problem and the Saga continues !

Observation:

I have done more that what I have posted above already (more posts coming), but I think it worth commenting on an observation here.

I followed a number of other threads discussing similar problems and the question one often may have before they do the tear down is:

Is the damage in a problem cylinder a valve or the rings ?

Of course you won't know until you tear it all down and my observation may not hold to all instances, but...

My impression is that when you do a compression test if the valve has broken (a chip) the compression many times drops to zero. If the rings are blown, you will have some compression but just very low.

In my case the compression in the bad cylinder (#3) was 45 psi. Previously when compression tests were done, it was the low cylinder, while the other three were close to specs, this one was about 20 psi lower, indicating an already weak cylinder.

As you will see in the next posts, the valves appear fine, but it is most likely the rings.

I would also venture to say that when doing a compression test, if you have one or more cylinders even 10 or 20 psi than the others that a rebuild is almost inevitable, since weak rings can blow at any time, especially if you have the high mileage to go with it.
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Old 10-07-2009, 09:56 AM   #8
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Default Re: Elusive P0172 code fixed, now new problem and the Saga continues !

Fill the #3 combustion chamber with naphtha once the head is off and see if it leaks out. Turn the cams so both the intake and exhaust is closed. It should not leak out at all. A seriously burned valve will have 25 to 50 psi compression.
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Old 10-07-2009, 10:05 AM   #9
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Default Re: Elusive P0172 code fixed, now new problem and the Saga continues !

This is where it gets interesting.

Time to take off the head.

Once everything else is out of the way and you are ready to remove the head, it is important to make sure you have a very good 6 sided socket for the bolts that will be slim enough to fit down into the tight spaces. I used one at first and didn't realize that it wasn't catching on two different bolts properly and had to go back to use a different socket.

I used a breaker bar, with a 6 inch extension and the socket.

As directed in the Haynes manual, I loosened each bolt 1/4 turn at a time using the tightened sequence in reverse order (instead of 1 to 10, you do it from bolt 10 to 1).

The first turn will nearly loosen the bolts (at least in my case), so don't go more than a 1/4 turn. Then keep loosening a 1/4 turn at a time until they are loose enough to turn by hand and simply loosen them by hand.

At this point I should point out that you have to make sure you removed the intake manifold brackets underneath, since when you slide the head off it won't come off otherwise. Also the bracket underneath the left side (near the PS unit), you should not only remove the bolt, but take off the whole bracket.

Once the bolts were off, I could take the head off.

Without the exhaust manifold on it, the head was light enough for me to pick up even with the intake manifold on it. I would estimate it is somewhere between 50 and 90 lbs.

It is important to make sure you have the CAM gears in set position (with drill bits and I taped mine so they would not slip out) so the valves aren't sticking out when you put the head down.

Also I had foam padding (an old seat cushion) ready to lay the head down one when I pulled it out just in case.

Once the head was out I then could remove the bolts for the intake manifold and took it off. I plan on replacing both the intake and exhaust manifold gaskets.

While one could attempt to leave the exhaust manifold and intake manifold on (if the head is fine and you are just reringing), I don't recommend it. At least take off the exhaust manifold since it will be easier to handle.

If you plan on cleaning or machining (the surface) of the head, I also would recommend taking off the intake manifold too.

Here are some more photos and I think you will be able to see where the problem lies.
Attached Images
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File Type: jpg job22.jpg (88.2 KB, 469 views)
File Type: jpg job23.jpg (92.8 KB, 454 views)
File Type: jpg job24.jpg (106.9 KB, 541 views)
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Old 10-07-2009, 10:10 AM   #10
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Default Re: Elusive P0172 code fixed, now new problem and the Saga continues !

OldNuc,

I posted some photos of the head off.

Notice the oil in cylinder #3.

Also, while very cruddy, the valves appear to have no damage at all.

I do believe the head was replaced or rebuilt as some time by a previous owner. Remember the pristine condition in my other thread of the head.

My best guess is that someone who owned the car before, did a head job, but did not put new rings or timing chain on it.
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Old 10-07-2009, 10:45 AM   #11
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Default Re: Elusive P0172 code fixed, now new problem and the Saga continues !

Put a spark plug in that cylinder, turn the head upside down and level and do as Nuc says! Pour a liquid in that chamber and check for leaks.
Too me the intake valves look bent.
Edit: second look, cam could be holding the intake valves open a bit.
Still need to perform leak test.

If the head was replaced they sure did not clean it very well before installation. Look at the build up on those valves!
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Old 10-07-2009, 11:33 AM   #12
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Default Re: Elusive P0172 code fixed, now new problem and the Saga continues !

I am in the process if cleaning the bottom of the head (and valves) right now so I can get a better look at their condition. With all the crud on them its hard to tell anything. I have the head sitting in about 1 inch of hot water and purple power right now. I started cleaning it with purple power cleaner and a steam cleaner. The soaking softens the crud and the steam cleaner works it off.

There is a very good auto machine shop here locally that can do work on it.

They can pressure test it for about $20, which I most likely will have done.
Even if the head is in good shape the bottom needs to be machined to make sure it is flat, so I can bring it to them to pressure test it and also machine it. If the head needs to be rebuilt they can do it for less than buying a rebuilt one on ebay (the shipping usually gets you).

These guys are good from what I hear (a mechanic recommended them).
I had them repair an exhaust manifold for me once (for my geo). They do hot spray welding stuff. They can repair and rebuild alumimum parts on old engines and all sorts of stuff.

It may be worth having them rebuild the head just for safe measure.
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Old 10-07-2009, 12:16 PM   #13
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Default Re: Elusive P0172 code fixed, now new problem and the Saga continues !

Would Sea Foam work for a leak test ?

(put it in to see if valves leak)
(also put it in cylinder to see how fast it leaks)
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Old 10-07-2009, 12:18 PM   #14
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Default Re: Elusive P0172 code fixed, now new problem and the Saga continues !

Do not cut the head unless absolutely necessary. Check for leaks. Position the engine at 90 degrees past TDC and you do not have to worry about the valves. Then release the cams so you can close all of the valves.
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Old 10-07-2009, 12:19 PM   #15
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Default Re: Elusive P0172 code fixed, now new problem and the Saga continues !

Sea foam will work, any liquid is OK. Clean the top of the bores and check for wear with finger nail.
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Old 10-07-2009, 05:25 PM   #16
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Default Re: Elusive P0172 code fixed, now new problem and the Saga continues !

Ok,

I put some Sea Foam in all four cylinders, about 1/4 inch in each and about 3/8 inch in the bad cylinder. I'll see how long it takes for each to drain out.

I am still cleaning the valves (will have some pictures soon).

Then I'll test each cylinder with some Sea Foam and see if they leak.

OldNuc, some questions:

(1) When the CAM are both in the set position where the 3/16 drill goes through the alignment hole, will all the valves in all four cylinders be perfect closed or will some be slightly open ?

(2) If the valve has no obvious physical damage (no chips, no burned edge, no cracks) can it still leak badly enough to give me only 45 psi ? (and why)

If it can, then it is possible for it to be fine one minute and then just go while driving (like it did with mine) ?

(3) When I do the finger nail test on the cylinder walls, is it possible for it to have just a very slight lip (almost catch the nail but maybe not quite) on one side of the cylinder and yet not on the other side ?

(4) How does one test the cylinder for its diameter to determine the size rings to use ? (standard or oversized)
(what tool)

(5) If the head is still suspect, is it necessary for all the parts to be replaced when rebuilt (ie. bearings, valves, springs, seals, etc.) or is it only necessary to replace what is out of spec ?
(I need to know this before deciding on a local rebuilder shop or to simply buy an Ebay already rebuilt head)

(6) The oil that was in cylinder #3 (see previous pictures), where would that most likely come from (valve seal bad or bad cylinder rings) ?
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Old 10-07-2009, 06:43 PM   #17
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Default Re: Elusive P0172 code fixed, now new problem and the Saga continues !

Quote:
Originally Posted by cboss View Post
Ok,

I put some Sea Foam in all four cylinders, about 1/4 inch in each and about 3/8 inch in the bad cylinder. I'll see how long it takes for each to drain out.

I am still cleaning the valves (will have some pictures soon).

Then I'll test each cylinder with some Sea Foam and see if they leak.

OldNuc, some questions:

(1) When the CAM are both in the set position where the 3/16 drill goes through the alignment hole, will all the valves in all four cylinders be perfect closed or will some be slightly open ?

Some will be open.

(2) If the valve has no obvious physical damage (no chips, no burned edge, no cracks) can it still leak badly enough to give me only 45 psi ? (and why)

Leak like sieve. The valve seat can be shot and it will look just fine by eyeball.

If it can, then it is possible for it to be fine one minute and then just go while driving (like it did with mine) ?

Most likely your problem is rings but a valve can fail suddenly. When a single cylinder is low compression and it is valve leakage through an exhaust valve the hot exhaust gas will eventually cut the seat out. Bad oil ring makes it worse as the combustion process is retarded from the oil and that raises the exhaust gas temperature.

(3) When I do the finger nail test on the cylinder walls, is it possible for it to have just a very slight lip (almost catch the nail but maybe not quite) on one side of the cylinder and yet not on the other side ?

Yes, 8-10 thou will catch hard, 3-5 thou will hang up and almost catch, 1-2 thou will just be felt. If ther is any ridge it has to be removed with a ridge reamer before honing or you will break the top off the piston with the new rings.


(4) How does one test the cylinder for its diameter to determine the size rings to use ? (standard or oversized)
(what tool)

The usual approach is to figure that if you pass the fingernail test then you can use standard rings. The first oversize is 0.5mm or 20 thou. That requires new pistons also. As you will have the pistons out you can look at he thrust face of the pistons and tell how worn they are. Pistons MUST come out the top so the ridge needs to go away first. Take a scotch brite to the top of each cylinder and get the carbon out of it and then see what is left.

(5) If the head is still suspect, is it necessary for all the parts to be replaced when rebuilt (ie. bearings, valves, springs, seals, etc.) or is it only necessary to replace what is out of spec ?
(I need to know this before deciding on a local rebuilder shop or to simply buy an Ebay already rebuilt head)

Usually a local head job only costs you a set of valve seals. You get to disassemble and clean the lifters. Keep track of which position they are in or you get to have them resurfaced. The eBay heads are highly suspect. Clearwater Cylinder heads ( http://www.cylinder-heads.com/ ) are good and about the same price as the eBay head. The local rebuild will be about $50.00 cheaper than a Clearwater head.

(6) The oil that was in cylinder #3 (see previous pictures), where would that most likely come from (valve seal bad or bad cylinder rings) ?
All of that oil is probably past the oil ring and it eventually stuck teh compression rings. You will know as soon as the piston is out. Compression rings do not work if stuck.
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Old 10-07-2009, 08:04 PM   #18
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Default Re: Elusive P0172 code fixed, now new problem and the Saga continues !

I finished cleaning the valves.

I tested the cylinders (all pistons half way up the cylinder) by pouring some Sea Foam into them. Cylinder #3 (problem cylinder) I put the most sea foam to see how quickly it would leak. I put abouty 3/8 inch sea foam and after 3 hours most of it was still there. Cylinder 4 had about 1/4 inch sea foam and it leaks most out in a few hours.

Results of the fingernail test.

Same for all four cylinders.

The back side of the engine side of each cylinder had no lip or edge at all. Perfectly smooth. The front side of the engine side of each cylinder has enough of a lip to catch my fingernail.

I tested the valves by pouring sea foam into each cylinder group of valves (put spark plug in). It was hard to test since you have to put a wrench on the CAM bolt and tuen them just right so they seal (feel pressure on wrench), but some of the cylinders leaked a little.

Cylinder #3 leaked a lot.

I found a better (cleaner) way to test for leaks though.

I closed the valves and then put the steam cleaner into the exhaust (or intake) hole where the manifold is normally connected. By spraying hot steam into the valve from the back side, you can actually see where the leak is. The hot steam will get through the tiniest of space. One of the exhaust valves on cylinder #3 , you could see the water (steam) come through quickly at the lower side of the valve.

There is no obvious damage on any of the valves, so it must be the seat.

If the seat is off even a little is that enough to bring the compression down to 45 psi and also is that enough for all that oil to come through ?

Now the question is, where do I go from here ?

Have the local shop rebuild the head ?

Do I have to ream out the cylinders before honing ? before removing ?
(can I do that myself ?)

Will I have to go to oversize rings ?

Will I have to get new pistons ?


Here are two photos. The first is after I cleaned the valves and the second is the #3 and #4 cylinder valves before being cleaned (for comparison).

Ok, OldNuc, what do I do next ?
(yeh, almost forgot, I still have to take the pistons out)
Attached Images
File Type: jpg valve01.jpg (202.4 KB, 442 views)
File Type: jpg valve02.jpg (143.3 KB, 367 views)

Last edited by cboss; 10-07-2009 at 08:11 PM.
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Old 10-07-2009, 08:05 PM   #19
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Default Re: Elusive P0172 code fixed, now new problem and the Saga continues !

One more question:

Is it possible my head gasket failed as well (could that be the cause of the oil) ?
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Old 10-08-2009, 12:14 AM   #20
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1998 SC2
Default Re: Elusive P0172 code fixed, now new problem and the Saga continues !

There is an oil return on the front of the block close to #3. You do need a valve job and new valve seals. The pistons are probably good and all you need to do is ream the ridge. Standard size rings. Might as well replace the rod bearings also. Usually if you have a head gasket fail into a oil return you end up with teh engine severely overpressureized from the combustion gas blowing into the return. Inspect the head and block carefully and you can tell. What were your compression readings from before for the other cylinders?

It is best to ream out the ridge before pulling pistons. Do not cut too far into the cylinder as it will foul up the top ring seating. Just the ridge has to go away. Non symmetrical wear is unusual. Have you got it cleaned out good?

If you do not press your nail hard against the cylinder wall does it catch? The nail should make a 20 - 30 degree angle with the cylinder wall.

This is what you use to measure the cylinders.
http://cgi.ebay.com/ebaymotors/Dial-...motiveQ5fTools
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