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Just in time for "bonbon's rebuild" :)


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Just a brief update for anyone who cares :lol:

 

I reinstalled the cams with new buckets on the driver side on Saturday. I will not touch the passenger side for now. The annoying part is that I had to reinstall the driver side cams twice. As meticulous as I was, I still managed to put too much rtv on one of the cam caps, and it ended up 'leaking' on the cam bearing area and mixing with the assembly lube :mad:. So I took everything apart and repeated the same step again!

Moral of the story: if you are going to put rtv on these cam caps, just add a super small amount at each corner edge of the caps. Even then, I am not even sure it is required to have rtv on these. When I took them off, there was no trace of rtv on them. But the FSM states you should put some..

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Yes there should be a small amount on those caps, it doesn't take much. I just put a little on my finger and spread as far as I could, just leaving a slight smug on the surface.
My wife's balls are delicious.
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  • 2 weeks later...

Thanks guys. I am staying cautious of course, but so far so good. No misfire count at all, she is idling very well and pulls strong. Oh, and not apparent oil leak, especially from the new cam seals.

 

This is what I ended up doing to it:

-sent all four injectors to Deatschwerks for cleaning. They actually called me back and said that the pre-test showed that all four injectors were performing very well, had a consistent spraying pattern, etc.., and therefore did not need cleaning and stuff. I was pleasantly surprised. cost: $45 (which includes a 14$ oring kit/super lube just in case --I asked for it)

-changed a coil pack on #3. Was noticing some roughness count at idle and the coil metal 'shell' was beginning to fall apart. cost: $76.53

-3 new valve lifters for the driver side. cost: 18.54*3=$55.62

-2 additional valve lifters from BMB (cost: 2 lifters of mine+shipping)

-valve cover gasket set. cost: $54

-4 cam seals (only used two though). Cost: $21.99-$20 ebay discount=$1.99

 

Total cost: ~$233

 

As I previously mentioned, I ended up only fixing the valve clearance on the driver side. The passenger side values were within specs (except one exhaust valve that was just a tad out of spec on #1). I'll keep an eye on the roughness count anyway.

 

I finished all the work yesterday. Had a bit of Boxkitty drama when it was time to start the car :spin::

I first 'primed' the fuel system a few times.

I then went ahead to WOT (to cut fuel) and got the engine cranking to get everything lubricated. Right away, I got scared cause it sounded like a cylinder had low comp. Checked timing a few times. It was spot on. Checked the spark plugs on the passenger side and tightened them a bit.

Put everything back. Was sweating like crazy cause I was scared that I screwed up somewhere. But I felt that I should try again to crank it. And so I did. Went to the car, depressed the clutch and she started right away :). I *think* the first time I tried, I forgot to depress the clutch pedal! But I can't recall. I was too anxious or something.

 

Already put 25+ miles so far. She is running great. Hit 18+ psi of boost no problem. No hesitation, nothing. Very pleased so far.

 

 

Moral of the story, the scratches you see using a borescope may not necessarily be due to cracked ringland. As with Sktmls rebuild, he had scratches a bit similar to mine most likely due to piston slap. They were all located at the top of the cylinder wall, between 11 and 1 o'clock or so.

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Sure. I understand.

 

FJuan, did you have significant marks on your cylinder walls in #4?

 

In my case, my engine hardly burns oil. But then again, Rhitter had a failed ringland in #4 and was not burning any oil either.

 

I know it's an old post and rather late, but I'll forward the knowledge I've acquired over the last two months, in the case anyone actually cares :)

 

Remember, how much oil the engine burns in the case of a cracked ringland is purely dependent upon what ringlands are cracked. The pistons have a total of five rings stacked like this:

 

~~~Piston Top~~~

(Compression ring)

~~~Ringland~~~

(Oil Scraper Ring)

~~~Ringland~~~

(Flat Oil Control Ring)

(Wavy Oil Control Ring)

(Flat Oil Control Ring)

~~~Piston Skirt~~~

 

Usually, the ringland between the compression and scraper rings is what cracks, from either knock or the compression ring butting together due to thermal expansion and load. If that's the case, you'll burn very little oil as the oil control rings remove 99% of it from the cylinder bore. When the piston is damaged badly enough that the lower ringland is cracked as well, that's when you start burning large amounts of oil. In this case, the oil control rings deform and flop around due to lack of support as the piston moves up and down in the bore, allowing oil to seep past them. Once the oil is past the control rings, it will either work it's way around the scraper and compression rings the same way, or through the ring gaps, and proceed to be burnt. I'm no engine specialist, but this seems to be exactly what happened in my engine. See below:

 

29316812075_a7a268ea47_h.jpg

 

This particular piston burned damn near a quart of oil in just a half hour period. There are roughly 10 separate ringland failures, across both ringlands, throughout the unit. The piston top has also failed resulting in poor compression. As you can see, the failed ringlands allow oil to be channeled through the piston and into the combustion chamber. On top of that, they are not supportive enough to keep the rings properly set and formed, allowing oil to be drawn in during the intake stroke. The opposite also happens on the compression stroke and during the combustion process; high cylinder pressures force burnt gasses past the rings and into the crankcase. Hence, many people will pull their oil caps and watch their boxer go "choo choo" oil the oil fill tube.

MTBwrench's Stage 3 5EAT #racewagon 266awhp/255awtq @17.5psi, Tuned By Graham of Boosted Performance

 

Everyone knows what I taste like.
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Yeah. I actually began to realize that we do have different types of rings on the pistons. And so I also gathered, as you explained, that it is indeed possible to have a cracked ringland and yet not burn oil.

 

On a side note, you must have been knocking like crazy or something to have a piston fail like this!!

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  • 2 weeks later...

I know. And it's been pretty stable and staying like this for a while, as long as that freakin MAF wiring harness does not move much of course :mad:. Still need to address that issue.

 

I can also say that when the fuel trims are that way, I can confidently WOT that thing!

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