Dead Engine Autopsy (picture intensive)
 

So I finally got around to taking the head and oil pan/MBSC off the engine that died. I was hoping for a definitive cause of death....but, I'll let the pictures do the explaining. Also, on the head where I suspected the fatal compression loss to have occurred, I turned the cams and watched the valves seat across the board just fine. No signs of any valves sitting even 1mm out of place...nothing. Couldn't find any cracks in any piston, headgasket was fine.... I guess when everyhting comes apart (valves, springs, cams, rods, pistons) there may be something more obvious.

I did find a few interesting things though...but none of which I believe was a specific cause...I'll let you guys find them in the pictures.

Remember I am running a coolant re-route on the stock 01+ headgasket.

Discuss-


Valves Cylinder 1

http://farm5.static.flickr.com/4097/...2dceaf70_b.jpg

Valves Cylinder 1

http://farm5.static.flickr.com/4098/...d85bce95_b.jpg

Valves Cylinder 2

http://farm5.static.flickr.com/4141/...5322fe03_b.jpg

Valves Cylinder 2

http://farm5.static.flickr.com/4081/...c851b5e4_b.jpg

Valves Cylinder 4

http://farm5.static.flickr.com/4120/...797b75ab_b.jpg

Valves Cylinder 3

http://farm5.static.flickr.com/4140/...6d516765_b.jpg

Valves Cylinder 2

http://farm5.static.flickr.com/4122/...9cfd5d0a_b.jpg

Valves Cylinder 1

http://farm5.static.flickr.com/4082/...71e61497_b.jpg

Engine Bottom

http://farm5.static.flickr.com/4094/...e572551e_b.jpg

Cylinder 4 Rod

http://farm5.static.flickr.com/4074/...ca910673_b.jpg

Cylinder 3 Rod

http://farm5.static.flickr.com/4115/...98f45ab9_b.jpg

Cylinder 2 Rod

http://farm5.static.flickr.com/4123/...02116936_b.jpg

Cylinder 1 rod

http://farm5.static.flickr.com/4140/...0e6ccf7f_b.jpg

Piston 4 w/flash

http://farm5.static.flickr.com/4077/...387f89fa_b.jpg

Piston 3 w/flash

http://farm5.static.flickr.com/4119/...eaaea008_b.jpg

Piston 2 w/flash

http://farm5.static.flickr.com/4102/...537a8091_b.jpg

Piston 1 w/flash

http://farm5.static.flickr.com/4080/...805cdb85_b.jpg

Piston 1 closeup

http://farm5.static.flickr.com/4121/...75b98991_b.jpg

Piston 2 closeup

http://farm5.static.flickr.com/4122/...3a1d51ed_b.jpg

Piston 3 closeup

http://farm5.static.flickr.com/4093/...5d8b9386_b.jpg

Piston 4 closeup

http://farm5.static.flickr.com/4075/...58298ee5_b.jpg

Top of engine

http://farm5.static.flickr.com/4136/...f157603d_b.jpg

I see bunch of detonation.

it looks like rod #1 is slightly bent.....but its probly due to the angles in the picture.

i'll second detonation. You can see it really bad on the closeup for 1 and 2.

Holy carbon build up Batman! It does look like #1 is bent, it's even pushing against one side of the piston, where as the other three look centered.

Things I'm thinking-

1) Detonation- I have a strong feeling the spots on valves 1 & 2 are a direct issue with the coolant reroute and the lack of flow to 1 & 2 because of the headgasket design. A track day the week before brought on some ignition-like problems. I have a feeling the cylinder head was getting VERY hot on 1 & 2. Odd how there is detonation on PISTON 4, but not on VALVE 4, PISTON 1 looks decent/no metallic dust from detonation like #4.

Carbon buildup-
I had been on the track for a few sessions a week before and had some ignition issues that produced a metric TON of unburnt fuel. I didn't drive the car much after that track day and didn't "blow it out". Also, I tried a TON of times to fire the engine back up and there were several MINUTES where it ran stupid rich because the engine was barely turning over...massive amounts of unburned fuel fumes filled my garage...plugs fouled. Oh and when the engine died (while moving and in gear) I opened the throttle multiple times to see if it would return to normal...lots of flames came out the exhaust doing so...more unburned fuel.

Bent rod- Dunno. Considering the detonation on the top of #4, I'd think that would be the logical one to be bent. Only thing that makes sense to me is excessive heat and detonation from the coolant reroute.



What do you guys think of what I think?

i think you should pull the pistons out.


i bet there is a chunk of missing ringlands.

Detonation.

Also, that looks like a perfect candidate for methanol/water injection.

Did you already post pictures of the spark plugs? If not, do so.

i was bout the say the same thing,

+1 on water/meth..

what was the mileage on the motor?

How far are you retarded from MBT or detonation? I'm 6* back from MBT for this reason.

Is it the pictures of the valves that is giving away the detonation? I have been staring at the pictures of the pistons for five minutes and can not see a noticeable difference between them..

If you look closely you can see small pits in the tops of the pistons

I agree, #1 and #2 valves look like detonation.

Like everyone has already said, I agree with detonation in 1 and 2. And #1 rod does look bent in the pic.
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This.

1 & 2 will be ugly, and were probably a week from losing material on the crown by the time you started losing compression.


#1 rod definitely bent, and I imagine another one is bent on the other axis. Mine were split dead even like that...one on each axis, and one on both axes, last one fine.


I've seen worse carbon on valves, but the head and pistons have a LOT. Detonation probably worked the surface a little giving it more of a foothold, although the build-up may have been there long before, contributing to the det. I forget how many of your miles were boosted...

Carbon build up can also create hot spots that will aggravate your tendency to detonate.

Would you mind posting your spark map when you get a chance?

Very curious about your timing map. Your detonation doesn't look nearly as bad as mine did though.

Attachment 195789
Attachment 195790

You have a detonation problem on all 4 cylinders clearly. Those clean spots on the piston edges and ridges are not good. I would rule out the coolant reroute, and concentrate on tuning issues. I think you have the timing way to hot.

When you pull the pistons, report on how much tension you have in the rings. Over heating would make them weak, and you will notice cylinder wall scuffing and piston scuffing. Detonation will not necessarily have an affect on ring tension. Over heating will.

Got ya beat
Attachment 195786

You pussies don't even know what det is...

Attachment 195783

Attachment 195784

Attachment 195785

You fuckers need to learn how to tune lol.

<- hopes to never eat those words.
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This should all be making Mr. Ganger feel better about his engine.

Attachment 195782

lol @ pushing it and not finding the conservative happy place.

why do #1 & #2 rods have rust on them?

is the head flat?

My tune was conservative, for me. Water injection, Brainy's advance dialed back a few degrees...

You know who killed mine, you met him. Let him borrow it over Christmas break and he brought it back smoking.


New tune will be higher resolution MS2, crank trigger, and real, new injectors. Water injection soon to come, just missed a good deal from Sav, but eyeing splittime's setup.




Dopple, I'm in to see where your tuning went wrong as well. I thought my timing advance table was gravy, but you can see from the above there were some bad spots in it that ate up the motor during consecutive pulls (although he said he was eating up STis and such and having fun, so oh well).

Well, it was tuned by a VERY respectable tuner here in GA. The guys tunes TONS of stuff...everything from carb'ed turbo cars, to SPEED challenge cars, to Spec Miatas, to high-strung all motor Hondas. I trust him. Actually, I was running that tune since a month after I bought the car. Tracked it, drove it across the country, daily'ed it...everything. Something happened pretty quickly..as in within a couple of weeks before the failure. I'm almost wondering about a bad tank of gas that I got the week before at some podunk station in Alabama.

Cylinder walls are perfect and the cross-hatching is visible as it should be. No scoring, gouging or scratches at all.

How many miles did you have on that setup again? I think it was a lot if I remember right

FWIW, I wiped the carbon off the pistons tonight and found some small pitting on #1 and #2 by the exhaust valve area but not much on #3 or #4.

Edit- fuckit here are pics of the pistons with a little rubbing off...

piston #1

http://farm5.static.flickr.com/4083/...8e7d898c_b.jpg

#2 on right #3 on left

http://farm5.static.flickr.com/4150/...d3073f93_b.jpg

#2 close

http://farm5.static.flickr.com/4103/...bfd85cd2_b.jpg

cross-hatching

http://farm5.static.flickr.com/4152/...01df810d_b.jpg

#4

http://farm5.static.flickr.com/4106/...b98d3f1c_b.jpg

What about air temps? I've seen the hottest AITs ever in my car during this never ending heat wave. Yesterday was the nicest day we've had in two months up here.

I agree with the above mentioned thoughts as well. 1&2 look bad and the#1 rod does look bent. Don't be surprised if the ring lands fall off of #1 when you pull it. Post that spark map anyway, inquiring minds want to know.

So Doppelganger, do you think the reroute with the 01+ headgasket was the primary problem or do you think your tune needed less spark advance when IATs get above a certain threshold as was proposed by Lordrigamus?

I think it was the reroute. Seems the lack of flow around the topend on 1 & 2 indeed caused excessive heat/detonation. I will be adding a front t-stat and plumbing to my reroute very shortly.

I have my doubts about the reroute. All four pistons look like they have been in a tumbler. That is not a overheating issue That is many miles of fun.

Let's face it, a boosted engine that is beat on is not going to come out unscathed with stock pistons forever. Even with a conservative map.

I don't have a map on my work computer, but I do have a 1st-4th gear pull .csv log where you can see what my timing was doing under boost :dunno:

True, but there is obviously more issues with 1&2 where it's known that the design of the 01+ HG reduces coolant flow significantly.

Just out of curiosity, you weren't the one that posted a recent vid of your car hitting 26 psi, were you? :giggle:

nope, not me.

I just pulled apart a high mileage spare motor I had, and I looked at the piston and compared it to the pics you posted. You can clearly see that your pistons have had all of the sharp edges worn off, and all the machining marks on the surface are gone. Also, it almost looks like the metal is porous from all the little speckeling on the surface.

Did you have the piston surface modified? If not, it would be a continued low level detonation that caused it.

On the pistons that I pulled, there are machine marks on the surface that are visable. Also, there is not that pot marked appearance like on yours.

I will get a pic of the piston for you to compare.

That would be appreciated :)
Considering this was 2.5 years (and enough miles) of daily driving, track days, punded on 12+psi, run hot a few times, run with dead WB02, very rich at times, autocrossed and generally abused....I don't think it looks all that bad.

They don't live forever.

FYI- Here is a picture of a brand new 1.8 piston from the factory. You can tell be the machined spot at the center of the poston, that mine is not pitted. So it seems there wasn't any severe detonation other than the spots on #3 and #4 by the exhaust valve. Although no detonation is "good", mine was by no means severe nor catastrophic.

http://lh5.ggpht.com/_GblnWek7MVQ/Sj...0/DSCN0159.JPG

That is interesting. They must have changed piston manufacturer or build method. The 99 piston I just pulled and cleaned (I was meaning to get a pic) has machining marks on the top, with only the valve reliefs with casting flash.

Edit: The machined button in the center of the piston should have been a clue to me that the pits were normal.:facepalm: