Dead Engine Autopsy (picture intensive) - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


Engine Performance This section is for discussion on all engine building related questions.
Sponsored by:
Sponsored by:

Reply
 
 
 
LinkBack Thread Tools Search this Thread
Old 07-21-2010, 11:31 PM   #1
Elite Member
Thread Starter
iTrader: (12)
 
Join Date: Sep 2007
Location: Charlotte, NC
Posts: 6,868
Total Cats: 66
Default 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



Valves Cylinder 1



Valves Cylinder 2



Valves Cylinder 2



Valves Cylinder 4



Valves Cylinder 3



Valves Cylinder 2



Valves Cylinder 1



Engine Bottom



Cylinder 4 Rod



Cylinder 3 Rod



Cylinder 2 Rod



Cylinder 1 rod



Piston 4 w/flash



Piston 3 w/flash



Piston 2 w/flash



Piston 1 w/flash



Piston 1 closeup



Piston 2 closeup



Piston 3 closeup



Piston 4 closeup



Top of engine

Doppelgänger is offline   Reply With Quote
Old 07-21-2010, 11:34 PM   #2
Miotta FTW!
iTrader: (24)
 
Splitime's Avatar
 
Join Date: Jun 2006
Location: Chicagoland, IL
Posts: 4,292
Total Cats: 26
Default

I see bunch of detonation.
Splitime is offline   Reply With Quote
Old 07-21-2010, 11:35 PM   #3
Elite Member
iTrader: (17)
 
Join Date: Apr 2009
Location: Atlanta, GA
Posts: 2,831
Total Cats: 0
Default

it looks like rod #1 is slightly bent.....but its probly due to the angles in the picture.
WonTon is offline   Reply With Quote
Old 07-21-2010, 11:38 PM   #4
Elite Member
iTrader: (41)
 
Join Date: Jan 2006
Location: Seabrook, TX
Posts: 2,409
Total Cats: 19
Default

i'll second detonation. You can see it really bad on the closeup for 1 and 2.
rharris19 is offline   Reply With Quote
Old 07-21-2010, 11:42 PM   #5
Cpt. Slow
iTrader: (25)
 
curly's Avatar
 
Join Date: Oct 2005
Location: Oregon City, OR
Posts: 12,105
Total Cats: 518
Default

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.
curly is offline   Reply With Quote
Old 07-21-2010, 11:55 PM   #6
Elite Member
Thread Starter
iTrader: (12)
 
Join Date: Sep 2007
Location: Charlotte, NC
Posts: 6,868
Total Cats: 66
Default

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?
Doppelgänger is offline   Reply With Quote
Old 07-22-2010, 12:01 AM   #7
Elite Member
iTrader: (8)
 
Join Date: Dec 2008
Location: Kingston, Ontario
Posts: 2,791
Total Cats: 71
Default

i think you should pull the pistons out.


i bet there is a chunk of missing ringlands.
shlammed is offline   Reply With Quote
Old 07-22-2010, 01:31 AM   #8
Elite Member
iTrader: (24)
 
Join Date: Jul 2007
Location: Cypress, TX
Posts: 3,778
Total Cats: 35
Default

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.
Bryce is offline   Reply With Quote
Old 07-22-2010, 01:32 AM   #9
Elite Member
iTrader: (17)
 
Join Date: Apr 2009
Location: Atlanta, GA
Posts: 2,831
Total Cats: 0
Default

i was bout the say the same thing,

+1 on water/meth..
WonTon is offline   Reply With Quote
Old 07-22-2010, 01:39 AM   #10
Junior Member
iTrader: (1)
 
Join Date: May 2010
Posts: 103
Total Cats: 0
Default

what was the mileage on the motor?
old_s13 is offline   Reply With Quote
Old 07-22-2010, 01:40 AM   #11
Tour de Franzia
iTrader: (6)
 
hustler's Avatar
 
Join Date: Jun 2006
Location: Republic of Dallas
Posts: 29,114
Total Cats: 351
Default

How far are you retarded from MBT or detonation? I'm 6* back from MBT for this reason.
hustler is offline   Reply With Quote
Old 07-22-2010, 06:30 AM   #12
Senior Member
iTrader: (14)
 
Join Date: Oct 2006
Location: South East Florida
Posts: 690
Total Cats: 6
Default

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..
94mx5red is offline   Reply With Quote
Old 07-22-2010, 09:12 AM   #13
Senior Member
iTrader: (8)
 
Join Date: Feb 2009
Location: Jax, Fl
Posts: 907
Total Cats: 0
Default

Quote:
Originally Posted by 94mx5red View Post
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
johnmatt is offline   Reply With Quote
Old 07-22-2010, 09:13 AM   #14
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,842
Total Cats: 1,787
Default

I agree, #1 and #2 valves look like detonation.
Braineack is offline   Reply With Quote
Old 07-22-2010, 10:39 AM   #15
Elite Member
iTrader: (10)
 
leatherface24's Avatar
 
Join Date: Dec 2006
Location: Pembroke Pines
Posts: 4,033
Total Cats: 2
Default

leatherface24 is offline   Reply With Quote
Old 07-22-2010, 10:44 AM   #16
Elite Member
iTrader: (30)
 
Join Date: Aug 2007
Location: Va Beach
Posts: 7,282
Total Cats: 0
Default

Like everyone has already said, I agree with detonation in 1 and 2. And #1 rod does look bent in the pic.
__________________
Best Car Insurance | Auto Protection Today | FREE Trade-In Quote
levnubhin is offline   Reply With Quote
Old 07-22-2010, 11:22 AM   #17
meatbag
iTrader: (50)
 
gospeed81's Avatar
 
Join Date: Nov 2008
Location: Houston, TX
Posts: 7,357
Total Cats: 26
Default

Quote:
Originally Posted by shlammed View Post
i think you should pull the pistons out.


i bet there is a chunk of missing ringlands.
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...
gospeed81 is offline   Reply With Quote
Old 07-22-2010, 01:32 PM   #18
Moderator
iTrader: (11)
 
sixshooter's Avatar
 
Join Date: Nov 2008
Location: Tampa, Florida
Posts: 15,660
Total Cats: 1,559
Default

Carbon build up can also create hot spots that will aggravate your tendency to detonate.
sixshooter is offline   Reply With Quote
Old 07-22-2010, 01:41 PM   #19
Elite Member
iTrader: (17)
 
Join Date: Aug 2007
Location: Fort Myers, FL
Posts: 2,790
Total Cats: 128
Default

Would you mind posting your spark map when you get a chance?
pdexta is offline   Reply With Quote
Old 07-22-2010, 04:26 PM   #20
Elite Member
iTrader: (8)
 
Join Date: Aug 2007
Location: Bellingham, Wa
Posts: 2,732
Total Cats: 3
Default

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

Name:  DSC02219.jpg
Views: 1
Size:  90.6 KB
Name:  DSC02189.jpg
Views: 1
Size:  189.8 KB
wayne_curr is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Project Gemini - Turbo Civic on the Cheap Full_Tilt_Boogie Build Threads 57 07-19-2017 05:11 PM
Changing from 460cc to flow force 610cc in diypnp 90 Turbo MEGAsquirt 19 10-19-2015 04:23 PM
1991 special edition with hard top full part out JC, NJ russian Miata parts for sale/trade 6 10-08-2015 04:01 PM
Expected intake temps on the track? tazswing Race Prep 20 10-03-2015 12:04 PM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 04:05 PM.