my summer project!

Facime

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Jun 1, 2006
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Why I lost compression this week:

DSCF2956.jpg




Why this happened I really dont know, but Im rebuilding...
 

Facime

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LOL, yeah, but the trick is getting all the pieces back in the right order!


The good news was that the crank and main bearings look pristine! Also despite all the pieces floating around in there nothing ended up anywhere else that it shouldnt be. The cylinder walls looked fine too. There is no carbon build up on anything. I wasnt burning oil before I lost compression, but I did notice a fair amount of oil out the breather...

DSCF2949.JPG


There is no carbon build up on anything. I wasnt burning oil before I lost compression, but I did notice a fair amount of oil out the breather...
I can only guess the rings werent gapped right? I dont know, Ian, any other ideas?
 

Facime

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all the little pieces of piston ring are numbered? how fortuitious of toyota to know just how and where they would break! ;)


top rings, the others are ok (or at least in one piece)
 

Facime

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yes, #2 ring was pretty easy to break. Gotta admit my experience in the bottom end of a motor is limited. Care to clue me in on some explanations here? I would sure love to see that his doesnt happen again.
 

Facime

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oic.

I have pretty much babied this motor since day one. The carb is jetted a tad on the rich side just in case and the plug readings have confirmed that. No evidence of detonation and its pretty rare that I even go WOT or push close to redline with it. The head was just rebuilt after I broke a valve spring at freeway cruise speed with no warning. The head checked out ok otherwise and we did a valve job.

The only other thing that I think is just a coincidence is I did the 500 mile head retorque the night before I really noticed something wrong and upon diagnostics found near complete compression loss in #2. compression readings that day were 75, 0, 90, 90, and obviously LOTS better with a couple teaspoons of oil. I had driven it 25 miles to town just the day before and it seemed "ok" then.

In hindsight though, It has been a little hard to start hot for a while, and like I said noticed more oil out the breather than I thought normal.


edit: sorry, ring lands look ok, these pistons look to be pretty fresh, no polishing or scoring on the skirts. Rings seem to fit them normally
 

Facime

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Jun 1, 2006
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Ok well it turns out the best guess was the top ring groove was too loose causing ring chatter and making them shatter. At least thats our theory. Anyway, after a start and stop and re-start on the rebuild, I completed the rebuild today and took her for her break in run.


Jody the shop dog approves of my work!
DSCF3030.jpg




By the end of yesterday I had the motor in the car and all hooked up but when I went to start it, it just cranked and didnt even sound like it wanted to fire. I was tired and hungry and decided I should sleep on it.

how it looked at the end of yesterday:
DSCF3035.jpg


This morning after a late start looking at wiring diagrams since I was fairly sure it was a spark issue, I tested spark right off and found I had it...hmmm. Some basic diagnostics later I discovered that even though this time around I didnt even touch the head other than clean the mating surface, assuming the previous valve lash adjustment was good enough for a first start was a bad idea. I wasnt getting complete valve closure. Set the lash and it fired right up! WOOT!

http://www.youtube.com/watch?v=AUjGMm8JNwg

going through basic break in now after a few minor tweaks. It runs good and Im happy with it. Just a mostly stock 20R but Im proud of the work Ive put into it.
 

Facime

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Jun 1, 2006
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I never intended to keep it. It was intended to be a for fun and profit project from the start, but things havent really worked out. I had hoped to not have to put a penny into the motor and that ended up being the thing Ive put the most into. So now its at least mechanically nice but still looks like crap.

At this point I couldnt sell it and make money on it so I plan to put a fairly high pricetag on it and keep working on it. If someone offers enough money I'll sell it but I dont think I will get top dollar for it until the body/paint work is complete.


Yesterday I picked up a bigger carb for it. I was at the high end of demand for the 32/36 so I opted for a more aggressive 38. The 32/36 is a progressive and the 38 is syncronous so I can say goodbye to any gas mileage probably, but it should be a kick in the pants to drive.

Ive got 200 miles on the motor and this weekend I ran into an electrical problem that left me on the side of the road at 2AM, but was an easy fix in the light of the next morning. I think I can almost say now that I trust it will not leave me stranded again anytime soon.
 

Facime

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Jun 1, 2006
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on a related note I have another 2xR motor in the shop right now, a 93 22RE that Im replacing due to the following failure:

between #1 and #2 cylinders
DSCF3061.JPG


This was bad but the motor still had cold compression in 1 and 2. As I worked my way back I found with the plugs removed from all cylinders that 3 and 4 had ZERO compression. So I knew they were cross channeling. I had no idea it was going to be this bad when I took it apart...!

DSCF3060.JPG


obviously complete failure of the gasket right? ohh, it gets worse!




these two pics do a decent job of illustrating the depth of the failure:
DSCF3065.JPG


DSCF3068.JPG


PLEASE NOTE: #3 combustion chamber is essentially powder coated in aluminum from the scouring effect.


I LOVE port-mortems on failures like this. I try to imagine the forces and processes that lead to the failure and it blows my mind when shit like this still actually runs and drives into the shop.