stealth-wrx

Well today was a day of learning. As most of you know I took my motor out about 2 months ago to pull my blown transmission out and prepare it for an automatic transmission swap. My motor always made a loud piston slap and it only had 1800 miles on it. 1500 miles were break in, 300 were street use under 16 psi and it always had good gas. Today I went to have my motor inspected by Quirt Crawford of Crawford Performance. I met up with two fellow club members and loaded my long block into the car and took the motor down to him. We had all assumed my belt tensioner was bad or my piston clearances were too large. The motor had been drinking about a quart of oil ever 300 miles. However this was not the case at all. It was much worse.

We first proceeded with a leak down test of each cylinder. We started with the cylinder on the driverside rear. Our in pressure was set at 85 psi and the cylinder could only hold 20 psi. That is completely bad and unacceptable. We then proceeded to the drivers front cylinder which held 67 psi. Then we went to the other side of the motor. The front passenger cylinder held 70 psi and the rear passenger cylinder held 75 psi. From see those numbers we were positive that the rings were completely shot or that the cylinder was out of round.

Next we pulled the heads off where the surprise came. It was not a matter of a large ring gap it was a matter of a MISSING SECTION OF PISTON. We were all amazed and wondering how this happened. We pulled the piston out of the drivers rear cylinder and inspected it. Then the second head was pulled off. Three of the four pistons had sections broken off of them and fed up threw both intake and exhaust ports of the head. The particles that went through my intake wedged in between valves and also fused into my cylinder head combustion chamber. The particles that went to threw my exhaust ports found their way to destroy my turbine wheel.

At this point in the day I was wondering what I did wrong. I babied the motor and never pushed it. My air/fuel ratios were always safe and everything always sounded good. It always sounded the same so I didnt know if something was wrong. Quirt had made quick guess to what happened when seeing the first piston. When the piston that didnt have a chunk taken out of it was removed it was realized what had actually caused this damage.

The damage was due to two things. One being that JE Pistons are poor quality and the second the ring gap being WAY to small. I will start with JE.

First off the pistons tolerances are not as good as they should have been. Pistons are designed to slightly taper inwards towards the top of the piston from the skirt. I had my pistons poly moly coated and the wear marks on the side of the piston skirt explain everything. If you look at the wear on the piston skirt you will see that there is a high spot on the bottom section of the skirt and a high spot on the top of the skirt. However on the middle of the skirt it was on untouched. The the skirt section of the piston should be completely flat and you can see how its not. The second flaw of the JE piston is how thin the area is from the top of the ring to the top of the piston. They can break off as you saw.

The second problem with my motor is the ring gap being too small. Basically if the ring gaps are too small and they expand they will seize in the cylinder. Mine heated up, seized in the cylinder and on the down stroke ripped a section of piston off of it. On one of the rings that we inspeced on the drivers rear cylinder we saw too marks where the rings had smashed into eachother. You can clearly see were the rings touch. One the piston with no damage the rings were touching together to further prove the error.

While removing the head we had noticed a poor assembly of the cams and a dirty area. Dirt had gotton in the cam journals and messed up the cams pretty bad. The main and rods bearings also showed the same dirt and scaring.

What do I do now you may ask. Well I am currently sending my heads back to DPR. He does quality work and I know it done right. As for the block that is out of round and my messed up pistons? I am leaving everything with Crawford Performance. My block will be getting bored and honed to extremely tight tolerances and I will be getting a custom sized set of CP pistons.

stealth-wrx

As far as the person's who sold me pistons for $800 that cost $400 and rods for $800 that retail for $400. I wont bash them. I take full responsibility for not doing enough research and trusting a dealership. I hope the everyone will learn from me and not go to these people for custom work. There are others like me who went to these places that share my experience.. I will not say their name, but I will say that one is a dealership and one is a subaru shop that also works on exotic cars. I put my full trust in these people for them to rip me off and lie to me about what brand parts I had and the quality of work. If anyone wants to know any more info on what happened, please dont hesitate to ask or pm me.

Please enjoy my pictures as I have enjoyed seeing the real thing.

Ventral

Damn that sucks. Im sorry that happend to you.

andyhidley

Detonation I bet was the cause... Cheap pistons ???? well were they forged? If I were you I would invest in a 10X magnifier and after a hard run I would look at the spark plugs with the 10X. If there is any detonation there will be little ***** of aluminum on the plugs. Thats a tell tale sign of things to come like what happened to your motor pictured.

Adjust your fuel/air mixture to achieve no aluminum particles on the plugs.. !!

You need the 10X magnifier because you wont be able to see them with the naked eye.

I bet you can find pics of plugs with detonation if you do a search on the net

meilers

Just to be totally clear about this, you are talking about a "built" engine and not a factory one, correct? Besides the rods and pistons, what else did you change about that engine? What type of ECU/timing control were you using? Did this engine do track days and 0-60 times, or was it for street?

Yeah, detonation, you think? Look how black those valves are, he must have sounded like a movie-theater popcorn popper.

stealth-wrx

Quirt removed the rings and placed them in the cylinder bore. They are very very springy. Because of the spring in the rings you can tell that it was not detonation. If detontation was the factor the rings would have heated up and lost their spring. He inspected two of the rings. The passenger rear and the driver rear. The passenger rear clyinder was definately in the best condition. The driver side ring sat tightly in the bore and Quirt said that the ring gap was clearly the main problem. I went home and called him a few hours later and he further inspected the rings and block. He looked further into the cylinder 4 which had the good piston and the ring gap had closed completely. Anyother thing why it was not detonation is because the spark plugs had absolutely no signs of detonation and cylinder 4 was the only perfect cylider.

stealth-wrx

I was running the autronic sm2 ecu. Black valves are not an indication of detonation.

andyhidley

The black valves are not important because the motor was run after it self destructed. Thus with almost no compression and holding the gas to the floor (thinking , "uh-oh, sumtin is wrong!") Just a really rich mixture of unburned fuel......

I did read somewhere about the top ring land being too narrow in WRXs and an after market company made pistons that moved the rings lower to increase the upper ring land thickness...

You stated that it was not detonation because the rings did not get heated.. I disagree. High heat may cause detonation or be a result of detonation. But the forces generated when it detonates may be what caused the mechanical failure of the piston. and your theory of too small of an end gap would cause more stress on the ring lands . But when a ring heats up and the ends touch then there is ALOT of pressure on the cylinder wall and that WILL generate alot of heat. Toasting the ring in short order.

But you also said that there were no metal ***** on teh spark plugs. That means that there was no detonation... That is confusing because 1/2 the piston and head went out the valves right past the plugs????????? I'm confused .................

stealth-wrx

I am only relaying information from my new engine builder and my head guy I just came back from.

andyhidley

ok, ok... I"m just letting you know what I think... I dont want to argue........... Have a great day

stealth-wrx

it broke the top section of the piston off.

TurnWRX

iTrader: (3)

If I remember correctly, this is the same StealthWrx who posts at Clubwrx.

Here's his list of mods and pictures as well.

http://www.clubwrx.net/forums/showth...ght=stealthwrx

stealth-wrx

I think the only problem with them was the dirt from the assembly in the main and rod bearings.