Could the blocked pushrod damage the pistons?

[Irek]

Hi Guys

Last month I have experienced a serious problem with my car. I am trying to analyze right now what could happen and I would like to check if my way of thinking is correct. The story looks as follow:

My Camaro SS 2010 (L99) is equipped with TVS 2300 Magnuson compressor, as on the picture below:



During one of the visits in the garage my mechanic removed the compressor (for cleaning purposes) and installed it back. After that I have started to hear a clear metallic knocking in the engine. It was following the RPM, so the higher engine speed – the faster knocking.
I was driving with it for 2-3 months as nobody could locate the reason. After several weeks I started to hear strange „shots” during stronger acceleration, which sounded like coming from the exhaust system but from the front of the car. I could feel inside that the "shots" were shaking the whole car and were influencing the acceleration.
My mechanic was blaming the injectors which according to him were pouring too much fuel to the combustion chamber. The fact it that two of the injectors were really functioning a bit incorrectly, which was diagnosed during the previous checks.

However after deeper examination my mechanic found the following pushrod damage:



It appeared that one of the screw sockets in my compressor has a bigger depth than the other 7 sockets:



We have noticed that there was a little bit shorter screw installed in the deeper socket, which was by mistake replaced with another screw – a bit longer. The difference was really just 2 millimeters.
The longer screw was hitting the pushrod and this was a reason for metallic knocking in the engine.



The screw was corrected, pushrod replaced with a new one, but while driving I could still hear and feel the „shots” influencing acceleration and pulling the whole car.
One month later I have noticed additional sound like metal parts rattling in the engine. Then I decided to disassemble the engine.

This is what we found inside:



Two of the pistons were damaged and that’s why I heard the rattling of the metallic parts in the engine.

Now I am trying to found out what could be a reason of this damage, as my further discussions with the mechanic depend on that (in field of responsibility for the damage). I can see 2 options:

OPTION 1 – the blocked pushrod cased incorrect valve functionality, which in the final stage caused the damage. The fact it that the broken piston was exactly on the cylinder where the pushrod was blocked. But in this case I am not sure if this could cause also damage in the next cylinder.

OPTION 2 – my mechanic is convincing me that the blocked pushrod could not make such a damage, and according to him the reason were two incorrectly working injectors. According to this hypotheses the fuel was getting to the combustion chamber as a fluid instead of the mist. This could result in the high pressure pushing the lower side of the piston, which could explain damage in the upper part on the other side.

I would appreciate your opinion about this issue. Thanks in advance.

[InFiD3ViL]

Wow man, that really sucks!

Good catch though, just a shame you couldn't get to it before the damage to the piston skirts.

Have you taken a look at the crank yet?

[8balldeluxe]

I'd like to see the crank as well

[Black_SS10]

Well damn. That sucks but good thing there wasnt more damage!!!

[JusticePete]

1. Is this an out of the box new Maggie, an off the shelf kit or a kit that was 'assembled' from used parts purchased or acquired from more than one source?

2. What was the RWHP?

3. How did the technician know two injectors were streaming raw gas into the cylinder as opposed to vaporizing the fuel as designed?

4. Why were the malfunctioning injectors not replaced?

[rjs1le]

Everything was fine until the mechanic pulled it apart. Hmmm, sounds like he's buying a new motor.

[Irek]

Originally Posted by InFiD3ViL

Wow man, that really sucks!

Good catch though, just a shame you couldn't get to it before the damage to the piston skirts.

Have you taken a look at the crank yet?

___________

Originally Posted by 8balldeluxe

I'd like to see the crank as well

___________

In general the crank was not damaged. There are some minor spots which needs to be polished before assembling the engine.

[Irek]

Originally Posted by JusticePete

1. Is this an out of the box new Maggie, an off the shelf kit or a kit that was 'assembled' from used parts purchased or acquired from more than one source?

2. What was the RWHP?

3. How did the technician know two injectors were streaming raw gas into the cylinder as opposed to vaporizing the fuel as designed?

4. Why were the malfunctioning injectors not replaced?

____________

1. I am not sure if I understand your question correctly (sorry my English is far from perfection). The engine was original and nothing was modified in the past except for the installation of the compressor 6 years ago. Of course it was followed by new exhaust system, suspension, additional fuel pump etc. However the car made 30.000 miles after the tuning.

2. RWHP was around 480hp. It was never pushed to higher level due to the automatic transmission.

3. Few months before the engine damage mechanic was replacing the spark plugs and at the same time mechanic removed the injectors and examined them in outside conditions. He connected it to the fuel rail and pumped some fuel through the injectors.

4. Mechanic informed me that it would be good to replace 2 of them. The injectors were ordered in US with delivery to Europe but in the meantime the engine was mounted and I was using the car.

I am not able to check if these 2 injectors were installed exactly in the cylinders with the broken pistons. I have to rely on statement from the mechanic - he is saying so.

But the coincidence is that the damaged pushrod was installed for sure on the cylinder with the broken piston. This is why I am confused about the reason of the damage.

If the reason would be the pushrod than I would be in the position to claim this damage.
If the reason would be the injectors, than I could not blame mechanic about it.

[sdynak]

Is there damage to the top of the pistons? That would be the area if the pushrod was held up by the bolt and the piston hit the valve.. But as you mentioned would really only see this in the cylinder the pushrod was held up on.. Did you actually see the faulty injector spray? Really don't see how 2 cylinders could be affected by 1 pushrod and the damage would start at the top. Share pictures of the top of the pistons. Is there any valve damage in that cylinder? Bent or anything visual?

[CFD]

If an injector caused piston damage it would typically be from fuel bleeding past the rings and causing no lubrication to the cylinder wall. You would see evidence of this by scuffed skirts. I'm not seeing that in the picture. The broken piston appears to be from a mechanical failure.

[Irek]

Originally Posted by sdynak

Is there damage to the top of the pistons? That would be the area if the pushrod was held up by the bolt and the piston hit the valve.. But as you mentioned would really only see this in the cylinder the pushrod was held up on.. Did you actually see the faulty injector spray? Really don't see how 2 cylinders could be affected by 1 pushrod and the damage would start at the top. Share pictures of the top of the pistons. Is there any valve damage in that cylinder? Bent or anything visual?

This is good idea. I will be visiting mechanic today so I will take a closer picture of the top of the pistons and will check for any mechanical damage. However I am not sure if the blocked pushord kept the valve in open or closed position. If in closed then the valve would not have any contact with the piston.

[Irek]

Originally Posted by CFD

If an injector caused piston damage it would typically be from fuel bleeding past the rings and causing no lubrication to the cylinder wall. You would see evidence of this by scuffed skirts. I'm not seeing that in the picture. The broken piston appears to be from a mechanical failure.

This is also a very good point. While taking the pictures, I will pay attention to the cylinder wall. Thank you for your advice.

[CFD]

Originally Posted by Irek

This is also a very good point. While taking the pictures, I will pay attention to the cylinder wall. Thank you for your advice.

Sometimes it can cause the rings to overheat and seize in the ring land but doesn't seem to be the case here. Still looks to be a mechanical failure from what I see.

[JusticePete]

We are going with detonation due to bad injectors.

The damage to the pushrod we believe is a one time thing. Pushrods rotate. If the screw was in contact it would have a mark all the way around the pushrod.