Another M96 Engine Failure

[Jake Priber]

We have seen so many different failures for the M96 engine's. These are the engine in the 996 and 986. The failures have been related to loss of oil pressure causing the main bearings and/or rod bearings to fail, cylinder's scoring resulting in lots of oil consumption and loss of power, broken timing chains, bad head gaskets, and the list goes on.

Most of these failures result in a complete engine rebuild. The last failure we have seen was the strangest one yet. Let me give you a background story first.

This particular car needed a clutch replacement. So the trans, clutch, and flywheel were removed. At that point they figured now is a good time to change the IMS bearing (smart thinking as it is a ton of labor savings). So the engine was attempted to be rotated to top dead center for removal of the IMS bearing. I say attempted to be rotated because at that time the engine would not make a complete revolution.

[Jake Priber]

Everyone may ask how is this possible when the car was driven in for the service? Well that is a very good question. We removed the engine, partially disassemble the engine, and removed the cylinder heads. You will not believe what we found. Take a look at this link for the results http://pwr-tech.com/project_links.php?prID=6

[sparks259]

i take it that this car was driven by a little old lady that never revved it above 6k?

[Jake Priber]

Actually not. The car is strictly a street car but the customer drove the car in all different RPM ranges. He did not use any cheap off brand fuel in the car. I cannot tell you what had happened prior to us removing the engine as it was in for the service at a different shop. Our guess it that as the shop was removing the transmission and flywheel they had used an impact gun. We assume that the carbon was knocked off of the pistons during that process and that is when the car was then towed to us in pieces.

It is interesting how many different failures we have seen. The list is growing every time we have an engine in here and apart.

[sparks259]

if there was so much carbon in the cylinders, why didn't it throw a code because of detonation?
I still find it hard to believe that the could have deposits like that living in mid to upper rpm ranges.

[Jake Priber]

We don't know if the car ever had any codes or check engine lights. The car went into a different shop for a clutch replacement. The other shop had taken it apart, and when the customer added the replacement IMS bearing they were unable to fully rotate the engine.

That is when the car came to us and we found that. We removed the heads, cleaned the carbon out, and reassembled the engine. At that point the engine rotated perfectly and the car drove out of here no problem at all.

I am only able to tell you the facts of what happened and the driving habbits that the customer stated to us.

[Arnie]

Ok how many miles on the car. That seems like an awful lot of carbon. Are you sure he was telling the truth about what gas he was using

[Jake Priber]

I don't see why he would lie about the gas he was using.