6. July 2010 21:02
Since we've opened up there has been one thing we have not had a shortage of and that is Duramax engine failures. You can say what you want about Duramax engines but I've seen first hand the fact that they do fail. We've had one massive head gasket failure resulting in toasted bearings, one hole in a piston, and now; one wristpin bushing failure. This particular truck came in with a very loud knock but showed good oil pressure. The driver had been going down the road and noticed a slight knock that gradually got worse and worse. We had it pulled in on a rollback and began diagnosing. The first thing we wanted to check was the flexplate because the driver thought the noise was coming from the flexplate area and after listening to it we knew it was either from the flexplate or the rear of the engine. We had just replaced the flexplate in the last year and so I didn't think it was that but we had to check just to be sure and after removing the transmission and running the engine we had definitely eliminated the flexplate from the equation. We still were unsure about the source of the knock so we pulled the driver's side valve cover to check for any damage. Here's a good view of the driver's side with the top valve cover removed. The Duramax is definitely a challenge when it comes to trying to run it with the valve cover off. As you can see to check the pushrods, rocker arms, and rocker shaft you have to pull all the injectors, injector lines, and return line assemblies just to remove the lower valve cover. To make it worse the lower valve cover has to be reinstalled in order for the injectors to seat and all the above components have to be reinstalled along with the wiring harnesses in order to run it. After checking the valvetrains under both sides of the engine we decided it was time to pull it out and tear it down.
Here are some pics of the engine removal. It makes things a lot easier to remove the wheels since so many components are accessed through the wheelwells. The upper radiator support crossbar has been removed as well and we've tried pulling an engine without pulling this crossbar and trust me it a pain.
We took and fabbed up a bracket that bolts on where the A/C compressor mounts and we attached a lifting hook on that bracket and in the rear where the EGR cooler mounts. You can see from this angle if you get a good small chain in the right place you can pull her straight out and up.
Here Dustin's got her out and on the stand tearing it down.
Now you can see what a hellacious mess we found in the oil pan. Ouch!
After seeing this mess we had determined it was definitely a wristpin bushing and after pulling the upper oil pan we turned the engine over until we found the sound and low and behold the #8 rod was jumping around on the wristpin. If you look closely you can see the bushing protruding in the space between the rod and wristpin. With this bushing MIA the rod was smacking the piston and the piston had developed a pretty good sized crack around the wristpin. At this point we are waiting for a decision from the owner on what road to take as far as repairing this engine but I wanted to walk you guys through a basic engine diagnostic procedure. Basic?? HA.
Here are some additional pics for you guys.
Look closely in this pic and you will see why a water pump job costs so much on a Duramax. The circular piece in the bottom right is the water pump. Note how both brackets have been removed (A/C comp bracket and alternator bracket). You've got to remove both brackets to get to the coolant crossover pipe (the upside down y-shaped piece in the middle) and then you have to remove the balancer to get the water pump out! People commonly look at me like I'm crazy when I quote 8 hrs. labor to replace the water pump but hopefully if you compare the pic above before we removed the engine to this pic you'll see why it takes so much work.
It helps to unplug the turbo before you remove it Dustin. DUH DUH DUH
This is our little Duramax buddy. Hey Max!
I hope you guys got something out of this blog and I'm about to put up another today. Thanks for all the support and we hope to see you soon. AJ