I’ve heard of the rocker arm failing on the maxxforce 7 diesel engines and when I got a call from one of the drivers saying they were driving and suddenly had a power issue with a very rough running engine the rocker arm issue was on my mind. The bus limped back to the yard and listening to the engine there was definitely a dead miss. After running some tests we found a low compression problem on the # 2 cylinder. This has happened to a few of the maxxforce 7 diesel engines in our fleet already. The lack of compression caused by excessive engine wear turned into an engine replacement which luckily for us was covered by warranty.
Before doing the condemnation on the bottom end it was worth the time to remove the driver’s side valve cover and inspect the #2 cylinder valve train. This is a longer than average task since the compressor and fuel filter housing has to be removed first. It turned out to be well worth the time because one of the rocker arms was no longer attached to the valve train assembly. The plastic retainer had failed and caused to rocker arm to become loose and disconnected from the crosshead and the push tube.
This was a lucky break for us since this diesel was no longer covered by warranty expiring 10 days earlier. The parts would not be excessive and labor would be our own. The last time we were just over warranty on a failed engine the dealer said they would put the repair through a policy which meant they would do the work and we would get a partial compensation. The failure turned out to be a complete engine in-frame which got up to $11,000.00
All we got back on the policy was 800.00 for the failed parts… a piston and liner. The main problem with this scenario is the dealer shop rate is 140.00 an hour which adds up very fast. If we do the labor the savings is substantial. Rule of thumb is don’t bother going for a policy. If you’re diesel engine is even a few days over warranty it’s not worth it to push for policy because you’ll be lucky to get a fraction of the cost of repair back.
I hope this advice helps somebody out because it’s a shame to see more MaxxForce diesel engine owners go through this unnecessary expense. I would find a dependable diesel mechanic to do your work for you after warranty expires. We have spent enough of our budget on engine repairs after warranty was up and I’m hoping we won’t experience any more problems for a long time.