Detroit Diesel 4-71 Smoking and Missing

[471DetroitKid]

Well, we got the head off! And, I think we found our problem! Now, do I need to take the head to a machine shop and get a valve job? Or, can I just buy a new valve and stick it in? The seat looks pretty good, it's not pitted really deep or anything.

[The Diesel Doctor]

Allan is at work right now. But the answer to your question is YES.

[The Diesel Doctor]

Clean the space between the broken valve and the valve below it with a wire brush and sand paper. It may be just the photo but it looks like it may be a small crack. The pieces that broke off the valve bounced around a bit before it went out the exhaust pipe. If the head is not cracked the damage does not look to bad. There probably some marks on the piston head . What you need to do is bar the engine over until the #4 piston top ring is visible in the liner port. Take a small screwdriver and push it in to see if it springs back. This will tell you if the ring groove got damaged. The cylinder liners may move when you bar the engine, just push them down until you get to the right spot. As what to do about the head. If it is cracked it should be replaced. You could replace and lap in that one valve and maybe get away with it. Replacing all 4 valves in that cylinder would be better. Best option would be to have a machine shop or Detroit dealer rebuild it. They also have exchange heads. You might also find a online. Good luck AL

[471DetroitKid]

Well folks, I am happy to say after getting a valve job on the bad cylinder, she is running like a dream. Thanks to all for your input. Special thanks to The Diesel Doctor. It would have been extremely difficult without your help!