View Full Version : Dropped a valve on my D4 7U

02-25-2017, 08:20 AM
The tractor was running along perfectly then rattled and banged and came to a stop. I was able to get it started to load it to get it to the shop. Pulled the valve cover and found a broken outer intake valve spring and the intake valve stem sitting a lot taller than all the rest. Pulled the head yesterday and this is what I found:




So, I'm guessing that the spring broke then let the keepers loose which let the valve drop and get hammered by the piston since the relief is shiny until it dropped too far and bent it and then broke it and slammed it back into the head.

My question is whether the rod is bent or can I clean up the top of the piston and fix the head and put it back together? I think I got lucky on where the valve broke since it had room to turn and push it into the head sideways.

02-25-2017, 09:04 AM
That was a lucky hit to put it into the port like that!

Unless the piston is not coming up to the top of the cylinder like the others or you can feel a place where it binds as you rotate the crankshaft by hand, I would replace the valve etc and run it. I think the piston is soft enough to deform when it hit the valve edge-on vs a situation like hydrolock where the rod would be more likely to bend.

02-25-2017, 09:41 AM
I had a 3412 drop a valve like that. Looks like the piston did not crushed near the outer edge. I would put a head on it and run it.

02-25-2017, 01:45 PM
That was my thinking too since it didn't hit the outer edge of the piston. I guess I will take a drift and try to massage that gouge back into shape to clear the valve.

Good thinking on the piston height, didn't think of that.

02-25-2017, 07:11 PM
Last time I dropped a valve on a D2, it bent the rod!
Slight bend but once I rolled the crank, I could see the piston was just a hair lower plus shredded the top of the piston.

Old Cats
02-26-2017, 03:37 PM
I think you should consider removing the piston to make sure it is not crushed down on the ring lands and binding the rings. That is if it doesn't have a loader or some other thing that makes it a real pain to remove the pan. Just a thought.

02-27-2017, 05:52 PM
Roll it through and compare the piston top dead center to the others .

03-04-2017, 07:30 PM
This engine serial number is 6U5853 so its been transplanted. I only have the 7U parts book. I see that there is a change to the valve springs in the later 7U engines. I don't want to order the wrong ones, so what does my serial number equate to in 7U series?

03-04-2017, 08:02 PM
your serial number shows its an early 1951----the 1951 7U ran from 11888 to 16008

03-05-2017, 10:01 AM
Thanks Dan, I see what you did there.