Been awhile since I've posted, but I'm kind of stumped here. I had to replace the head on my father's Bobcat 763 b/c it overheated and cracked around the injectors. We had a diesel shop check our valves and springs over and swap them into a new head which I installed. When I removed the rack from the old head I didn't notice it, but when I re-installed it on the new one, I had close to .120 clearance between the rocker arms and top of the all 8 valves. It was almost enough that the ends of the pushrods could fall out of the socket on the rocker arms. I've run the engine to the bleed air out the cooling system and long enough to make sure it's not leaking, but that gap was making a ton of noise on the top end. I've got the Bobcat service manual, and it specs .0071"-.0087" for gap, but that's where it gets confusing. The book says to set valve lash you turn the engine over until both rockers on the #4 cyl. are on contact with the valves. You then set both valves on the #1 cyl, and set the rest in a similar fashion. Well that is/was impossible for me to do, whether because of the out of whack lash or something else, I couldn't get that result. I set my valve lash to .008" with a feeler by bringing each piston to TDC on the compression and exhaust strokes, and then set the respective valves. Will this work for me or not? I did find the thread where willie59 spelled out how he does it, which sounds similar to what I did but I'm not sure. Any help/insight is much appreciated.
I can't speak for why the Bobcat service manual didn't work out trukfan, but as you noted about comments I made in a different thread, in the absence of an official procedure I've always used the method "end of intake, beginning of exhaust". Basically works like this; start with #1 cylinder, bar the engine over until the intake valve rocker moves. Keep turning engine until the intake valve rocker just closes the intake valve, "end of intake". Now adjust #1 exhaust valve rocker. Bar engine over until exhaust valve rocker just begins to react (move), "beginning of exhaust", adjust the intake valve rocker. I've done a pile of engines using this method and I've never had a problem.
Did you swap over the little caps on top of all the valve stems? #7
I will have to check that out. I didn't do the head work. The machine shop that pressure checked the old head for me swapped the parts over. I think everything is there but now I'm starting to wonder.
The caps are just a tiny metal puck with a counterbore on one side and just set on top of the valve stem, they're small, loose, and easy to lose. When you pull the rocker shaft you need to collect them all as they fall off and disappear. Don't ask how I know this, lol.
Well I checked out my engine after work and I don't think I have the caps. I've attached 2 pics showing what I have currently and it doesn't look like or match the description you gave me lantraxco. However, I looked in the box my head came in and found 8 of the caps like the one in my other pic. I assumed they were the old valve spring seals, but is it possible these are my missing pieces. I can't see how since they're plastic and rubber like, but sometimes you see some odd stuff working on things.
Nope, look like this generic picture, they're hard steel:
Yep, missing pieces makes a big difference.
Good to know. I was beginning to wonder if I was missing something or not. Hopefully my dealer has them in stock on Monday. In the mean time I'll just have to try find my hydrostatic drive leak
Just an update, I got the caps for my valve stems and that made a huge difference. I attached the pics just to be sure it looks right to those more knowledgeable than I on these engines. I assumed the caps would ride further down on the valve stem, not just on the radius on top of the valve stem. But, after I put the adjusting screws back to where they were before and put the caps on, they were all pretty close. Plus, I was able to set my valve lash using the method spelled out in the Bobcat service manual, which seems to be the same way willie59 said to do it. Haven't had time to test run it yet, but I hope to after work tomorrow.
Looks bettah!
Kudos to lantraxco for having the intuition to ask about the valve stem caps. :notworthy
Flashbacks old friend, lol, flashbacks
LMAO...don't ask me how I know eh?