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Hello everybody so today we are going to talk about how to do tune-ups on mid-range diesel engines. So to start with we got to go back to some basics so we understand why we're doing some of the things that we're doing and one of the things we understand is the ratio between crankshaft revolutions and camshaft revolutions. So these inline six-cylinder diesel engines that we have here are four-stroke engines which means that the four strokes are compression, power, intake, and exhaust not necessarily in that order. So if we look down here you got the crankshaft. The crankshaft has to rotate two times in order to get this cam gear to rotate one time. So that means that every rocker arm on the top of the engine is going to push a valve open every two rotations of this crankshaft. Now the reason why that is important is if we come over here and look at this guy you can see right inside here that there is a little notch on the back of the pulley and a little arrow pointing down at it. Now what that says right above it, I know you can't see it in the video, but it says TDC top dead center. So when that little notch is lined up with that arrow what that means is that cylinders number one and six are at top dead center. Now the reason why what I showed you before applies here is that just because that crankshaft pulley is lining up with the TDC arrow doesn't mean that the cam is putting number one at TDC compression right. It could be all the way down there at the end number six could be at TDC compression. So the way that you tell once you've got the timing mark lined up is you will come over to the valve train after you take off your valve cover and anything else that you need to get to the rocker arms and you check for something called valve overlap right. So valve overlap is going to be when both rocker arms on a cylinder are both pushing their valves down at the same time. The only time that happens is at top dead center of the exhaust stroke. All these cylinders have a travel companion. The firing order of this inline six-cylinder engine is one five three six two four. Now cylinders number one and six they are travel companions and if one is at top dead center compression that means that six is at top dead center exhaust and vice versa. If six is at top dead center compression then one is at top dead center exhaust. Valve overlap is how we can confirm which of those positions one and six are in because valve overlap only occurs at the very top of the exhaust stroke. So if I came over here and I wiggled both of these rocker arms on six and they were both tight that would tell me that both sets of valves intake and exhaust are both being pushed open at the same time which means number one is top dead center exhaust or number six is top dead center exhaust which tells me in turn that it's travel made up there at the front number one is at top dead center compression. Now why that's important is because on these mid-range engines I can adjust half of these rocker arms with number one at tdc compression and then I have to rotate it 360 degrees and then I can adjust the other half because then number six is at tdc compression. So once I find out which one is at compression I will use this table right here. All right so once you've used that table and used the valve overlap method and you've figured out where you are then you can start adjusting rocker arms. So we are at number six top dead center compression so according to that table we can adjust the rocker arms on six and so I'm going to just show you right here on this one the procedure and then you're just going to repeat it you know a lot more times basically because it's the same on each one of these but the first thing you want to do when you're doing the adjustment is you want to break loose the lock nut right so the lock nut you want to put the box into the wrench on and then break it loose now you can see that if I don't have my ratchet on top that the nut is moving but so is the adjusting screw so I need to put my ratchet on the adjusting screw so that I can keep the adjusting screw from moving while I break loose the lock nut right I don't need to break loose the lock nut and I don't need to run it like all the way up here because I'm only adjusting a few thousandths of an inch all right I just need the lock nut out of loose enough that I can move the adjusting screw back and forth a little bit so that's step one right is to loosen that lock nut once that lock nut is loose then what I'm going to do is I'm going to insert my feeler gauge so the feeler gauge is going to go right between what we call the elephant's foot of the rocker arm and the bridge that goes between the two valves so you take your feeler gauge you put it between those two things and then you're going to tighten the adjusting screw while you feel for drag and what you want to feel here is like an equal amount of drag on both the top and the bottom this is one of those things that's very objective and you really need someone who's trained to do this to kind of feel one that's adjusted correctly and tell you that's how it should feel so this is the hard part if you're but here's a quick tip if you look at the very side of the feeler gauge if you could rock it up and down like I am on this one then that tells you that you're a little bit too loose you want to be able to move in and out but not have too much wiggle room like that right so I would adjust this a little tighter now I can't wiggle it but I can go in and out now once I'm at that point I want to take my wrench again and I want to tighten my adjustment down I do not want my adjusting screw to turn with it because that will mess up the adjustment I just did so that's why we use the box in put it down over the lock nut and then I will tighten the lock nut while holding the adjusting screw with the ratchet then the one critical step that a lot of people don't do that's really critical is that this is an imperfect method that adjusting screw no matter how strong I am might move a little bit while I'm tightening this lock nut so I always want to re-address my setting I want to recheck it after I've tightened that lock nut to make sure I didn't mess up the adjustment and then you just repeat that on the half of the valves that that chart says that you can then rotate the engine 360 degrees and then do this exact same procedure on the other half of the rocker arms and then you're done you've done a tune-up on a mid-range diesel engine which is going to help improve fuel mileage it's going to reduce emissions it's going to increase engine life and it's something that probably doesn't get done often enough on these types of engines so why are we doing these adjustments Mr. G why are we doing these adjustments? We are compensating for wear. Exactly if you don't do these adjustments then eventually you're going to lose the room between these for heat expansion and you're going to have valves that hang open when the engine gets up to operating temperature which is going to reduce compression reduce engine power increase the amount of fuel it takes to use the engine so a tune-up is basically a spark plug and wires for a diesel engine all right we're doing this instead of spark plugs and wires but it's the same result it makes the engine run better