616 - Missing cam sprocket, how to line up chain?
 

I am mid process of putting together my 240D. Anyway, this car did not have a cam sprocket on the cam (they're on the way), but the chain was supported (go figure) and I'm curious how the hell I can reinstall the sprocket on the chain and lined up properly?

I need to be able to rotate the motor by hand to remove the rockers then pull the cam then then head.

What I'm figuring is just guess and put it on, then rotate by hand and see what the balancer shows? If I can't turn it over by hand, can I assume it's too far Adv or Ret?

This is an interference motor too correct?

You really get into it. Thats good. As I understand your post you are yet going to remove the head. If that is so you can wait awhile to deal with this. Just do not instal the rockers before the head is put back on and chain timing dealt with. Also as I think you are aware all those rockers have to eventually go back on the same lobes so number them. It should be little effort to retime the engine later. If you have the glowplugs out leave them out as it makes the final timing check much easier. With this tackled this particular way it makes it much easier to make sure that the cam and pump are syncronised on the same top dead centre. Why are you removing the head?

From your post I am confused about what stage of the project you are currently in. You begin by saying that you will be putting it back together, but then you ask about removing the head.

All diesels are interference engines of the highest order. If the cam is advanced even one notch there will be piston valve contact.

You do not have to remove the cam to remove the head. Just turn the crankshaft to top dead center and make sure that the cam mark is lined up. If not turn the engine one more turn to top dead center and make sure the cam mark is lined up, then remove the cam sprocket and tie off the chain with the engine in that position. Then when putting the head back on, line up the cam mark and set it on, then put the chain carefully on the cam and slip the sprocket in place. You will, of course have to remove the tensioner for installation and then check timing when tensioner is reset and put back in place.

After all that is in place with both crank and cam marks aligned and everything is together, turn the engine almost two full turns to the correct timing mark, like 22 BTDC and then check injection timing for proper drip.

Hope this helps,

HitMan bought the car with partial work started on replacing a head gasket. Sprocket was removed and missing.
He has to remove head, replace head gasket and re-assemble everything.

It will never run, you need to get rid of it. :D

I don't think you can rotate it until you have pulled the cam (or head). All the valves need to be closed before ANY of the pistons reach TDC.

That's correct, do not rotate the engine unless the sprocket is put back on and properly aligned or until the head or cam is removed.

That said, I don't know why you would want to do that anyway if you are in the process of tearing it apart. If it were me, I would just remove the head and go from there. Then before putting the the head in place, turn the engine to TDC and time as described above.

Most the time I do not express myself well. I assumed and that is dangerous. I expected you would at least have the valves and seats touched up a little at low cost if possible. Checking the valve guides out for being too sloppy as well. You will have the head off and you have no compression tests from the recent past. The bad head gasket makes it impossible right now. The engine may have never had a valve job but probably has plenty of miles.
This means at some stage the rockers are off the head. Never a better time to do it and you can change out the valve seals as well. A slight valve touch up can also do wonders on old engines.
An alternate if I seem to be complicating this is to invert that head and put a small amount of thin fluid in to cover the valves. You want the same amount of fluid present the next morning. Still again the rockers are off to do that test as well as change out the valve seals. If it will not pass this test do the valves for sure.
Also you might get away with just touching up the exhaust seats and hand lapping the exhaust valves a little as you cannot turn the exhaust valves. Thats if they are sodium filled. Check with an automotive machinist on this if hand lapping them is practical. They are about 25.00 a piece now if sodium filled I hear. You can of course usually turn the intake valves.
I personally think the effort worthwhile. As for the money angle it should not cost much if you shop around properly.
Since this is a 240d engine like mine you want the maximum perfomance available at reasonable cost. This means reasonable condition valve guides and good valve seating.
I am glad some people are starting to change guides themselves now if required by the way. Sometimes you just need a couple,sometimes none, sometimes many. This reduces the machine shop bill. But if badly worn when the valve closes it does not hit the seat properly and seal quickly. The timing and cam sprocket issue is relatively minor. What it all boils down to is this car in good enough shape to warrant the effort?

Let me try to clarify. :)

Yes, the car apparently needs a HG and was partially disassembled prior to my purchase. The sprocket and some topend bits are missing currently, thanks to Jimmy they are on the way!

I haven't a clue where the timing is on the crank in relation to the cam.

From my reading in the FSM, I have to be able to rotate the motor over by hand in order to remove the rocker assemblies. THEN I can go back and remove the rest of the top end parts. At least that is how I understand to disassemble the parts to pull the head.:confused:

I have a good machinist so maybe I'll do a valve job, I was going to do seals 100%.

Well I wish you were asking this about a week ago, and I would have found comfort in my misery with some company. I just did a 617 head and during reassembly, I managed to turn engine over (both directions) without cam gear in place. I know, I know, rookie mistake. But most credible sources told me that it was almost impossible for the chain to skip gears on the crank and IP, so as long as I knew I was on the compression stroke at TDC, line up the timing mark on cam with the timing mark on the tower, and booyah, I'd be good to go. After, of course, testing engine rotation by hand. And it didn't hurt to know that on the compression stroke on my motor, the first cam lobe points 90deg to the driver's side. And whaddayano? It worked--on the second shot of course. First shot didn't confirm IP was squirting on that #1. I was off four cam teeth, which for the math wizzes out there, is 72deg (4x18 per tooth), which is 1/5 of 360. Oooh, kinda creepy isn't it. Anyway, don't worry about getting timing back. If I could get my timing back after what I did, anybody should be able to do it. Just keep in mind that you can always solve for the third variable with a reference mark i.e. cam tower mark, as long as the other two remain constant and in perfect relation to each other. Good luck!

Install your chain and cam gear. there is a good chance the cam and crank relationships have not moved. If wrong the engine will not turn by wrench much. You can eyeball things a little during the installation of the cam sprocket to verify this by the marks orientation to each other if you want. No matter where they are. Remember crank turns twice to the cam gears once. I know you are up to speed in this area. You are not going to do any harm. Only really excess applied force can do harm.
Then go through the proccedure of removing the rockers. Other than this you just move the crank a little and then move the cam a little when the piston hits a valve. Continue back and forth in this fashion until the lifter is off the cam lobe. Remove the lifters you can get and go back to moving things until you get them all. Again no harm is done.
Since you do not have the sprocket yet you will probably go this way. I would get the chain under very light tension a little by pushing a large dowel or something through it and suspended it from overhead. This will stop any tendency of the chain to gather as you turn. Or change the relationship with crank to injection pump. It should be much simpler than it sounds. Really. You are not going to get into trouble or break anything. I will drop back to your thread each day for the next while for sure.

Right now I am working during the week in SouthEast Fort Worth and staying with my parents in the evening in Grand Prairie so I roll through Arlington every evening. In fact I had the pleasure of meeting an Arlington Police Officer on I-20 last night and gave him my autograph.

Anyway, if you are home around 5:15 or 5:30 in the evenings, maybe I could stop by and help you get it timed.

Let me know.

If the car was up there I would love the assistance!

Heck, I'd tow it from Houston to Arlington for an offer like that!! ;)

Update -

Got the manifolds off today. Yanked water pump, thermo housing, the old rad hoses, the rad, and some other misc junk.

Installed cam sprocket and removed rockers. Cam is still attached to the cylinder head. Motor rotates over well by hand, so nothing is broken from what I can tell.

BUT

I am unable to line up the balancer with the cam tower mark. :confused: It usually shows just a few degrees but it's not close. I guess I need to reinstall the chain tensioner? :idea2:

When I wondered my cam gear around, I found the same thing, but you can kind of simulate chain tension by pushing on the side of the chain that contacts the tensioner. Maybe I got lucky, but it worked for me. Don't know about your car, but the 617 #1 cam lobe points 90deg to driver's side. So I eyeballed that and pushed on the chain to simulate the tension. Voila! And then I said a little prayer of thanks to the MB gods. Good luck!

Okay rad, I'll toss it back in tomorrow and give it a shot.

I forgot the car has a Bosch reman alt, starter, and injectors for MB! :D

Okay, almost all the topend stuff has been removed minus the head... I want the cam and crank lined up before I yank them. It's about 16-20° out currently, which is around one tooth on the cam sprocket from what I've been told.

To get closer to zero on the balancer, which direction should I rotate the camshaft (standing in front of the vehicle) to get it lined up? My instinct is telling me left.

Getting close to driving my 62hp of fury! :D

Anyone? :(

It depends which direction you are off. If you have the bottom on zero, and you're applying some kind of tension to the chain on the left hand side, is the timing mark high or low on the tower mark?

It's to the left side of the balancer. The side that shows the stretch. So, it's retarded I presume.

Going to say it's above the tower mark at zero on the balancer.